Novel Expression Patterns of PI3K/Akt/mTOR Signaling Pathway Components in Colorectal Cancer
- 31 May 2010
- journal article
- research article
- Published by Ovid Technologies (Wolters Kluwer Health) in Journal of the American College of Surgeons
- Vol. 210 (5), 767-776
- https://doi.org/10.1016/j.jamcollsurg.2009.12.008
Abstract
Background The phosphatidylinositol 3-kinase/Akt/mammalian target of rapamycin (PI3K/Akt/mTOR) pathway plays a critical role in the growth and progression of colorectal cancer (CRC). The purpose of our study was 2-fold: (1) to determine the expression levels of several key components of this pathway, including p85α, Akt1, Akt2, p-mTOR Ser2448, and p-p70S6K Thr389 in CRCs; and (2) to correlate the expression of these proteins with cancer stage and location (left versus right side). Study Design Immunohistochemistry for p85α, Akt1, Akt2, p-mTOR Ser2448, and p-p70S6K Thr389 was performed on normal colon and CRCs from 154 patients. Results All proteins investigated were significantly overexpressed in CRCs compared with matched normal colonic tissue from the same patient (p < 0.0001). PI3K pathway component proteins were moderately correlated across normal and malignant colon tissues; correlations tended to be stronger in normal tissues as compared with the same correlations in cancers. Expression levels of p85α were significantly higher in stage IV cancers than in stage I to III cancers (p = 0.0005). p85α expression was also significantly increased in the adjacent normal colonic mucosa of patients with stage IV CRC compared with earlier stages (p = 0.003). Finally, expression of Akt1, Akt2, and p-p70S6K Thr389 was higher in left-sided CRCs compared with CRCs in the right colon (p = 0.007, p = 0.0008, and p = 0.04, respectively). Conclusions The PI3K/Akt/mTOR pathway components, p85α, Akt1, Akt2, p-mTOR Ser2448, and p-p70S6K Thr389 are highly overexpressed in CRCs, providing the rationale for targeting this pathway therapeutically in CRC patients. The increased expression of p85α in the adjacent normal mucosa of stage IV patients suggests an important field defect, which may contribute to the growth and progression of these cancers.Keywords
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