ABSTRACT
Marine bacterial strains are of great interest for their ability to produce secondary metabolites with anticancer potentials. Isolation, identification, characterization and anticancer activities of isolated bacteria from El-Hamra Lake, Wadi El-Natrun (Egypt) were the objectives of this study. The isolated bacteria were identified as a moderately halophilic alkaliphilic strain. Ethyl acetate extraction was performed and identified by liquid chromatography-mass spectrophotometry (LC-MS-MS) and nuclear magnetic resonance analysis (NMR). Cytotoxicity of the extract was assessed on the HepG2 cell line and normal human peripheral lymphocytes (HPBL) in vitro. Halomonas sp. HA1 extract analyses revealed anticancer potential. Many compounds have been identified including cyclo-(Leu-Leu), cyclo-(Pro-Phe), C17-sphinganine, hexanedioic acid, bis (2-ethylhexyl) ester, surfactin C14 and C15. The extract exhibited an IC50 of 68 ± 1.8 µg/mL and caused marked morphological changes in treated HepG2 cells. For mechanistic anticancer evaluation, 20 and 40 µg/mL of bacterial extract were examined. The up-regulation of apoptosis-related genes' expression, P53, CASP-3, and BAX/BCL-2 at mRNA and protein levels proved the involvement of P53-dependant mitochondrial apoptotic pathway. The anti-proliferative properties were confirmed by significant G2/M cell cycle arrest and PCNA down-regulation in the treated cells. Low cytotoxicity was observed in HPBL compared to HepG2 cells. In conclusion, results suggest that the apoptotic and anti-proliferative effects of Halomonas sp. HA1 extract on HepG2 cells can provide it as a candidate for future pharmaceutical industries.
