Senescent Colon and Breast Cancer Cells Induced by Doxorubicin Exhibit Enhanced Sensitivity to Curcumin, Caffeine, and Thymoquinone

Abstract

Cellular senescence is a process of physiological growth arrest that can be induced by intrinsic or extrinsic stress signals. Some cancer therapies are associated with senescence of cancer cells with a typical cell cycle arrest. Doxorubicin (Dox) induces senescence by a p53-dependent pathway and telomere dysfunction of numerous cancers. However, cellular senescence induces suppression in proliferation activity, and these cells will remain metabolically active and play an important role in tumor relapse and development of drug resistance. In the current study, we investigated the apoptotic effect of curcumin (Cur), caffeine (Caff), and thymoquinone (TQ) on senescent colon cancer HCT116 and breast cancer MCF7 cell lines treated with Dox. Results showed typical senescence markers including decreased bromodeoxyuridine incorporation, increased accumulation of senescence-associated β-galactosidase (SA-β-gal), cell cycle arrest, and upregulation of p53, P-p53, and p21 proteins. Annexin-V analysis by flow cytometry revealed 2- to 6-fold increases in annexin-V–positive cells in Dox-treated MCF7 and HCT116 cells by Cur (15 µM), Caff (10 mM), and TQ (50 µM; P < .001). In comparison between proliferative and senescent of either HCT116 or MCF7 cells, Caff at 15 mM and TQ at 25 µM induced significant increases in apoptosis of Dox-treated cells compared with proliferative cells ( P < .001). Data revealed that Cur, Caff, and TQ potentially induced apoptosis of both proliferative and senescent HCT116 and MCF7 cells. In vivo and clinical trials are of great importance to validate this result.

Thymoquinone and Costunolide Induce Extensive Apoptosis of Senescent Colon and Senescent Breast Cancer Cells

“…The same results were found when HCT116 or MCF7 cell lines were treated with 100 nM of Dox [2,27,28]. HCT116 exposed to 50 nM [29][30][31], 75 nM [32], 100 nM [2,31,[33][34][35][36], and 200 nM [37] for 1-4 days exhibited the features of senescence. Higher doses of Dox induced senescence in HCT116 by doses of 1 µM for 2 h [38] and 500 nM for 4 h [39].…”

“…Higher doses of Dox induced senescence in HCT116 by doses of 1 µM for 2 h [38] and 500 nM for 4 h [39]. In the same manner, MCF7 exhibited the senescence feature when subjected to different levels of Dox such as 38 nM [40], 50 nM [29,41], 75 nM [32,42], 100 nM [2,27,28], and 500 nM [43] for 1-5 days. Also, high doses of Dox 1 µM [44] and 10 µM [45] for 2 h were used to induce senescence in a short time period.…”

“…After 24 h, cells were treated with bromodeoxyuridine (BrdU, Sigma-Aldrich, MO, USA). The extent of BrdU incorporation in cells was examined using a uorescence microscope (Nikon, Melville, NY, U.S.A) after mounting with DAPI [2]. BrdU positive cells were counted with ImageJ software (National Institutes of Health, Bethesda, MD, USA).…”

“…The amounts of SA-β-gal in Sen-HCT116 and Sen-MCF7 cells for 5 days were determined according to the method of Dimri et al [25]. Cells were examined using the uorescence microscope after mounting with DAPI [2]. SA-β-gal positive cells were counted with ImageJ software.…”

“…The principal bioactive ingredient of Nigella sativa seeds is thymoquinone (TQ), which has a number of biological activities such as antioxidant, anticancer, and antitoxicant [1][2][3][4][5][6]. Gali-Muhtasib et al [7] stated that TQ prompted apoptosis of a human colon cancer (HCT116) cell line via a p53 dependence.…”