# Selinexor enhances the sensitivity of hepatocellular carcinoma cells to sorafenib by regulating the BAX/Bcl-2/PUMA apoptotic pathway and the XPO1/p27 cell cycle pathway

## TL;DR

This study shows that combining selinexor with sorafenib improves treatment effectiveness in liver cancer by enhancing cell death and blocking cell cycle progression.

## Contribution

The novel contribution is demonstrating that selinexor enhances sorafenib sensitivity in HCC via modulating BAX/Bcl-2/PUMA and XPO1/p27 pathways.

## Key findings

- Selinexor and sorafenib combination significantly inhibited tumor growth in nude mice models.
- The drug combination induced G1 phase arrest and increased apoptosis in HCC cell lines.
- The treatment upregulated BAX, PUMA, and p27 while downregulating Bcl-2 and XPO1.

## Abstract

Sorafenib remains the first-line targeted therapy for advanced hepatocellular carcinoma (HCC), but its clinical efficacy is severely limited by intrinsic and acquired drug resistance. Dysregulation of the BAX/Bcl-2/PUMA apoptotic pathway and XPO1/p27 cell cycle pathway is closely associated with sorafenib resistance. This study aimed to explore whether selinexor, a selective nuclear export inhibitor, could enhance the sensitivity of HCC cells to sorafenib and to clarify the underlying molecular mechanism.

A series of in vitro cell experiments (Huh7, SK-HEP-1, HepG2) and in vivo Huh7 xenograft nude mouse models were conducted. CCK-8 assay, flow cytometry, Western blot and immunohistochemistry were used to detect cell proliferation, cell cycle distribution, apoptosis, and the expression levels of key proteins related to apoptosis and cell cycle pathways. The additive effect of the drug combination was verified by comparing the experimental inhibitory rate with the theoretical additive effect.

Selinexor combined with sorafenib significantly inhibited tumor growth in nude mice, with a stronger inhibitory effect than monotherapy. In vitro, the two drugs exerted an additive effect on suppressing the proliferation of Huh7, SK-HEP-1 and HepG2 cells. Meanwhile, the combination treatment induced obvious G1 phase arrest in Huh7 cells and markedly increased the apoptosis rate of Huh7 and HepG2 cells. Mechanistically, the combined therapy upregulated the expression of pro-apoptotic proteins BAX and PUMA as well as cell cycle regulator p27, while downregulating anti-apoptotic protein Bcl-2 and nuclear export protein XPO1.

This study confirms that selinexor enhances the sensitivity of HCC cells to sorafenib by regulating the BAX/Bcl-2/PUMA apoptotic pathway and the XPO1/p27 cell cycle pathway. The combination strategy provides a novel potential approach for improving the therapeutic efficacy of sorafenib and overcoming both intrinsic and acquired sorafenib resistance in HCC. The main limitations of this study are the lack of RT-PCR verification and further detection of downstream apoptotic effector molecules, which need to be explored in future research.