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

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.

A Computational QSAR, Molecular Docking and In Vitro Cytotoxicity Study of Novel Thiouracil-Based Drugs with Anticancer Activity against Human-DNA Topoisomerase II

“…After 48 h of incubation of 7H and 9H , more cells became unattached, rounded shaped cells, as shown in Figure 10 , echinoid spike and rounded floating cells corresponded to dying or dead cells, and more cellular debris were noted ( Figure 13 d). In another study [ 73 , 74 ], it has been reported that the cells undergoing apoptosis are manifested in other types of morphological changes such as echinoid spikes on the surface of apoptotic cell, apoptotic bodies, and the decrement in cell number with an increase in the time of incubation. The apoptotic cells produced a loss of cellular adhesion to the substrate and most of the cells even detached from the surface of the tissue culture dish plate and appeared to be floating in the culture medium.…”

“…The apoptotic cells produced a loss of cellular adhesion to the substrate and most of the cells even detached from the surface of the tissue culture dish plate and appeared to be floating in the culture medium. Relatively early detachment from their basal membrane is characteristic of the apoptosis of monolayer adherent cells and is called anoikis [ 74 ]. It was noted that the result was similar on the HCT cell line after 48 h of incubation with the tested compounds ( 7H, 9H ).…”

Utilization of Marine Seaweeds as a Promising Defense Against COVID-19: a Mini-review

“…Marine seaweeds have been identified as an important source of bioactive compounds comparable or superior to herbal medicines. In the last few years, marine seaweeds have been widely studied due to the presence of human-beneficial bioactive components (Gunathilaka et al 2021a , b , c ). Marine seaweeds are categorized into three groups as red algae (Rhodophyta), brown algae (Phaeophyta), and green algae (Chlorophyta) depending on the presence of accessory pigments.…”

“…Dieckol (IC 50 : 1.47 Mm) extracted from E. cava inhibited ACE in a non-competitive manner. Furthermore, phlorotannins extracted from Ecklonia stolonifera including eckol, dieckol, and phlorofucofuroeckol A exhibited a potent inhibitory activity on angiotensin-converting enzymes with IC 50 values of 70:82 ± 0:25 μM, 34:25 ± 3:56 μM, and 12:74 ± 0:15 μM, respectively (Gunathilaka et al 2021a , b , c ). Among the isolated phlorotannins, dieckol inhibited the ACE non-competitively.…”

“…Macroalgae are extremely diverse groups of aquatic, eukaryotic, multicellular, photosynthetic organisms possessing chlorophyll a , ranging in size from a few millimeters to several meters (Adl et al 2012 ; Baldauf 2008 ; Burki et al 2016 ). The bioactive compounds in seaweeds have been reported to exhibit significant pharmacological effects such as antiviral (Wang et al 2008 ; Gheda et al 2016 ), antibacterial (Perez et al 2016 ), antidiabetic (Gunathilaka et al 2021a , b ; Gunathilaka et al 2020 ), anticancer (Gunathilaka et al 2021c ; Gutierrez-Rodriguez et al 2018 ), anti-inflammatory (Barbalace et al 2019 ), immunomodulatory (Palstra et al 2018 ), and antioxidant (Farasat et al 2014 ) effects. Recent research has confirmed that the sulfated polysaccharides in seaweeds have the potential ability to act against SARS-CoV-2 (Kwon et al 2020 ).…”