Recombinant sFRP1 in cancer theranostics

W pathway is a critical aspect in the complex network of signaling molecules implicated in cancer. In non-malignant cells, Wnt signal cascade is blocked by the Secreted Frizzled-related proteins (sFRPs), a family of glycoproteins. However, they are epigenetically silenced in cancer cells. In this study, we attempted to administer recombinant human sFRP1 purified from bacterial culture on to cervical cancer cells (HeLa) to determine its anti-cancer activity. Human sFRP1 gene was cloned into bacterial expression vector pGEX-4T2. Recombinant protein was over-expressed as inclusion bodies in E.coli BL21 (DE3). After optimization of the process of solubilization of protein using detergents, GST-sFRP1 was purified to homogeneity by glutathione agarose affinity chromatography. MALDI analysis verified peptide signature particular to GST-sFRP1 and structural integrity was characterized by circular dichroism spectra. Purified recombinant protein was found to exert significant anti-proliferative effect on HeLa cells at nanomolar concentrations. Western blotting with antibodies against beta-catenin and phosphorylated beta-catenin confirmed the implication of canonical Wnt pathway. Combination therapy exhibited that recombinant sFRP1 substantially chemo sensitized HeLa cells towards conventional chemotherapeutic drug cisplatin. Coating of the therapeutic protein over gold nano-cluster embedded novel composite nanoparticles facilitated sustained release of the protein and enhanced its functional activity. The remarkable fluorescence property of gold nano-clusters was exploited for tracking and imaging purposes. Overall, therapeutic sFRP1 based nano-system may prove to be revolutionary in the field of cancer theranostics.