Preliminary Study Of CMT-8as A New Anti-cancer Agent And Radiosensitizer

Objective: To investigate the effects of chemically modified tetracycline-8(CMT-8) on growth, migration and radiosensitivity of cancer cells.Methods:(1) MTT assay was used to determine cell viability of different celllines, including normal human skin fibroblast cells (GM), two human cervical cell lines(HeLa and SiHa), two human breast cancer cell lines (MCF-7and MDA-MB-231),human small cell lung cancer cells (NCI-H446), human prostate cancer cells (DU-145),and human nasopharyngeal carcinoma cells (CNE-1);(2) Wound healing assays wereused to measure cell migration and invasion;(3) Annexin V/PI assay was used todetecte cell apoptosis;(4) Flow cytometry and Western blot assay were respectivelyperformed to analyze cell cycle alteration and protein expression.Results:(1) CMT-8significantly reduced growth of all cancer cell lines testedherein, and such inhibition of CMT-8was in a dose-and time-dependent fashion andcell-type dependent. The order of cell sensitivity to CMT-8(24h exposure) was:MDA-MB-231>CNE-1>DU-145>NCI-H446>MCF-7>HeLa>SiHa>GM, indicating thatthere is a higher suscepbility of tumer cells than normal cells in response to CMT-8.(2)CMT-8inhibited cell migration and invation in MCF-7, MDA-MB-231and HeLacells, and this inhibitian was aslo in a dose-and time dependent fashion.(3) CMT-8caused an S arrest in MCF-7cells, while in MDA-MB-231cells, CMT-8did notproduce any significant alteration of cell cycle progression. Furthermore, CMT-8caused a G0/G1arrest in HeLa cells without any affects of cell cycle profile.(4)Annexin V/PI asssy revealed that CMT-8induced cell apoptosis in MDA-MB-231cells via a dose-dependent manner.(5) CMT-8down-regulated Cyclin E and CDK2protein expression in MCF-7cells. CMT-8up-regulated expression of caspase-3andBax proteins and down-regulated expression of NF-κB and Bcl-2proteins inMDA-MB-231cells. While in HeLa cells, a dose-dependent reduction of Cyclin D andCyclin E protein expression was observed.(6) HeLa cells pre-treated with CMT-8at non-cytotoxic concentrations became more sensitive to subsequent irradiation ofX-rays, which was related to a decreased expression of Ku70and DNA-PKcsproteins.Conclusion: Our present findings indicate that CMT-8is a new anti-cancercompound via inhibiting cell growth and migration as well as mediatingradiosensitivity.