Xiyi Chen

IGF2BP2 promotes ovarian cancer growth and metastasis by upregulating CKAP2L protein expression in an m 6 A ‐dependent manner

Abstract Ovarian cancer (OC) is the second leading cause of gynecological cancer‐related death in women worldwide. N6‐methyladenosine (m 6 A) is the most abundant internal modification in eukaryotic RNA. Human insulin‐like growth factor 2 mRNA‐binding protein 2 (IGF2BP2), an m 6 A reader, can enhance mRNA stability and promote translation by recognizing m 6 A modifications. Its tumor‐promoting effects have been demonstrated in several cancers. However, the roles of m 6 A modification and IGF2BP2 in OC remain unclear. Here, by using methylated RNA immunoprecipitation sequencing, we demonstrated that there is widespread dysregulation of m 6 A modification in OC tissues. The m 6 A modification and the mRNA and protein levels of IGF2BP2 were significantly elevated in OC. Overexpression of IGF2BP2 facilitated OC cell proliferation, migration, and invasion in vitro and accelerated tumor growth and metastasis in vivo. While IGF2BP2‐knockdown showed the opposite effect. Mechanistically, we identified cytoskeleton‐associated protein 2‐like (CKAP2L) as a target of IGF2BP2. IGF2BP2 promoted CKAP2L translation dependent on m 6 A modification, rather than affecting mRNA and protein stability. Overexpression of CKAP2L rescued the tumor‐suppressive effect of IGF2BP2 knockdown in OC cells. In conclusion, this study revealed the potential role of IGF2BP2 in tumor progression, at least partially via promoting the translation of CKAP2L in an m 6 A‐dependent manner.

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

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. 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. 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. 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-β-STAT1 signaling pathway.

Plasma circRNA microarray profiling identifies novel circRNA biomarkers for the diagnosis of ovarian cancer

Abstract Background Circular RNA (circRNA), a class of RNA with a covalent closed circular structure that widely existed in serum and plasma, has been considered an ideal liquid biopsy marker in many diseases. In this study, we employed microarray and qRT-PCR to evaluate the potential circulating circRNAs with diagnostic efficacy in ovarian cancer. Methods We used microarray to explore the circRNA expression profile in ovarian cancer patients’ plasma and quantitative real-time (qRT)-PCR approach to assessing the candidate circRNA’s expression. Then the receiver operating characteristic (ROC) curve was employed to analyze the diagnostic values of candidate circRNAs. The diagnostic model circCOMBO was a combination of hsa_circ_0003972 and hsa_circ_0007288 built by binary logistic regression. Then bioinformatic tools were used to predict their potential mechanisms. Results Hsa_circ_0003972 and hsa_circ_0007288 were downregulated in ovarian cancer patients’ plasma, tissues, and cell lines, comparing with the controls. Hsa_circ_0003972 and hsa_circ_0007288 exhibited diagnostic values with the Area Under Curve (AUC) of 0.724 and 0.790, respectively. circCOMBO showed a better diagnostic utility (AUC: 0.781), while the combination of circCOMBO and carbohydrate antigen 125 (CA125) showed the highest diagnostic value (AUC: 0.923). Furthermore, the higher expression level of hsa_circ_0007288 in both plasma and ovarian cancer tissues was associated with lower lymph node metastasis potential in ovarian cancer. Conclusions Our results revealed that hsa_circ_0003972 and hsa_circ_0007288 may serve as novel circulating biomarkers for ovarian cancer diagnosis.