Antiproliferative and Proapoptotic Effects of Crocin Combined with Hyperthermia on Human Breast Cancer Cells

Abstract

We investigated the suppressive effects of crocin alone and in combination with hyperthermia (HT) on proliferation of breast cancer cells. Cell viability, colony formation ability, and apoptosis were assessed by 3-(4,5-dimetylthiazol-2-Yl)-2,5-diphenyltetrazolium bromide (MTT), soft agar, Hoechst 33258 staining, and percentage of lactate dehydrogenase (LDH) release methods, respectively. The mRNA levels Hsp27, Hsp70, Hsp90, Bax, and Bcl-2 were measured by quantitative real-time polymerase chain reaction (qRT-PCR). Hsp70 and Hsp90 proteins were determined using enzyme-linked immunosorbent assay (ELISA) technique. Crocin in combination with HT significantly inhibited the proliferation of cancer cells in a dose- and time-dependent manner. There was a degree of synergism in the combined treatment. However, crocin did not show the high cytotoxic effect on normal cells. This treatment decreased colony formation of cancer cells up to 94%. Changed nuclear morphology and increased LDH indicated that crocin combined with HT has a more apoptotic effect than crocin alone. Furthermore, in treated cells Bax/Bcl-2 ratio markedly increased, whereas expression of heat-induced genes decreased. Also, the Hsp70 and Hsp90 proteins decreased in the treated cells. Our study indicated that combination of crocin and HT has strong antiproliferative and apoptotic activities against breast cancer cells. Hence, it is suggested that more studies are warranted to apply crocin as a possible, safe, and promising anticancer agent in cancer.