Putative Tumor Suppressor Research Articles

Reversible role of MIR654/3P and MIR9/3P in pathogenesis of Epstein-Barr Virus negative, but not positive, Burkitt's lymphoma.

The role of MIR654 in Burkitt's lymphoma (BL) and whether it impacts expression of MYC, and its downstream activated MIR9 is not known. Expression of MYC, MYCN, MYCL, MIR9/3P, MIR654/5P, and MIR654/3P were assessed by qRT-PCR in biopsy samples from Epstein-Barr virus (EBV)- and EBV+ BL patients and BL cell lines. Effects of modulation of MIR9/3P and MIR654/3P on cell proliferation, apoptosis and chemosensitivity were evaluated. Luciferase reporter assay was performed to validate putative target of MIR654/5P. Effects of MIR9/3P and MIR654/3P on tumor burden and disease outcome were evaluated using xenograft model of BL. Expression of MYC, MYCN, and MIR9/3P was higher in all BL patient samples and cell lines. Expression of MIR654/3P was downregulated in EBV- BL patient samples and cell lines compared to either noncancer lymphoid reactive hyperplasia (LRH) or EBV+ samples and cell lines. Additionally, MIR654/3P overexpression inhibited cell proliferation, induced apoptosis, and increased chemosensitivity in EBV- BL cell lines. Luciferase reporter assay confirmed that MYC is a target of MIR654/3P in both EBV- and EBV+ BL cell lines; however, the effect of MIR654/3P-mediated targeting of MYC is overridden in EBV+ cells. Administration of MIR654/3P mimic or MIR9/3P antagomir in the xenograft model decreased tumor burden and increased survival. Combined intervention with MIR654/3P mimic and MIR9/3P antagomir had synergistic action on decreasing tumor burden and improving disease outcome. MIR654/3P, as a putative tumor suppressor in EBV- BL, collaborated MIR9/3P might serve as a therapeutic agent to treat EBV- BL patients in combination with existing chemotherapy and immunotherapy regimes.

ARHGAP26 deficiency drives the oocyte aneuploidy and early embryonic development failure.

Aneuploidy, the presence of a chromosomal anomaly, is a major cause of spontaneous abortions and recurrent pregnancy loss in humans. However, the underlying molecular mechanisms still remain poorly understood. Here, we report that ARHGAP26, a putative tumor suppressor gene, is a newly identified regulator of oocyte quality to maintain mitochondrial integrity and chromosome euploidy, thus ensuring normal embryonic development and fertility. Taking advantage of knockout mouse model, we revealed that genetic ablation of Arhgap26 caused the oocyte death at GV stage due to the mitochondrial dysfunction-induced ROS accumulation. Lack of Arhgap26 also impaired both in vitro and in vivo maturation of survived oocytes which results in maturation arrest and aneuploidy, and consequently leading to early embryonic development defects and subfertility. These observations were further verified by transcriptome analysis. Mechanistically, we discovered that Arhgap26 interacted with Cofilin1 to maintain the mitochondrial integrity by regulating Drp1 dynamics, and restoration of Arhgap26 protein level recovered the quality of Arhgap26-null oocytes. Importantly, we found an ARHGAP26 mutation in a patient with history of recurrent miscarriage by chromosomal microarray analysis. Altogether, our findings uncover a novel function of ARHGAP26 in the oocyte quality control and prevention of aneuploidy and provide a potential treatment strategy for infertile women caused by ARHGAP26 mutation.

Functional Analysis of RE1 Silencing Transcription Factor as a Putative Tumor Suppressor in Human Endometrial Cancer.

Uterine cancer is the most common gynecologic malignancy in the United States, with endometrioid endometrial adenocarcinoma (EC) being the most common histologic sub-type. Considering the molecular classifications of EC, efforts have been made to identify additional biomarkers that can assist in diagnosis, prognosis, and individualized therapy. We sought to explore the relationship of Repressor Element 1 (RE1) silencing transcription factor (REST), which downregulates neuronal genes in non-neuronal tissue, along with matrix metalloproteinase-24 (MMP24) and EC. We analyzed the expression of REST and MMP24 in 31 cases of endometrial cancer and 16 controls. We then explored the baseline expression of REST and MMP24 in two EC cell lines (Ishikawa and HEC-1-A) compared to a benign cell line (t-HESC) and subsequently evaluated proliferation, migration, and invasion in the setting of loss of REST gene expression. REST and MMP24 expression were significantly lower in human EC samples compared to control samples. REST was highly expressed in EC cell lines, but decreasing REST gene expression increased proliferation (FC: 1.13X, p < 0.0001), migration (1.72X, p < 0.0001), and invasion (FC: 7.77X, p < 0.05) in Ishikawa cells, which are hallmarks of cancer progression and metastasis. These findings elicit a potential role for REST as a putative tumor suppressor in EC.

ADCY5 act as a putative tumor suppressor in glioblastoma: An integrated analysis

BackgroundAdenylyl cyclase (AC) isoforms played a key role in the multiple cancer pathology, However, the expression, prognostic value and function of ADCY5 in Glioblastoma (GBM) have not been reported yet. This research intends to discover the expression, epigenetic alteration and biological function of ADCY5 in GBM and its value on patients' prognosis. Methods① Transcriptional level, epigenetic alteration, prognostic value and molecular network of ADCY5 were analyzed by using of public online datasets. ② The mRNA expression profile of ADCY5 was explored by using GEPIA database and protein expression levels were detected by HPA Database. ③ The prognostic value of ADCY5 was determined by Kaplan-Meier Plotter, GEPIA and CGGA database. ④ The epigenetic characteristics of ADCY5 were determined by DiseaseMeth database. ⑤ Identification of genes co-expressed with ADCY5 and potential mechanism analyses were performed by using DAVID cBioPorta and STRING. ⑥ Reverse transcription-polymerase chain reaction (RT-PCR), cell counting kit-8 (CCK-8), colony formation, wound-healing scratch and transwell assay were applied to detect relative mRNA expression and biological function of ADCY5 in GMB cells. ResultsADCY5 mRNA and protein were downregulated in GBM compared with normal tissues. Analysis of the genetics and epigenetics of ADCY5 suggested that its expression was negatively correlated with DNA methylation. High expression of ADCY5 was significantly associated with age, grade, IDH mutation, 1p19q_codeletion, radiotherapy and chemotherapy and acted as an independent prognostic factor in GBM. ADCY5 mRNA also down-expressed in GBM cell lines and re-expressed of ADCY5 could inhibit cell proliferation, viability, migration/invasion and epithelial-mesenchymal transition (EMT) in vitro. In the analysis of genes co-expressed with ADCY5, we found that cAMP/AKT pathway, cGMP-PKG pathway, Wnts pathway were dissimilarly enriched. ConclusionOur study indicated that ADCY5 could act as an epigenetic biomarker in GBM, as well as a prognosis target in patients with GBM.

Cornulin as a Key Diagnostic and Prognostic Biomarker in Cancers of the Squamous Epithelium.

The prevalence of squamous cell carcinoma is increasing, and efforts that aid in an early and accurate diagnosis are crucial to improve clinical outcomes for patients. Cornulin, a squamous epithelium-specific protein, has recently garnered attention due to its implications in the progression of squamous cell carcinoma developed in several tissues. As an epidermal differentiation marker, it is involved in skin anchoring, regulating cellular proliferation, and is a putative tumor suppressor. The physiologically healthy squamous epithelium displays a considerable level of Cornulin, whereas squamous cell carcinomas have marked downregulation, suggesting that Cornulin expression levels can be utilized for the early detection and follow-up on the progression of these types of cancer. Cornulin's expression patterns in cervical cancer have been examined, and findings support the stepwise downregulation of Cornulin levels that accompanies the progression to neoplasia in the cervix. Additional studies documented a similar trend in expression in other types of cancer, such as cutaneous, esophageal, and oropharyngeal squamous cell carcinomas. The consistent and predictable pattern of Cornulin expression across several squamous cell carcinomas and its correlation with key clinicopathological parameters make it a reliable biomarker for assessing the transformation and progression events in the squamous epithelium, thus potentially contributing to the early detection, definitive diagnosis, and more favorable prognosis for these cancer patients.

Epigenetic identification of LTBP4 as a putative tumor suppressor in breast cancer.

Aim: To explore the LTBP4's expression, prognostic significance and molecular mechanism of action in breast cancer (BC).Methods: On the basis of omics datasets and experiments, we conducted a synthetical analysis of LTBP4 in BC.Results & conclusion: LTBP4 was downregulated in BC with high promoter methylation and low genetic alteration. DNA methylation was negatively associated with LTBP4 mRNA expression. Higher LTBP4 associated with better survival. LTBP4 was enrichment in extracellular matrix receptor interactions, cell adhesion molecules, cell cycle and MAPK pathway.LTBP4 expression and methylation were positively and negatively associated with tumor infiltrating immune cells, respectively. In conclusion, LTBP4 is a putative tumor suppressor in BC, which expression is regulated by DNA methylation and relates with prognosis.

Multilevel Regulation of NF-κB Signaling by NSD2 Suppresses Kras-Driven Pancreatic Tumorigenesis.

Pancreatic ductal adenocarcinoma (PDAC) is a clinically challenging cancer with a dismal overall prognosis. NSD2 is an H3K36-specific di-methyltransferase that has been reported to play a crucial role in promoting tumorigenesis. Here, the study demonstrates that NSD2 acts as a putative tumor suppressor in Kras-driven pancreatic tumorigenesis. NSD2 restrains the mice from inflammation and Kras-induced ductal metaplasia, while NSD2 loss facilitates pancreatic tumorigenesis. Mechanistically, NSD2-mediated H3K36me2 promotes the expression of IκBα, which inhibits the phosphorylation of p65 and NF-κB nuclear translocation. More importantly, NSD2 interacts with the DNA binding domain of p65, attenuating NF-κB transcriptional activity. Furthermore, inhibition of NF-κB signaling relieves the symptoms of Nsd2-deficient mice and sensitizes Nsd2-null PDAC to gemcitabine. Clinically, NSD2 expression decreased in PDAC patients and negatively correlated to nuclear p65 expression. Together, the study reveals the important tumor suppressor role of NSD2 and multiple mechanisms by which NSD2 suppresses both p65 phosphorylation and downstream transcriptional activity during pancreatic tumorigenesis. This study opens therapeutic opportunities for PDAC patients with NSD2 low/loss by combined treatment with gemcitabine and NF-κBi.

Involvement of N4BP2L1, PLEKHA4, and BEGAIN genes in breast cancer and muscle cell development.

Patients with breast cancer show altered expression of genes within the pectoralis major skeletal muscle cells of the breast. Through analyses of The Cancer Genome Atlas (TCGA)-breast cancer (BRCA), we identified three previously uncharacterized putative novel tumor suppressor genes expressed in normal muscle cells, whose expression was downregulated in breast tumors. We found that NEDD4 binding protein 2-like 1 (N4BP2L1), pleckstrin homology domain-containing family A member 4 (PLEKHA4), and brain-enriched guanylate kinase-associated protein (BEGAIN) that are normally highly expressed in breast myoepithelial cells and smooth muscle cells were significantly downregulated in breast tumor tissues of a cohort of 50 patients with this cancer. Our data revealed that the low expression of PLEKHA4 in patients with menopause below 50years correlated with a higher risk of breast cancer. Moreover, we identified N4BP2L1 and BEGAIN as potential biomarkers of HER2-positive breast cancer. Furthermore, low BEGAIN expression in breast cancer patients with blood fat, heart problems, and diabetes correlated with a higher risk of this cancer. In addition, protein and RNA expression analysis of TCGA-BRCA revealed N4BP2L1 as a promising diagnostic protein biomarker in breast cancer. In addition, the in silico data of scRNA-seq showed high expression of these genes in several cell types of normal breast tissue, including breast myoepithelial cells and smooth muscle cells. Thus, our results suggest their possible tumor-suppressive function in breast cancer and muscle development.

MEF2D Functions as a Tumor Suppressor in Breast Cancer.

The myocyte enhancer factor 2 (MEF2) gene family play fundamental roles in the genetic programs that control cell differentiation, morphogenesis, proliferation, and survival in a wide range of cell types. More recently, these genes have also been implicated as drivers of carcinogenesis, by acting as oncogenes or tumor suppressors depending on the biological context. Nonetheless, the molecular programs they regulate and their roles in tumor development and progression remain incompletely understood. The present study evaluated whether the MEF2D transcription factor functions as a tumor suppressor in breast cancer. The knockout of the MEF2D gene in mouse mammary epithelial cells resulted in phenotypic changes characteristic of neoplastic transformation. These changes included enhanced cell proliferation, a loss of contact inhibition, and anchorage-independent growth in soft agar, as well as the capacity for tumor development in mice. Mechanistically, the knockout of MEF2D induced the epithelial-to-mesenchymal transition (EMT) and activated several oncogenic signaling pathways, including AKT, ERK, and Hippo-YAP. Correspondingly, a reduced expression of MEF2D was observed in human triple-negative breast cancer cell lines, and a low MEF2D expression in tissue samples was found to be correlated with a worse overall survival and relapse-free survival in breast cancer patients. MEF2D may, thus, be a putative tumor suppressor, acting through selective gene regulatory programs that have clinical and therapeutic significance.

Lung-derived soluble factors support stemness/plasticity and metastatic behaviour of breast cancer cells via the FGF2-DACH1 axis

Patients with triple-negative breast cancer (TNBC) have an increased propensity to develop lung metastasis. Our previous studies demonstrated that stem-like ALDHhiCD44+ breast cancer cells interact with lung-derived soluble factors, resulting in enhanced migration and lung metastasis particularly in TNBC models. We have also observed that the presence of a primary TNBC tumor can ‘prime’ the lung microenvironment in preparation for metastasis. In this study, we hypothesized that soluble lung-derived factors secreted in the presence of a primary TNBC tumor can influence stemness/plasticity of breast cancer cells. Using an ex vivo pulmonary metastasis assay (PuMA), we observed that the lung microenvironment supports colonization and growth of ALDHhiCD44+ TNBC cells, potentially via interactions with lung-derived FGF2. Exposure of TNBC cells to lung-conditioned media (LCM) generated from mice bearing TNBC primary tumors (tbLCM) significantly enhanced the proportion of ALDHhiCD44+ cells compared to control or LCM from tumor-naïve mice (tnLCM). Further analysis using a human cancer stem cell qPCR array revealed that, relative to tnLCM or control, exposure of TNBC cells to tbLCM leads to downregulation of the transcription factor and putative tumor suppressor Dachshund homolog 1 (DACH1), a downstream regulator of FGF2. In addition, inhibition of DACH1 using siRNA or treatment with recombinant FGF2 enhanced the ALDHhiCD44+ phenotype. Taken together, our findings suggest that the FGF2-DACH1 signaling axis supports stemness/plasticity of TNBC cells in the lung microenvironment and lays the foundation for future evaluation of FGF2 as a potential novel therapeutic target for treatment or prevention of breast cancer metastasis to the lung.

Multifaced roles of the long non-coding RNA DRAIC in cancer progression.

Long non-coding RNAs (lncRNA) are functional RNAs, with over 200 nucleotides in length and lacking protein-coding potential. Studies have indicated that lncRNAs are important gene regulators under physiological conditions. Aberrant lncRNA expression is associated with the initiation and progression of various diseases, including cancers. High-throughput transcriptome analyses have revealed thousands of lncRNAs as putative tumor suppressors or promoters in various cancers, but the detailed molecular mechanisms of each lncRNA remain unclear. Downregulated RNA In Cancer, inhibitor of cell invasion and migration (DRAIC) (also known as LOC145837 and RP11-279F6.1) is a lncRNA that inhibits or promotes cancer progression with several modes of action. DRAIC was originally identified as a tumor-suppressive lncRNA in prostate adenocarcinoma. Subsequent studies also revealed that it has an anti-tumor role in glioblastoma, triple-negative breast cancer, and stomach adenocarcinoma. However, DRAIC exhibits oncogenic functions in other malignancies, such as lung adenocarcinoma and esophageal carcinoma, indicating its highly context-dependent effects on cancer progression and clinical outcomes. DRAIC and its associated pathways regulate various biological processes, including proliferation, invasion, metastasis, autophagy, and neuroendocrine function. This review introduces the multifaceted roles of DRAIC, particularly in cancer progression, and discusses its biological significance and clinical implications.

Abstract 458: Nanoparticle-mediated delivery of miR-590-3p decreases recurrent GBM tumor growth by inhibits multiple oncogenic nodes

Abstract Glioblastoma (GBM) is the most lethal and aggressive form of brain cancer. Despite aggressive therapy consisting of surgery followed by radio/chemotherapy GBM recurs in almost all patients and, currently, there are no proven therapies to treat recurrent GBM (rGBM). Recent developments in nanomedicine provide new and promising opportunities to develop new targeted therapeutics to treat brain tumors. We have recently developed PBAE nanoparticle formulations optimized for in vivo miRNA delivery to brain tumor stem cells, or GSCs. Carefully selecting one miRNA to target several mRNAs dysregulated within a pathway can allow the targeting of multiple nodes using a single agent, mimicking combinatorial therapies. To test this hypothesis, we performed bioinformatic analysis of RNA sequencing from GSCs and clinical rGBM specimens combined with gene set enrichment analysis (GSEA) and identified TGFBR2 signaling as a targetable pathway in rGBM. We show that SMAD2 signaling, a downstream effector of TGFBR2, is enriched in rGBM and that patients with elevated TGFBR2 transcripts respond poorly to current standard of care. Utilizing patient-derived xenograft lines from rGBM, we show that blocking TGFBR2 signaling using siRNAs or ITD1, a selective TGFBR2 inhibitor, decreases the stem cell capacity, cell viability and re-sensitizes clinical rGBM cells to temozolomide (TMZ) in-vitro. In vivo, we show that ITD1 is modestly effective in subcutaneous and ineffective in orthotopic rGBM models. Not surprisingly, these tumors exhibited classical growth patterns associated with acquisition of resistance. To overcome this obstacle, we performed a miRNA-based network analysis in rGBM and identified miR-590-3p as a putative tumor suppressor that targets SMAD2 signaling at multiple nodes in rGBM. In-vitro, transgenic miR-590-3p robustly decreased the expression of 37 putative oncogenes simultaneously concurrent with decreasing stem cell capacity, cell viability and re-sensitizing rGBM PDX cells to TMZ. In vivo delivery of miR-590-3p to established PDX-derived rGBM orthotopic tumors using novel PBAE nanocarriers robustly decreased tumor sizes and increased tumor necrosis. These results show that the promiscuous nature of miRNAs, in combination with cutting-edge nucleic acid delivery vehicles, can be leveraged as advanced targeted therapeutics for rGBM bypasses the resistance that is developed to standard of care and available small molecules. Citation Format: Hernando Lopez-Bertoni, Sophie Sall, Harmon Khela, Jack Korleski, Katherine Luly, Maya Johnson, Bachchu Lal, Amanda Johnson, Stephany Tzeng, Jordan Green, John Laterra. Nanoparticle-mediated delivery of miR-590-3p decreases recurrent GBM tumor growth by inhibits multiple oncogenic nodes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 458.

Abstract 2748: Single cell biomechanical profiling of the metastatic potential of MDA-MB-231 cells

Abstract Cancer metastasis is a multistep complex process accompanied by changes in the mechanical properties of cancer cells, such as adhesion, viscoelasticity, deformability, and motility. Connexin 43 (Cx43), a gap junction protein with a putative tumor suppressor function, plays a pivotal role in Epithelial to Mesenchymal transition (EMT). It affects cell motility indicators and promotes cytoskeleton reorganization and, ultimately, metastasis when downregulated, corroborating resistance to chemotherapy. The lack of universal markers that can predict the metastatic ability of cancer cells necessitates the evaluation of parameters, such as cell adhesion, viscoelasticity, and stiffness, to serve as unique biophysical metrics that predict cancer cell metastatic potential and elucidate how metastasis and cell mechanics are coupled. Therefore, we utilized fluidic-based single-cell force spectroscopy (SCFS) and Quartz Crystal Microbalance with Dissipation Monitoring (QCM-D) to measure the mechanical properties of single cancer cells with different metastatic potential. To explore the relationship between cell mechanics and metastatic cell behavior, we quantitatively demonstrate the progression of cancer cell biomechanics across different metastatic states using MDA-MB-231 breast cancer cells with varying connexin 43 (Cx43) expression as a model of cells with varying metastatic potential. We measured, at a single-cell level and in real-time, the adhesion and viscoelastic properties of MDA-MB-231 cells and their response to chemotherapy. Our data show that cells with higher metastatic potential (down-regulated Cx43 expression) exhibited a softer, less adherent, and more viscoelastic phenotype, consistent with their metastatic state when in clusters compared to cells at the lower spectrum of metastatic potential (up-regulated Cx43 expression). These mechanical biomarkers are significantly absent in single cells outside of a cluster. Of particular interest, we also observed significant cellular stiffening upon treatment with docetaxel (DTX), a chemotherapeutic agent that targets microtubules, with a rapid and profound response of highly aggressive cells when compared to cells with attenuated metastatic potential. Such treatment schemes could render cancer cells less deformable, potentially impeding their ability to invade and metastasize to other tissues. Our study demonstrates a unique quantitative metric that unfolds biomechanical markers for discerning the metastatic state of cancer cells. Our data represents a stepping stone to understanding how mechanical changes in cancer cells may determine how cancer progresses and responds to chemotherapeutic agents and may provide novel modalities to inhibit metastasis. Citation Format: Zeina Habli, Ahmad Zantout, Nadine Al Hajj, Raya Saab, Marwan El-Sabban, Massoud L. Khraiche. Single cell biomechanical profiling of the metastatic potential of MDA-MB-231 cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2748.

Computational Analysis of Single Nucleotide Polymorphisms in Human HIC1 Gene.

Background A putative tumor suppressor gene called HIC1 (hypermethylated in cancer) is situated at 17p13.3, a locus where the allelic loss occurs often in human malignancies, including breast cancer. Hypermethylated in cancer 1 protein is a protein that in humans is encoded by the HIC1 gene and it's aHomo sapiens(Human). This gene functions as a growth regulatory and tumor repressor gene. The molecular function of HIC1 gene includes DNA-binding transcription factor activity, sequence-specific DNA binding, DNA binding, histone deacetylase binding, protein binding, metal ion binding, nucleic acid binding, DNA-binding transcription repressor activity, RNA polymerase II-specific, DNA-binding transcription factor activity, RNA polymerase II-specific. The biological process of HIC1 gene includes multicellular organism development, negative regulation of Wnt signaling pathway, positive regulation of DNA damage response, signal transduction by p53 class mediator regulation of transcription, DNA-templated, negative regulation of transcription by RNA polymerase II, Wnt signaling pathway, transcription, DNA-templated, intrinsic apoptotic signaling pathway in response to DNA damage, cellular response to DNA damage stimulus. The study aimed to predict the stability and structure of the protein that will arise from single nucleotide polymorphisms (SNPs) in the human HIC1 gene. Methodology To investigate the possible negative effects associated with these SNPs, bioinformatic analysis is typically essential. The following tools were employed for forecasting harmful SNPs: scale-invariant feature transform (SIFT), Protein Analysis Through Evolutionary Relationships (PANTHER), nonsynonymous SNP by Protein Variation Effect Analyzer (PROVEAN), and nonsynonymous SNP by Single Nucleotide Polymorphism Annotation Platform (SNAP). Results The present study identified a total of 36 SNPs using the SIFT approach, which were shown to have functional significance. Twenty-six were determined to be tolerable, whereas 10 were shown to be detrimental. Out of 20 SNPs, seven (P370A, P646S, R654P, A476T, S400S, D666N, D7V) SNPs were predicted as "Possibly damaging" and seven (L9F, G468R, G490R, L482R, S12W, G489D, S12P) were identified as "probably benign", and six (R725G, G620S, A56V, E463D, D394N, L338V) were identified as "probably damaging" according to the predictions made by PANTHER tools. The majority of the pixels on the strip were red, indicating that the gene changes may have dangerous consequences. These results highlight the need for more research to fully comprehend how these mutations affect the hic1 protein's function, which is essential for the emergence of different types of cancer. Conclusion The current research has provided us with essential information about how SNPs might be used as a diagnostic marker for cancer, given that SNPs may be candidates for cellular changes caused by mutations linked to cancer.

Cancer-associated polybromo-1 bromodomain 4 missense variants variably impact bromodomain ligand binding and cell growth suppression

The Polybromo, BRG1-associated factors (PBAF) chromatin remodeling complex subunit Polybromo-1 (PBRM1) contains six bromodomains that recognize and bind acetylated lysine residues on histone tails and other nuclear proteins. PBRM1 bromodomains thus provide a link between epigenetic post-translational modifications and PBAF modulation of chromatin accessibility and transcription. As a putative tumor suppressor in several cancers, PBRM1 protein expression is often abrogated by truncations and deletions. However, ∼33% of PBRM1 mutations in cancer are missense and cluster within its bromodomains. Such mutations may generate full-length PBRM1 variant proteins with undetermined structural and functional characteristics. Here, we employed computational, biophysical, and cellular assays to interrogate the effects of PBRM1 bromodomain missense variants on bromodomain stability and function. Since mutations in the fourth bromodomain of PBRM1 (PBRM1-BD4) comprise nearly 20% of all cancer-associated PBRM1 missense mutations, we focused our analysis on PBRM1-BD4 missense protein variants. Selecting 16 potentially deleterious PBRM1-BD4 missense protein variants for further study based on high residue mutational frequency and/or conservation, we show that cancer-associated PBRM1-BD4 missense variants exhibit varied bromodomain stability and ability to bind acetylated histones. Our results demonstrate the effectiveness of identifying the unique impacts of individual PBRM1-BD4 missense variants on protein structure and function, based on affected residue location within the bromodomain. This knowledge provides a foundation for drawing correlations between specific cancer-associated PBRM1 missense variants and distinct alterations in PBRM1 function, informing future cancer personalized medicine approaches.

Familial bilateral macronodular adrenal hyperplasia due to a novel ARMC 5 germline mutation: Clinical status and possible association with other neoplasms

Introduction/ObjectivesMutations in the ARMC5 (armadillo repeat containing 5, OMIM 615549) gene, a putative tumor suppressor gene, have recently been identified as a common cause of sporadic and familial bilateral macronodular adrenal hyperplasia (BMAH). Familial BMAH is thought to be caused by two mutations, one germline and the other somatic, as suggested by the 2-hit theory. The objective is to describe a new mutation and develop its clinical characteristics and implications. Methods, Results and ConclusionsWe present an affected family with 11 members carrying a novel mutation of the ARMC5 gene (NM_001288767.1): c.2162T>C p. (Leu721Pro). Two of the carriers developed clinical Cushing's syndrome (CS), two mild autonomous cortisol secretion (MACS) and one presented with autonomous cortisol secretion (ACS). Four patients developed other tumors, three of whom died from this cause. It is not known whether these tumors could be related to the described mutation.

Familial bilateral macronodular adrenal hyperplasia due to a novel ARMC 5 germline mutation: Clinical status and possible association with other neoplasms

Introduction/ObjectivesMutations in the ARMC5 (armadillo repeat containing 5, OMIM 615549) gene, a putative tumor suppressor gene, have recently been identified as a common cause of sporadic and familial bilateral macronodular adrenal hyperplasia (BMAH). Familial BMAH is thought to be caused by two mutations, one germline and the other somatic, as suggested by the 2-hit theory. The objective is to describe a new mutation and develop its clinical characteristics and implications. Methods, Results and ConclusionsWe present an affected family with 11 members carrying a novel mutation of the ARMC5 gene (NM_001288767.1): c.2162T>C p. (Leu721Pro). Two of the carriers developed clinical Cushing's syndrome (CS), two mild autonomous cortisol secretion (MACS) and one presented with autonomous cortisol secretion (ACS). Four patients developed other tumors, three of whom died from this cause. It is not known whether these tumors could be related to the described mutation.

An integrative pan-cancer analysis of WWC family genes and functional validation in lung cancer

The WW and C2 domain containing (WWC) protein family functions as scaffolds regulating cell proliferation and organ growth control through the Hippo signaling pathway. However, their pan-cancer dysregulation and mechanistic roles in signaling transduction have remained unclear. We performed integrated pan-cancer analyses of WWC family gene expression using data from The Cancer Genome Atlas (TCGA) across 33 different cancer types. Prognostic relevance was evaluated by survival analyses. WWC genetic alterations, DNA methylation, pathway activities, drug response, and tumor immunology were analyzed using online databases. Furthermore, we examined the functional roles of WWCs in lung cancer cells. We observed aberrant WWC expression in various cancers, which associated with patient prognosis. WWC hypermethylation occurred in many cancers and exhibited negative correlation with expression, alongside mutations linked to poor outcomes. Pathway analysis implicated WWCs as Hippo pathway scaffolds, while drug sensitivity analysis suggested associations with diverse chemotherapies. Additionally, pan-cancer analyses elucidated vital immunomodulatory roles for WWC through heterogeneous correlations with immune cell infiltrates, checkpoint molecules, tumor mutation burden, microsatellite instability, and chemokine pathways across cancers. Experimentally, WWCs suppressed lung cancer cell proliferation, migration, and invasion while enhancing apoptosis and paclitaxel chemosensitivity. Mechanistically, WWCs bound large tumor suppressor 1 and 2 (LATS1/2) kinases to stimulate phosphorylation cascades, thereby inhibiting nuclear translocation of the Yes-associated protein (YAP) oncoprotein. Taken together, our multi-omics characterization provides comprehensive evidence for WWCs as putative tumor suppressors across cancers via Hippo pathway modulation. WWCs may serve as prognostic markers and therapeutic targets in lung cancer.

CLEC19A overexpression inhibits tumor cell proliferation/migration and promotes apoptosis concomitant suppression of PI3K/AKT/NF-κB signaling pathway in glioblastoma multiforme.

GBM is the most frequent malignant primary brain tumor in humans. The CLEC19A is a member of the C-type lectin family, which has a high expression in brain tissue. Herein, we sought to carry out an in-depth analysis to pinpoint the role of CLEC19A expression in GBM. To determine the localization of CLEC19A, this protein was detected using Western blot, Immunocytochemistry/Immunofluorescence, and confocal microscopy imaging. CLEC19A expression in glioma cells and tissues was evaluated by qRT-PCR. Cell viability, proliferation, migration, and apoptosis were examined through MTT assay, CFSE assay, colony formation, wound healing assay, transwell test, and flow cytometry respectively after CLEC19A overexpression. The effect of CLEC19A overexpression on the PI3K/AKT/NF-κB signaling pathway was investigated using Western blot. An in vivo experiment substantiated the in vitro results using the glioblastoma rat models. Our in-silico analysis using TCGA data and measuring CLEC19A expression level by qRT-PCR determined significantly lower expression of CLEC19A in human glioma tissues compared to healthy brain tissues. By employment of ICC/IF, confocal microscopy imaging, and Western blot we could show that CLEC19A is plausibly a secreted protein. Results obtained from several in vitro readouts showed that CLEC19A overexpression in U87 and C6 glioma cell lines is associated with the inhibition of cell proliferation, viability, and migration. Further, qRT-PCR and Western blot analysis showed CLEC19A overexpression could reduce the expression levels of PI3K, VEGFα, MMP2, and NF-κB and increase PTEN, TIMP3, RECK, and PDCD4 expression levels in glioma cell lines. Furthermore, flow cytometry results revealed that CLEC19A overexpression was associated with significant cell cycle arrest and promotion of apoptosis in glioma cell lines. Interestingly, using a glioma rat model we could substantiate that CLEC19A overexpression suppresses glioma tumor growth. To our knowledge, this is the first report providing in-silico, molecular, cellular, and in vivo evidences on the role of CLEC19A as a putative tumor suppressor gene in GBM. These results enhance our understanding of the role of CLEC19A in glioma and warrant further exploration of CLEC19A as a potential therapeutic target for GBM.

DOK1 facilitates the advancement of ccRCC.

Background: Renal cell carcinoma (RCC) is one of the most common human cancers. Clear cell renal cell carcinoma (ccRCC) is a major subtype of RCC. However, the molecular mechanisms underlying ccRCC oncogenesis require further investigation. Docking protein 1 (DOK1) is a putative tumor suppressor gene; however, its role in ccRCC remains unclear. Methods: Bioinformatic analysis was used to illustrate the poor prognosis associated with DOK1 expression and its role in tumor development in ccRCC in patients. qPCR (quantitative polymerase chain reaction) and western blotting assays were used to validate DOK1 expression in ccRCC cells. In vitro experiments were performed to further elucidate the biological role of DOK1 in ccRCC. Results: DOK1 was overexpressed in ccRCC tissues and cells at both mRNA and protein levels. High DOK1 expression closely correlated with poor survival in patients with ccRCC. DOK1 expression significantly accelerated ccRCC proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT). Through PI3K (phosphatidylin-ositol-3-kinase)/AKT (protein kinase B)/GSK3β (glycogen synthase kinase 3 beta) signaling, DOK1 may control the progression of ccRCC. Conclusion: DOK1 has the potential to serve as a valuable biomarker and target for treatment in ccRCC through its regulation of PI3K/AKT/GSK3β signaling to promote ccRCC progression.