PC2/CPE-mediated pro-protein processing in tumor cells and its differentiated cells or tissues

Abstract

Pro-protein convertase-2 (PC2) and carboxypeptidase-E (CPE) proteins are two major members of the pro-protein convertases that involve in the maturation of protein precursor. By using PC2 activity, immunocytochemistry (ICC) and Western blot method, PC2, CPE and preproNPY protein expression levels were compared among mature retina tissue, RGC-5 cells and its differentiated cells, or brain cortex tissue, NS20Y tumor cells and its differentiated cells, or mature breast tissue, breast tumor cell RM1 and breast adenocarcinoma tissue. The experimental results indicated that the differentiated cells or tissues had higher or highest PC2 activity. In the comparative experiments, more PC2 protein expression in the mature tissues and more CPE and preproNPY protein expression in the tumor cells or tumor tissue were observed, but no expression of preproNPY protein was observed in the mature tissues. Compared with NS20Y or RGC-5 undifferentiated cells, its differentiated cells showed less proPC2, more proCPE and more preproNPY protein expressions. The results demonstrated that the mature tissues showed stronger PC2/CPE-mediated pro-protein processing ability than the tumor cells or tissue. The results also showed that the artificial differentiation of RGC-5 or NS20Y cells was different from maturation of its corresponding normal tissue.

RETRACTED ARTICLE: Carboxypeptidase E: Elevated Expression Correlated with Tumor Growth and Metastasis in Pheochromocytomas and Other Cancers

“…The first evidence for the expression of CPE in cancerous cells was documented by Grimwood et al, 1989 in human hepatoma (Hep G2) cells, although this form of CPE was slightly larger in size than that found in endocrine cells. Tumor cells of non-endocrine tissues such as breast cancer cells have also have been shown to express CPE (Du et al, 2001; Tang et al, 2009). CPE is normally not expressed in cervical tissues, but during cancerous state it is highly expressed (Fig.…”

Carboxypeptidase E promotes cancer cell survival, but inhibits migration and invasion

“…Unlike CPE- N, CPE appears to be expressed only in endocrine and neuroendocrine tumors and in glioblastomas [6; 10]. Until recently, it was presumed that CPE expressed in these tumors function within secretory granules in the cell as an enzyme that processes immature hormone intermediates to mature peptide hormones and neuropeptides which are synthesized in abundance in these tumors [22; 23; 24]. However, a recent report indicated that CPE is secreted in abundance by glioblas-toma cells and has extracellular effects on tumor cell survival, proliferation, migration and invasion [6].…”

Insulin-like growth factor 2 rescues aging-related memory loss in rats

“…Hippocampal PC2 enzymatic activity was analyzed using a protocol adapted from Tang and colleagues (2009). Proteins were extracted from dorsal hippocampi as described in Hippocampal protein extracts and western blot analysis .…”