L. S. CHATURVEDI1,2,3, A. M. Patel3, T. Woldemariam2, D. VYAS1,3, D. VYAS1,3 1San Joaquin General Hospital,SURGERY,FRENCH CAMP, CALIFORNIA, USA 2California Northstate University,COLLEGE OF PHARMACY,ELK GROVE, CALIFORNIA, USA 3California Northstate University,COLLEGE OF MEDICINE,ELK GROVE, CALIFORNIA, USA
Introduction:
Breast cancer is the most frequently diagnosed cancer in women around the world. Triple-negative breast cancer (TNBC) is a subclass that does not express an estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth receptor (HER-2) which makes TNBC more aggressive and metastatic. Chemotherapy is the first-line therapy for the treatment but there are off-target effects and life-limit dose. Tulsi, also known as Holy Basil (Ocimum Sanctum Linn), is often used for various herbal remedies. Aqueous extracts of O. sanctum leaves (AEOS) have been shown to be anti-cancerous in other types of cancers but has not yet been evaluated in human TNBC. The aim of this study was to investigate the anti-proliferative effect and molecular targets of AEOS on human TNBC cells.
Methods:
The dried leaves of Ocimum sanctum was obtained from a commercial suppliers (Sacramento, CA) and reduced to fine powders and percolated with distilled water. Evaporation of the solvent at 37oC using Chefman-5 tray round food dehydrator. The residue was then dissolved with water at desired concentration required for bioassay. Human TNBC cell lines MDA-MB-231, MDA-MB-453, HCC70 and HCC1187 were obtained from ATCC and cultured in DMEM or RPMI with 10% fetal bovine serum. Cells were treated with various concentrations of AEOS (0-500µg/mL), doxorubicin (DOX, 0-500nM) or in a combination of both. Cell viability was measured at various time-points using cell counting kit (CCK-8) assay and cell proliferation was performed using BrdU assay kit. Gene expression was performed by using quantitative real-time PCR for cell-cycle regulatory genes.
Results:
The AEOS exhibited significant cytotoxic effect against human TNBC cells (MDA-MB-231, MDA-MB-453, HCC70 and HCC1187) in a time and dose dependent manner. Furthermore, we identified the pure bioactive compounds from AEOS and confirmed their antiproliferative properties and molecular targets in human TNBC cells. We observed that O. Sanctum significantly inhibited Cyclin D1, B1 and A1 gene expression without affecting Cyclin E1 gene expression. Furthermore, a combination with a low dose of doxorubicin with the AEOS further decreased Cyclin D1 and A1 expression in comparison to each agent alone confirming an additive effect. The AEOS (500µg/mL) was found to be non-toxic to human fibroblast cell line (CCD-Co18) in comparison untreated control cells.
Conclusion:
This study for the first time reports that AEOS have anti-carcinogenic potential through enhancing anti-proliferation in human TNBC cells with an additive effect by further decreasing Cyclin D1 and A1 when combined with low dose chemotherapeutic agent DOX. Collectively, this data provided evidence for the efficacy of AEOS as well as novel purified bioactive compound alone and/or in a combination may have potential in the treatment of drug resistant TNBC patients.