Cytotoxic effect of arsenic on the growth and morphological responses of mammalian cells

Abstract

Heavy metals, such as lead, cadmium, copper, chromium and arsenic are some of the most harmful toxicants responsible for a wide range of diseases starting from asthma to cancers. These are often found in surface water because of uncontrolled release of industrial wastewater and sometimes in groundwater as well. This has become a global concern and there are number of studies suggested the probable relation between the increased heavy metal concentration in nature in industrial proximity and the increased cases of melanoma and carcinoma patients. Unfortunately, it is not clear yet how cells respond to these heavy metal exposure and what kind of changes cells go through before initiation of cancer. A laboratory based prospective study has been designed and performed to evaluate cytotoxicity and morphological changes of mammalian cells in presence of arsenic (III) solution of different concentrations. To facilitate the study, HeLa as cancer cell and Vero as non-cancer cell were cultured and treated with different concentrations of As2O3 to generate dose response curve, from where LC50 (concentration at which 50% of the cells died) was determined quantitatively. 65 µM and 8 µM As3+ concentrations were found as LC50 for cancer and non-cancer cell, respectively. To assess cell growth, viable cell counting, specific growth rate constant and cell doubling time were determined for both cancer and non-cancer cells with different concentrations of As3+ solution below LC50. It was found that, severity of cytotoxicity was acute for the doses of arsenic (III) higher than 1 µM and the effect was negligible below 0.25 µM arsenic (III) concentration for regular mammalian cells. Cancer cells, being robust and tolerant, showed noticeable effect only beyond 1 µM arsenic (III) concentration and the effect was severe above 2 µM arsenic (III) concentration. Wound healing assays were performed with different concentrations of As3+ solution below LC50 to assess migration behavior from where it was observed that wound healing behavior was affected significantly by the arsenic (III) dosage. Morphological deformations were also noticed due to arsenic (III) dosing for both the regular and cancer cell lines. In addition, mammalian cells were found to be less affected by arsenic toxicity when treated with curcumin, the active component in turmeric. However, the extent of the effectiveness was dependent on the level of toxicity and curcumin concentration. This study paves the pathway to further investigation of the pre-cancer alterations of cells caused by arsenic exposure.