Epigenetic Silencing of STAT3-Targeted miR-193a, by Constitutive Activation of JAK/STAT Signaling, Leads to Tumor Progression Through Overexpression of YWHAZ in Gastric Cancer

Abstract

PurposeThe purpose of this study was to identify genes that were epigenetically silenced by STAT3 in gastric cancer.MethodsMBDcap-Seq and expression microarray were performed to identify genes that were epigenetically silenced in AGS gastric cancer cell lines depleted of STAT3. Cell lines and animal experiments were performed to investigate proliferation and metastasis of miR-193a and YWHAZ in gastric cancer cell lines. Bisulfite pyrosequencing and tissue microarray were performed to investigate the promoter methylation of miR-193a and expression of STAT3, YWHAZ in patients with gastritis (n = 8) and gastric cancer (n = 71). Quantitative methylation-specific PCR was performed to examine miR-193a promoter methylation in cell-free DNA of serum samples in gastric cancer patients (n = 19).ResultsAs compared with parental cells, depletion of STAT3 resulted in demethylation of a putative STAT3 target, miR-193a, in AGS gastric cancer cells. Although bisulfite pyrosequencing and epigenetic treatment confirmed that miR-193a was epigenetically silenced in gastric cancer cell lines, ChIP-PCR found that it may be indirectly affected by STAT3. Ectopic expression of miR-193a in AGS cells inhibited proliferation and migration of gastric cancer cells. Further expression microarray and bioinformatics analysis identified YWHAZ as one of the target of miR-193a in AGS gastric cancer cells, such that depletion of YWHAZ reduced migration in AGS cells, while its overexpression increased invasion in MKN45 cells in vitro and in vivo. Clinically, bisulfite pyrosequencing revealed that promoter methylation of miR-193a was significantly higher in human gastric cancer tissues (n = 11) as compared to gastritis (n = 8, p < 0.05). Patients infected with H. pylori showed a significantly higher miR-193a methylation than those without H. pylori infection (p < 0.05). Tissue microarray also showed a positive trend between STAT3 and YWHAZ expression in gastric cancer patients (n = 60). Patients with serum miR-193a methylation was associated with shorter overall survival than those without methylation (p < 0.05).ConclusionsConstitutive activation of JAK/STAT signaling may confer epigenetic silencing of the STAT3 indirect target and tumor suppressor microRNA, miR-193a in gastric cancer. Transcriptional suppression of miR-193a may led to overexpression of YWHAZ resulting in tumor progression. Targeted inhibition of STAT3 may be a novel therapeutic strategy against gastric cancer.

Downregulation of miR‐193a/b‐3p during HPV‐induced cervical carcinogenesis contributes to anchorage‐independent growth through PI3K–AKT pathway regulators

“…Chen et al 28 found hypermethylation and downregulation of miR-193a-3p in ovarian cancer clinical samples and ovarian cancer cells, and the expression in cells was reversed after treatment with a methylation inhibitor. Epigenetically silencing of miR-193a(-3p) was also observed in gastric cancer 29 and HER2-positive breast cancer. 30 At present, we have no evidence for MIR193 hypermethylation in cervical cancer cells and HPV-immortalized keratinocytes.…”

Triptolide impairs LUAD cells through the JAK-STAT signaling pathway by activating autophagy

“…The JAK-STAT signaling pathway is involved in regulating cell proliferation, differentiation, angiogenesis, apoptosis and migration [32,33]. An abnormal JAK-STAT signaling pathway contributes to the development of different cancers, such as colon cancer [34], gastric cancer [35], breast cancer[36], bladder cancer [37], and lung cancer [38,39]. In our present study, we analyzed gene expression data downloaded from the GEO database (GSE16760) and found that TPL affected A549 cells through the JAK-STAT signaling pathway.…”

Noncoding RNAs as regulators of STAT3 pathway in gastrointestinal cancers: Roles in cancer progression and therapeutic response

“…(1) The miRNA/STAT3 axis tightly modulates growth, invasion, immune activity, and therapy response in GC; (2) The in vitro and in vivo activities have confirmed the role of the miRNA/STAT3 axis in GC progression/inhibition and further effort should be made in introducing these results in the clinical course; (3) The miRNAs can directly bind to 3′UTR of STAT3 to affect its expression or can indirectly affect STAT3 activity by targeting other upstream mediators; (4) The miRNA/STAT3 axis can be targeted by antitumor compounds in GC therapy; and (5) STAT3 signaling can function as an upstream mediator of miRNAs, as confirmed by miR‐193a methylation in GC and enhance tumor progression (Table 2 and Figure 3). 195 …”