HAT1 Promotes Gemcitabine Resistance by Regulating the PVT1/EZH2 Complex in Pancreatic Cancer

Abstract Background: The poor prognosis of pancreatic cancer is primarily due to the development of resistance to therapies, including gemcitabine. PVT1 has been shown to interact with EZH2, promoting gemcitabine resistance in pancreatic cancer. Methods: In this study, we assessed the ability of PVT1/EZH2 targeting to reverse resistance to gemcitabine in pancreatic cancer cells. MTS assay, colony formation assay, and mouse xenotransplantation experiments were used to evaluate the anti-tumor effects of gemcitabine in HAT1 knockdown or overexpressing pancreatic cancer cells. The relationship between HAT1 and PVT1 in pancreatic cancer was determined by RNA sequencing, quantitative real-time PCR, and chromatin immunoprecipitation. Co-immunoprecipitation, pull-downs, western blotting, and immunohistochemistry were used to assess the relationship between HAT1 and EZH2 in pancreatic cancer. Chitosan (CS)-tripolyphosphate (TPP)-siHAT1 nanoparticles were developed to evaluate their effects on the anti-tumor potential of gemcitabine in pancreatic cancer. Student’s t-test, one-way analysis of variance (ANOVA), or two-way ANOVA was used to evaluate statistical significance. P-values <0.05 were considered statistically significant. All values were expressed as means ± SD. Results: Our results showed that the aberrant HAT1 expression promoted gemcitabine resistance in pancreatic cancer cells. We also found that HAT1 enhanced the binding of BRD4 to the PVT1 promoter, thereby promoting PVT1 transcription. Moreover, we found that HAT1 prevented EZH2 degradation by interfering with UBR4 binding to the N-terminal domain of EZH2, thus maintaining EZH2 protein stability. Finally, we showed that CS-TPP-siHAT1 nanoparticles augmented the anti-tumor effects of gemcitabine in pancreatic cancer cells in vitro and in vivo. Conclusions: Our findings suggest that by increasing the levels of the PVT1/EZH2 complex, HAT1 promotes gemcitabine resistance in pancreatic cancer. Therefore, HAT1 is a promising therapeutic target for pancreatic cancer.