Upregulation of CPE promotes cell proliferation and tumorigenicity in colorectal cancer

Abstract

BackgroundColorectal cancer (CRC) is one of the most common cancers worldwide and a leading cause of cancer related death. Although the mortality rate of CRC is decreasing, finding novel targets for its therapy remains urgent. Carboxypeptidase E (CPE), a member of the pro-protein convertases, which are involved in the maturation of protein precursors, has recently been reported as elevated in many types of cancer. However, its role and mechanisms in tumor progression are poorly understood.MethodsIn the present study, we investigated expression of CPE in CRC cell lines and tumor tissues using Western blot and real-time qRT-PCR. Plasmids for overexpression and depletion of CPE were constructed and analyzed by Western blot, MTT and colony formation assays and bromodeoxyuridine incorporation assays. The relative expression of p21, p27, and cyclin D1 were analyzed by Real-time qRT-PCR in the indicated cells.ResultsOur study showed that CPE was significantly upregulated in CRC cell lines and tumor tissues. MTT and colony formation assays indicated that overexpression of CPE enhanced cell growth rates. BrdU incorporation and flow-cytometry assays showed that ectopic expression of CPE increased the S-phase fraction cells. Soft agar assay proved enhanced tumorigenicity activity in CPE over-expressing CRC cells. Further studies of the molecular mechanisms of CPE indicated that is promoted cell proliferation and tumorigenicity through downregulation of p21 and p27, and upregulation of cyclin D1.ConclusionsTaken together, these data suggest that CPE plays an important role in cell cycle regulation and tumorigenicity, and may serve as a potential target for CRC therapeutics.

N-terminal truncated carboxypeptidase E expression is associated with poor prognosis of lung adenocarcinoma

“…Similar findings have been observed in primary pheochromocytomas/paragangliomas (PHEO/PGL) and colorectal cancer patients (17,18). Previous studies, which have used quantitative polymerase chain reaction to analyze CPEΔN expression, revealed that elevated CPEΔN expression is a statistically significant predictor of poor prognosis (17,18). Since HCC, PHEO/PGL and colorectal cancer are extremely different tumors with distinctive tumor origins, these findings suggest that CPEΔN may be a predictor of metastasis with a broad spectrum.…”

“…HCC patients with high CPEΔN expression levels exhibited significantly higher recurrence rates in the 2 years following surgery and lower median survival times than patients with low CPEΔN expression levels (15). Similar findings have been observed in primary pheochromocytomas/paragangliomas (PHEO/PGL) and colorectal cancer patients (17,18). Previous studies, which have used quantitative polymerase chain reaction to analyze CPEΔN expression, revealed that elevated CPEΔN expression is a statistically significant predictor of poor prognosis (17,18).…”

“…CPE exists in three different forms, which are expressed in various subcellular localizations with distinct functions (18). The first type is released by secretory granules, which results in the cleavage of basic residues to generate mature peptide hormones and neuropeptides.…”

Carboxypeptidase E (CPE) inhibits the secretion and activity of Wnt3a

“…17,8 CPE has also been implicated in cancer progression [18][19][20][21] and as a neuro-trophic factor regulating brain functions. [22][23][24][25][26] Lately, it was found that CPE is also involved in other biological processes such as bone homeostasis 27 and bowel disease.…”

“…After 24 h, the cells were fixed and visualized by a confocal microscope. (b) HEK293T cells were co-transfected with the HA-Wnt3a vector and GFP-peptide(1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) or Scr as a control. Forty-eight hours post transfection, cells were harvested and IP assay was performed using an anti-HA antibody.…”