Long noncoding RNA RFPL1S-202 inhibits ovarian cancer progression by downregulating the IFN-ß/STAT1 signaling.

BACKGROUND: RFPL1S was first identified as one of the pseudogenes located in the intrachromosomal duplications within 22q12-13. Our previous study found that one of the predicted transcripts of lncRNA RFPL1S, ENST00000419368.1 (GRCh37/hg19), also named as RFPL1S-202 in Ensembl website, is significantly downregulated in the chemoresistant ovarian cancer cells. However, its function and underlying mechanism have not been studied. METHODS: Quantitative Real-time PCR was used to analyze the expression. Cell Counting Kit-8, transwell, flow cytometry analysis and tail vein injected mouse model were used to test the function. RNA-sequencing, RNA pull down, western blot, ELISA and RNA-Binding Protein Immunoprecipitation were performed for studying the mechanism. 5' and 3' rapid amplification of complementary DNA ends were performed to analyze the full length of RFPL1S-202. RESULTS: RFPL1S-202 is significantly downregulated in epithelial ovarian cancer tissues and cell lines. Gain- and loss-of-function study indicated that RFPL1S-202 could enhance cisplatin or paclitaxel in cytotoxicity, inhibit cell proliferation, invasion and migration of ovarian cancer cells in vitro, and inhibit the liver metastasis of ovarian cancer cells in vivo. Mechanistically, RFPL1S-202 could physically interact with DEAD-Box Helicase 3 X-linked (DDX3X) protein, and decrease the expression of p-STAT1 and the IFN inducible genes by increasing the m6A modification of IFNB1. RFPL1S-202 is a spliced and polyadenylated non-coding RNA with a full length of 1071 bp. CONCLUSIONS: Our study suggested that the predicted lncRNA RFPL1S-202 exerts a tumor- suppressive function in oarian cancer chemoresistance and progression by interacting with DDX3X and down-regulating the IFN-ß-STAT1 signaling pathway.

Peptide PDHPS1 Inhibits Ovarian Cancer Growth through Disrupting YAP Signaling.

The lives of patients with ovarian cancer are threatened largely due to metastasis and drug resistance. Endogenous peptides attract increasing attention in oncologic therapeutic area, a few antitumor peptides have been approved by the FDA for clinical use over the past decades. However, only few peptides or peptide-derived drugs with antiovarian cancer effects have been identified. Here we focused on the biological roles and mechanism of a peptide named PDHPS1 in ovarian cancer development. Our results indicated that PDHPS1 reduced the proliferation ability of ovarian cancer cells in vitro and inhibited the ovarian cancer growth in vivo. Peptide pull down and following mass spectrometry, Western blot and qRT-PCR revealed that PDHPS1 could bind to protein phosphatase 2 phosphatase activator (PTPA), an essential activator of protein phosphatase 2A (PP2A), which resulted in increase of phosphorylated YAP, further inactivated YAP, and suppressed the expression of its downstream target genes. Flow cytometry, cell membrane permeability test, and IHC staining study demonstrated that there were no observable side effects of PDHPS1 on normal ovarian epithelium and hepatorenal function. Besides, modification of membrane penetration could improve the physicochemical properties and biological activity of PDHPS1. In conclusion, our study demonstrated that the endogenous peptide PDHPS1 serves as an antitumor peptide to inhibit YAP signaling pathway though interacting with PTPA in ovarian cancer.

Peptidome characterization of ovarian cancer serum and the identification of tumor suppressive peptide ZYX36-58.

BACKGROUND: Several serum biomarkers, including miRNA, mRNA, protein and peptides in cancer patients are also important mediators of cancer progression. METHODS: The differentially expressed peptides between the serum of ovarian cancer patients and healthy controls were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The function of the peptides was analyzed by CCK8, transwell, wound healing, and flow cytometry analysis. And the mechanism of the peptides was analyzed by peptide pull down, and high-throughput RNA-sequencing. RESULTS: A total of 7 and 46 peptides were significantly up-regulated and down-regulated in the serum of ovarian cancer patients, respectively. The precursor proteins of the differentially expressed peptides mainly involved in the complement and coagulation cascades, platelet activation, phagosome and focal adhesion pathways. Interestingly, focal adhesion, platelet activation, platelet-cancer cell interaction, complement activation, coagulation cascades and phagosome formation are all critical factors for cancer initiation or progression, which indicated that the peptides may play a crucial role in cancer development. And we identified one peptide, ZYX36-58, which was down-regulated in the serum of ovarian cancer patients, significantly inhibited invasion and migration and promoted the apoptosis of ovarian cancer cells. Mechanistic study indicated that ZYX36-58 interacted with and increased the protein level of the antiangiogenic protein thrombospondin-1 (TSP1), which has a tumor suppressive effect on ovarian cancer. CONCLUSIONS: ZYX36-58, which was significantly down-regulated in the serum of ovarian cancer patients can significantly inhibit cell invasion, migration and promote apoptosis of ovarian cancer cells by binding and up-regulating TSP1 protein expression.

Comprehensive circular RNA expression profiles and the tumor-suppressive function of circHIPK3 in ovarian cancer.

BACKGROUND: With the development of next-generation sequencing (NGS), thousands of circular RNAs (circRNAs) have been found. Many circRNAs have been verified to play vital roles in carcinogenesis. However, whether circRNAs engage in the development and progression of ovarian cancer remains to be clarified. METHODS: We analyzed circRNA expression profiling in epithelial ovarian cancer (EOC) and normal ovarian tissues (NOT) using NGS and validated six randomly selected circRNAs via quantitative real-time-PCR (qRT-PCR), reverse-transcription PCR (RT-PCR) and Sanger sequencing after RNase treatment. CircHIPK3, the most abundant circRNA in our sequencing data, was further knocked down by siRNA. The circHIPK3 function in proliferation, invasion, migration and apoptosis of ovarian cancer cells and normal ovarian epithelial cells was analyzed via cell counting-kit 8 (CCK8), wound healing, transwell and flow cytometry analyses after circHIPK3 was efficiently silenced. RESULTS: Altogether, we found 7333 circRNAs, of which 4505 (61.43%) were newly identified, 2431 were significantly upregulated and 3120 were remarkably downregulated. Six randomly selected differentially expressed circRNAs were examined in 18 EOC and 18 NOT. Furthermore, the results of RT-PCR and Sanger sequencing after RNase treatment confirmed head-to-tail back-splicing. Silencing of circHIPK3 promoted proliferation, migration, and invasion and inhibited apoptosis of ovarian cancer cells (A2780 and SKOV3) and normal ovarian epithelial cells (IOSE80). Additionally, the circHIPK3-miRNA-mRNA axis was predicted as the possible mechanism using bioinformatic approaches. CONCLUSIONS: We identified the circRNA expression profile in ovarian cancer tissues and further verified the existence and expression of six randomly selected differentially expressed circRNAs. Besides, we also found that circHIPK3 is an important regulator of ovarian cancer progression.

LncRNA KB-1471A8.2 Overexpression Suppresses Cell Proliferation and Migration and Antagonizes the Paclitaxel Resistance of Ovarian Cancer Cells.

Objective: The aim was to investigate the lncRNA KB-1471A8.2 function in ovarian cancer progression and paclitaxel resistance. Methods: The expression and distribution of KB-1471A8.2 was detected by qRT-PCR. The cell proliferation, apoptosis, invasion, migration and chemoresistance were analyzed by CCK8 assay, flow cytometry and transwell assay. The expression of DEPTOR, whose sequence is reverse overlapped with KB-1471A8.2 was analyzed by qRT-PCR, western blot and immunofluorescence. The cell cycle and the cell cycle related gene expression were analyzed by flow cytometry and qRT-PCR, respectively. Results: KB-1471A8.2 was significantly downregulated in both ovarian cancer tissues and chemoresistant ovarian cancer cells. Overexpression of KB-1471A8.2 significantly inhibited the proliferation, invasion, migration, and paclitaxel resistance, and increased the apoptosis of ovarian cancer cells. KB-1471A8.2 was mainly distributed in the nucleus of ovarian cancer cells. KB-1471A8.2 overexpression significantly decreased the S phase cell ratio, increased the G0/G1 phase cell ratio, but not affected the expression and distribution of DEPTOR. However, cyclin-dependent kinase 4 (CDK4), which is an important regulator of G1/S transition, was significantly decreased in KB-1471A8.2-overexpressed ovarian cancer cells. Conclusion: KB-1471A8.2 could significantly inhibit the development and paclitaxel resistance of ovarian cancer cells, at least partly, by suppressing CDK4 expression.

Mass spectrometry-based peptidome profiling of human serous ovarian cancer tissues.

BACKGROUND: Bioactive peptides existing in vivo have been considered as an important class of natural medicines for the treatment of diseases. Peptidome analysis of tissues and biofluids had provided important information about the differentially expressed bioactive peptides in vivo. METHODS: Here, we analyzed the peptidome of serous ovarian cancer tissue samples and normal ovarian epithelial tissue samples by mass spectrometry and further investigated the possible bioactive peptides that were differentially expressed. RESULTS: We identified 634 differentially expressed peptides, 508 of these peptides were highly abundant in serous ovarian cancer tissues, a result consistent with higher protease activity in ovarian cancer patients. The difference in preferred cleavage sites between the serous ovarian cancer tissues and normal ovarian epithelium indicated the characteristic peptidome of ovarian cancer and the nature of cancer-associated protease activity. Interestingly, KEGG pathway analysis of the peptide precursors indicated that the differentially regulated pathways in ovarian cancer are highly consistent with the pathways discovered in other cancers. Besides, we found that a proportion of the differentially expressed peptides are similar to the known immune-regulatory peptides and anti-bacterial peptides. Then we further investigated the function of the two down-regulated peptides in ovarian cancer cells and found that peptide P1DS significantly inhibited the invasion and migration of OVCAR3 and SKOV3 ovarian cancer cells. CONCLUSIONS: Our results are the first to identify the differentially expressed peptides between the serous ovarian cancer tissue and the normal ovarian epithelium. Our results indicate that bioactive peptides involved in tumorigenesis are existed in vivo.