Ovarian cancer (OC) remains the leading cause of cancer‐related death among gynecological cancers. The present study examined the role of collagen type V alpha 1 (COL5A1) and the characteristics of COL5A1 as an oncogenic protein in OC. The association of COL5A1 with paclitaxel (PTX)‐resistance and stemness in OC was also studied and the multidatabase and big data analyses of the prognostic value, coexpression network, genetic alterations, and tumor‐infiltrating immune cells of COL5A1 were elucidated. We found that COL5A1 expression was high in OC cells and tissues. Knockdown of COL5A1 inhibited the proliferation and migration of OC cells. Further study also showed that COL5A1 was overexpressed in PTX‐resistant OC cells compared to respective PTX‐sensitive cells. Additionally, COL5A1 was more enriched in OC stem cell‐like cells. Silencing COL5A1 expression decreased the OC cell resistance to PTX and inhibited the ability of OC‐spheroid formation. Survival analysis predicted that the elevated COL5A1 expression was associated with a worse survival outcome and correlated to the tumor stage of OC patients. The estimating relative subsets of RNA transcripts (CIBERSORT) algorithm analysis also unveiled the correlation of several tumor‐infiltrating immune cells with the expression of COL5A1. Taken together, our data demonstrate that COL5A1 is a biomarker to predict OC progression and PTX‐resistance and represents a promising target for OC treatment.

The primary chemotherapy of ovarian cancer (OC) often acquires chemoresistance. Sorcin (SRI), a soluble resistance-related calcium-binding protein, has been reported to be an oncogenic protein in cancer. However, the molecular mechanisms of SRI regulation and the role and aberrant expression of SRI in chemoresistant OC remain unclear. Here, we identified SRI as a key driver of paclitaxel (PTX)-resistance and explored its regulatory mechanism. Using transcriptome profiles, qRT-PCR, proteomics, Western blot, immunohistochemistry, and bioinformatics analyses, we found that SRI was overexpressed in PTX-resistant OC cells and the overexpression of SRI was related to the poor prognosis of patients. SRI was a key molecule required for growth, migration, and PTX-resistance in vitro and in vivo and was involved in epithelial–mesenchymal transition (EMT) and stemness. Mechanistic studies showed that miR-142-5p directly bound to the 3ʹ-UTR of SRI to suppress its expression, whereas a transcription factor zinc-finger E-box binding homeobox 1 (ZEB1) inhibited the transcription of miR-142-5p by directly binding to the E-box fragment in the miR-142 promoter region. Furthermore, ZEB1 was negatively regulated by SRI which physically interacted with Smad4 to block its translocation from the cytosol to the nucleus. Taken together, our findings unveil a novel homeostatic loop of SRI that drives the PTX-resistance and malignant progression via Smad4/ZEB1/miR-142-5p in human OC. Targeting this SRI/Smad4/ZEB1/miR-142-5p loop may reverse the PTX-resistance.

Background: Aberrant activities of signal transducer and activator of transcription 1 (STAT1) have been implicated in cancer development. However, the prognostic value of STAT1 remains unclear. This report identified the role of STAT1 in prognosis in patients with solid cancer through open literature and The Cancer Genome Atlas (TCGA) database. Methods: Published articles were obtained from PubMed, Web of Science, and Embase databases according to a search strategy up to October 2019. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were extracted to assess the prognostic factors of patients. TCGA datasets were used to explore the prognostic value of STAT1 in various cancers. Results: A total of 15 studies incorporating 2839 patients with solid cancers were included. Pooled data showed that overexpressed STAT1 favored long overall survival (OS) (HR = 0.604, 95% CI = 0.431–0.846, p = 0.003) and disease-specific survival (DSS) (HR = 0.650, 95% CI = 0.512–0.825, p = 0.000). In subgroup analyses, highly expressed STAT1 was correlated with long OS of patients with high-grade serous ovarian cancer and oral squamous cell carcinoma. Data extracted from TCGA datasets unveiled that STAT1 expression was significantly higher in 12 cancers (e.g. bladder and breast) than their adjacent normal tissues. Again, highly expressed STAT1 favored long OS of patients with ovarian cancer as well as rectum adenocarcinoma, sarcoma, and skin cutaneous melanoma. However, in renal carcinoma, brain lower grade glioma, lung adenocarcinoma, and pancreatic cancer, highly expressed STAT1 was correlated with poor OS of patients. Particularly in renal carcinoma, increased STAT1 expression was associated with high grade, later stage, large tumor size, and lymph node and distant metastasis. Conclusion: STAT1 has been identified to have prognostic value in patients with solid cancer. Highly expressed STAT1 may predict prognosis in cancer patients based on their tumor types.

Pyridoxine 5′-phosphate oxidase (PNPO) is a converting enzyme for an active form of vitamin B6. This study aims to evaluate the biological function and the regulatory mechanism of PNPO in human breast invasive ductal carcinoma (IDC). We unveiled for the first time that PNPO was upregulated in patients with IDC and was correlated with the overall survival of patients with metastasis at the later stages. Suppression of PNPO inhibited breast cancer cell proliferation, migration, invasion and colony formation, arrested cell cycle at the G2/M phase and induced cell apoptosis. PNPO was positively correlated with lncRNA MALAT1 which was negatively correlated with miR-216b-5p. PNPO was down-regulated and up-regulated by miR-216b-5p mimics and inhibitors, respectively, in breast cancer cells. A microRNA response element was found in both PNPO and MALAT1 transcripts for miR-216b-5p and the dual-luciferase reporter assay confirmed the binding of these transcripts. Knockdown of MALAT1 resulted in an increase of miR-216b-5p and a decrease of PNPO mRNA, indicating a regulatory mechanism of competing endogenous RNAs. Taken together, these results reveal the biological function and a regulatory mechanism of PNPO, in which the MALAT1/miR-216b-5p/PNPO axis may be important in IDC development. Targeting this axis may have therapeutic potential for breast cancer.