Cancer Gene Therapy

TMEM147, an ER membrane protein, is linked to lung adenocarcinoma (LUAD) but its role remains unclear. This study combines bioinformatics and experiments to explore TMEM147s function in LUAD progression. TMEM147 expression was analyzed using TCGA/GEO data and validated in LUAD cells. Survival analysis assessed its prognostic value. GO/KEGG and ssGSEA revealed functional pathways and immune microenvironment interactions. Transcription factor binding predictions and in vitro assays (migration, invasion, proliferation) evaluated TMEM147s role. TMEM147 was upregulated in LUAD and correlated with poor outcomes. FLI1 was predicted as a transcriptional regulator. TMEM147 influenced immune cell infiltration and was associated with ribonucleoprotein biogenesis and oxidative phosphorylation (OXPHOS) . Silencing TMEM147 reduced cancer cell migration, invasion, and proliferation, suggesting its potential as a biomarker and therapeutic target.

Lung cancer remains the leading cause of cancer-related deaths worldwide, with tumor recurrence a major contributor to its high mortality. The genetic and molecular mechanisms of recurrence remain poorly understood. Using whole-exome sequencing of 155 primary non-small cell lung cancers, we studied the mutational landscape and driver alterations associated with recurrence. Primary tumors that developed recurrence had higher mutational burden, including hypermutated tumors explained by mutations in DNA polymerase or mismatch repair pathways. Mutational signatures of reactive oxygen species were associated with recurrence. Combined mutations in TP53 and CDKN2A were enriched in non-recurrent tumors, while ATRNL1 mutations were enriched in recurrent tumors. Pathway analyses implicated DNA repair and cilium organisation processes with tumor recurrence and highlighted 50 additional candidate genes including BRCA2. Recurrence-associated genes showed essentiality in lung cancer cell lines and included known therapeutic markers, indicating their functional and translational relevance. This analysis provides insights into the molecular basis of lung cancer recurrence and informs experiments to develop diagnostic and therapeutic strategies.

The role of red blood cells (RBCs) in tumorigenesis is poorly understood. We previously identified RBC-microRNAs with aberrations linked to lung cancer, including miR-93-5p. Here we find that miR-93-5p levels are elevated in RBC-derived exosomes among lung cancer patients and are associated with their shorter survivals. RBC-derived miR-93-5p transfers to cancer cells primarily through the exosomal pathway. The transferred RBC-miR-93-5p can target PTEN in cancer cells, and hence increase cell proliferation, invasion, and migration. RBC-derived miR-93-5p accelerates, whereas targeting miR-93-5p diminishes tumor growth in xenograft models. These findings reveal a novel biological function of RBCs in tumorigenesis, where they facilitate cancer progression by transferring the oncomiR via exosomes, thereby offering new diagnostic and treatment strategies for lung cancer.

Our laboratory recently identified a novel long noncoding RNA termed CyKILR that has two splice variants with distinct cellular localizations and opposing roles in tumorigenesis. The cytoplasmic variant, CyKILRb (exon 3 exclusion), promotes tumorigenesis, whereas the nuclear variant, CyKILRa (exon 3 inclusion), functions as a tumor suppressor. In this study, the molecular mechanism of the tumorigenic role of CyKILRb was characterized. Specifically, deep RNA sequencing analysis revealed that CyKILRb regulated the PI3K/AKT signaling pathway to block downstream tumor suppressors. In particular, downregulation of CyKILRb induced the loss of PIK3R2, an activator of PI3K, as well as RPS6KB2 and GNB2, two implicated tumor promotors, with a concomitant increase in the tumor suppressors, CDKN1A (p21) and CDKN1B (p27). In contrast, CyKILRb ectopic expression produced the opposite effect, and suppression of either PIK3R2, PI3K or AKT attenuated CyKILRb-induced cell proliferation and clonogenic survival. CyKILRb negatively regulated CyKILRa expression, which was blocked by inhibition of either PI3K or AKT. PIK3R2 ectopic expression overcame the cellular effects of CyKILRb downregulation, but not PI3K or AKT inhibition orienting the signaling pathway from CyKILRb[->]{uparrow}PIK3R2[->]PI3K[->]AKT[->]{downarrow}CyKILRa[->]enhanced oncogenicity. These findings highlight the critical role of CyKILRb in tumorigenesis and define a novel feed-forward regulatory mechanism linked to alternative RNA splicing.

BackgroundButyrophilins (BTNs) are immunoglobulin superfamily proteins involved in immune regulation. Among them, BTNL9 has unique structural features, including a bZIP-like domain, suggesting a potential transcriptional role. While BTNL9 is known to suppress T cell activation, its function in cancer remains largely unexplored. Recent studies suggest it may inhibit tumor progression and correlate with improved prognosis in multiple cancers. However, its molecular mechanisms and regulatory impact on lung cancer remain unclear. This study investigates the role of BTNL9 as a transcription factor and its implications for tumor progression and therapy. MethodsChIP-seq identified BTNL9-binding sites, followed by RNA-seq to assess transcriptomic profiles and validated by western blot. Drug sensitivity was evaluated through cytotoxicity assays. A xenograft model was applied to assess the effect of BTNL9 on tumor growth. TCGA data analysis examined correlations with survival, cell cycle regulators, and immune infiltration. ResultsChIP-seq identified 26,610 BTNL9 binding peaks, mapping to 9,707 genes near transcription start sites. RNA-seq and western blotting showed BTNL9 regulates cell cycle (E2F1, CDKN1A, CDK1, CDC25C, FOXM1), DNA replication (MCM2/3/7, ORC6), and p53-related transcription (BBC3, GADD45A). Integrative analysis found that 74.8% of differentially expressed genes were directly regulated by BTNL9. Functionally, BTNL9 overexpression induced cell cycle arrest, reduced proliferation, and suppressed tumor growth in vivo. BTNL9 enhanced bortezomib sensitivity in both A549 and NCI-H460 cells, with etoposide effects being more pronounced in A549. Higher BTNL9 levels strongly suppressed the expression of FOXM1, CDC25C, CDK1, CDK2, CCNA2 and CCNB1 and negatively correlated with these markers in LUAD TCGA data. Elevated BTNL9 expression was associated with improved survival, complete remission, and increased immune infiltration, including macrophages, CD8+ T cells, NK cells, and B cells in cancer tissues. ConclusionsBTNL9 functions as a transcription factor, suppresses tumor growth, and enhances drug sensitivity. Its correlation with survival and immune infiltration suggests potential role as a tumor suppressor and predictive biomarker for chemotherapy response.

Breast, lung, and colorectal cancer resistance to molecular targeted therapy is a major challenge and unfavorably impacts clinical outcomes, leading to hundreds of thousands of deaths yearly. In ERBB2+ cancers regardless of the tissue of origin, ERBB2 is the driver oncogene of resistance. We discovered that the ERBB2+ cancers are enriched with poly U sequences on their 3UTR AU rich elements which are mRNA stabilizing sequences. We developed a novel technology, in which we engineered these ERBB2 mRNA stabilizing sequences to unstable forms and specifically controlled and degraded ERBB2 transcript and protein across multiple cancer types both in the wildtype and drug resistance settings in vitro and in vivo, offering a unique novel modality to control ERBB2 and other pervasive oncogenic signals where other therapies fail. One-Sentence SummaryEngineered destabilized 3UTR ARE of ERBB2 degrades ERBB2 in many cancer types and controlled resistance. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=163 SRC="FIGDIR/small/503914v1_ufig1.gif" ALT="Figure 1"> View larger version (34K): org.highwire.dtl.DTLVardef@139d8dborg.highwire.dtl.DTLVardef@cc1fd3org.highwire.dtl.DTLVardef@13d9086org.highwire.dtl.DTLVardef@db69bf_HPS_FORMAT_FIGEXP M_FIG A. Depiction represents multiple ERBB2 expressing cancer cells with stable 3UTR ARE and the signaling cascade known to cause chemo resistance. B. Depiction of the engineered destabilized 3UTR ARE of ERBB2 and the destabilization and degradation of the ERBB2 transcript, protein and kinases involved in mediation of drug resistance C_FIG

Non-small cell lung cancer (NSCLC) accounts for 80-85% cases of lung cancer cases. Diagnosis at advanced stages is common, after which therapy-refractory disease progression frequently occurs. Therefore, a better understanding of the molecular mechanisms that control NSCLC progression is necessary to develop new therapies. Overexpression of I{kappa}B kinase (IKK) in NSCLC correlates with poor patient survival. IKK is an NF-{kappa}B-activating kinase that is important in cell survival and differentiation, but its regulation of oncogenic signaling is not well understood. We recently demonstrated that IKK promotes NSCLC cell migration by physically interacting with dopamine- and cyclic AMP-regulated phosphoprotein, Mr 32000 (DARPP-32), and its truncated splice variant, t-DARPP. Here, we show that IKK phosphorylates DARPP-32 at threonine 34, resulting in DARPP-32-mediated inhibition of protein phosphatase 1 (PP1), subsequent PP1-mediated dephosphorylation of ERK, and activation of ERK signaling to promote lung oncogenesis. Correspondingly, DARPP-32 ablation in human lung adenocarcinoma cells reduced their anchorage-independent growth in soft agar. Mice challenged with IKK-ablated HCC827 cells exhibited less lung tumor growth than mice orthotopically administered control HCC827 cells. Our findings suggest that IKK drives NSCLC growth through activation of ERK signaling via DARPP-32-mediated inhibition of PP1 activity.

Adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with poor prognosis and limited therapies. To elucidate its post-transcriptional regulation, ceRNA networks were reconstructed from TCGA-ACC and GTEx 2025 data. Tumor networks exhibited compact topology and tumor-specific hub miRNAs (miR-466, miR-940, miR-507), which were downregulated, inversely correlated with oncogenic transcripts, and associated with adverse survival. Candidate targets were identified through dual validation by miRTarBase and miRDB, further confirmed with TargetScan, and filtered for inverse correlation, significant upregulation in tumors, and treatment-response association. The intersection of these stringent layers yielded four robust oncogenic biomarkers; CKS2, ERP44, ERG28, and FAM32A that were consistently upregulated and annotated to key processes: chromatin remodeling and cell cycle control (CKS2), apoptosis regulation (FAM32A), ER proteostasis and redox balance (ERP44), and sterol biosynthesis (ERG28). Network analysis highlighted CKS2 as central PPI hubs. Prognostic modeling demonstrated strong survival divergence, with CKS2 conferring the highest risk (HR = 4.49, p = 1.1e-06), while integration of the four-gene panel achieved near-perfect classification accuracy (AUC = 0.99). Collectively, these findings define CKS2, ERP44, ERG28, and FAM32A as high-confidence biomarkers in ACC, derived through multi-layered overlap filtering, and underscore their diagnostic and prognostic relevance.

BackgroundTriple-Negative Breast Cancer (TNBC), which lacks estrogen receptor, progesterone receptor and HER2 expression, has limited effective therapeutic options and unfavorable prognosis. Nicotinamide (NAM), a form of vitamin B3, has shown anti-tumor effects in TNBC, but the underlying regulatory mechanisms remains unclear. MethodsTranscriptomic and proteomic data from TNBC cell lines (BT20, MDA-MB-231, and MDA-MB-468) were analyzed using the ARACNe and VIPER/metaVIPER algorithms to infer regulatory activity and construct gene networks. Differentially expressed genes (DEGs) and proteins (DEPs) were integrated with regulator activity to identify key molecular drivers. Clinical outcomes were assessed using bc-GenExMiner and Kaplan- Meier Plotter, correlation and enrichment analyses were employed ICGC datasets and KEGG pathway mapping. ResultsNAM treatment induced distinct but overlapping regulatory activity profiles among TNBC cell lines, with PHGDH, TSPAN1, TACSTD2, and OSBPL6 emerging as shared regulators. Among these, PHGDH, a key enzyme in the serine biosynthesis pathway, showed consistent downregulation across datasets and was associated with poor overall survival (p< 0.001). Correlation analysis across three ICGC cohorts identified 384 genes significantly associated with PHGDH, enriched in Glycine, serine and threonine metabolicpathways. Network analysis revealed potential interactions between PHGDH, ERBB3 and other regulatory proteins, suggesting crosstalk between metabolic and signaling pathways. ConclusionsThis multi-omics integration highlights PHGDH as a central metabolic regulator linking transcriptional and translational responses to NAM treatment in TNBC. These findings support PHGDH as a potential biomarker and therapeutic target, emphasizing the role of metabolic regulation in TNBC progression and treatment response.

Epidermal growth factor receptor (EGFR) signaling is frequently dysregulated in various cancers. The ubiquitin ligase Cbl (Casitas B-lineage lymphoma proto-oncogene) regulates degradation of activated EGFR through ubiquitination and acts as an adaptor to recruit proteins required for trafficking. We used Stable Isotope Labeling with Amino Acids in Cell Culture (SILAC) mass spectrometry (MS) to compare Cbl complexes with or without epidermal growth factor (EGF) stimulation. We identified over a hundred novel Cbl interactors, and a secondary siRNA screen found that knockdown of Flotillin-2 (FLOT2) led to increased phosphorylation and degradation of EGFR upon EGF stimulation in HeLa cells. In PC9 and H441 cells, FLOT2 knockdown increased EGF-stimulated EGFR phosphorylation, ubiquitination, and downstream signaling, reversible by the EGFR inhibitor erlotinib. CRISPR knockout (KO) of FLOT2 in HeLa cells confirmed EGFR downregulation, increased signaling, and increased dimerization and trafficking to the early endosome. FLOT2 interacted with both Cbl and EGFR. EGFR downregulation upon FLOT2 loss was Cbl-dependent, as co-knockdown of Cbl and Cbl-b restored EGFR levels. Overexpression of FLOT2 decreased EGFR sjgnaling and growth. Overexpression of wild type (WT) FLOT2, but not the soluble G2A FLOT2 mutant, inhibited EGFR phosphorylation upon EGF stimulation in HEK293T cells. FLOT2 loss induced EGFR-dependent proliferation and anchorage-independent growth. Lastly, FLOT2 KO increased tumor formation and tumor volume in nude mice and NSG mice, respectively. These data demonstrated that FLOT2 negatively regulated EGFR activation and dimerization, as well as its subsequent ubiquitination, endosomal trafficking, and degradation, leading to reduced proliferation in vitro and in vivo.

Clinical responses to EGFR tyrosine kinase inhibitors are restricted only to tumors harboring specific activating mutations and even then, not all tyrosine kinase inhibitors provide clinical benefit. We here show that the addition of EGFR-TKIs results in a strong and rapid intracellular accumulation of the protein. However, this accumulation was observed only in the context of a combination of a TKI-sensitive mutation with a clinically effective TKI: TKI-insensitive mutations did not show this accumulation nor did clinically ineffective TKIs induce accumulation. All TKIs effectively inhibited EGFR phosphorylation and downstream pathway activation, irrespective of the mutation present in EGFR. The discrepancy between molecular activity of TKIs and their efficacy in patients therefore is mimicked by the mutation- and TKI-specificity of intracellular accumulation. Using this intracellular accumulation as assay, we were able to predict response to gefitinib in a panel of cell-lines (harboring different EGFR mutations) and predicted clinical benefit to EGFR TKIs on a cohort of unselected pulmonary adenocarcinoma patients (hazard ratio 0.21, P=0.0004). Even in patients harboring rare mutations with unknown TKI-sensitivity, intracellular accumulation was predictive of the clinical response. The intracellular accumulation depended on a continued presence of TKI indicating that TKIs exert a continued effect on the protein even after its dephosphorylation. It is therefore possible that accumulation is caused by conformational changes induced by both the mutation and the TKI and this change induces a block in intracellular trafficking. Interestingly, intracellular accumulation was observed independent of the genetic background of the cell, indicating that accumulation is almost entirely dictated by the combination of mutation and TKI. Our results therefore suggest that TKI-sensitivity is tumor-type independent.

We identified a germline TP53 c.758C>T (p.T253I) mutation in the TP53 tumor suppressor gene in a pediatric adrenocortical carcinoma (ACC) patient. Characteristic to pathogenic p53 mutations, we observed upregulation of total p53 protein levels in the patients ACC and concurrent suppression of the wild-type (WT) TP53 allele. As ACC can be associated with Li-Fraumeni Syndrome (LFS) and the mutation has not yet been linked to LFS, we sought to characterize the functionality of the T253I mutation. We acquired p53-/- HEK293 cells and stably transduced them with GFP-tagged wild type (T253) or T253I p53 as well as two established pathogenic p53 mutants (C176Y and R213X). Compared to p53 WT, levels of T253I p53 increased while MDM2 levels decreased, suggesting a loss of MDM2-mediated regulation of T253I p53. Additionally, T253I showed a reduction in DNA damage responsive events, diminished DNA binding capabilities, and blunted transactivation capacity. These experimental data lead us to conclude that T253I represents a pathologic variant in TP53 that may predispose to LFS-associated tumors.

The PI3K-AKT-MTOR signalling axis is pivotal in regulating cell survival, proliferation, and growth. TSC2 (tuberous sclerosis complex subunit 2) is a well-established negative regulator of this pathway, which primarily acts by suppressing the MTORC1 activity. While the cytoplasmic role of TSC2 is well characterized, emerging evidence suggests its additional nuclear functions. Previous work from our laboratory identified TSC2 as a transcriptional repressor of the EREG (Epiregulin) gene. Building on this foundation, the present study investigates the transcriptional role of TSC2 in miRNA (microRNA) gene regulation. A genome-wide miRNA microarray profiling of TSC2-depleted cells from an oral squamous cell carcinoma (OSCC) cell line, SCC131, identified 19 upregulated and 24 downregulated miRNAs. Of them, miR-514b-3p emerged as one of the most significantly upregulated miRNAs. TSC2 knockdown resulted in robust miR-514b-3p upregulation, whereas TSC2 overexpression suppressed its expression. Moreover, TSC2 negatively regulates MIR514B promoter activity in an NLS-dependent manner. The chromatin immunoprecipitation analysis showed direct binding between TSC2 and MIR514B promoter, establishing miR-514b-3p as a transcriptional target of TSC2. We further identified TSPAN9 (Tetraspanin 9) as a direct downstream target of miR-514b-3p. The dual-luciferase reporter assay and Western blot analysis confirmed direct interaction between miR-514b-3p and TSPAN9 3UTR. Furthermore, TSC2 positively regulates TSPAN9 levels by repressing miR-514b-3p, thereby establishing a novel TSC2-miR-514b-3p-TSPAN9 regulatory axis. Additionally, we uncovered crosstalk between TSC2-miR-514b-3p-TSPAN9 axis and the canonical PI3K-AKT-MTOR signalling, where miR-514b-3p positively, and TSPAN9 negatively regulates the PI3K-AKT-MTOR pathway. Interestingly, AKT functions as an upstream regulator of this axis by modulating TSC2 nuclear localization. Collectively, this study provides new insights into the non-canonical, nucleus-dependent transcriptional functions of TSC2, thus expanding its role beyond cytoplasmic signalling regulation and underscoring its significance in the cellular signalling networks.

1.Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality, driven by tumor heterogeneity, metastasis, and therapeutic resistance. While Rho GTPases are well-established regulators of oncogenic processes, the role of the atypical GTPases in NSCLC remains unexplored. Here, we identified RHOV as one of the commonly upregulated Rho GTPases in NSCLC. Analysis of four independent patient cohorts revealed that elevated RHOV expression serves as a robust and independent prognosticator of NSCLC patients specifically early-stage disease. Functionally, RHOV knockdown significantly inhibited cell proliferation, whereas its overexpression enhanced proliferation. Similarly, RHOV depletion suppressed cell migration by disrupting cytoskeletal dynamics, while its overexpression promoted migratory capacity. Mechanistically, we demonstrated that RHOV is a direct transcriptional target of the TGF{beta}-SMAD3 signaling pathway. RNA-seq analysis identified MYC as a critical downstream mediator of RHOV; RHOV knockdown reduced MYC expression, impairing mitochondrial oxidative phosphorylation and inducing ROS-mediated DNA damage--a phenotype rescued by MYC overexpression. Furthermore, RHOV inhibition sensitized NSCLC cells to etoposide but not doxorubicin. immunoprecipitation coupled with LC-MS revealed PEAK1 as a key interactor of RHOV. The RHOV-PEAK1 complex proved essential for NSCLC proliferation, as PEAK1 silencing abolished RHOV- driven MYC upregulation and tumor growth. This axis sustains MYC levels and activates PI3K/MAPK signaling. Intriguingly, PEAK1 depletion elevated TGF-{beta} levels, which suppressed RHOV expression, establishing a negative feedback loop wherein PEAK1 maintains RHOV by inhibiting TGF-{beta} signaling. Collectively, our findings establish RHOV as a prognostic biomarker and a driver of NSCLC progression via the RHOV-PEAK1-MYC axis, highlighting its potential as a therapeutic target. HighlightsO_LIRHOV upregulation predicts poor NSCLC survival, particularly in early-stage disease. C_LIO_LIThe RHOV-PEAK1 interaction is crucial for NSCLC growth and cell migration. C_LIO_LIRHOV inhibition sensitizes NSCLC cells to Etoposide treatment. C_LIO_LIRHOV expression is sustained via a PEAK1-TGF{beta} negative feedback loop. C_LI

ObjectivePFKP (Phosphofructokinase, Platelet Type isoform), as an essential metabolic enzyme, contributes to the high glycolysis rates seen in cancers, while its role in oncogenic pathways, especially from a non-metabolic aspect, is not fully understood. MethodsHere we performed a comprehensive analysis of published RNA-seq, microarray data, and immunohistochemistry of tissue microarray to evaluate the significance of PFKP expression in non-small cell lung cancer (NSCLC). Functionally, we tested the cell proliferation, colony formation, invasion, and migration upon PFKP knockdown in lung cancer cells. Mechanistically, we performed RNA-seq, DIA-mass spectrum, western blot, and qPCR to probe the change of cell signaling pathways upon PFKP silencing. Co-immunoprecipitation and mass spectrum were used to uncover potential PFKP interacting proteins. ResultsWe found that PFKP was highly expressed in NSCLC and was related to poor patient survival. Knockdown of PFKP significantly inhibited cell proliferation, colony formation, invasion, and migration of NSCLC cells. Mechanistically, we found that PFKP can directly bind with AXL and promote its phosphorylation at Y779, thus activating the AXL signaling pathway and promoting MET phosphorylation. In addition, several glycolysis, glutaminolysis, and TCA cycle proteins were downregulated following PFKP silencing. ConclusionsThese data demonstrate that PFKP, beyond its known role in glycolysis, also has a distinct non-metabolic function in affecting lung cancer progression by directly interacting with the AXL-MET axis, thus indicating a potential therapeutic target for lung cancer.

Breast cancer is a heterogeneous disease that can be molecularly classified based on the expression of hormone receptors and the overexpression of the HER2 receptor (ERBB2). Targeted therapies for HER2-positive breast cancer, including trastuzumab, antibody drug conjugates (ADCs) and tyrosine kinase inhibitors, have significantly improved patient outcomes. However, both primary and acquired resistance to these treatments pose challenges that can limit their long-term efficacy. Addressing these obstacles is vital for enhancing therapeutic strategies and patient care. Alternative splicing, a post-transcriptional mechanism that enhances transcript diversity (isoforms) within a cell, can result in isoform-encoded proteins with varied functions, cellular localizations, or binding properties. In this study, we undertook a comprehensive characterization of the alternative splicing isoforms of HER2, assessed their expression levels in primary breast tumors and cell lines, and explored their role in resistance to anti-HER2 therapies. Our results have significantly expanded the catalog of known HER2 protein-coding isoforms from 13 to 90, revealing distinct patterns of protein domains, cellular localization, and protein structures, as well as mapping their antibody-binding sites. Additionally, by profiling expression in 561 primary breast cancer samples and analyzing mass spectrometry data for translation evidence, we discovered a complex landscape of splicing isoform expression in primary tumors, revealing novel isoforms that were previously unrecognized and are not evaluated in routine clinical practice. This extends beyond the traditional profile based solely on HER2 gene expression and translation. Finally, by assessing HER2 isoform expression in cell cultures that are either sensitive or resistant to trastuzumab and ADCs (T-DM1 or T-DXd), we found that drug-resistant tumor cells shifted their expression toward splicing isoforms that lack the antibody-binding domains. Our results substantially broaden the understanding of HER2 protein-coding isoforms, revealing distinct mechanisms of potential resistance to anti-HER2 therapies, particularly ADCs, by uncovering a new dimension of splicing isoform diversity. This expanded landscape of HER2 isoforms, marked by unique domain patterns and altered antibody-binding sites, emphasizes the crucial role of alternative splicing investigations in advancing precision-targeted cancer therapies.

We previously reported that differential protein degradation of TKI-sensitive [L858R, del(E746-A750)] and resistant (T790M) epidermal growth factor receptor (EGFR) mutants upon erlotinib treatment correlates with drug sensitivity. However, the molecular mechanism remains unclear. We also reported SMAD ubiquitination regulatory factor 2 (SMURF2) ligase activity is important in stabilizing EGFR. Here, using in vitro and in vivo ubiquitination assays, mass spectrometry, and super-resolution microscopy, we show SMURF2-EGFR functional interaction is critical in receptor stability and TKI sensitivity. We found that L858R/T790M EGFR is a preferred substrate of SMURF2-UBCH5 (an E3-E2) complex-mediated K63-linked polyubiquitination, which preferentially stabilizes mutant receptor. We identified four lysine (K) residues (K721, 846, 1037 and 1164) as the sites of ubiquitination and replacement of K to acetylation-mimicking asparagine (Q) at K1037 position in L858R/T790M background converts the stable protein sensitive to erlotinib-induced degradation. Using STochastic Optical Reconstruction Microscopy (STORM) imaging, we show that SMURF2 presence allows longer membrane retention of activated EGFR upon EGF treatment, whereas, siRNA-mediated SMURF2 knockdown fastens receptor endocytosis and lysosome enrichment. In an erlotinib-sensitive PC9 cells, SMURF2 overexpression increased EGFR levels with improved erlotinib tolerance, whereas, SMURF2 knockdown decreased EGFR steady state levels in NCI-H1975 and PC9-AR cells to overcome erlotinib and AZD-9291 resistance respectively. Additionally, by genetically altering the SMURF2-UBCH5 complex formation destabilized EGFR. Together, we propose that SMURF2-mediated preferential polyubiquitination of L858R/T790M EGFR may be competing with acetylation-mediated receptor internalization to provide enhanced receptor stability and that disruption of the E3-E2 complex may be an attractive alternate to overcome TKI resistance.

The balance of protein phosphorylation is often disrupted in cancer, with hyperactivity of kinases and inactivation of phosphatases driving cell proliferation and survival pathways. PTPRH, a protein tyrosine phosphatase, is mutated in [~]5% of non-small cell lung cancers (NSCLC). However, how PTPRH contributes to biological processes and tumorigenesis was unknown. We uncovered PTPRHs candidate interactors and associated pathways by applying a proximity-dependent biotinylation assay (BioID) and generating a signature transcriptome in two NSCLC cell lines derived from the primary tumor (NCI-H23) or a metastatic site (NCI-H2023), followed by functional validation. Candidate interactors included signaling molecules and structural proteins linked to integrins and focal adhesions, adherens junctions, migration, and the cytoskeleton, in addition to interactions with the receptor tyrosine kinases EGFR, EPHA2, and ROR2, and the phosphatases PTPN3 and PTPRJ. Considering the importance of EGFR in lung cancers and the role of EPHA2 in regulating cell adhesion, we examined how PTPRH regulates their signaling. Overexpression of PTPRH decreased EGFR phosphorylation at tyrosine 1173. It also reduced phospho-EPHA2, with one of the target tyrosine residues identified as the ligand-dependent Y588. At the cellular level, PTPRH and EPHA2 colocalize, with PTPRH gain inducing morphological alterations, such as increased eccentricity, smaller size and changes in the cytoskeleton organization in NCI-H23 cells. These changes are accompanied by increased FAK Y397 phosphorylation, but reduced cell adhesion to the ECM. Additionally, pathway enrichment analysis revealed downregulation of multiple oncogenic, metabolic, and cell adhesion signaling pathways, with increased levels of PTPRH leading to reduced migration in vitro, suppressed tumor growth and lung colonization and tumor differentiation in vivo. Interestingly, some alterations may be independent of PTPRH catalytic activity and tailored to a cell lines site of origin and genetic background. These results indicate that PTPRH regulates key signaling, structural networks, and tumor behavior with loss facilitating NSCLC progression.

Objective: Tumor protein D52 (TPD52) is aberrantly expressed in various malignancies; however, its systematic expression profile, prognostic significance, tumor microenvironment associations, and functional mechanisms in breast cancer remain poorly defined. Methods: GEO and TCGA breast cancer expression datasets were integrated to identify differentially expressed genes (DEGs). We evaluated the diagnostic performance of TPD52 via protein-protein interaction (PPI) network analysis, GO/KEGG enrichment analysis and eleven machine learning algorithms. Immunohistochemistry verified TPD52 protein expression in clinical specimens, and Kaplan-Meier analysis assessed its prognostic significance. Analysis of single-cell transcriptomic data (GSE176078) revealed the cell-type-specific distribution of TPD52 and its intercellular communication network in the breast cancer microenvironment. Weighted gene co-expression network analysis (WGCNA) explored relationships between TPD52 and tumor microbiome, hypoxia signatures as well as microsatellite instability. Moreover, TPD52 was knocked down by siRNA in MCF7 cells, and its impacts on cell migration, invasion, proliferation and the MAPK/ERK signaling pathway were examined through wound healing, Transwell, CCK-8 and Western blot assays. Results: TPD52 was significantly overexpressed in breast cancer tissues at both the mRNA and protein levels. A random forest-based diagnostic model demonstrated high accuracy across multiple datasets. Kaplan-Meier analysis revealed that elevated TPD52 expression was associated with longer overall survival in specific subgroups, including the basal-like subtype, invasive lobular carcinoma, and N0/N1 stages. Single-cell analysis showed that TPD52 was predominantly expressed in tumor epithelial cells, which occupied a central position within the intercellular communication network. WGCNA further identified a positive correlation between TPD52 and a hypoxia-associated microbial module, as well as a negative correlation with a microsatellite instability module. In vitro functional assays confirmed that TPD52 knockdown significantly suppressed the migration, invasion, and proliferation of MCF7 cells, and led to reduced p-ERK1/2 protein levels. Conclusion: TPD52 promotes the malignant phenotypes of breast cancer cells through activation of the MAPK/ERK signaling pathway, yet its prognostic significance is subtype- and microenvironment-dependent. These findings establish TPD52 as both a diagnostically valuable biomarker and a mechanistically defined potential therapeutic target.

Large-scale sequencing studies on glioblastoma have identified numerous genetic alterations. Leucine-zipper-like transcription regulator 1 (LZTR1) is inactivated by non-synonymous mutations and copy number losses, suggesting that it is a tumor suppressor in glioblastoma. However, how LZTR1 mutations contribute to glioblastoma pathogenesis remains poorly understood. Here, we revealed that LZTR1, as an adaptor of the CUL3 E3 ubiquitin ligase complex, recognizes and triggers ubiquitin-dependent degradation of oncoprotein RIT1, a RAS-like GTPase. Wild-type LZTR1 suppresses glioblastoma cell proliferation and migration by inactivating the MAPK/ERK signaling pathway in a RIT1-dependent manner. However, the effects were abrogated by the glioblastoma-associated LZTR1 mutations. Our findings revealed the underlying molecular mechanism of LZTR1 mutations-driven glioblastoma, and provide novel therapeutic target for LZTR1 mutations-driven glioblastoma.