Colorectal cancer tumorigenesis

Additional genes and protein receptors are believed to be important in colorectal tumorigenesis. Cyclooxygenase 2 (COX-2), which is induced in colorectal cancer cells, influences apoptosis and other cellular functions in colon cells, and overexpression of the epidermal growth factor receptor (EGFR), a transmembrane glycoprotein involved... 

Fearnhead NS, Wilding JL, Bodmer WF. Genetics of colorectal cancer hereditary aspects and overview of colorectal tumorigenesis. Brit Med Bulletin 2002 64 27-43. 

A genetic model has been proposed for colorectal tumorigenesis that describes a process of transformation from adenoma to carcinoma. However, at least three separate additional molecular pathways to developing colorectal cancer have been identifled. These include a pathway for HNPCC, an ulcerative cohtis-dysplasia-carcinoma sequence, and a pathway involving loss of function of the estrogen receptor gene through hypermethylation. Some of the molecular processes are common to more than one pathway. 

The precise role of immunological surveillance in tumorigenesis is not well dehned for the majority of malignancies. The occurrence of a unique spectrum of malignancies in immunosuppressed individuals suggests either that immune surveillance is only important in certain tumors or that the duration needed to see an increased incidence of many more common tumors (e.g., colorectal, breast, lung, or prostate carcinomas) is not reached. Suppression of T cell mediated immunity has, however, been unequivocally associated with an increased incidence of certain mahgnancies. In patients with profound defects in T cell immunity the time to tumor detection is often shorter than for cancers induced by other mechanisms. 

P. Schlag, K.P. Janssen, M. Gottlicher, Induction of HDAC2 expression upon loss of APC in colorectal tumorigenesis, Cancer Cell 2004, 5, 455-463 (b) K. Halkidou,... 

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