Role of Resveratrol as Radiosensitizer by Targeting Cancer Stem Cells in Radioresistant Prostate Cancer Cells (PC-3)

Abstract

Aim of work: Here, we examined the role of resveratrol as a radiosensitizer by targeting cancer stem cells in radioresistant prostate cancer cells (PC-3) using stem cell markers CD44, CD49b and CD29, SOX2, OCT4, CXCR4, DCLK1 and EMT markers such as VIM and E-cadherin.

Material and methods: This study was an in vitro study involving PC-3 cell line which was dividing into four groups. Group I (CO): Control group composed of cells grown in the same medium without treatment with ionizing radiation or resveratrol. Group II (IR): Cells were treated with ionizing radiation alone. Group III (RV): Cells were treated with resveratrol alone. Group VI (IR&RV): The cells were treated with ionizing radiation and resveratrol in combination. The viability of cells was assessed by MTT assay. Genes of interest were measured by RT-PCR and the radiosensitizing efficacy of RV on proliferating cancer cells was determined by clonogenic assay.

Results: Ionizing radiation significantly reduced PC-3 viability, lowered stem cell markers and affected epithelial to mesenchymal transition (EMT) genes expression at all doses (2, 4, 6 and 8 Gray). Resveratrol significantly decreased PC-3 viability and lowered stem cell markers and EMT genes expression at concentrations 35, 70 and 140 µM. Combining resveratrol treatment with ionizing radiation leads to significant reduction in cell viability and stem cell markers genes which was noticed with increasing the radiation dose when compared to ionizing radiation alone treated group.

Conclusion: Resveratrol has a radiosensitizing effect, that ability is triggered by reducing the expression of cancer stem cell markers and affecting EMT markers. Resveratrol showed to be a good candidate for further studies as anticancer drug in the treatment of human prostate cancer.

Keywords: DCLK1; epithelial mesenchymal transition; ionizing radiation.

Figure 1

Morphological Alterations of PC-3Cell Line Observed by Inverted Microscopy. (A) untreated control (B) Resveratrol at different concentrations (140, 70 and 35 µM) group; (C) Ionizing radiation at different doses (2, 4, 6 and 8 Gy); (D) Combination of ionizing radiation and resveratrol at 35 µM; (E) Combination of ionizing radiation and resveratrol at 70 µM; (F) Combination of ionizing radiation and resveratrol at 140 µM

Figure 2

(a) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC₅₀ (140 µM) on CD44 gene expression in PC-3 cell line. (b) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC₅₀ (140 µM) on CD49b gene expression in PC-3 cell line. (c) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC₅₀ (140 µM) on CD29 gene expression in PC-3 cell line

Figure 3

(a) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC50 (140 µM) on SOX2 gene expression in PC-3 cell line. (b) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC50 (140 µM) on OCT4 gene expression in PC-3 cell line. (c) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC50 (140 µM) on DCLK1 gene expression in PC-3 cell line

Figure 4

(a) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC₅₀ (140 µM) on CXCR4 gene expression in PC-3 cell line. (b) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC₅₀ (140 µM) on VIM gene expression in PC-3 cell line. (c) Bar chart illustrating the effect of combination treatment of both ionizing radiation and resveratrol at IC₅₀ (140 µM) on E-cadherin gene expression in PC-3 cell line

Figure 5

Bar Chart Illustrating Clonogenic Survival Curves for Ionizing Radiation (2, 4, 6 and 8 Gy) alone and Combination Treatment of Both Ionizing Radiation and Resveratrol (35 µM) on PC-3 Cell Line