EVALUATION OF ANTICANCER PROPERTY OF RECOMBINANT GOAT LACTOFERRIN
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Date
2023-02-08
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COLLEGE OF VETERINARY AND ANIMAL SCIENCES MANNUTHY, THRISSUR, KERALA VETERINARY AND ANIMAL SCIENCES UNIVERSITY
Abstract
The present study was conducted with the objective to express and purifyrecombinant Malabari goat lactoferrin in Escherichia coli (E. coli). The study was carried out in three phases. In the phase I, a portion of lactoferrin (Lf) gene encoding the N lobe of Malabari goat lactoferrin (cLf-N) was cloned into pJET1.2/blunt cloning vector and transformed into E. coli strain JM109 and was sequenced which revealed a 793 bp fragment with 100 per cent similarity to goat Lf in the database. This ampliconwas subcloned into pET28a(+) expression vector and transformed into BL-21 (DE3) pLysS bacterial host. The transformed E. coli BL21 (DE3) pLysS containing the recombinant plasmid expressed maximum recombinant protein (rcLf-N) upon induction with 1mM IPTG at 37°C for five hours. The recombinant protein, rcLf-N, containing polyhistidine tag was purified using Ni-NTA affinity column chromatography and confirmed as a derivative of Lf by Western blotting. In phase II, rcLf-N was analysed for its in vitro anticancer activity in Daltons Lymphoma Ascites (DLA) cell lines. In MTT assay there was a significant (p<0.05) reduction in the per cent inhibition of cell proliferation in a concentration-dependent manner from 800μg/mL to 8.75μg/mL, indicating the cytotoxic effect of rcLf-N in a dose-dependent manner upon DLA cell lines. The half-maximal inhibitory concentration (IC50) value was found to be 263.5 μg/mL using Graph pad prism. Further, upon Acridine orange/ Ethidium bromide (AO/EB) and Hoechst staining of the treated cells, the apoptotic changes produced by rcLf-N and standard drug Cisplatin in DLA cells were highlighted. During phase III trial, the in vivo anticancer activity of rcLf-N was analysed on Swiss albino mice bearing DLA induced solid tumour. Based on preliminary studies the concentrations 50μg and 75μg of rcLf-N per animal were selected for comparison with the standard drug Cisplatin. A significant (p<0.05) reduction in tumour weight, tumour volume and tumour weight to body weight ratio was observed in the rcLf-N and cisplatin treated groups compared to the control group. Maximum reduction was observed in group treated with rcLf-N @75μg intratumourally for three days. Histopathological examination of tumour tissue in all the groups treated with rcLf-N and cisplatin showed the presence of apoptotic changes with decreased spread of neoplastic cells into surrounding tissues and decreased neovasculature.Relative expression of VEGF and Caspase-3 genes was analysed in both in vivo and in vitro studies with GAPDH as the reference gene via quantitative real-time PCR. A dose-dependent downregulation of VEGF and upregulation of Caspase-3 was revealed in the cells/tissues treated with IC50 and double IC50 doses of rcLf-N both in vitro and in vivo. Similar results were observed with IC50 Cisplatin. On comparison between intratumoural and intraperitoneal routes of treatment in vivo, the intratumoural route of treatment was better in downregulating VEGF and activating Caspase-3 on day 7 and 14, although the fold change was non-significant. From the present study, it could beconcluded that the novel recombinant protein produced antineoplastic activity through apoptosis and rcLf-N @75μg exhibited most potent anticancer activity against DLA cells.