The serine protease inhibitor serpinE2 is a novel target of ERK signaling involved in human colorectal tumorigenesis

Abstract

BackgroundAmong the most harmful of all genetic abnormalities that appear in colorectal cancer (CRC) development are mutations of KRAS and its downstream effector BRAF as they result in abnormal extracellular signal-related kinase (ERK) signaling. In a previous report, we had shown that expression of a constitutive active mutant of MEK1 (caMEK) in normal rat intestinal epithelial cells (IECs) induced morphological transformation associated with epithelial to mesenchymal transition, growth in soft agar, invasion and metastases in nude mice. Results from microarrays comparing control to caMEK-expressing IECs identified the gene encoding for serpinE2, a serine protease inhibitor, as a potential target of activated MEK1.Results1- RT-PCR and western blot analyses confirmed the strong up-regulation of serpinE2 expression and secretion by IECs expressing oncogenic MEK, Ras or BRAF. 2- Interestingly, serpinE2 mRNA and protein were also markedly enhanced in human CRC cells exhibiting mutation in KRAS and BRAF. 3- RNAi directed against serpinE2 in caMEK-transformed rat IECs or in human CRC cell lines HCT116 and LoVo markedly decreased foci formation, anchorage-independent growth in soft agarose, cell migration and tumor formation in nude mice. 4- Treatment of CRC cell lines with U0126 markedly reduced serpinE2 mRNA levels, indicating that expression of serpinE2 is likely dependent of ERK activity. 5- Finally, Q-PCR analyses demonstrated that mRNA levels of serpinE2 were markedly increased in human adenomas in comparison to healthy adjacent tissues and in colorectal tumors, regardless of tumor stage and grade.ConclusionsOur data indicate that serpinE2 is up-regulated by oncogenic activation of Ras, BRAF and MEK1 and contributes to pro-neoplastic actions of ERK signaling in intestinal epithelial cells. Hence, serpinE2 may be a potential therapeutic target for colorectal cancer treatment.

Sj7170, a Unique Dual-function Peptide with a Specific α-Chymotrypsin Inhibitory Activity and a Potent Tumor-activating Effect from Scorpion Venom

“…Other oncogenic pathways have been associated with induction of serpinE2 expression. MET and PTEN deletion can up-regulate the expression of serpinE2 (25). SPINK1, a Kazal type 1 serine protease inhibitor, acts as a growth factor involved in cancer progression and local invasion through EGF receptor signaling and its downstream signaling pathway MAPK/ERK (26).…”

Expression Profiling of a Human Thyroid Cell Line Stably Expressing the BRAFV600E Mutation

“…The SERPINE2 gene encodes a member of the serpine protein family that inhibits serine proteases. In a study using human colorectal cell lines, BRAF V600E increased SERPINE2 mRNA and protein levels and subsequent MEK/ERK activity (35). In a pancreatic cancer study using nude mouse xenografts, SERPINE2 overexpression increased invasion through the extracellular matrix.…”

Expression pattern of human SERPINE2 in a variety of human tumors

“…In vitro experiments show that SERPINE2 can stimulate cell proliferation and promote drug-resistance in osteosarcoma (19). Thus SERPINE2 appears pro-neoplastic in such scenarios (15). Ultimately, tissue specificity, individual genetic differences, and different expression levels may all contribute to the complicated effects of SERPINE2 in various types of tumors.…”

“…Indeed, since the interaction between SERPINE2 and MMP9 is complex, the resultant effects can be discrepant. Furthermore, SERPINE2 was shown to be involved in BRAF-and MEK-induced tumorigenesis in colon epithelial cells and to promote pancreatic cancer invasion by up-regulating ECM production (14,15).…”

“…SERPINE2 is overexpressed in many cancers including breast cancer (6), pancreatic cancer, gastric cancer, colorectal cancer (14)(15)(16), thyroid cancer (17), oral carcinoma (18) and osteosarcoma (19), and contributes to tumor invasion and metastasis. It has been identified that up-regulation of SERPINE2 is related to oncogenic activation of RAS, BRAF and MEK, which leads to the pro-neoplastic actions of extracellular signal-regulated kinase (ERK) signaling in intestinal epithelial cells (15). SERPINE2 could also promote drug resistance in osteosarcoma (19) and lymph node metastasis in testicular germ cell tumors (20).…”