Normal colonic mucosa and hyperplastic polyps exhibited no significant AKT expression, in marked contrast to the dramatic AKT immunoreactivity seen in colorectal cancers (57% positive) and in both human colorectal cancer cell lines examined.
In addition, immunohistochemical staining of tumor sections derived from CRC patients showed elevated expression levels of AKT1, correlating with enhanced cytoplasmic/nuclear expression of beta-catenin.
Activation of extracellular regulated kinases (ERK1/2) but not AKT predicts poor prognosis in colorectal carcinoma and is associated with k-ras mutations.
In this study, we aimed to examine the influence of PIK3CA mutation and K-Ras mutation on AKT activation, and to clarify whether PIK3CA mutation, K-Ras mutation and p-AKT expression may be used as parameters for predicting prognosis in colorectal cancer.
A high prevalence of genetic alterations in PI3K/AKT pathway in Saudi cohort of CRC, predominance of PIK3CA mutations in the MSI subgroup and their possible involvement in development/progression of this subset of CRC are some of the significant findings of our study.
Gene expression patterns in mismatch repair-deficient colorectal cancers highlight the potential therapeutic role of inhibitors of the phosphatidylinositol 3-kinase-AKT-mammalian target of rapamycin pathway.
Although AKT activity was elevated in KRAS mutant cells, and PI3K inhibition did impair the growth of MEK inhibitor-insensitive CRC cell lines, concurrent treatment with selumetinib did not provide additional antitumor activity.
None of the 14 SNPs of the PI3K/PTEN/AKT/mTOR pathway genes investigated in this study was found to be an independent prognostic marker for Korean patients with surgically resected colorectal cancer.
p-AKT expression in colorectal cancer is associated with low stage and good prognosis. p-AKT may serve as a tissue biomarker to identify patients with superior prognosis and a possible therapeutic target (analogous to estrogen receptor ESR1 in breast cancer).
Notably, rolipram reduced the AKT phosphorylation, which is known to be associated with the disruption of luminal cavity formation and CRC development.
Here, we characterised the expression of two major HSP proteins (HSP27 and 72) by immunohistochemistry (IHC), the mutation status of TP53, KRAS and PIK3CA genes by direct sequencing and the activation status of AKT by IHC in a cohort of unselected primary CRC (n=74).
We show that activation of the PI3K/AKT pathway is a mechanism of both innate and acquired resistance to BRAF inhibitors in BRAF(V600E) CRC and suggest combinatorial approaches to improve outcomes in this poor prognosis subset of patients.
This suggests that mutations in the PIK3CA/PTEN/AKT branch of the EGFR pathway are less important than those of the RAS/RAF/MAPK branch for the progression of CRC.
In conclusion, our data revealed that miR-126 functions as a tumor suppressor in CRC cells by regulating CXCR4 expression via the AKT and ERK1/2 signaling pathways and might be a novel target for therapeutic strategies in CRC.