Oncogene

The non-canonical translation of specific mRNAs has been implicated in oncogenesis and cancer progression. We previously identified eukaryotic Initiation Factor 5B (eIF5B) as a key factor in Internal Ribosome Entry Site (IRES)-mediated translation of a subset of mRNAs encoding anti-apoptotic proteins. Here, we demonstrate that EIF5B is predominantly expressed in cancer cells compared to other cell types in the Oral Squamous Cell Carcinoma (OSCC) microenvironment. Higher EIF5B mRNA and protein expression are associated with poor patient outcomes. We show that eIF5B depletion in OSCC cells blunted pro-growth, pro-inflammatory, and pro-angiogenic signaling pathways and significantly increased TNF-related apoptosis-inducing ligand (TRAIL)-induced cell death. This is achieved through decreased translation of mRNAs encoding critical factors associated with OSCC pathophysiology. Importantly, the level of interaction of eIF5B with tRNAiMet was significantly higher in OSCC cells compared to non-cancerous fibroblasts. This suggests that OSCC cells (but not non-cancerous fibroblasts) rely heavily on eIF5B for translation initiation. In an in vivo flank xenograft model using nude mice, eIF5B knockdown in UMSCC-29 cells led to a significant reduction in tumor volume compared to control tumors. Also, the immunohistochemical analysis of the xenografted tumor sections demonstrated decreased staining intensity of critical factors associated with OSCC pathophysiology in eIF5B-depleted tumors relative to controls. Collectively, our data demonstrate that OSCC cells are uniquely dependent on eIF5B-tRNA interactions to sustain translation of pro-survival mRNAs. Targeting eIF5B disrupts these oncogenic programs, sensitizing OSCC cells to apoptosis and suppressing pro-angiogenic and pro-growth signaling.

Cancer-testis antigens (CTAs) are germ cell-restricted proteins aberrantly expressed in diverse malignancies, yet whether these proteins contribute to tumor progression remains poorly defined. The CTA Testis-Specific Serine Kinase 6 (TSSK6) is frequently expressed in colorectal cancer (CRC), where it promotes key hallmarks of tumor progression, including anchorage-independent growth, invasion, and in vivo tumor formation. However, the signaling network by which ectopic TSSK6 drives these phenotypes has not been established. Here, we define the signaling pathways regulated by TSSK6 in CRC cells. We demonstrate that TSSK6 promotes focal adhesion kinase (FAK) activation, leading to enhanced STAT3 Ser727 phosphorylation and increased STAT3-dependent transcription. Transcriptomic analyses revealed induction of gene programs enriched for extracellular matrix remodeling, cytoskeletal organization, adhesion, and motility in a STAT3-dependent manner. Disruption of the FAK-STAT3 signaling axis abrogated anchorage-independent growth and invasive outgrowth in a spheroid model. Collectively, these findings demonstrate that aberrant expression of a germline-restricted kinase promotes focal adhesion signaling, which activates STAT3-dependent transcriptional programs that promote anoikis resistance and invasive behavior in CRC.

Autophagy, a key lysosomal degradation pathway regulating metabolic adaptation in cancer, plays fundamental roles in both the tumor and host stromal compartments during cancer progression. An important unanswered question is whether and how autophagy in specific host stromal elements, such as endothelial cells, influences metastasis. Here, we scrutinize how the genetic loss of autophagy in endothelial cells impacts primary tumor progression and metastasis in the Polyoma Middle T (PyMT) model of luminal B breast cancer. In both autochthonous and orthotopic mammary transplant models, PyMT primary tumor growth is significantly delayed upon endothelial cell Atg12 or Atg5 genetic deletion (Atg12 or 5 ECKO), which correlates with increased tumor cell apoptosis and HIF1 activation. In contrast, PyMT-bearing Atg12 ECKO mice exhibit increased metastasis, as well as higher rates of primary tumor and lung metastatic recurrence following surgical resection of PyMT primary tumors. Experimental metastasis assays further corroborate that loss of endothelial cell autophagy in Atg12 ECKO host animals promotes PyMT metastatic colonization and outgrowth, resulting in increased lung metastases compared to controls. Similarly, in the Rat Insulin Promoter T antigen pancreatic neuroendocrine tumor (RT2-PNET) model, endothelial cell deletion of Atg12 promotes liver micro-metastases. Taken together, these results from distinct preclinical cancer models reveal that endothelial cell autophagy suppresses metastatic seeding and progression and broach that autophagy inhibition in host endothelial cells may adversely influence the efficacy of systemic autophagy-lysosomal pathway inhibition in the clinical oncology setting.

Since its discovery in a metastatic lymph node in breast cancer patients, LIM and SH3 Domain Protein (LASP1) has been shown to be over-expressed in and promote the progression of various cancers. We recently demonstrated that LASP1 is highly expressed in human Papillomavirus positive (HPV+) cervical cancers where it promotes cell proliferation and invasion. Importantly, we showed that the HPV E7 oncoprotein increased LASP1 expression by downregulating the microRNA miR-203, which directly targets the LASP1 mRNA 3UTR. However, whether LASP1 is regulated by other mechanisms in HPV+ cervical cancers is unclear. Here, we demonstrate an additional mechanism by which HPV E7 regulates LASP1 transcription. Our data demonstrates an important the role for Rb/E2F1 signalling in promoting LASP1 expression in HPV+ cervical cancer cells. Mechanistically, E7-mediated Rb binding and degradation is required for E7-driven LASP1 promoter activity. Overexpression of Rb decreased LASP1 promoter activity, LASP1 mRNA expression and LASP1 protein levels, whereas E2F1 expression promoted LASP1 expression. Importantly, E2F1 directly bound to the LASP1 promoter region and the E2F1 binding sites are essential for LASP1 expression in HPV+ cervical cancer cells. Finally, we demonstrate that LASP1 can partially rescue the growth defects observed in E2F1 knockdown cervical cancer cells. Taken together, our data show that HPV E7 regulates LASP1 expression via the Rb/E2F1 signalling pathway. In combination with our previous work, our studies demonstrate that HPV E7 employs multiple mechanisms to drive LASP1 expression, reinforcing the importance of LASP1 in HPV+ cervical cancer.

Cancer metabolism rewiring is one of the hallmarks of cancer, enabling cancer cell survival in a nutrient deprived microenvironment. Key to this is nutrient scavenging where cancer cells rely on extracellular proteins, including extracellular matrix (ECM) components, to sustain their proliferation. ECM uptake is mediated by 2{beta}1 integrin, however it is not clear how this process is controlled by nutrient availability. Here we demonstrated that amino acid starvation promoted ECM internalisation, by inducing the expression of 2 integrin. Mechanistically, starvation-driven RAS/MAPK pathway activation in cells harbouring oncogenic RAS mutations and mTOR inhibition increased 2 integrin, while the GCN2-depedent integrated stress response was not required. Functionally, elevated 2 integrin levels promoted cell adhesion and migration in nutrient starved cells. Finally, 2 integrin was found upregulated in pancreatic tumours and correlated with poor prognosis in pancreatic adenocarcinoma patients. Together, these data indicate that the nutrient- starved pancreatic cancer microenvironment synergises with KRAS mutation to drive pancreatic cancer aggressiveness.

TP53 mutations occur in 80-90% of triple-negative breast cancers (TNBCs) and drive genomic instability and metastatic progression. Poly (ADP-ribose) polymerase (PARP) is critical for DNA repair and replication fork stability. How oncogenic signaling influences PARP function to sustain proliferation during replication stress remains unclear. Mutant p53 (mtp53) R273H associates tightly with chromatin, forms complexes with PARP, and enhances PARP recruitment to replication forks [1-3]. The C-terminal region of mtp53 mediates mtp53-PARP and mtp53-Poly (ADP-ribose) (PAR) interactions that facilitate S phase progression [4, 5]. The PARP inhibitor talazoparib (TAL) combined with the alkylating agent temozolomide (TMZ) produces synergistic cytotoxicity selectively in mtp53, but not wild-type p53 (wtp53), breast cancer cells and organoids. Herein we evaluated the mechanism of mtp53-associated cell death and tested if this could translate to a preclinical xenograft model. We found that TMZ+TAL treatment induced elevated cleaved PARP and {gamma}H2AX and reduced the metastasis-promoting oncoprotein MDMX. In orthotopic xenografts expressing mtp53 R273H, but not wtp53, combination therapy significantly decreased circulating tumor cells (CTCs) and lung metastases. Transcriptomic profiling of tumors from combination treated animals demonstrated downregulation of MDMX, VEGF, and NF-{kappa}B, consistent with the observed suppression of CTCs and lung metastasis, and increased {gamma}H2AX, indicative of replication stress in mtp53 xenografts. Inhibition of metastasis was also observed in mtp53 R273H WHIM25 and p53-undetectable WHIM6 TNBC patient-derived xenografts (PDX). The mtp53 C-terminal domain (347-393) demonstrated a critical tumor promoting function, as CRISPR-mediated deletion impaired replication fork progression, tumor growth, and metastatic dissemination. DNA fiber combing showed that expression of full-length mtp53 R273H, but not C-terminal deleted {Delta}347-393, supported sustained single-stranded DNA gaps (ssGAPs) following Poly (ADP-ribose) glycohydrolase (PARG) inhibition. These findings support that mtp53 uses C-terminal amino acids to exploit PARP to enable replication stress adaptation and that mtp53 is a predictive biomarker for combined PARP inhibitor and DNA damaging therapies targeting TNBC. Significance statementTP53 mutations are the most common genetic alterations in TNBC and a major driver of replication stress and metastasis. This study shows that missense mutant p53 uses C-terminal amino acids to reprogram PARP activity to maintain tumor cell survival under replication stress. We demonstrate that p53 status governs the response to combined PARP inhibitor (PARPi) and DNA-damaging chemotherapy, establishing an additional molecular basis beyond BRCA1 mutations for treating TNBC with PARPi therapy. These findings reveal a previously unrecognized mechanism by which the mutant p53-PARP axis enables replication stress tolerance and drives cancer metastasis. We show mutation of p53 in TNBC provides an additional biomarker-guided framework to improve PARPi therapeutic outcomes.

The formation of the premetastatic niche prepares distant tissues for tumor cell engraftment. Endothelial cells are critical mediators of premetastatic niche formation, orchestrating extravasation of circulating tumor cells and critical pro-tumor immune cells, such as neutrophils. In mouse models of breast cancer, we show that primary tumors upregulate the non-signaling chemokine receptor ACKR1 in the endothelium of the lung premetastatic niche. ACKR1-expressing venules were found to be preferential sites of neutrophil and tumor cell localization within lung tissue. A newly generated conditional ACKR1 allele was used to show that endothelial-specific removal of ACKR1 expression significantly reduces metastatic engraftment in the lung. When ACKR1 is activated by tumor-secreted factors, endothelial ACKR1 functions to promote neutrophil recruitment within the lung parenchyma. We conclude that ACKR1 is a critical component of the endothelial response to tumors at the metastatic site of the lung, leading to neutrophil recruitment and promotion of tumor cell metastasis. SUMMARYEndothelial cells play critical roles in breast cancer metastasis. ACKR1 is upregulated in the endothelium of the lung metastatic niche in response to primary mammary tumors. Endothelial ACKR1 expression was found to promote neutrophil infiltration into the metastatic niche and support breast tumor cell metastasis to the lung.

The PBAF is one of three biochemically distinct BAF chromatin remodelers in humans. We previously proposed the role of ARID2, a PBAF component, as a bonafide tumor suppressor in colorectal cancer (CRC). Here, we validated loss of tumor suppression under conditions of ARID2 deficiency emanating from a marked reduction in PBAF complex assembly resulting from destabilization of PBAF-specific components BRD7, PHF10, and PBRM1. Transcriptome profiling of ARID2 deficient CRC cells revealed perturbation of disease processes, including CRC and neurodegenerative disorders, as well as CRC relevant pathways including Wnt/{beta}-catenin signalling, but transcript levels of PBAF-specific components remained unchanged, confirmed by RT-qPCR and TCGA data analysis. Our study establishes ARID2 as a critical stabilizer of the PBAF complex of relevance to CRC.

The nuclear oncoprotein SET (patient "SE" translocation) has been implicated in the etiology of MLL/KMT2A-fusion induced leukemia. Here we examine the details of this dependency in murine, primary hematopoietic cells. Experiments demonstrated Set as downstream target of HoxA9 and a direct interactor of Mll/Kmt2A. Mll/Kmt2A and Set globally co-bound promoter regions. Impairing Set expression induced a metabolic shift towards oxidative phosphorylation phenocopying a knockdown of Mll/Kmt2A fusion targets. Set acted predominantly as transcriptional activator driving a pro-proliferative gene expression program with features indicative for Mll/Kmt2A involvement. Molecularly, Set depletion caused dissociation of Mll/Kmt2A from chromatin accompanied by a selective loss of elongating RNA PolymeraseII Ser2-P. Concomitant with a function of Set as inhibitor of protein phosphatase 2A (PP2A), specific recruitment of PP2A to the Meis1 promoter, a known Mll/Kmt2A target, inhibited transcription in reporter assays and in a natural chromatin environment. We identified Mitogen and stress induced kinase 1 (Msk1) as potential substrate protected by Set from dephosphorylation. Active and phosphorylated Msk1-P colocalized with Mll and disappeared from chromatin upon Set depletion. Biochemically, Msk-1 bound directly to Mll/Kmt2A as well as to menin, a known Mll/Kmt2a tethering factor. Loss of Set/Mll/Msk1 selectively affected H3K14 acetylation at promoters and this could be partially attributed to the reduced presence of the histone acetyltransferase Moz/Kat6a. Finally, we show that kinase and menin inhibitors cooperate in leukemia cells indicating that the relay function of Mll/Kmt2A, allowing control of hematopoiesis by cellular signaling, is retained in MLL-fusion proteins.

Despite progress in recent decades, breast cancers remain the most diagnosed malignancies, and second leading cause of cancer death, in women. Although improved screening and systemic and endocrine adjuvant approaches have contributed to major declines in breast cancer mortality, current standard of care drugs are extremely toxic, and many women continue to be overtreated. Although nearly two-thirds of breast cancers are hormone-responsive, aggressive subtypes, particularly Triple Negative Breast Cancer (TNBC), still lack safe oral medications. Recently the roles that mitochondria play in TNBC carcinogenesis, metastasis, and resistance to treatment have garnered a great deal of attention. Contrary to the popular dogma that cancer cells are powered by glycolysis, metastatic breast cancer cells have enhanced mitochondrial function. Our work identified that Mitochondrial Nuclear Retrograde Regulator 1 (MNRR1; also, CHCHD2, PARK22), a key coordinator of mitochondrial-nuclear crosstalk that is physically present in both compartments, is overexpressed in TNBC cells and is an important regulator of metastasis signaling. We have identified Heat Shock Factor 1 (HSF1) as the main transcription factor that activates the MNRR1 promoter in TNBC cell lines. In the mitochondria, MNRR1 protein facilitates ATP production and inhibits apoptosis, whereas in the nucleus it regulates the transcription of stress-responsive genes including several required for epithelial to mesenchymal transition (EMT), metabolic flexibility, and cell growth. Thus, each of the bi-organellar functions of MNRR1 constitutes processes regarded as hallmarks of cancer. For reasons that are not yet fully understood, MNRR1 levels display a significant and robust ancestry bias, showing increased expression in tumor samples from Non-Hispanic Black (NHB) women when compared to disease-matched tumors from Non-Hispanic White (NHW) patients. It is possible that increased levels of MNRR1 may underlie the aggressive metastatic phenotype observed in many NHB patients. In further support of this observation, loss of MNRR1 function, either genetically or by use of inhibitors, reduces TNBC growth and metastasis. MNRR1 therefore is an attractive therapeutic target that could be exploited for design of novel therapies or as adjuncts to existing ones.

Cancer testis antigens are widely expressed in human malignancies. Melanoma-Associated Antigens (MAGE) A3 and A6 have been proposed to modulate protein turnover and metabolism in cancer cells. However, the substrate specificity of MAGE-A3/6 and the impact on cancer cell behavior remain poorly understood. Although previous research has identified binding partners, a molecularly validated target for MAGE-A3/6-mediated proteasomal degradation has not been described. In this study, we redefine the substrate specificity of MAGE-A3/6 and present a mechanistic framework for substrate binding, polyubiquitination, and subsequent degradation. We identify BPTF-Associated Protein of 18kDa (BAP18) as a bona fide novel substrate of MAGE-A3/6 and demonstrate its direct regulation via a molecularly defined substrate-degron-E3-adaptor interaction. The degradation of BAP18 by MAGE-A3/6 underlies phenotypic alterations in cancer cells, such as enhanced migratory capacity. This previously unrecognized molecular link is observed in both cancer cell lines and human cancer tissues, supporting a role as a fundamental oncogenic process. The discovery of a molecularly defined interaction between MAGE-A3/6 and their substrate enables systematic investigation into oncogenic protein degradation in human cancers and may inform future therapeutic strategies that leverage the molecular function of aberrantly reexpressed germline proteins in cancer.

Metastatic disease is the leading cause of mortality in prostate cancer (PC), with bone as the preferential site of dissemination and the lung frequently affected secondarily. Metabolic interactions between disseminated tumor cells and tissue-specific microenvironments play a key role in shaping site-specific metastatic patterns. In particular, the availability of certain metabolites before, during, and after the establishment of overt metastases represents a critical determinant of colonization. Here we show that asparagine (Asn) is selectively enriched in bone and lung microenvironments and supports PC metastatic colonization. Dietary Asn restriction selectively impairs bone and lung metastases in vivo, without affecting metastatic burden in other organs. Mechanistically, disseminated PC cells arriving at Asn-rich niches rely on extracellular Asn due to decreased asparagine synthetase (ASNS) expression enabling the activation of mTORC1-dependent translational program. Elevated Asn availability selectively promotes the synthesis of Asn-rich proteins enriched in N-glycosylation motifs (Asn-X-Ser/Thr), leading to enhanced global protein N-glycosylation during early metastatic colonization. This metabolic adaptation facilitates cell-cell interactions and promotes adhesion to bone- and lung-specific extracellular matrices. Among the N-glycosylated proteins induced by Asn, CD44 emerges as a central effector of PC bone metastases. Extracellular Asn shortening, genetic or pharmacological disruption N-glycosylation, or silencing of CD44 abolish the pro-metastatic advantage conferred by Asn. Together, these findings identify environmental Asn as a niche-specific metabolic cue that drives PC organotropism by rewiring translation toward proteins enriched in N-glycosylation sites, thereby enhancing adhesive interactions and revealing metabolic vulnerabilities that could be therapeutically exploited to interfere with earliest steps of metastatic colonization in PC.

Chemoresistance is a major contributor to poor clinical outcomes in AML patients and can arise from interactions between AML cells and the bone marrow microenvironment (BME). How immune cells, particularly macrophages (M{varphi}s), facilitate this process requires better clarification. This study shows that M2-like M{varphi}s protect AML cells from apoptosis induced by daunorubicin (DNR) and cytarabine (Ara-C). This protection occurs via co-culture and is linked to enhanced mitochondrial transfer from M{varphi}s to AML cells. M{varphi}s interacted with AML cells via tunneling nanotube (TNT)-like structures. Furthermore, inhibition of mitochondrial transfer using cytochalasin B reduced the protective effect, indicating that mitochondria mediate this process. M{varphi}s transferred functional mitochondria to AML cells as evidenced by enhanced metabolic capacity and reduced reactive oxygen species levels in AML cells under chemotherapy stress. TH-257 (LIMK inhibitor) and metformin blocked mitochondrial transfer and M{varphi}-driven chemoprotection. Moreover, increased transcript expression levels of RhoC and cofilin correlate with inferior overall survival in AML patients. These findings suggest that M2-like M{varphi}s contribute to chemoresistance through TNT-mediated mitochondrial transfer and the LIMK-Cofilin pathway, identifying potential therapeutic targets to circumvent chemoresistance in AML.

Y-box binding protein 1 (YB-1; YBX1) is a multifunctional DNA- and RNA-binding protein involved in cell cycle regulation, DNA repair, stress adaptation, and therapy resistance. Elevated YBX1 mRNA expression is associated with aggressive disease across multiple cancers, yet its pan-cancer genomic and clinical correlates remain unclear. Here, we performed a comprehensive pan-cancer analysis across 53 datasets spanning 33 tumour types, integrating RNA expression, somatic mutations, copy number, hypoxia, and clinical outcomes. YBX1 was rarely mutated or amplified, indicating that oncogenic relevance is primarily driven by its expression. Tumours with high YBX1 mRNA exhibited a conserved transcriptional program enriched for cell cycle, DNA repair, and chromatin regulation pathways, and were preferentially mutated in genes involved in maintaining genomic stability, including TP53. These tumours were associated with increased mutation burden, fraction of genome altered, homologous recombination deficiency, and elevated hypoxia. Clinically, high YBX1 mRNA associated with advanced stage, higher grade, shorter progression-free survival, and reduced overall survival. Collectively, high YBX1 mRNA expression defines a conserved, genomically unstable, and clinically aggressive tumour state across multiple cancer types.

Inactivating mutations in BRCA1-associated protein 1 (BAP1) are observed in approximately 45% of primary and [~]85% of metastatic uveal melanoma (UM) cases and are strongly correlated with aggressive phenotypes and poor prognosis. However, the mechanistic contribution of BAP1 to tumor aggressiveness remains elusive. This study investigates the role of BAP1 loss in senescence and explores the potential therapeutic implications of targeting senescence pathway. Analysis of The Cancer Genome Atlas UM cohort revealed that BAP1-mutant tumors exhibited increased senescence pathway activity score, and elevated expression of multiple cytokines, chemokines, growth factors and matrix-remodeling enzymes related to senescence-associated secretory phase. Functional assays revealed that BAP1 loss promotes senescence hallmarks including upregulated p16, p21, and phospho-ATM proteins, increased {beta}-gal positive cells, accumulated {gamma}H2AX foci, depleted lamin B1, and reduced PARP1 cleavage and Ki67 levels. These effects were further exacerbated following radiation exposure. Importantly, BAP1 knockdown, alone or in combination with ionizing radiation, sensitized UM cells to senolytic agents, dasatinib and quercetin. In conclusion, our findings identify BAP1 loss as a driver of senescence and suggest that BAP1-mutant tumors may benefit from senolytics treatment.

Epigenetic deregulation can alter the expression of cancer-related genes in tumor cells and may promote metastasis by influencing interactions between tumor cells and their immune microenvironment. However, the underlying immune mechanisms remain poorly understood. LSD1 (KDM1A) is a histone demethylase that has been proposed to function as a tumor and metastasis suppressor in breast cancer. Here, using the MMTV-PyMT breast cancer mouse model, we show that natural killer (NK) cells play a critical role in suppressing tumor cell metastasis to the lung, and that ablation of LSD1 leads to increased lung metastasis. This phenotype is accompanied by pronounced upregulation of immune-related genes, including major histocompatibility complex class I (MHC-I) genes, in tumor cells and by extensive remodeling of the tumor immune microenvironment, characterized by reduced abundance and maturation of NK cells. Consistent with these observations, NK cells exhibit reduced cytotoxicity toward Lsd1-null PyMT tumor cells. Notably, NK cell-mediated killing can be restored by disrupting expression of the non-classical MHC-I molecule Qa-1, a ligand for the inhibitory NK receptor CD94/NKG2A, in tumor cells. In transplantation experiments, Lsd1-null PyMT tumor cells formed significantly larger lung metastatic lesions than Lsd1-wildtype tumor cells in SCID mice, which possess functional NK cells, but not in NSG mice that lack NK cells. Collectively, these findings suggest that epigenetic deregulation in LSD1-deficient mammary tumor cells reprograms the tumor immune microenvironment, resulting in impaired NK cell-mediated tumor surveillance and enhanced metastatic progression.

Despite the availability of several FDA-approved therapies, metastatic melanoma remains a significant clinical challenge, particularly for patients with brain metastases, which frequently represent the site of treatment failure and a major cause of melanoma-related mortality. Melanoma exhibits a strong propensity to metastasize to the brain, yet the molecular mechanisms driving this lethal progression remain incompletely understood, limiting the development of effective treatment options. Building on our prior discovery that focal adhesion kinase (FAK) is a key mediator of AKT1-driven brain metastasis, we sought to validate the role of FAK in melanoma progression and metastatic dissemination. Using complementary autochthonous and syngeneic mouse models of BRAF-mutant melanoma, we evaluated the impact of FAK expression on overall survival, primary tumor growth, and metastasis. Through the generation of targeted FAK mutants, we distinguished kinase-dependent from kinase-independent functions and demonstrate that FAK promotes melanoma metastasis in a kinase-dependent manner. Furthermore, we establish that FAK functions downstream of PTEN to drive metastatic progression. Collectively, these findings support the therapeutic potential of FAK inhibition, either alone or in combination with existing treatments, to more effectively combat metastatic melanoma and inform the development of emerging FAK-targeted therapies.

Activation-induced cytidine deaminase (AID), which is essential for antibody diversification, exhibits elevated expression in the activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL). Here, we demonstrate that AID modulates transcriptional programs linked to cell cycle progression, proliferation, and DLBCL subtype identity. AID loss in ABC-type DLBCL cell lines negatively impacts MYC and E2F pathway activity, while AID re-expression restores activity, establishing a causal link. Consequently, loss of AID delays G1/S cell cycle transition and reduces proliferation. In addition, AID expression skews transcriptional programs towards ABC-type DLBCL in cell lines. In agreement, AID expression correlates with ABC-type gene expression in primary DLBCL patient samples. Moreover, AID overexpression resulted in increased IRF4 protein levels, and enhanced NF-{kappa}B activity, supporting AIDs role in reinforcing the ABC-type identity. Shared enrichment of the IRF4 co-factor BATF in AID-high tumors of both ABC- and GCB-subtypes points towards a common mechanism driving subtype skewing. These findings underscore a broader role for AID in DLBCL pathogenesis, establishing AID as a key regulator of transcriptional programs linked to cell cycle progression and DLBCL subtype.

Ionizing radiation can be an effective therapy for prostate cancer. Unfortunately, however, more aggressive prostate cancers such as neuroendocrine prostate cancer (NEPC) are often radiation resistant, which contributes to their high degree of morbidity and mortality. In this study, we used an unbiased approach to identify novel mechanisms that contribute to resistance to radiation and that are associated with neuroendocrine differentiation. Specifically, we compared the expression of cell surface proteins by mass spectrometry in prostate cancer cell lines that had been either untreated or treated with radiation to induce resistance, a process that also promotes neuroendocrine differentiation. Among the proteins identified by this screen, we focused on folate receptor (FR) because of its known biological functions and the fact that it is a validated therapeutic target. Our data reveal that FR has a causal role in enabling prostate cancer cells to resist radiation. Importantly, we also demonstrate that the expression of FR is regulated by HIF-1, which also has a causal role in radiation resistance and neuroendocrine differentiation. Given that the ability of cells to resist damage and death in response to ionizing radiation depends largely on their ability to buffer the substantial increase in reactive oxygen species (ROS) that is generated by radiation, we also demonstrate that the folate-FR axis promotes radiation resistance by sustaining intracellular glutathione levels that buffer this increase in ROS. In summary, the data reported here highlight a novel role for FR in resistance to ionizing radiation that is intimately associated with the hypoxic microenvironment of NEPC and the ability of the folate-FRa axis to maintain redox homeostasis.

Cancer cell-autonomous type 1 interferon (IFN-1) production and signaling is frequently activated in response to DNA damage and has been associated with the development of therapy resistance in several cancer types. However, its cell-autonomous role in driving resistance in high-grade serous ovarian cancer (HGSOC), a disease defined by near-universal exposure to genotoxic therapy as frontline treatment, remains unclear. Specifically, whether IFN-1 functions in HGSOC as only a response to genotoxic stress or can independently act in driving resistance phenotypes has not been studied. Utilizing a syngeneic patient-derived model of cisplatin-sensitive (SE) and -resistant (CR) HGSOC, we demonstrate that chronic cisplatin exposure is associated with enrichment of IFN-1 signaling and the interferon-related DNA damage resistance signature (IRDS). Acute cisplatin treatment elicited dynamic, temporal IFN-1 signaling and responses in both sensitive and resistant cells, indicating a conserved stress response in resistant cells. Chronic, low-level exposure to exogenous IFN{beta}, in the absence of a DNA-damaging agent, was sufficient to phenocopy several features of chronic cisplatin driven resistance, including reduced therapeutic sensitivity, cell cycle arrest, and decreased proliferation. Notably, IFN{beta} driven resistance occurred without sustained IRDS or canonical interferon stimulated gene (ISG) induction, revealing alternative mechanisms for IFN-1 mediated therapy resistance. Together, these findings identify IFN{beta} as a functional driver of the development of resistance-associated phenotypes and highlight cell-autonomous IFN-1 signaling as a potential biomarker for resistance and a therapeutic target in platinum-resistant disease.