Molecular Oncology

Anal squamous cell carcinoma (ASCC) is a rare tumour, but with increasing incidence for local and metastatic tumours. Current therapy is based on chemoradiotherapy, associated with immunotherapy in advanced stages, with frequent side effects, poor results in advanced stages and recurrence. New therapeutics, including targeted therapies, are then needed. In this context, we identified here a IKZF2-ERBB4 gene fusion in a patient ASCC tumour, leading to overexpressed mRNA encoding a functional ERBB4 protein. This gene fusion has been already reported in other tumour types but not yet investigated as therapeutical target. The matched patient tumour-derived xenograft displays the same gene fusion and mRNA overexpression. It provided biological material for anti-ERBB4 testing in different cell models (in vivo xenograft, in vitro cell cultures). We used afatinib and lapatinib, 2 chemical pan-ERBB inhibitors approved in clinics, with anti-ERBB4 properties. ERBB4 inhibition did not lead to tumour growth inhibition although afatinib and lapatinib dramatically decreased ERBB4 phosphorylation with impact on downstream signalling MAPK/ERK but not PI3K/AKT pathways. Likewise, specific ERBB4 knock-outing did not affect tumour cell proliferation. These negative results must be put in line with reported potential crosstalk between PI3K/AKT and MAPK/ERK pathways in therapeutic resistance.

Polo-like kinase 4 (Plk4), the major regulator of centriole biogenesis, has emerged as a putative therapeutic target in cancer due to its abnormal expression in human carcinomas, leading to centrosome number deregulation, mitotic defects and chromosomal instability. Moreover, Plk4 deregulation promotes tumor growth and metastasis in mouse models and is significantly associated with poor patient prognosis. Here, we further investigate the role of Plk4 in carcinogenesis and show that its overexpression significantly potentiates resistance to cell death by anoikis of non-tumorigenic p53 knock-out (p53KO) mammary epithelial cells. Importantly, this effect is independent of Plk4s role in centrosome biogenesis, suggesting that this kinase has additional cellular functions. Interestingly, the Plk4-induced anoikis resistance is associated with the induction of a stable hybrid epithelial-mesenchymal phenotype and is partially dependent on P-cadherin upregulation. Furthermore, we found that the conditioned media of Plk4-induced p53KO mammary epithelial cells also induces anoikis resistance of breast cancer cells in a paracrine way, being also partially dependent on soluble P-cadherin secretion. Our work shows, for the first time, that high expression levels of Plk4 induce anoikis resistance of both mammary epithelial cells with p53KO background, as well as of breast cancer cells exposed to their secretome, which is partially mediated through P-cadherin upregulation. These results reinforce the idea that Plk4, independently of its role in centrosome biogenesis, functions as an oncogene, by impacting the tumor microenvironment to promote malignancy.

The presence of supernumerary centrosomes is a hallmark of cancer and is frequently observed in aggressive tumors. Cancer cells with centrosome amplification achieve pseudo-bipolar spindles through specific coping mechanisms in order to survive. However, their distribution and prevalence in cancer remain largely unknown. Here, using the NCI60 panel of cancer cell lines, we show that the presence of coping strategies correlates with centrosome amplification, with the clustering of extra-centrosomes within the two spindle poles being the most widespread mechanism. Moreover, we report an association between centrosome clustering ability and the epithelial-to-mesenchymal transition (EMT) and observe that the induction of mesenchymal characteristics in breast cancer cells with centrosome amplification promotes clustering. Furthermore, we unveil hematological malignancies, which lack epithelial characteristics, as the most proficient in centrosome clustering. Finally, we show that acute lymphoblastic leukemia is particularly sensitive to targeting clustering through inhibition of the spindle assembly checkpoint. Our study reveals how centrosome clustering and the EMT collaborate to promote carcinogenesis, suggesting new possibilities to treat tumors with low epithelial characteristics, in particular leukemias. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=74 SRC="FIGDIR/small/532472v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@12a713dorg.highwire.dtl.DTLVardef@1706edborg.highwire.dtl.DTLVardef@7deea7org.highwire.dtl.DTLVardef@1bf2280_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LICentrosome clustering is widespread in the NCI60 panel and particularly strong in leukemia. C_LIO_LIThe EMT enhances the ability of cancer cells to cope with multiple centrosomes through centrosome clustering. C_LIO_LICentrosome clustering gene expression peaks at the invasive stage and has prognostic value in breast cancer. C_LIO_LIThe inhibition of MPS1 is a good strategy to promote the death of acute lymphoblastic leukemia (ALL) cells with CA. C_LI

Therapy resistance leading to local recurrence and metastases remains highly problematic in head and neck squamous cell carcinomas (HNSCC). Single cell RNA-sequencing defined a partial epithelial-to-mesenchymal transition (p-EMT) signature associated with metastases in HNSCC. However, the prognostic value of the p-EMT signature and potential drivers of p-EMT in HNSCC remain unclear. Here, single sample scoring of molecular phenotypes (Singscoring) served to establish clinical p-EMT-Singscores that were significantly associated with nodal metastases and predicted overall survival in two independent HNSCC cohorts. p-EMT-Singscores correlated most strongly with EMT transcription factor (EMT-TF) Slug. In vitro, Slug promoted p-EMT, enhanced invasion, and resistance to irradiation. In patients, Slug protein levels in tumors predicted disease-free survival and its peripheral expression at the interphase to tumor-microenvironment was significantly increased in recurring patients. Thus, p-EMT represents a novel clinical risk-predictor that impacts on HNSCC patients outcome and is partly controlled by Slug.

Early detection of oesophageal squamous cell carcinoma (OSCC) significantly improves patients survival. Nonetheless, the availability of non-endoscopic, effective, and minimally invasive diagnostic approaches is limited. Here, we evaluated the utility of minimally invasive pan-oesophageal sampling using a capsule-sponge and aneuploidy detection using shallow whole genome sequencing (sWGS) for early detection of OSCC and precancerous intraepithelial neoplasia (IEN). In the prospective arm, 200 participants underwent the capsule-sponge procedure, and we performed sWGS from 178 successfully collected specimens (89%). We combined newly developed genome-wide copy-number alteration (GW-CNA) score and copy number alterations (CNAs) at chromosomal arm level to measure global and local aneuploidy, respectively. Logistic regression model identified GW-CNA and CNAs on chromosomal arms 2q, 3q, 9p and 11q as key diagnostic predictors differentiating OSCC and IEN from healthy controls (AUC of 0.920 (95% CI: 0.907-0.933), accuracy: 0.888, sensitivity: 0.896, specificity: 0.887). The model outperformed histology-based diagnosis using H&E staining and p53 immunohistological assessment. Finally, the analysis of microdissected samples derived from retrospective endoscopic en-bloc resections, and spanning the entire pathological continuum of OSCC demonstrated stepwise increase in GW-CNA and CNAs of 2q, 3q, 9p and 11q, validating their biological significance. This study demonstrates the high potential of combined pan-oesophageal sampling and sWGS aneuploidy analysis for early detection of OSCC and as a potential path to improved patients outcomes.

Protein aggregation is an underappreciated mechanism that may contribute to the loss- and oncogenic-gain-of-function of mutant tumor suppressors such as p53 and axin. In the present study, we describe amyloid-like aggregation behaviour of the second most frequently mutated tumor suppressor in human cancer, PTEN. In silico analysis revealed a particularly high aggregation vulnerability for this protein, which was corroborated by in vitro aggregation assays. In cultured tumor cells, we found that under stress conditions, PTEN readily undergoes amyloid-like aggregation as a result of mutation. However, we also show that severe dysregulation of protein homeostasis may lead to aggregation of wild-type PTEN. These observations were supported by a small survey of patient-derived uterine tumor tissues, which found that more than 25% of tumors analyzed displayed wild-type PTEN aggregation. Finally, in an exploratory clinical study we found that PTEN aggregation status was correlated with a decline in clinical outcome. Our findings establish that the tumor suppressor PTEN is highly aggregation-prone and our work suggests that protein aggregation might be an underestimated but prevalent component of cancer cell biology.

Major driver oncogenes CMYC, mutant KRAS and mutant TP53 often co-exist and cooperate in promoting human neoplasia. By CRISPR-Cas9-mediated downregulation we determined their proteomics and transcriptomics downstream programs in a panel of cell lines with activated either single or three oncogenes - in cancers of lung, colon and pancreas. This allowed to define and screen the oncogenes common functional program for anti-cancer target candidates, and find protocols which efficiently kill cancer cells and organoids by targeting pathways represented by a signature of three genes: RUVBL1, HSPA9 and XPO1. We found that these genes were controlled by the driver oncoproteins in a redundant or competitive manner, rather than by cooperation. Each oncoprotein individually was able to upregulate the three target genes, while upon oncogene co-expression each target was controlled preferably by a specific oncoprotein which reduced the influence of the others. Mechanistically this redundancy was mediated by parallel routes of the target gene activation - as in the case of mutant KRAS signaling to C-JUN and GLI-2 transcription factors bypassing CMYC, and by competition - as in the case of mutant p53 and CMYC competing for biding to the target promoters. The transcriptomics data from the cell lines and patient samples indicate that the redundancy of the oncogenic programs is a broad phenomenon which may comprise even a majority of the genes dependent on the oncoprotein, as shown for mutant p53 in colon and lung cancer cell lines. Nevertheless, we demonstrate that the redundant oncogene programs harbor targets of efficient anti-cancer drug combinations, bypassing limitations of a direct oncoprotein inhibition.

Diffuse Large B-cell lymphoma (DLBCL) is the most common aggressive lymphoma in the Western world. First-line immunochemotherapy fails in approximately 30-40% of patients, with refractory and relapse patients presenting a dismal prognosis. Currently, these high-risk patients cannot be accurately identified at diagnosis. Using statistical modeling and machine learning approaches applied to large public DLBCL datasets, we identified a novel predictive signature based on the reactivation of eight normally silent tissue-dependent genes associated with survival. We then developed a multiplex RT-MLPseq based assay, compatible with formalin-fixed paraffin-embedded (FFPE) samples and transferable into routine clinical practice, enabling analysis of expression of these eight genes and validated their prognosis impact in an independent real-life cohort. This signature could be integrated with current prognostic indices and molecular classifications to improve patient stratification and guide treatment selection toward a personalized theragnostic approach, thereby enhancing management of non-responder patients. Data Sharing StatementFor access to original data, please contact: anouk.emadali@univ-grenoble-alpes.fr Key points- Ectopic activation of 8 tissue-specific genes defines a robust prognostic signature for survival stratification in DLBCL patients - A FFPE-compatible RT-MLPseq assay enables clinical use and improves risk stratification beyond IPI and COO, especially in high-risk patients

Oral squamous cell carcinoma (OSCC) often arises from oral epithelial dysplasia (OED); however, the gene expression changes during OED progression and its microenvironment are not fully understood. This study used spatial transcriptomics to identify differentially expressed genes and microenvironmental alterations associated with OEDs malignant transformation of OED. A ten-year retrospective analysis of paired OSCC and prior OED samples was conducted at the University of Toronto Oral Pathology Laboratory. A total of 24 paired progressing OED cases and 23 matched non-progressing OED cases were examined using spatial transcriptomics in PanCK+ (dysplastic epithelium or OSCC) and PanCK- (stroma) regions. The analysis included differential gene expression, pathway analysis and spatial deconvolution. Three genes (STOM, KIF26A, and CDKN2A) showed increased expression in the epithelial component of progressing OED compared with non-progressing OED, whereas 41 genes were differentially expressed in OSCC versus the precursor samples. Ubiquitination-related pathways were enriched during OED progression. Functional validation identified TNFRSF12A (Fn14) as a potential regulator of OED progression to OSCC. The OSCC microenvironment displayed increased numbers of fibroblasts, neutrophils, monocytes, and mast cells compared with that of the precursor samples. Our findings suggest that spatial profiling of OED can help identify unique gene signatures and microenvironmental changes that occur before the malignant transformation.

In the last years, several efforts have been made to classify colorectal cancer (CRC) into well-defined molecular subgroups, representing the intrinsic inter-patient heterogeneity, known as Consensus Molecular Subtypes (CMSs). In this work, we performed a meta-analysis of 1700 CRC patients stratified into four CMSs. We identified a negative correlation between a high level of anaplastic lymphoma kinase (ALK) expression and relapse-free survival, exclusively in CMS1 subtype. Stemming from this observation, we tested several CMSs in vitro models with crizotinib (CZB) or alectinib (ALC), potent ALK inhibitors, already approved for clinical use. ALK interception strongly inhibits cell proliferation already at nanomolar doses, specifically in CMS1 cell lines, while no effect was found in CMS2/3/4 groups. Furthermore, in vivo imaging identified a role for ALK in the dynamic formation of 3D spheroids, which was impaired by the pharmacological inhibition of ALK. Consistently, CZB was responsible for the dampened activation of ALK along with the downstream AKT cascade. Mechanistically, we found a specific pro-apoptotic effect of ALK inhibition in CMS1 cell lines, both in 2D and 3D. Confocal analysis suggests that inhibition in CMS1 cells enhances cell-cell adhesion when growing in 3D. In agreement with our findings, an ALK signature encompassing 65 genes statistically associated with worse relapse-free survival in CMS1 subtype. Finally, the efficacy of ALK inhibition treatment was demonstrated in patient-derived organoids. Collectively, our findings suggest that ALK inhibition may represent an attractive therapy for CRC, and CMS classification may provide a useful tool to identify patients who could benefit from this treatment. These findings offer rationale and pharmacological strategies for the treatment of CMS1 CRC.

Targeted therapy interventions using tyrosine kinase inhibitors (TKIs) provide encouraging treatment responses in ALK-rearranged lung adenocarcinomas, yet resistances occur almost inevitably. Apart from tumor cell-intrinsic resistance mechanisms, accumulating evidence supports a role of cancer-associated fibroblasts (CAFs) in affecting the therapeutic vulnerability of lung cancer cells. Here, we aimed to investigate underlying molecular networks shaping the therapeutic susceptibility of ALK-driven lung adenocarcinoma cells via tumor microenvironmental cues using three-dimensional (3D) spheroid co-culture settings. We show that CAFs promote therapy resistance of lung tumor cells against ALK inhibition by reducing apoptotic cell death and increasing cell proliferation. Using single-cell RNA-sequencing analysis, we show that genes involved in lipogenesis constitute the major transcriptional difference between TKI-treated homo- and heterotypic lung tumor spheroids. CAF-conditioned medium and CAF-secreted factors HGF and NRG1 were both able to promote resistance of 3D-cultured ALK-rearranged lung tumor cells via AKT signaling, which was accompanied by enhanced de novo lipogenesis and supression of lipid peroxidation. Notably, simultaneous targeting of ALK and SREBP-1 was able to overcome the established CAF-driven lipid metabolic-supportive niche of TKI-resistant lung tumor spheroids. Our findings highlight a crucial role of CAFs in mediating ALK-TKI resistance via lipid metabolic reprogramming and suggest new ways to overcome resistance towards molecular directed drugs by targeting vulnerabilities downstream of oncogenic signaling.

Missense mutations in the DNA binding domain of p53 are observed frequently in Esophageal Squamous Cell Carcinoma (ESCC). Recent studies have revealed the potentially oncogenic transcriptional networks regulated by mutant p53 proteins. However, majority of these studies have focused on common hotspot p53 mutations while rarer mutations are poorly characterized. We had previously identified SMARCD1 as an oncogenic transcriptional target of rare non-hotspot p53 mutants detected from squamous cell carcinoma of the oral tongue (SCCOT). We now report the characterization of non-hotspot p53 mutations from ESCC. In-vitro tumorigenic assays performed following ectopic-expression of non-hotspot mutant p53 proteins caused enhancement of oncogenic properties in squamous carcinoma cell lines. Genome-wide transcript profiling of ESCC tumor samples stratified for p53 status, revealed several genes exhibiting elevated transcript levels in tumors harbouring mutant p53. Of these, ARF6, C1QBP and TRIM23 were studied further due to their previously reported pro-oncogenic roles. Reverse transcription quantitative PCR (RT-qPCR) performed on RNA isolated from ESCC tumor samples revealed significant correlation of TP53 transcript levels with those of the three target genes. Ectopic expression of wild type and several mutant p53 forms followed by RT-qPCR, Chromatin affinity-purification and Promoter-luciferase assays indicated the exclusive recruitment of p53 mutants - P190T and P278L, to the target genes leading to activation of expression. Several functional assays following knockdown of the target genes revealed a significant suppression of tumorigenicity in squamous carcinoma cell lines. Rescue experiments confirmed the specificity of the knockdown. The tumorigenic effect of the genes was confirmed in nude mice xenograft assays. This study has therefore identified novel oncogenic targets of rare non-hotspot mutant p53 proteins relevant for ESCC besides validating the functional heterogeneity of the spectrum of tumor specific p53 mutations.

BackgroundTriple-negative breast cancer (TNBC) is a clinically aggressive breast cancer subtype. It is a heterogeneous disease that remains difficult to stratify and that still lacks durable and biomarker-guided therapeutic options. Low expression of the tumour suppressor MTUS1 is associated with aggressive breast cancer features, but the biological properties of MTUS1-low TNBC remain insufficiently defined. Our goal was to determine whether low MTUS1 expression defines shared proliferative and stress-adaptation mechanisms that could guide candidate therapeutic strategies and corresponding target/drug pairs in MTUS1-low TNBC. MethodsWe labelled tumours from seven public TNBC RNA-seq cohorts based on the lowest and highest MTUS1 expression tertiles. Differential gene expression was analysed using gene set enrichment analysis (GSEA) on the Hallmark pathway database to identify deregulated biological pathways between MTUS1-low TNBC tumours and their MTUS1-high counterparts. Reproducibility was examined across independent TNBC cohorts and secondarily in broader breast cancer and selected TCGA tumour cohorts. Gene essentiality scores from CRISPR-Cas9 experiments in TNBC cell-line models were correlated to MTUS1 expression in these cell lines, to propose therapeutic strategies and their corresponding candidate target/drug pairs. ResultsMTUS1-low tumours showed a reproducible pathway-level proliferation mechanism driven by the MYC oncogene and sustained by up-regulated oxidative phosphorylation, combined with stress adaptation mechanisms involving unfolded protein response (UPR), and DNA repair Hallmark gene sets. Based on CRISPR data, we propose 3 therapeutic strategies: (1) targeting MYC to reduce its transcriptional activity, (2) targeting proteins from UPR, (3) targeting DNA-repair. We also propose corresponding candidate target/drug pairs to allow experimental validation of these strategies. ConclusionsProliferation in low MTUS1 TNBC is driven by MYC and stress-adaptation mechanisms. By linking this tumour profile to CRISPR-derived dependency signals, our analysis prioritises experimentally testable target-pathway hypotheses centred on MYC, UPR/proteostasis, and DNA-repair or checkpoint control. Although the proposed therapeutic strategies and candidate targets remain to be experimentally tested, the latter finding is consistent with published work showing that ATIP3-deficient TNBC cell line models are sensitive to inhibition of the WEE1 PKMYT1 G2/M checkpoint kinases.

Although important advances have been made in the knowledge of the molecular mechanisms leading to the development, of head and neck squamous cell carcinoma (HNSCC), only PDL1 is used for the immunotherapy (pemborlizumab) treatment in the first line of metastatic or recurrent disease. There are no other molecular biomarkers currently used in clinical practice. The objective of the study was to identify transcriptional alterations in patients with oral cavity cancer that identify gene networks responsible for resistance to treatment and prognosis. To identify possible targets for the treatment or prevention of these tumors, we screened for changes in transcription of genes that were recurrently altered in patients and that successfully stratify tumoral and non-tumoral samples, as well as patient survival, based on expression levels. The gene panels are primarily related to the cell cycle, DNA damage response, cytokine signaling and the immune system but also to the embryonic stem cell core. Validation of these panels in an independent cohort led to the identification of three non-interconnected genes, WDR66, SERPINH1 and ZNF622, that can predict patient survival and are differentially expressed in 3D cultures from HNSCC primary cell lines. These genes are related to stemness phenotype are transcriptional targets of the pluripotency transcription factors Sox2 and c-Myc. Our results suggest that WDR66, SERPINH1 and ZNF622 con-stitute a minimal signature of stemness transcriptional targets able to predict the prognosis of HNSCC tumors. Simple SummaryThe objective of the study was to identify transcriptional alterations in patients with oral cavity cancer to possibly identify gene networks responsible for resistance to treatment and prognosis. We identify bioinformatically gene panels are primarily related to the cell cycle, DNA damage response, cytokine signaling and the immune system but also to the embryonic stem cell core. Validation of these panels in patients independent cohorts led to the identification of three non-interconnected genes, WDR66, SERPINHl and ZNF622, that can predict patient survival and are differentially expressed in cancer stem cells cultures from HNSCC. These genes are related to stemness phenotype and epithelial-to-mesenchymal transition and are transcriptional targets of the pluripotency transcription factors Sox2 and c-Myc.

Ovarian cancer (OvCa) is an aggressive disease usually treated with cisplatin (CDDP)-based therapy. However, among the different types of cancers treated with CDDP, OvCa commonly develops chemoresistance to this treatment. The small extracellular vesicles (sEVs) play a central role in chemoresistance. In response to chemotherapy, resistant cells secrete sEVs named chemo-sEVs characterized by specific cargo landscape content involved in the transfer of chemoresistance to recipient cells. sEVs encompass a variety of vesicle types, including exosomes, and are formed as intraluminal vesicles (ILVs) within multivesicular endosomes (MVEs). MVEs follow at least two trafficking pathways regulated by RAB GTPase family members; 1) a secretory pathway where MVEs fuse with the plasma membrane (PM) for sEVs secretion, where RAB27A is the most studied; 2) a degradative pathway where MVEs fuse with lysosomes, an event controlled by RAB7. There is growing evidence suggesting that a loss of lysosomal function can increase sEVs secretion; however, whether sEVs secretion and the transfer of CDDP chemoresistance in OvCa is the result of a fine regulation between these two MVEs trafficking pathways is unknown. In this work, we study the status of these two pathways, between CDDP-sensitive (A2780) and CDDP-resistant (A2780cis) OvCa cells. We found A2780cis cells have an increased number of MVEs and ILVs structures, together with higher levels of ESCRTs machinery components and RAB27A, compared to A2780 cells. Moreover, CDDP promotes the secretion of chemo-sEVs in A2780cis cells. Interestingly, chemo-sEVs contain a high number of proteins related to DNA damage response. In addition, we determine A2780cis cells have a poor lysosomal function with reduced levels of RAB7. Surprisingly, silencing of RAB27A in A2780cis cells was found to be sufficient to restore lysosomal function and levels of RAB7 in A2780cis cells, switching into an A2780-like cellular phenotype. Next, we found rapamycin, a potent enhancer of lysosomal function, reduced the secretion of chemo-sEVs. Taken together, these results indicate that the secretion of chemo-sEVs in OvCa cells is determined by the balance between secretory MVEs and MVEs that are destined for lysosomal degradation. Thus, our results suggest that adjusting this balance between these two MVEs trafficking pathways could be a promising strategy for overcoming CDDP chemoresistance in OvCa. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=147 HEIGHT=200 SRC="FIGDIR/small/526974v1_ufig1.gif" ALT="Figure 1"> View larger version (51K): org.highwire.dtl.DTLVardef@167227corg.highwire.dtl.DTLVardef@91c6forg.highwire.dtl.DTLVardef@29e997org.highwire.dtl.DTLVardef@1a6bebe_HPS_FORMAT_FIGEXP M_FIG C_FIG

SAMHD1 is discussed as a tumour suppressor protein, but its potential role in cancer has only been investigated in very few cancer types. Here, we performed a systematic analysis of the TCGA (adult cancer) and TARGET (paediatric cancer) databases, the results of which did not suggest that SAMHD1 should be regarded as a bona fide tumour suppressor. SAMHD1 mutations that interfere with SAMHD1 function were not associated with poor outcome, which would be expected for a tumour suppressor. High SAMHD1 tumour levels were associated with increased survival in some cancer entities and reduced survival in others. Moreover, the data suggested differences in the role of SAMHD1 between males and females and between different races. Often, there was no significant relationship between SAMHD1 levels and cancer outcome. Taken together, our results indicate that SAMHD1 may exert pro-or anti-tumourigenic effects and that SAMHD1 is involved in the oncogenic process in a minority of cancer cases. These findings seem to be in disaccord with a perception and narrative forming in the field suggesting that SAMHD1 is a tumour suppressor. A systematic literature review confirmed that most of the available scientific articles focus on a potential role of SAMHD1 as a tumour suppressor. The reasons for this remain unclear but may include confirmation bias and publication bias. Our findings emphasise that hypotheses, perceptions, and assumptions need to be continuously challenged by using all available data and evidence.

Glioblastoma (GBM) is the most common form of a malignant primary brain tumour in adults for which therapeutic options are minimal. The rapid onset of the resistance mechanisms against the chemotherapeutic agent Temozolomide (TMZ), the first line of pharmacological care for patients, prevents the long-term validity of this approach. The underpinning biology for this remains poorly understood thus compromising the efficacy of this approach. The Translocator Protein (TSPO) is an 18kDa ubiquitous cholesterol-binding molecule on the outer membrane of mitochondria (OMM). Upregulated in cancers TSPO is required to form contacts between mitochondria and the nucleus termed: Nucleus Associated Mitochondria (NAM). In GBM tissues as well as in 2D and 3D cell cultures we assayed patterns of TSPO expression (i), autophagy/mitophagy (ii), transcription factors (iii) and susceptibility to TMZ-induced demise (iv). Confocal and ultrastructural imaging detailed the organization and redistribution of the mitochondrial network (v). Our findings show that TMZ exploits mitochondria via TSPO to aid the formation of NAM which couples the expression of the nuclear transcription factor Sterol regulatory element-binding transcription factor 1 (SREBP1) and the stabilization of YAP/TAZ. Pharmacological modulation of TSPO counteracts all the above and re-instates susceptibility to TMZ-induced demise. NAM is therefore proposed as a variable in the engagement and execution of pro-survival mechanisms in GBM thus offering a means to both insight into the pathophysiology of this disease and offer novel therapeutic strategies. Key PointsO_LITMZ exploits TSPO to curb mitochondrial quality control in glioblastoma cells. C_LIO_LITMZ-mediated MRR is associated with the relocation of mitochondria to the nucleus and modulation of transcriptional factors involved in cholesterol metabolism and adaptation to aggressive growth. C_LIO_LITSPO represents a pharmacological target to revert chemoresistance in glioblastoma cells. C_LI Importance of the StudyThis study elucidates a mitochondrion-driven mechanism of chemoresistance in human glioblastoma cells, which depends on the mitochondrial translocator protein TSPO. The administration of TSPO ligands restores susceptibility to TMZ by influencing the dynamics of transcriptional factors associated with cholesterol metabolism and mechanical transduction.

CK2 is considered a constitutively active protein kinase promoting/supporting several neoplastic properties and inducing a so-called non-oncogene addiction in tumor cells. Compared to the extensive body of pre-clinical research, the translational and clinical information on CK2 is still limited. The holoenzyme, composed by a tetrameric array of two catalytic (CSNK2A1 and/or CSNK2A1) and two regulatory (CSNK2B) subunits, remains to be clinically validated. Herein, we interrogated available cancer multiomics databases to unravel CK2 deregulated expression in NSCLC. We focused our analysis on individual CK2 subunits assuming subunit-specific tumor supportive roles across cancers and particularly, within two major NSCLC subtypes. Moreover, we performed meta-analysis to uncover associations between CK2 expression and patient survival, as well as further correlations analysis with components of the tumor-microenvironment. The genomic and transcriptomic data analysis was complemented by IHC evaluation of CSNK2A1, CSNK2A2 and CSNK2B subunit expression, and CK2 enzymatic activity thereof. Overall, our data suggests that epigenetic, transcriptional and post-transcriptional regulatory mechanisms rather than mutational/gene amplification events may account for differential CK2 subunits expression/activity in NSCLC. Of note, CSNK2A1 and CSNK2B mRNA up-regulation consistently determine a worse patient prognosis in LUAD and correlated with increased infiltration of MDSCs/CAFs. Importantly, we corroborated that CK2 protein subunits levels and enzymatic activity are significantly exacerbated in LUAD and LUSC, but only CSNK2A1 positively correlated with tumor size and disease stage in the analyzed patient cohort, thus supporting our transcriptomic-based correlation analysis. Finally, we concluded that CSNK2A1 alone and/or the homo-tetramer thereof may be more instrumental to support NSCLC than CSNK2A2; thus, tailored drugs against these molecular CK2 entities may achieve better therapeutic windows at least for advanced lung cancer treatment.

Recurrent therapy resistance is a major limitation in clinical efficacy and for the outcome of glioblastoma (GBM) patients, positioning GBM among the tumor types with the poorest survival outcomes. In this work, we dissected resistance mechanisms in GBM, which resulted in the identification of FGFR1 pathway as a major regulator of the signaling and metabolic rewiring associated with temozolomide (TMZ) resistance in GBM. Hence, we described a mechanism of resistance that operates at two major levels. First, a p53-mediated regulation of cell cycle inducing cell cycle arrest to allow DNA repair in response to TMZ. And second, a complete metabolic rewiring promoting lipid catabolism and preventing lipid peroxidation. Both the p53-mediated response and the metabolic adaptation are controlled by FGFR1, as inhibition of the FGFR1 pathway completely abolishes this signaling and metabolic reprograming, restoring sensitivity to TMZ. Our results also indicated a correlation of FGFR1 levels with poor prognosis in GBM patients, and validated the treatment of TMZ in combination with FGFR1 inhibitors as an efficient strategy to induce tumor cell death in pre-clinical animal models. This data position the receptor FGFR1 as a very promising candidate for evaluation in future clinical approaches to limit the development of therapy resistance to TMZ in GBM patients.

Glioma progression and resistance to temozolomide (TMZ) remain major clinical challenges. Here, we investigated whether dysregulated autophagy and cholesterol metabolism are coordinately remodeled during glioma progression and TMZ resistance. Tissue microarray analysis of astrocytoma and glioblastoma specimens revealed progressive autophagosome accumulation, reflected by increased LC3{beta} puncta, coupled with impaired autophagic flux compared with adjacent normal brain tissue. These alterations intensified with tumor grade and were associated with upregulation of farnesyl diphosphate synthase (FDPS), linking malignant progression to cholesterol pathway remodeling. TMZ-resistant (R) glioblastoma cells exhibited epithelial-to-mesenchymal transition, mitotic quiescence, and mitochondrial remodeling consistent with a therapy-tolerant phenotype. Bioenergetic profiling demonstrated reduced respiratory reserve, diminished ATP-linked respiration, and elevated proton leak, indicating constrained metabolic flexibility. In parallel, impaired autophagy flux was associated with suppression of de novo cholesterol synthesis and transcriptional downregulation of SREBP-2 and LDL-R. Comprehensive lipidomic profiling revealed marked cholesterol metabolic reprogramming in R cells, characterized by accumulation of specific cholesteryl esters, including CE 22:5, CE 22:6, CE 22:4, and CE 20:4, despite reduced cholesterol biosynthesis. Pharmacologic inhibition of the mevalonate pathway with simvastatin significantly altered cholesteryl ester profiles but failed to restore autophagy flux or sensitize R cells to TMZ-induced apoptosis, even under combined TMZ-simvastatin treatment. Lay AbstractAs gliomas progress from astrocytoma to glioblastoma, autophagy becomes dysregulated and cholesterol metabolism is rewired. This coordinated remodeling supports tumor survival, metabolic plasticity, and resistance to temozolomide therapy. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/697885v2_ufig1.gif" ALT="Figure 1000"> View larger version (79K): org.highwire.dtl.DTLVardef@1183dd2org.highwire.dtl.DTLVardef@82e20dorg.highwire.dtl.DTLVardef@c6c8dforg.highwire.dtl.DTLVardef@adb427_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsAutophagy flux blockade intensifies during progression from astrocytoma to glioblastoma Dysregulated autophagy is coupled to altered cholesterol metabolism in malignant gliomas TMZ-resistant glioblastoma cells undergo epithelial-to-mesenchymal transition and mitotic quiescence Resistant cells exhibit constrained bioenergetic capacity and mitochondrial remodeling Impaired autophagy suppresses de novo cholesterol synthesis and lipid recycling Lipidomics reveals accumulation of long-chain cholesteryl esters in TMZ-resistant cells Statin-based cholesterol inhibition fails to resensitize glioblastoma cells to temozolomide