Hedyotis diffusae Herba-Andrographis Herba inhibits the cellular proliferation of nasopharyngeal carcinoma and triggers DNA damage through activation of p53 and p21.

Dysregulation of the cell cycle and the resulting aberrant cellular proliferation has been highlighted as a hallmark of cancer. Certain traditional Chinese medicines can inhibit cancer growth by inducing cell cycle arrest. In this study we explore the effect of Hedyotis diffusae Herba-Andrographis Herba on the cell cycle of nasopharyngeal carcinoma (NPC). Hedyotis diffusae Herba-Andrographis Herba-containing serum was prepared and then added to the cell culture medium. BrdU, comet, and FUCCI assays, western blot analysis and flow cytometry analysis revealed that Hedyotis diffusae Herba-Andrographis Herba treatment significantly alters cell proliferation, DNA damage, and cell cycle distribution. Xenograft mouse model experiments were performed, confirming these in vitro findings in vivo. Treatment with Hedyotis diffusae Herba-Andrographis Herba inhibited cell proliferation, promoted DNA damage, and arrested NPC cells progression from G1 to S phase. Further examination of the underlying molecular mechanisms revealed that treatment with Hedyotis diffusae Herba-Andrographis Herba increased the expression of p53 and p21, while reducing that of CCND1, Phospho-Rb, E2F1, γH2AX, and Ki-67 both in vivo and in vitro. Conversely, the inhibition of p53 and p21 could abolish the promoting effect of Hedyotis diffusae Herba-Andrographis Herba on the NPC cell cycle arrest at the G1 phase, contributing to the proliferation of NPC cells. Hedyotis diffusae Herba-Andrographis Herba suppressed the tumor growth in vivo. Overall, these findings suggest that Hedyotis Diffusae Herba-Andrographis prevent the progression of NPC by inducing NPC cell cycle arrest at the G1 phase through a p53/p21-dependent mechanism, providing a novel potential therapeutic treatment against NPC.