# Platycodin D2 enhances P21/CyclinA2-mediated senescence of HCC cells by regulating NIX-induced mitophagy

## TL;DR

Platycodin D2, a compound from a Chinese herb, kills liver cancer cells by boosting cell aging and autophagy without harming normal cells.

## Contribution

PD2 induces mitophagy via NIX and activates P21/CyclinA2 to promote HCC cell senescence, offering a new treatment strategy.

## Key findings

- PD2 inhibits HCC cell proliferation without affecting normal hepatocytes.
- PD2 induces mitophagy through NIX and activates P21/CyclinA2 to promote cell senescence.
- PD2's effects were confirmed in vitro and in a mouse tumor model.

## Abstract

Hepatocellular carcinoma (HCC) cells usually show strong resistance to chemotherapy, which not only reduces the efficacy of chemotherapy but also increases the side effects. Regulation of autophagy plays an important role in tumor treatment. Cell senescence is also an important anti-cancer mechanism, which has become an important target for tumor treatment. Therefore, it is of great clinical significance to find anti-HCC drugs that act through this new mechanism. Platycodin D2 (PD2) is a new saponin compound extracted from the traditional Chinese medicine Platycodon grandiflorum.

Our study aimed to explore the effects of PD2 on HCC and identify the underlying mechanisms.

First, the CCK8 assay was used to detect the inhibitory effect of PD2 on HCC cells. Then, different pathways of programmed cell death and cell cycle regulators were measured. In addition, we assessed the effects of PD2 on the autophagy and senescence of HCC cells by flow cytometry, immunofluorescence staining, and Western blotting. Finally, we studied the in vivo effect of PD2 on HCC cells by using a mouse tumor-bearing model.

Studies have shown that PD2 has a good anti-tumor effect, but the specific molecular mechanism has not been clarified. In this study, we found that PD2 has no obvious toxic effect on normal hepatocytes, but it can significantly inhibit the proliferation of HCC cells, induce mitochondrial dysfunction, enhance autophagy and cell senescence, upregulate NIX and P21, and downregulate CyclinA2. Gene silencing and overexpression indicated that PD2 induced mitophagy in HCC cells through NIX, thereby activating the P21/CyclinA2 pathway and promoting cell senescence.

These results indicate that PD2 induces HCC cell death through autophagy and aging. Our findings provide a new strategy for treating HCC.

The online version contains supplementary material available at 10.1186/s12935-024-03263-y.