Mechanistic Insight into Apoptotic Induction in Human Rhabdomyosarcoma and Breast Adenocarcinoma Cells by Chnoospora minima: A Sri Lankan Brown Seaweed.

L. Dinithi C. Peiris,Kulathungage Hiranthi Dilrangi,Kalpa W. Samarakoon,Pathmasiri Ranasinghe,Thilina Lakmini Gunathilaka

doi:10.3390/ph14111154

Abstract

The current study determined the cytotoxic and apoptotic potential of the polyphenol-rich methanol extract of Chnoospora minima (C. minima) and its fractions against human breast adenocarcinoma (MCF-7) and rhabdomyosarcoma (RMS) cells. MTT and neutral red assays were used to determine cytotoxicity. The clonogenic assay evaluated the antineoplastic activity, while the apoptotic activity was determined by cellular morphological changes, caspase 3/7 activity, and DNA fragmentation. Morphological alterations in apoptosis were observed by an inverted phase-contrast microscope and Hoechst 33342 staining methods. The total phenolic, flavonoids, alkaloids, and antioxidant activity in the hexane and chloroform fractions were determined, based on their cytotoxic activity. The hexane fraction of C. minima effectively reduced the cell growth that is concentration-dependent in human RMS and MCF-7 cell lines. It also exhibited low cytotoxicity on Vero cells. The characteristic cellular and nuclear apoptotic morphological features were observed. A noticeable caspase 3/7 activation and the fragmented DNA were detected only in the hexane fraction treated RMS cells, whereas MCF-7 cells showed low caspase 3/7 activation due to a lack of caspase 3 and no evidence of having a typical ladder pattern of apoptosis. Further analysis revealed that the hexane fraction-treated RMS cells upregulated the p53 gene twofold (2.72) compared to the p21 (0.77) gene, whereas in the MCF-7 cells, a 2.21-fold upregulation of p53 was observed compared to the p21 (0.64) gene. The hexane fraction exhibited moderate total phenolics, flavonoids, alkaloids content, and antioxidant activity. According to the different antioxidant mechanisms, hexane and chloroform fractions showed the highest antioxidant activities by FRAP and ORAC assays, respectively. GC-MS analysis of hexane fraction revealed the presence of methyl tetradecanoate (38.314%) as the most abundant compound. The study’s findings highlighted that the non-polar compounds present in the hexane fraction of C. minima suppressed cell proliferation and induced apoptosis-mediated cell death in RMS and MCF-7 cells, mainly via the activation of the p53 gene. Hence, the isolation of compounds is warranted. However, more studies are required to understand the mechanistic insights of these observations.

Highlights

IntroductionBrown algae are one of the fascinating groups of macroalgae that have been a part of the diet of Asian humans for centuries, especially in Japan and Korea [1]
The percentage yield of crude methanol extract from Chnoospora minima was based on their dried algae materials
IC50 values obtained for MTT and neutral red assays demonstrated that MCF-7 cells are more sensitive to the fractions of C. minima compared to the RMS cells

Summary

Introduction

Brown algae are one of the fascinating groups of macroalgae that have been a part of the diet of Asian humans for centuries, especially in Japan and Korea [1]. The presence of bioactive compounds contributes to prominent health-promoting effects that can be used in research into anticancer agents [2]. Cancer is the world’s second leading cause of death and is due to uncontrolled cell proliferation [3]. Organization estimated 24 million cancer diagnoses and 14.5 million cancer-related deaths by 2035 [1]. In Sri Lanka, around 29,604 new cancer patients were identified in 2020, accompanied by 16,691 deaths [2]. Breast cancer is the most common cancer in women [4] and the highest prevalence of breast cancer was seen in countries like

Methods

Discussion

Conclusion