Synergistic effect of the combination of Chrysanthemum cinerariifolium (Trev.) and doxorubicin in inhibiting PI3K and Cyclin D in oral squamous cell carcinoma: in vitro study [version 1; peer review: awaiting peer review]

Background: The most common type of lips and oral cavity cancer is oral squamous cell carcinoma (OSCC). Doxorubicin (DX) is commonly used as a chemotherapy drug, but its use is limited due to risk factors and drug resistance. Chrysanthemum cinerariifolium (Trev.) (CC) has potential as an anticancer agent. Combining the plant extract and chemotherapy drug might prevent OSCC proliferation by inhibiting PI3K and cyclin D protein. Therefore, the present study aimed to determine the synergistic effect of the combination of C. cinerariifolium (Trev.) and doxorubicin in inhibiting PI3K and Cyclin D protein. Methods: Human oral squamous carcinoma cell lines SCC-9 were used in this study. A cytotoxicity assay was performed to obtain the IC 50 value of CC ethanol extract and DX on the SCC-9 cell line. Synergism evaluation of the combination CC and DX was analyzed using CompuSyn software. ELISA and the immunofluorescent assay were performed to determine the level of PI3K and cyclin D in the SCC-9 cell line after being treated with IC 50 value of CC, IC 50 value of DX and three combinations of CC and DX [7/8 IC 50 CC + 1/8 IC 50 DX (dose 1), 6/8 IC 50 CC + 2/8 IC 50 DX (dose 2), and 4/8 IC 50 CC + 4/8 IC 50 DX (dose 3). Results: CC stem ethanol extract and DX inhibited the proliferation of SCC-9 cell lines with the IC 50 value of 133.4 µg/mL and 288.3 nM, respectively. The combination of CC and DX at dose 2 (6/8 IC 50 CC + 2/8 IC 50 DX) exhibited a high decrease in PI3K and cyclin D expression. Conclusions: The combination of C. cinerariifolium and doxorubicin synergistically declined OSCC proliferation by inhibiting PI3K and cyclin D expression.