A parasporin from Bacillus thuringiensis native to Peninsular India induces apoptosis in cancer cells through intrinsic pathway

Abstract

Parasporins, a class of non-insecticidal crystal proteins of Bacillus thuringiensis (Bt) are being explored as promising anticancer agents due to their specific toxicity to cancer cells. The present study has identified 25 Bt isolates harbouring parasporin genes from Western Ghats region, the hotspot of biodiversity in India. Among these, the isolate, KAU 41 (Kerala Agricultural University isolate 41) contained non-hemolytic homogenous crystals showing specific cytotoxicity towards cancer cells. SDS-PAGE analysis of this crystal, isolated by aqueous biphasic separation, revealed a 31 kDa sized peptide. The N-terminal sequence deciphered in BLAST analysis showed homology to a hypothetical Bt protein. Upon proteolysis, a 29 kDa active peptide was generated which exhibited heterogenic cytotoxic spectrum on various cancer cells. HeLa cells were highly susceptible to this peptide with IC 50 1 lg/mL and showed characteristics of apoptosis. RT-qPCR analysis revealed the overexpression of APAF1, caspase 3 and 9 by 14.9, 8 and 7.4 fold, respectively which indicates the activation of intrinsic pathway of apoptosis. However, at higher concentrations of peptide (greater than 3 lg/mL), necrotic death was prominent. The results suggest that the 31 kDa protein from Bt isolate, KAU 41 is a parasporin that may have high therapeutic potential.

Specific Cytotoxic Effects of Parasporal Crystal Proteins Isolated from Native Saudi Arabian Bacillus thuringiensis Strains against Cervical Cancer Cells

“…Many countries including Saudi Arabia (our research team) are continuing to screen and isolate novel strains in natural environments to apply for biological pest management programs whereby reducing insect resistance to Bt [12,20,21,22,23]. Moreover, global efforts are currently being intensified towards the discovery of local Bt isolates with unique anticancer properties [13,19,24,25,26].…”

Parasporin A13-2 of Bacillus thuringiensis Isolates from the Papaloapan Region (Mexico) Induce a Cytotoxic Effect by Late Apoptosis against Breast Cancer Cells

“…Maher [ 19 ] identified two strains J61 and J72, with cytotoxic activity against MCF-7 that reduce to 50% cell viability at 1 µg/mL and 2.79 µg/mL, respectively. Other authors tested differents parasporins observing no significant cytotoxic activity against MCF-7 [ 20 , 21 , 22 ]. It has been reported that a parasporin could affect more than one cancer line of cells.…”

Glabralysins, Potential New β-Pore-Forming Toxin Family Members from the Schistosomiasis Vector Snail Biomphalaria glabrata

“…First, using recombinant proteins, the hemolytic activity of Glabralysins will be investigated, and then their cytotoxic/cytolytic effects on micro-organisms or pathogens will be analyzed, as was done for Biomphalysin [25]. Moreover, as some the members of the Bt β-PFT family (the parasporins) have selective against specific human tumor cell lines [90,[93][94][95][96][97], any possible anticancer activity of Glabralysins will be investigated, and any molecules showing a positive activity can be considered as potential new chemotherapeutic drugs [98][99][100].…”