Cytotoxic and apoptotic evaluations of marine bacteria isolated from brine-seawater interface of the Red Sea

Abstract

BackgroundHigh salinity and temperature combined with presence of heavy metals and low oxygen renders deep-sea anoxic brines of the Red Sea as one of the most extreme environments on Earth. The ability to adapt and survive in these extreme environments makes inhabiting bacteria interesting candidates for the search of novel bioactive molecules.MethodsTotal 20 i.e. lipophilic (chloroform) and hydrophilic (70% ethanol) extracts of marine bacteria isolated from brine-seawater interface of the Red Sea were tested for cytotoxic and apoptotic activity against three human cancer cell lines, i.e. HeLa (cervical carcinoma), MCF-7 (Breast Adenocarcinoma) and DU145 (Prostate carcinoma).ResultsAmong these, twelve extracts were found to be very active after 24 hours of treatment, which were further evaluated for their cytotoxic and apoptotic effects at 48 hr. The extracts from the isolates P1-37B and P3-37A (Halomonas) and P1-17B (Sulfitobacter) have been found to be the most potent against tested cancer cell lines.ConclusionOverall, bacterial isolates from the Red Sea displayed promising results and can be explored further to find novel drug-like molecules. The cell line specific activity of the extracts may be attributed to the presence of different polarity compounds or the cancer type i.e. biological differences in cell lines and different mechanisms of action of programmed cell death prevalent in different cancer cell lines.

Characterization and Antimicrobial Potential of Marine Actinomycetes From Estuaries of Uttara Kannada District, Karnataka

“…A total of 43 isolates were obtained from these three estuaries. Similar studies were carried out by 31,32 showing presence of actinomycetes in soil samples of sea shores and estuary, mangrove forests 33 , saline waters 34,35 , sediments 6,36,37 , marine soils 4,38,39,9 .…”

Red Sea Microbial Diversity for Antimicrobial and Anticancer Agents

“…Red Sea microbial diversity (bacteria/fungi) are interesting objects for further studies to discover novel metabolites and new chemotherapeutic agents. Recently, Sagar et al have shown significant cytotoxic activities of some halophilic bacterial species that were isolated from Red sea (Jeddah), and subsequently demonstrated the possible mechanisms of anticancer effect of bacterial extracts on different cancer cell lines [28,29]. While in another study, they have observed significant apoptotic and cytotoxic activities in cancer cell lines treated with marine bacterial extracts that were isolated from brine-seawater interface of the Red Sea.…”

“…The antimicrobial activity will be calculated by measuring diameters of inhibition zones surrounding the tested organisms. On the other hand, the anticancer activity was determined by using cell culture, MTT assay (cytotoxicity effect), and apoptosis % assay and all of which were described in previous studies [29]. Most of cell lines were cultured in Dulbecco's Modified Eagle's Medium (DMEM), supplemented with 10% Fecal calf serum (FCS) and placed it into incubator at 5% CO 2 in a 37 o C. Furthermore, the MTT assay was used to assess the cytotoxic effect of marine bacterial extracts against different cancer cell lines, in which the cultured cells were treated with the compound (3-(4,5-Dimethylthiazol-2-yl), 5-diphenyltetrazolium bromide).…”

“…After incubation, obtained fresh cultured cell lines were treated with different concentrations of marine bacterial extracts, which were diluted in DMEM., Thereafter, the treated cells were incubated at different time intervals, at 37 o C, and positive control was treated with H 2 O 2 . After treatment and incubation, cells were lifted and stained with dye and apoptotic cells were determined by high throughput flow cytometer (HTFC) screening system [29]. Similarly, Yi et al have followed strict criteria in order to explore the signaling pathways of cytotoxic marine-bacterial extracts [112], which include: (i) MTT assay was conducted for cytotoxicity test, (ii) morphological examination after acridine orange (AO) or ethidium bromide (EB) staining (looking for cell shrinkage or nuclei condensation), (iii) DNA fragmentation was detected by labeling of nuclear DNA fragments and gel electrophoresis analysis, and (vi) flow cytometry was used for cell cycle analysis and apoptotic cell death quantification.…”

Autophagy Inhibition Enhances the Mitochondrial-Mediated Apoptosis Induced by Mangrove (Avicennia marina) Extract in Human Breast Cancer Cells

“…The MTT assay was used to determine cytotoxicity of AM [20]. Cells (2.5 x 10 3 per well) grown in 384-well plates were treated for 48 and 72 h (hours) with 100 and 200 µg/ml of AM extract.…”