PTOV1 facilitates colorectal cancer cell proliferation through activating AKT1 signaling pathway.

Background: Colorectal cancer is a predominant contributor to global cancer-related morbidity and mortality. The oncogene PTOV1 has been linked to various human malignancies, yet its specific role in CRC pathogenesis requires further elucidation. Methods: Our study used a comprehensive array of authoritative bioinformatics tools, such as TIMER, UCSC Xena, GEO, Human Protein Atlas, UALCAN, CIBERSORTx and others which used to investigate the complex effects of PTOV1 on gene expression profiles, diagnostic and prognostic biomarkers, tumor immunology, signaling pathways, epigenetic alterations, and genetic mutations. Gene expression validation was conducted using Western blot and qRT-PCR. The in vitro proliferative and migratory potentials of CRC cells were evaluated using CCK-8 assays, colony formation, and transwell migration assays, respectively. MSP was applied to assess the methylation status of the PTOV1 promoter region. Results: Our results reveal a significant association between increased PTOV1 expression, driven by promoter hypomethylation, and poor patient prognosis in CRC. Elevated PTOV1 levels were positively correlated with the enrichment of diverse immune cell subsets and immune-related molecules within the tumor microenvironment. In vitro assays demonstrated that PTOV1 knockdown markedly reduced CRC cell proliferation, colony formation, and migration, while ectopic PTOV1 expression had the opposite effect. Importantly, PTOV1 was shown to regulate the PI3K-AKT signaling pathway, significantly influencing the phosphorylation of AKT1 and the expression of cell cycle regulators P21 and P27. The pharmacological inhibition of AKT1 phosphorylation using MK2206 effectively counteracted the proliferative effects induced by PTOV1 overexpression. Conclusion: The ability of PTOV1 to enhance CRC cell proliferation via modulation of the AKT1 signaling pathway establishes it as a potential therapeutic target and a promising biomarker for prognostic stratification in CRC.

PTOV1-AS1 desensitizes colorectal cancer cells to 5-FU through depressing miR-149-5p to activate the positive feedback loop with Wnt/ß-catenin pathway.

5-Fluorouracil is a commonly used chemotherapy drug for colorectal cancer. Resistance to 5-Fluorouracil remains a challenge. This research aimed to explore the mechanism of 5-Fluorouracil resistance in colorectal cancer. RT-qPCR and Western blot were used to determine the RNA and protein expression in both cells and exosome. Assays in vitro and in vivo were performed to measure the role of miR-149-5p in colorectal cancer cells. RIP, luciferase activity report, and RNA pulldown assay were applied to detect the association of PTOV1-AS1, SUV39H1, miR-149-5p, and FOXM1. MiR-149-5p was down-expressed in 5-Fluorouracil-resistant cells. MiR-149-5p enhanced the effectiveness of 5-Fluorouracil both in vitro and in vivo. Sensitive colorectal cancer cells released exosomal miR-149-5p to sensitize resistant cells to chemotherapy. Mechanistically, miR-149-5p targeted the FOXM1 to inactivate Wnt/ß-catenin pathway, and PTOV1-AS1 recruited SUV39H1 to suppress miR-149-5p transcription, in turn activating Wnt/ß-catenin pathway, and forming a positive feedback loop with FOXM1. PTOV1-AS1 inhibits miR-149-5p by a positive feedback loop with FOXM1-mediated Wnt/ß-catenin pathway, which provides insights into a potential novel target for enhancing the effectiveness of chemotherapy in colorectal cancer patients.

Upregulation of lncRNA PTOV1-AS1 in hepatocellular carcinoma contributes to disease progression and sorafenib resistance through regulating miR-505.

Increasing evidence has displayed the vital influence of lncRNA in tumorigenesis and chemoresistance of cancer treatment. This study investigated the function of lncRNA PTOV1-AS1 in hepatocellular carcinoma (HCC) and its role in sorafenib resistance. The relative expression of lncRNA and miRNA was measured by RT-qPCR. The cellular activities including cell proliferation and invasion were explored by CCK-8 and Transwell assays. Bioinformatics analysis and dual-luciferase reporter assay were used to predict the targeting miRNA of PTOV1-AS1. The expression levels of PTOV1-AS1 were higher in HCC tissues than that in the normal tissues and associated with patients' overall survival. Knockdown of PTOV1-AS1 decreased cell proliferation rate and invasion number. After treatment with different concentrations of sorafenib, the sorafenib-resistant hepatoma cells were conducted. PTOV1-AS1 expression levels were increased in HepG2-SR and Huh7-SR cells. PTOV1-AS1 knockdown repressed the proliferation, invasion, and drug resistance of sorafenib-resistant HCC cells by targeting the expression of miR-505. In conclusion, the expression of PTOV1-AS1 is increased in HCC and sorafenib-resistance HCC cells, as well as is associated with patients' prognosis. Inhibition of PTOV1-AS1 expression can reduce the resistance of sorafenib-resistant HCC cells, which may play a role by targeting the negative regulation of miR-505 expression.

PTOV1 promotes cisplatin-induced chemotherapy resistance by activating the nuclear factor kappa B pathway in ovarian cancer.

Chemotherapy resistance is a bottleneck for ovarian cancer treatment; therefore, revealing its regulatory mechanism is critical. In the present study, we found that prostate tumor overexpressed-1 (PTOV1) was upregulated significantly in ovarian cancer cells and tissues. Patients with high PTOV1 levels had a poor outcome. In addition, PTOV1 overexpression increased CDDP (cisplatin) resistance, while PTOV1 knockdown inhibited CDDP resistance, as determined using cell viability assays, apoptosis assays, and an animal model. Mechanistic analysis showed that PTOV1 increased nuclear factor kappa B (NF-κB) pathway activity, reflected by increased nuclear translocation of its p65 subunit and the phosphorylation of inhibitor of nuclear factor kappa-B kinase subunits alpha and beta, which are markers of NF-κB pathway activation. Inhibition of the NF-κB pathway in PTOV1-overexpressing ovarian cancer cells increased CDDP-induced apoptosis, suggesting that PTOV1 promoted chemotherapy resistance by activating the NF-κB pathway. In summary, we identified PTOV1 as a prognostic factor for patients with ovarian cancer. PTOV1 might be a target for inhibition of chemotherapy resistance.

Effect of PTOV1 on proliferation and migration of esophageal squamous cell carcinoma cell line / 中国医师杂志

Objective:To investigate the effects of silencing and overexpression of prostate tumor overexpressed 1 (PTOV1) on the proliferation and migration of esophageal squamous cell lines Ec9706 and TE-1, in order to explore the role of PTOV1 in the development of esophageal cancer.Methods:Esophageal squamous cell carcinoma cell lines were cultured in vitro. Lentivirus transfection was used to knock down the expression of PTOV1 in Ec9706 cells, up regulate the expression of PTOV1 in TE-1 cell lines. The expression of PTOV1 in the above cell lines was detected by Western blot. Scratch test, transwell cell migration test, cell counting kit-8 (CCK8) test and colony formation test were used to study the difference of proliferation and migration ability of homologous esophageal squamous cell carcinoma cells with different expression levels of PTOV1. Results:Western blot showed that the expression of PTOV1 in Ec9706 cells transfected with lentivirus was significantly lower than that in the empty vector group, and the expression of PTOV1 in TE-1 cells transfected with lentivirus was significantly higher than that in the empty vector group, which confirmed that the transfection was successful. After silencing the expression of PTOV1 in Ec9706 cell line, the cell migration rate, the number of transmembrane cells, proliferation ability and colony formation rate decreased compared with the empty vector group ( P<0.05). After overexpression of PTOV1 in TE-1 cell line, the cell migration rate, the number of transmembrane cells, proliferation ability and colony formation rate were higher than those in empty vector group ( P<0.05). Conclusions:PTOV1 can promote cell proliferation and migration in esophageal squamous cell cancer (ESCC) cell line.

Depleting PTOV1 sensitizes non-small cell lung cancer cells to chemotherapy through attenuating cancer stem cell traits.

BACKGROUND: Prostate tumor over expressed gene 1 (PTOV1) has been reported as an oncogene in several human cancers. However, the clinical significance and biological role of PTOV1 remain elusive in non-small cell lung cancer (NSCLC). METHODS: The Cancer Genome Atlas (TCGA) data and NCBI/GEO data mining, western blotting analysis and immunohistochemistry were employed to characterize the expression of PTOV1 in NSCLC cell lines and tissues. The clinical significance of PTOV1 in NSCLC was studied by immunohistochemistry statistical analysis and Kaplan-Meier Plotter database mining. A series of in-vivo and in-vitro assays, including colony formation, CCK-8 assays, flow cytometry, wound healing, trans-well assay, tumor sphere formation, quantitative PCR, gene set enrichment analysis (GSEA), immunostaining and xenografts tumor model, were performed to demonstrate the effects of PTOV1 on chemosensitivity of NSCLC cells and the underlying mechanisms. RESULTS: PTOV1 is overexpressed in NSCLC cell lines and tissues. High PTOV1 level indicates a short survival time and poor response to chemotherapy of NSCLC patients. Depleting PTOV1 increased sensitivity to chemotherapy drugs cisplatin and docetaxel by increasing cell apoptosis, inhibiting cell migration and invasion. Our study verified that depleting PTOV1 attenuated cancer stem cell traits through impairing DKK1/ß-catenin signaling to enhance chemosensitivity of NSCLC cells. CONCLUSION: These results suggest that PTOV1 plays an important role in the development and progression of human NSCLC and PTOV1 may serve as a therapeutic target for NSCLC patients.

A novel DNA-binding motif in prostate tumor overexpressed-1 (PTOV1) required for the expression of ALDH1A1 and CCNG2 in cancer cells.

PTOV1 is a transcription and translation regulator and a promoter of cancer progression. Its overexpression in prostate cancer induces transcription of drug resistance and self-renewal genes, and docetaxel resistance. Here we studied PTOV1 ability to directly activate the transcription of ALDH1A1 and CCNG2 by binding to specific promoter sequences. Chromatin immunoprecipitation and electrophoretic mobility shift assays identified a DNA-binding motif inside the PTOV-A domain with similarities to known AT-hooks that specifically interacts with ALDH1A1 and CCNG2 promoters. Mutation of this AT-hook-like sequence significantly decreased the expression of ALDH1A1 and CCNG2 promoted by PTOV1. Immunohistochemistry revealed the association of PTOV1 with mitotic chromosomes in high grade prostate, colon, bladder, and breast carcinomas. Overexpression of PTOV1, ALDH1A1, and CCNG2 significantly correlated with poor prognosis in prostate carcinomas and with shorter relapse-free survival in colon carcinoma. The previously described interaction with translation complexes and its direct binding to ALDH1A1 and CCNG2 promoters found here reveal the PTOV1 capacity to modulate the expression of critical genes at multiple levels in aggressive cancers. Remarkably, the AT-hook motifs in PTOV1 open possibilities for selective targeting its nuclear and/or cytoplasmic activities.

Prostate Tumor Overexpressed-1 (PTOV1) promotes docetaxel-resistance and survival of castration resistant prostate cancer cells.

Metastatic prostate cancer is presently incurable. The oncogenic protein PTOV1, first described in prostate cancer, was reported as overexpressed and significantly correlated with poor survival in numerous tumors. Here, we investigated the role of PTOV1 in prostate cancer survival to docetaxel and self-renewal ability. Transduction of PTOV1 in docetaxel-sensitive Du145 and PC3 cells significantly increased cell survival after docetaxel exposure and induced docetaxel-resistance genes expression (ABCB1, CCNG2 and TUBB2B). In addition, PTOV1 induced prostatospheres formation and self-renewal genes expression (ALDH1A1, LIN28A, MYC and NANOG). In contrast, Du145 and PC3 cells knockdown for PTOV1 significantly accumulated in the G2/M phase, presented a concomitant increased subG1 peak, and cell death by apoptosis. These effects were enhanced in docetaxel-resistant cells. Analyses of tumor datasets show that PTOV1 expression significantly correlated with prostate tumor grade, drug resistance (CCNG2) and self-renewal (ALDH1A1, MYC) markers. These genes are concurrently overexpressed in most metastatic lesions. Metastases also show PTOV1 genomic amplification in significant co-occurrence with docetaxel-resistance and self-renewal genes. Our findings identify PTOV1 as a promoter of docetaxel-resistance and self-renewal characteristics for castration resistant prostate cancer. The concomitant increased expression of PTOV1, ALDH1A1 and CCNG2 in primary tumors, may predict metastasis and bad prognosis.

Overexpressed PTOV1 associates with tumorigenesis and progression of esophageal squamous cell carcinoma.

PTOV1 has been demonstrated to play an extensive role in many types of cancers. This study takes the first step to clarify the potential relationship between esophageal squamous cell carcinoma and PTOV1 expression and highlight the link between PTOV1 and the tumorigenesis, progression, and prognosis of esophageal squamous cell carcinoma. PTOV1 expression was detected by quantitative reverse transcription polymerase chain reaction and western blotting or immunohistochemical staining in esophageal squamous cell carcinoma cell lines, esophageal squamous cell carcinoma tissues, and its paired adjacent non-cancerous tissues. Moreover, we have analyzed the relationship between PTOV1 expression and clinicopathological features of esophageal squamous cell carcinoma. Survival analysis and Cox regression analysis were used to assess its prognostic significance. We found that PTOV1 expression was significantly higher in the esophageal squamous cell carcinoma cell lines and tissues at messenger RNA level (p < 0.001) and protein level (p < 0.001). Gender, tumor size, or differentiation was tightly associated with the PTOV1 expression. Lymph node involvement (p < 0.001) and TNM stage (p < 0.001) promoted a high PTOV1 expression. A prognostic significance of PTOV1 was also found by Log-rank method, and the overexpression of PTOV1 was related to a shorter OS and DFS. Multiple Cox regression analysis indicated overexpressed PTOV1 as an independent indicator for adverse prognosis. In conclusion, this study takes the lead to demonstrate that the overexpressed PTOV1 plays a vital role in the tumorigenesis and progression of esophageal squamous cell carcinoma, and it is potentially a valuable prognostic predicator and new chemotherapeutic target for esophageal squamous cell carcinoma.

The role of prostate tumor overexpressed 1 in cancer progression.

Prostate-Tumor-Overexpressed-1 (PTOV1) is a conserved adaptor protein discovered as overexpressed in prostate cancer. Since its discovery, the number of binding partners and associated cellular functions has increased and helped to identify PTOV1 as regulator of gene expression at transcription and translation levels. Its overexpression is associated with increased tumor grade and proliferation in prostate cancer and other neoplasms, including breast, ovarian, nasopharyngeal, squamous laryngeal, hepatocellular and urothelial carcinomas. An important contribution to higher levels of PTOV1 in prostate tumors is given by the frequent rate of gene amplifications, also found in other tumor types. The recent resolution of the structure by NMR of the PTOV domain in PTOV2, also identified as Arc92/ACID1/MED25, has helped to shed light on the functions of PTOV1 as a transcription factor. In parallel, by studying its interaction with RACK1, we have discovered PTOV1 action in promoting mRNAs translation. Here, we will focus on the role of PTOV1 in cancer, re-examine its pro-oncogenic effects and re-evaluate the most relevant interactions and evidences of its cellular functions. The data are used to formulate a model for the mechanisms of action of PTOV1 in line with its recently described activities and cellular pathways modulated in cancer.

High expression of prostate tumor overexpressed 1 (PTOV1) is a potential prognostic biomarker for cervical cancer.

BACKGROUND: To investigate the role of prostate tumor overexpressed 1 (PTOV1) in the development and progression of human cervical cancer. METHODS: Real-time quantitative PCR, Western blot, and immunohistochemistry were used to explore PTOV1 expression in cervical cancer tissues and cell lines. Cell proliferation capability was examined by MTT assay. Statistical analyzes were applied to evaluate the correlation of PTOV1 expression with clinical parameters and prognosis. RESULTS: The expression level of PTOV1 was markedly higher in cervical cancer tissues and cell lines than that in adjacent noncancerous tissues and the normal cervical epithelial cells. PTOV1 overexpression was correlated with higher tumor stage (P = 0.001), larger tumor size (P = 0.004), and lymph node involvement (P = 0.036). Moreover, patients with high PTOV1 expression showed shorter overall and recurrence-free survival time (P = 0.013 and P = 0.010, respectively). PTOV1 knockdown by short hairpin RNAi inhibited cancer cell growth in vitro. CONCLUSION: PTOV1 may be an important factor associated with proliferation of cervical cancer.

Prostate tumour overexpressed-1 promotes tumourigenicity in human breast cancer via activation of Wnt/ß-catenin signalling.

Breast cancer is the most common malignancy in females. The presence of cancer stem cells (CSCs) is the main cause of local and distant tumour recurrence and is associated with poor outcome in breast cancer. However, the molecular mechanisms underlying the maintenance of CSCs remain largely unknown. This study demonstrates that prostate tumour overexpressed-1 (PTOV1) enhances the CSC population and augments the tumourigenicity of breast cancer cells both in vitro and in vivo. Moreover, PTOV1 suppresses transcription of Dickkopf-1 (DKK1) by recruiting histone deacetylases and subsequently reducing DKK1 promoter histone acetylation, followed by activation of Wnt/ß-catenin signalling. Restoration of DKK1 expression in PTOV1-overexpressing cells counteracts the effects of PTOV1 on Wnt/ß-catenin activation and the CSC population. Collectively, these results suggest that PTOV1 positively regulates the Wnt/ß-catenin signalling pathway and enhances tumourigenicity in breast cancer; this novel mechanism may represent a therapeutic target for breast cancer. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Prostate tumor overexpressed 1 expression in invasive urothelial carcinoma.

PURPOSE: To determine the expression patterns of the proliferation marker prostate tumor overexpressed 1 (PTOV1) in invasive urothelial cancer (UC). METHODS: Corresponding UC and benign samples from paraffin-embedded tissue of 102 patients treated with cystectomy for invasive UC were immunohistochemically (IHC) assessed for PTOV1. Expression was evaluated gradually separated for cytoplasmic and nuclear staining. Results were correlated to histological and clinical data. To correlate PTOV1 expression with molecular subtypes of UC, analysis of PTOV1 RNA expression data of the Cancer Genome Atlas UC cohort was performed. RESULTS: PTOV1 expression was present in UC and benign urothelium, whereby nuclear staining was significantly more frequent in UC tissue (p = 0.0004). Lower cytoplasmic expression was significantly associated with pathological stage >pT2 (p = 0.0014) and grade ≥G3 (p = 0.0041), respectively. IHC expression patterns did not show correlation to survival data. PTOV1 RNA expression correlated with features of the luminal UC subtype. CONCLUSIONS: Subcellular distribution seems to be the most important feature of PTOV1 expression in UC. Nuclear localization of PTOV1 along with cytoplasmic decrease in PTOV1 expression was identified as putative surrogate for PTOV1-associated cellular proliferation and dedifferentiation in UC. The functional relevance as well as the potential role of PTOV1 as a biomarker in UC remains to be specified in future studies.

The extended AT-hook is a novel RNA binding motif.

The AT-hook has been defined as a DNA binding peptide motif that contains a glycine-arginine-proline (G-R-P) tripeptide core flanked by basic amino acids. Recent reports documented variations in the sequence of AT-hooks and revealed RNA binding activity of some canonical AT-hooks, suggesting a higher structural and functional variability of this protein domain than previously anticipated. Here we describe the discovery and characterization of the extended AT-hook peptide motif (eAT-hook), in which basic amino acids appear symmetrical mainly at a distance of 12-15 amino acids from the G-R-P core. We identified 80 human and 60 mouse eAT-hook proteins and biochemically characterized the eAT-hooks of Tip5/BAZ2A, PTOV1 and GPBP1. Microscale thermophoresis and electrophoretic mobility shift assays reveal the nucleic acid binding features of this peptide motif, and show that eAT-hooks bind RNA with one order of magnitude higher affinity than DNA. In addition, cellular localization studies suggest a role for the N-terminal eAT-hook of PTOV1 in nucleocytoplasmic shuttling. In summary, our findings classify the eAT-hook as a novel nucleic acid binding motif, which potentially mediates various RNA-dependent cellular processes.