Abstract 1240: Boric acid inhibits cell proliferation through RB1 protein in head and neck cancer

Abstract Boric acid is a very common chemical used in a wide variety of applications as well as in medicine. In this study, the usage of boric acid as a potential alternative cancer therapeutic was investigated by examining its effect in head and neck cancer cell line proliferation and tumor suppressor gene expression. Head and neck cancer cell lines UT-SCC 6A, 6B, 9A, 16A, 16B, 24A, 54C, 74A, and 74B were treated with varying doses of boric acid, ranging from 200 ug/mL to 1800 ug/mL and XTT assay was used to measure the dose response. Subsequently, RNA was isolated from treated cells and was converted to cDNA to evaluate the expression of P53, RB1, ING1 and ING3 via Real-time PCR. Also protein was isolated from the same cell lines for Western Blot analysis. Boric acid treatment caused a significant decrease in proliferation in all of the head and neck cancer cell lines investigated, including UT-SCC 6A, 6B, 9A, 16A, 16B, 24A, 54C, 74A, and 74B. Results from boric acid treatment and untreated controls were analyzed for statistical significance using Mann Whitney U test. The results approached statistical significance with p value of 0.05. After determining the effective doses, cell lines were treated with boric acid and gene expression of P53, RB, ING1 and ING3 were analyzed. All of the genes’ expression were increased in several of the cell lines examined. We couldn't detect the protein expression of ING1 and ING3. But we’ve detected the higher expression of Phospho (PP)-RB and Bax, lower expression of bcl2 protein. In short, our results displayed similar results to prostate cancer reported in literature in terms of inhibition of proliferation. We’ve showed that boric acid has reduced levels of cell proliferation in head and neck cancer cell lines for the first time in our study. Also higher expression of PP-RB indicated that boric acid stopped cell cycle at G1. As a pro-apoptotic Bax expression was up-regulated and anti-apoptotic bcl2 was down-regulated in some of the cell lines showing that boric acid may lead the cells to apoptosis. In the light of these results, boric acid appears to be a candidate alternative therapeutic agent for cancer. Of course, further experiments are necessary in order to strengthen this conclusion. Citation Format: Esra Gunduz, Omer Faruk Hatipoglu, Sadık Cigdem, Kubra Erdogan, Mustafa Semih Elitok, Reidar Grenman, Husamettin Erdamar, Mehmet Gunduz. Boric acid inhibits cell proliferation through RB1 protein in head and neck cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1240. doi:10.1158/1538-7445.AM2015-1240