Search

Recent reports have shown that bromelain (BL), a pineapple extract, acts as an adjuvant therapy in cancer treatment and prevention of carcinogenesis. The present study was designed to investigate the possible mechanisms by which BL could radiosensitize tumor cells in vitro and in a mouse tumor model. BL has shown a significant reduction in the viability of the radioresistant human breast carcinoma (MCF-7) cell line using cell proliferation assay. The in vivo study was designed using the Ehrlich model in female albino mice, treated with BL (6 mg/kg b. wt., intraperitoneal, once daily for 10 days) 1 hour before exposure to a fractionated dose of gamma radiation (5 Gy, 1 Gy for 5 subsequent days). The radiosensitizing effect of BL was evident in terms of a significant reduction in tumor volume, poly ADP ribose polymerase-1 (PARP-1), the proliferation marker Ki-67 and nuclear factor kappa activated B cells (NF-κB) with a significant elevation in the reactive oxygen species (ROS) content and lipid peroxidation (LPO) in tumor cells. The present findings offer a novel insight into the radiosensitizing effect of BL and its potential application in the radiotherapy course.

This study hypothesizes that, bromelain (BL) acts as radiosensitizer of tumor cells and that it protects normal cells from radiation effects. In vitro and in vivo studies have been carried out to prove that assumption. In vitro MTT cell proliferation assay has shown that the irradiated Ehrlich ascites carcinoma (EAC) cell line could be sensitized by BL pretreatment. In vivo: animals were randomly divided into 5 groups, Group 1: control (PBS i.p for 10 days), Group 2: Ehrlich solid tumor (EST) bearing mice, Group 3: EST + γ-radiation (fractionated dose, 1 Gy × 5), Group 4: EST + BL (6 mg/kg, i.p), daily for 10 days, Group 5: EST + BL for 10 days followed by γ-irradiation (1 Gy × 5). The size and weight of tumors in gamma-irradiated EST bearing mice treated with BL decreased significantly with a significant amelioration in the histopathological examination. Besides, BL mitigated the effect of γ-irradiation on the liver relative gene expression of poly ADP ribose polymerase-1 (PARP1), nuclear factor kappa activated B cells (NF-κB), and peroxisome proliferator-activated receptor α (PPAR-α), and it restored liver function via amelioration of paraoxonase1 (PON1) activity, reactive oxygen species (ROS) content, lipid peroxidation (LPO) and serum aspartate transaminase (AST), alanine transaminase (ALT), and albumin (ALB). It is concluded that BL can be considered as a radio-sensitizer and radio-protector, suggesting a possible role in reducing radiation exposure dose during radiotherapy.