Cisplatin has been widely used in
cancer treatments. Recent evidence indicates that
adenine has potential anticancer activities against various types of
cancers. However, the effects of the combination of
adenine and
cisplatin on
hepatocellular carcinoma (HCC) cells remain sketchy. Here, our objective was to elucidate the anticancer activity of
adenine in combination with
cisplatin in HCC cells and its mechanistic pathways. Cell viability and cell cycle progression were assessed by the SRB assay and flow cytometry, respectively. Apoptosis was demonstrated by PI/
annexin V staining and flow cytometric analysis.
Protein expression, signaling cascade, and
mRNA expression were analyzed by Western blotting and quantitative RT-PCR, respectively. Our results showed that
adenine jointly potentiated the inhibitory effects of
cisplatin on the cell viability of SK-Hep1 and Huh7 cells. Further investigation showed that
adenine combined with
cisplatin induced higher S phase arrest and apoptosis in HCC cells. Mechanically,
adenine induced AMPK activation, reduced mTOR phosphorylation, and increased p53 and p21 levels. The combination of
adenine and
cisplatin synergistically reduced Bcl-2 and increased PUMA, cleaved
caspase-3, and PARP in HCC cells.
Adenine also upregulated the
mRNA expression of p53, p21, PUMA, and PARP, while knockdown of AMPK reduced the increased expression of these genes. Furthermore,
adenine also induced the activation of
p38 MAPK through AMPK signaling, and the inhibition of
p38 MAPK reduced the apoptosis of HCC cells with exposure to
adenine combined with
cisplatin. Collectively, these findings reveal that the combination of
adenine and
cisplatin synergistically enhances apoptosis of HCC cells, which may be attributed to the AMPK-mediated p53/p21 and
p38 MAPK cascades. It suggests that
adenine may be a potential adjuvant for the treatment of HCC in combination with
cisplatin.