Novel Antiproliferative and Antioxidant Role of BjAnn1, a Mustard Annexin Protein in Human Glioblastoma Cell Lines

Abstract

Glioblastoma represents the deadliest tumors of the central nervous systems and their bleak prognosis remains unchanged over the past few decades and requiring new treatments that curb the tumor progression. Cancer cells possess high reactive oxygen species (ROS) levels when compared to their normal control counterparts. We have earlier characterized the ROS-scavenging annexin protein, BjAnn1 from Brassica juncea and demonstrated its peroxidase activity. Since annexins are widely conserved across evolutionary lines with involvement in stress alleviation, we attempted to verify the effect of ectopic expression of ROS-scavenging BjAnn1 in human glioblastoma cell lines. The multiple sequence alignment revealed that BjAnn1 showed homology to human annexin A13 (73.18%), annexin A2 (70.66%), annexin A3 (72.53%) and annexin A8 (70.03%). Stable expression of BjAnn1 in U251 and U87 cells inhibited proliferation, migration and invading abilities in correlation with significant decrease in ROS levels in comparison to the empty vector (EV)-expressing controls. Multiple gene-profiling using cDNAPCR arrays revealed a prominent transcriptional upregulation of oxidative stress responsive genes including CCS, CYB, DUOX2, FOXM, GSS, MBL2, MT3, MTL5, NME5, PXDN, SOD2 and SOD3 in BjAnn1-expressing glioblastoma cells. Western blotting confirmed the significant increase in the expression of antioxidant enzymes SOD2 (MnSOD) and SOD3 (Cu/ZnSOD) in BjAnn1-expressing cells. We also observed a significant inhibition in nuclear translocation of p65 and p50, NF-κB reporter activity and expression of NF-κB-target genes in BjAnn1 expressing cells. In summary, our study shows a prominent tumor-suppressive role of ROS-scavenging BjAnn1 in glioblastoma cell lines suggesting it as a novel candidate for efficient gene therapy in glioblastoma.