Proinsulin C-peptide inhibits high glucose-induced migration and invasion of ovarian cancer cells.

Proinsulin C-peptide, a biologically active polypeptide released from pancreatic ß-cells, is known to prevent hyperglycemia-induced microvascular leakage; however, the role of C-peptide in migration and invasion of cancer cells is unknown. Here, we investigated high glucose-induced migration and invasion of ovarian cancer cells and the inhibitory effects of human C-peptide on metastatic cellular responses. In SKOV3 human ovarian cancer cells, high glucose conditions activated a vicious cycle of reactive oxygen species (ROS) generation and transglutaminase 2 (TGase2) activation through elevation of intracellular Ca2+ levels. TGase2 played a critical role in high glucose-induced ovarian cancer cell migration and invasion through ß-catenin disassembly. Human C-peptide inhibited high glucose-induced disassembly of adherens junctions and ovarian cancer cell migration and invasion through inhibition of ROS generation and TGase2 activation. The preventive effect of C-peptide on high glucose-induced ovarian cancer cell migration and invasion was further demonstrated in ID8 murine ovarian cancer cells. Our findings suggest that high glucose conditions induce the migration and invasion of ovarian cancer cells, and human C-peptide inhibits these metastatic responses by preventing ROS generation, TGase2 activation, and subsequent disassembly of adherens junctions.

Potent anti-inflammatory and anti-apoptotic activities of electrostatically complexed C-peptide nanospheres ameliorate diabetic nephropathy.

In the present era of "Diabetic Pandemic", peptide-based therapies have generated immense interest however, are facing odds due to inevitable limitations like stability, delivery complications and off-target effects. One such promising molecule is C-peptide (CPep, 31 amino acid polypeptide with t1/2 30 min); it is a cleaved subunit of pro-insulin, well known to suppress microvascular complications in kidney but has not been able to undergo translation to the clinic till date. Herein, a polymeric CPep nano-complexes (NPX) was prepared by leveraging electrostatic interaction between in-house synthesized cationic, polyethylene carbonate (PEC) based copolymer (Mol. wt. 44,767 Da) and negatively charged CPep (Mol. wt. 3299 Da) at pH 7.4 and further evaluated in vitro and in vivo. NPX exhibited a spherical morphology with a particle size of 167 nm and zeta potential equivalent to +10.3, with 85.70 % of CPep complexation efficiency. The cellular uptake of FITC-tagged CPep NPX was 95.61 % in normal rat kidney cells, NRK-52E. Additionally, the hemocompatible NPX showed prominent cell-proliferative, anti-oxidative (1.8 folds increased GSH; 2.8 folds reduced nitrite concentration) and anti-inflammatory activity in metabolic stress induced NRK-52E cells as well. The observation was further confirmed by upregulation of anti-apoptotic protein BCl2 by 3.5 folds, and proliferative markers (ß1-integrin and EGFR) by 3.5 and 2.3 folds, respectively, compared to the high glucose treated control group. Pharmacokinetic study of NPX in Wistar rats revealed a 6.34 folds greater half-life than free CPep. In in-vivo efficacy study in STZ-induced diabetic nephropathy animal model, NPX reduced blood glucose levels and IL-6 levels significantly by 1.3 and 2.5 folds, respectively, as compared to the disease control group. The above findings suggested that NPX has tremendous potential to impart sustained release of CPep, resulting in enhanced efficacy to treat diabetes-induced nephropathy and significantly improved renal pathology.