Apc deficiency is associated with increased Egfr activity in the intestinal enterocytes and adenomas of C57BL/6J-Min/+ mice.
Overexpression of the epidermal growth factor receptor (EGFR) and its increased tyrosine kinase activity are implicated in colorectal cancer (CRC) development and malignant progression. The C57BL/6J-Min/+ (Min/+) mouse is a model for CRC and develops numerous intestinal adenomas. We analyzed the normal mucosa of Min/+ and Apc+/+ (WT) littermate mice together with Apc-null adenomas to gain insight into the roles of Egfr in these intestinal tissues. Protein analyses showed that Egfr activity was highest in the tumors, and also up-regulated in Min/+ relative to WT enterocytes. Expression of ubiquitylated Egfr (Egfr-Ub) was increased in Min/+ enterocytes and tumors. Tumors exhibited increased association of Egfr with clathrin heavy chain (CHC), Gab1, and p85alpha, the regulatory subunit of phosphoinositide 3-kinase (PI3K), and tumors also overexpressed c-Src, PDK1, and Akt. Immunohistochemistry for Akt-p-Ser473 revealed a low level of this active kinase in Min/+ and WT enterocytes and its strong presence in tumors. Prostaglandin E2 (PGE2) is a product of cyclooxygenase-2 (Cox-2) activity that is up-regulated in Min/+ tumors and transactivates Egfr. PGE2 expression was significantly higher in untreated Min/+ tumors and reduced by treatment with the Cox-2 inhibitor, celecoxib. Dietary administration of this NSAID also inhibited Egfr activity in tumors. Increased activation of the EGFR-PI3K-Akt signaling pathway in tumors relative to Apc+/+ and ApcMin/+ enterocytes provides potential opportunities for therapeutic interventions to differentially suppress tumor formation, promotion, progression, and/or recurrence.
Moran
Amy E
AE
Department of Surgery, Weill College of Medicine of Cornell University, and Strang Cancer Prevention Center, New York, New York 10021, USA.
Hunt
Daniel H
DH
Javid
Sara H
SH
Redston
Mark
M
Carothers
Adelaide M
AM
Bertagnolli
Monica M
MM
D048868:Adaptor Proteins, Signal Transducing; D000236:Adenoma / Q000378:metabolism* / Q000473:pathology; D025601:Adenomatous Polyposis Coli Protein / Q000172:deficiency*; D000483:Alleles; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D002460:Cell Line; D002966:Clathrin / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000378:metabolism; D051546:Cyclooxygenase 2; D015232:Dinoprostone / Q000378:metabolism; D018450:Disease Progression; D020895:Enterocytes / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay; D066246:ErbB Receptors / Q000378:metabolism*; D017491:Genes, APC; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007413:Intestinal Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000378:metabolism; D007527:Isoenzymes / Q000378:metabolism; D019169:Jurkat Cells; D008565:Membrane Proteins; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D008954:Models, Biological; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D012008:Recurrence; D015398:Signal Transduction; D014018:Tissue Distribution; D015533:Transcriptional Activation; D014443:Tyrosine / Q000737:chemistry; D025801:Ubiquitin / Q000378:metabolism; D015854:Up-Regulation; D014638:Vanadates / Q000494:pharmacology; D019061:src-Family Kinases / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D025601:Adenomatous Polyposis Coli Protein; D000894:Anti-Inflammatory Agents, Non-Steroidal; D002966:Clathrin; D051546:Cyclooxygenase 2; D015232:Dinoprostone; D066246:ErbB Receptors; D007527:Isoenzymes; D008565:Membrane Proteins; D019869:Phosphatidylinositol 3-Kinases; D010750:Phosphoproteins; D011451:Prostaglandin-Endoperoxide Synthases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; D014443:Tyrosine; D025801:Ubiquitin; D014638:Vanadates; D019061:src-Family Kinases; C098587:GAB1 protein, human; C076715:pervanadate; C496540:PTGS2 protein, human; C494918:AKT1 protein, human