ABSTRACT
Synthetic lethality is a novel model for cancer therapy. To understand the function and mechanism of BEN domain-containing protein 4 (BEND4) in pancreatic cancer, eight cell lines and a total of 492 cases of pancreatic neoplasia samples were included in this study. Methylation-specific polymerase chain reaction, CRISPR/Cas9, immunoprecipitation assay, comet assay, and xenograft mouse model were used. BEND4 is a new member of the BEN domain family. The expression of BEND4 is regulated by promoter region methylation. It is methylated in 58.1% (176/303) of pancreatic ductal adenocarcinoma (PDAC), 33.3% (14/42) of intraductal papillary mucinous neoplasm, 31.0% (13/42) of pancreatic neuroendocrine tumor, 14.3% (3/21) of mucinous cystic neoplasm, 4.3% (2/47) of solid pseudopapillary neoplasm, and 2.7% (1/37) of serous cystic neoplasm. BEND4 methylation is significantly associated with late-onset PDAC (> 50 years, P < 0.01) and tumor differentiation (P < 0.0001), and methylation of BEND4 is an independent poor prognostic marker (P < 0.01) in PDAC. Furthermore, BEND4 plays tumor-suppressive roles in vitro and in vivo. Mechanistically, BEND4 involves non-homologous end joining signaling by interacting with Ku80 and promotes DNA damage repair. Loss of BEND4 increased the sensitivity of PDAC cells to ATM inhibitor. Collectively, the present study revealed an uncharacterized tumor suppressor BEND4 and indicated that methylation of BEND4 may serve as a potential synthetic lethal marker for ATM inhibitor in PDAC treatment.
ABSTRACT
Background: Pancreatic ductal adenocarcinoma (PDAC), the most prevalent type of pancreatic cancer, is a highly lethal malignancy with poor prognosis. Polypeptide N-acetylgalactosaminyltransferase-6 (GALNT6) is frequently overexpressed in PDAC. However, the role of GALNT6 in the PDAC remains unclear. Methods: The expression of GALNT6 in pancreatic cancer and normal tissues were analyzed by bioinformatic analyses and immunohistochemistry. CCK8 and colony formation were used to detect cell proliferation. Flow cytometry was applied to detect cell cycle.The pyroptosis was detected by scanning electron microscopy. The mRNA expression was detected by qRT-PCR. The protein expression and localization were detected by western blot and immunofluorescence assay. ELISA was used to detect the levels of inflammatory factors. Results: The expression of GALNT6 was associated with advanced tumor stage, and had an area under curve (AUC) value of 0.919 in pancreatic cancer based on the cancer genome atlas (TCGA) dataset. Knockdown of GALNT6 inhibited cell proliferation, migration, invasion and cell cycle arrest of PDAC cells. Meanwhile, knockdown of GALNT6 increased the expression levels of interleukin-1ß (IL-1ß), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-18 (IL-18), the release of inflammasome and an increasing of Gasdermin D (GSDMD), N-terminal of GSDMD (GSDMD-N), Gasdermin E (GSDME) and N-terminal of GSDME (GSDME-N) in PDAC cells. GALNT6 suppressed the expression of NOD-like receptor thermal protein domain associated protein 3 (NLRP3) and GSDMD by glycosylation of NF-κB and inhibiting the nucleus localization of NF-κB. Additionally, GALNT6 promotes the degradation of GSDME by O-glycosylation. Conclusion: We found that GALNT6 is highly expressed in pancreatic cancer and plays a carcinogenic role. The results suggested that GALNT6 regulates the pyroptosis of PDAC cells through NF-κB/NLRP3/GSDMD and GSDME signaling. Our study might provides novel insights into the roles of GALNT6 in PDAC progression.
ABSTRACT
BACKGROUND: The role of JAM3 in different tumors is controversial. The epigenetic regulation and the mechanism of JAM3 remain to be elucidated in human esophageal cancer (EC). METHODS: Eleven EC cell lines, 49 cases of esophageal intraepithelial neoplasia (EIN) and 760 cases of primary EC samples were employed. Methylation-specific polymerase chain reaction, immunohistochemistry, MTT, western blot and xenograft mouse models were applied in this study. RESULTS: The inverse association between RNA expression and promoter region methylation of JAM3 was found by analyzing 185 cases of EC samples extracted from the TCGA database (p < 0.05). JAM3 was highly expressed in KYSE450, KYSE520, TE1 and YES2 cells, low level expressed in KYSE70 cells and unexpressed in KYSE30, KYSE150, KYSE410, KYSE510, TE13 and BIC1 cells. JAM3 was unmethylated in KYSE450, KYSE520, TE1 and YES2 cells, partial methylated in KYSE70 cells and completely methylated in KYSE30, KYSE150, KYSE410, KYSE510, TE13 and BIC1 cells. The expression of JAM3 is correlated with methylation status. The levels of JAM3 were unchanged in KYSE450, KYSE520, TE1 and YES2 cells, increased in KYSE70 cells and restored expression in KYSE30, KYSE150, KYSE410, KYSE510, TE13 and BIC1 cells after 5-aza-2'-deoxycytidine treatment, suggesting that the expression of JAM3 is regulated by promoter region methylation. JAM3 was methylated in 26.5% (13/49) of EIN and 51.1% (388/760) of primary EC, and methylation of JAM3 was associated significantly with tumor differentiation and family history (all p < 0.05). Methylation of JAM3 is an independent prognostic factor of poor 5-year overall survival (p < 0.05). JAM3 suppresses cell proliferation, colony formation, migration and invasion and induces G1/S arrest and apoptosis in EC. Further study demonstrated that JAM3 suppressed EC cells and xenograft tumor growth by inhibiting Wnt/ß-catenin signaling. CONCLUSION: JAM3 is frequently methylated in human EC, and the expression of JAM3 is regulated by promoter region methylation. JAM3 methylation is an early detection and prognostic marker of EC. JAM3 suppresses EC growth both in vitro and in vivo by inhibiting Wnt signaling.
