Nobiletin selectively inhibits oral cancer cell growth by promoting apoptosis and DNA damage in vitro

Abstract

The aim of this study was to investigate whether nobiletin (NOB) can inhibit the proliferation of oral squamous cell carcinoma (OSCC) cells by promoting apoptosis, oxidative stress (reactive oxygen species [ROS]), and DNA damage. OSCCs were treated with different concentrations of NOB (25, 50, and 100 µM) for different amounts of time (0, 24, 48, and 72 hours). The viability of NOB was assessed by using MTT-based cell viability assays. Flow cytometry was used to assess cell apoptosis, and the expressions of capase-3 and poly (adenosine diphosphate-ribose) polymerase (PARP) were assessed by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot analyses. The intensity of ROS fluorescence was measured by using a spectrophotometer. The expression of γH2AX and 8-Oxo-20-deoxyguanosine (8-oxodG) were assessed to determine the degree of DNA damage. We observed that NOB decreased OSCC cell viability in a dose- and time-dependent manner but had little effect on primary normal human oral epithelial cells (H0 ECs). Moreover, with the increase in NOB concentration and treatment time, capase-3, PARP messenger RNA (mRNA), and protein levels gradually increased, as did annexin V- and 7 adducin (ADD)-mediated apoptosis. In addition, NOB also increased the levels of ROS and DNA damage in a concentration- and time-dependent manner. NOB can inhibit OSCC cell by promoting apoptosis, ROS production, and DNA damage.