Scorpion Venom Causes Apoptosis by Increasing Reactive Oxygen Species and Cell Cycle Arrest in MDA-MB-231 and HCT-8 Cancer Cell Lines

Abstract

Objectives: The objective of this study was to examine the effect of scorpion venoms on cancer cell progression, apoptosis, and cell cycle arrest. Scorpion venoms are known to possess numerous bioactive compounds that act against cancer progression by inducing apoptosis. In this study, we have taken the venoms from the following 2 species of scorpion- Androctonus crassicauda and Leiurus quinquestriatus-and tested the anticancer properties of the venom against breast and colorectal cancer cell lines.

Methods: Milking of scorpion venom and culturing the breast and colorectal cancer cell lines were done according to the standard procedure. The venom cytotoxicity was assessed by MTT methods, and the cellular and nuclear changes were studied with phase contrast and propidium iodide staining, respectively. The cell cycle arrest and accumulation of reactive oxygen species were analyzed on a Muse cell analyzer.

Results: The venoms exerted cytotoxic effects on breast and colorectal cell lines in a dose- and time-dependent manner. Enhanced apoptotic cells, increase in reactive oxygen species, and cell cycle arrest were observed after challenging these cell lines with scorpion venoms.

Conclusions: Scorpion venom induces apoptosis in breast and colorectal cell lines as reflected by the changes in the cell morphology and cell cycle studies. Furthermore, a high percentage of total reactive oxygen species as well as apoptotic cells also contribute to cell death as observed after venom treatments. To the best of authors' knowledge, this is the first scientific evidence demonstrating the induction of apoptosis and cell cycle arrest by these species of scorpion venoms.

Keywords: G0/G1 phase; MTT assay; breast cancer cell lines; cell cycle assay; colorectal.

Figure 1.

Bar graphs showing the cytotoxic effect and hence IC50 values of scorpion venoms on breast and colorectal cancer cell lines. Columns (A) and (C) show the cell viability pattern after venom 1 treatment for 24 hours on breast and colorectal cancer cell lines, respectively. Columns (B) and (D) represents the effect of venom 2 on the cell lines as mentioned above. An asterisk indicates IC50 values.

Figure 2.

Histogram showing the extent of reactive oxygen species (ROS) generation after scorpion venoms treatment on (A) MDA-MB-213 and (C) HCT-8 cancer cell lines. Bar graphs (B and D) show the quantitative analyses of the ROS generation after venom treatment. A significant increase in ROS formation was observed both in breast and colorectal cancer cell lines, P < .05.

Figure 3.

Phase contrast and propidium iodide (PI) staining: (A and C) MDA-MB-231 (breast) and HCT-8 (colorectal) cancer cell lines treated with venom 1 for 24 hours and 48 hours, respectively. Phase contrast field (upper panel) and PI staining (lower panel) (B and D) bar graphs represent the number of viable, apoptotic, and necrotic cells after venom treatment. Statistically significant (P ≤ .05).

Figure 4.

Histogram (left panel) showing cell cycle arrest after venom 1 treatment in (A and C) breast and colorectal cancer cell lines, respectively. Bar graphs (B and D) show the quantitative analyses of the histogram described above. Right panel shows the cell cycle arrest after venom 2 treatment breast and colorectal cancer cell lines (E and G), respectively. Bar graphs (F and H) show the quantitative analyses of the histogram described above. Asterisks mark, statistically significant (P ≤ .05).

Figure 5.

Schema showing the probable mechanism of action of scorpion venom against breast and colorectal cancer cell lines.