ANTICANCER EFFECTS OF RETINOIC ACID IN CERVICAL CANCER CELLS

Abstract

Cervical cancer is a leading cause of cancer-related death in women, and it is known to have a poor prognosis. This is because, patients develop progressive or recurrent tumours after primary treatment, and the major reason for tumour recurrence is the presence of cancer stem cells (CSCs). It is known that retinoic acid (RA) has potential therapeutic effects on cervical cancer. However, the possible mode of action of RA in cervical cancer cells, and its relation to CSCs remains elusive. The aim of this research was to determine the anticancer effect of RA in cervical cancer cells (HeLa). HeLa cells were treated by various concentrations of RA ranging from 5-50µM to determine the effect of RA on cell viability, and cell proliferation. Both experiments were carried out using Celltiter-glo 2.0 assay and CyQuant NF assay, respectively. Apoptosis activity was determined using Caspase-Glo 3/7 assay. Immunofluorescent staining was conducted to detect the expression of differentiation marker (pan-keratin), and stem cell markers (CD133 and SSEA4) on untreated and treated HeLa cells with 10µM of RA. The findings showed that RA reduced cell viability and proliferation in a dose-dependent manner by 12-83% and 22-86%, respectively. However, a change in caspase3/7 activity between untreated, and 10µM RA-treated Hela cells were not detected indicating absence of apoptotic activity. The study also revealed that expression of differentiation marker (pan-keratin) was up-regulated, while expressions of stem cell markers (CD133 and SSEA4) were down-regulated. In addition, morphology of HeLa cells displayed a more differentiated phenotype that is less proliferative upon RA treatment. These findings suggest that RA showed its anticancer effect on cervical cancer cells by exhibiting cytotoxicity, inhibiting proliferation capacity, and inducing differentiation of cervical cancer cells. This finding shows that retinoic acid may potentially serve as a potent targeted therapy for cervical cancer and other cancers possessing CSCs within its tumors.