Excessive activation of HOXB13/PIMREG axis promotes hepatocellular carcinoma progression and drug resistance.

The transcription factor HOXB13 is bound up with the occurrence, progression and drug fast of many kinds of cancer. Nevertheless, the specific molecular mechanism of HOXB13 in hepatocellular carcinoma (HCC) is still unknown. This provides an obstacle to the exploration of HCC treatments targeting HOXB13. This study found that HOXB13 was up-regulated in HCC tissues. HOXB13 enhanced the multiplication and metastasis of HCC cells. It enhanced HCC cell drug and anoikis resistance. The analysis of HCC RNA seq data indicated that the expression of HOXB13 and PIMREG were positively correlated. Luciferase report assay showed that HOXB13 could activate PIMREG promoter transcription. The results of RT-qPCR and western blot showed that HOXB13 regulated the transcription of PIMREG. Western blot proved that high expression of PIMREG participated in DNA damage repair and cell cycle regulation by up-regulating RAD51, BRCA1, CDC25A, CDC25B and CDC25C and down-regulating HIPK2. This led to a significant increase in DNA repair capacity, accelerated cell cycle progression, and insensitive to DNA damage. Down-regulation of PIMREG in Hep3B cells overexpressing HOXB13 attenuated the phenotype induced by HOXB13. Therefore, HOXB13 functioned through PIMREG instead of directly regulating the transcription of RAD51, BRCA1, CDC25A, CDC25B and CDC25C. The same results were obtained in vivo. It was concluded that HOXB13 affected the expression of cell cycle and DNA repair related factors by up-regulating the transcription of PIMREG, thereby promoting the progression of HCC and enhancing the resistance of HCC to chemotherapeutics.