Crocin induces autophagic cell death and inhibits cell invasion of cervical cancer SiHa cells through activation of PI3K/AKT.

Cervical cancer is a prevalent tumor mainly induced by Human Papilloma Virus (HPV). Autophagy was inactivated with HPV to promote cancer progression. Here we explored the effects of crocin on cervical cancer cells, mainly on autophagy and apoptosis. SiHa cells were treated with crocin, and proliferation, metastases, apoptosis and autophagy were measured using a CCK-8 assay, transwell migration assay, flow cytometry and immunofluorescence. Protein levels were measured using western blotting. The antitumor effects of crocin were validated in female BALB/c nude mice injected with SiHa cells. The result showed that 2, 4, 8 and 16 mM of crocin significantly reduced the viability of SiHa cells within 24 h. Subsequently, 0, 1, 2 and 4 mM crocin concentrations were used in later experiments. Treatment with crocin reduced invasive cells, while increasing autophagic and apoptotic cells dose-dependently. The enhanced apoptosis and autophagy were partly validated by an increase in cleaved caspase-3/caspase-3, cleaved caspase-9/caspase9, LC3B II/I, Beclin1 and ATG7. AMPK and mTOR were inactivated with crocin treatment, while PI3K was activated. These results indicated that crocin might promote autophagy and apoptosis by inactivating AMPK and mTOR signaling. Tumor progression was inhibited in mice treated with 50 mg/kg/d of crocin, which was demonstrated by smaller tumor volumes, less VEGF expression, more intense caspase-3 staining and increased LC3B II/I in the tumor tissues. Crocin inhibited the progression of cervical cancer in vitro and in vivo, possibly through inactivation of AMPK and mTOR, inhibition of proliferation and invasion, and promotion of autophagy and apoptosis. These results support the potential therapeutic value of crocin in treating cervical cancer.