JAK proteins are known to enhance STAT3 transcription, thus we measured the effect of CPT on JAK mediated STAT3 transcription. We found that STAT3 transcriptional activity is significantly increased in cells transfected with JAK1 and JAK2. However, the addition of CPT decreased JAK1 and JAK2 mediated STAT3 transcription. CPT diminishes pRKIP levels through the inhibition of STAT3 by interacting table 1 with GP130 To delineate the observed changes in pY705 STAT3 levels after CPT treatment we performed an immunoprecipita tion assay. Western blot analysis revealed that the inter action between gp130 and STAT3 is IL 6 dependent and that this interaction is interrupted by CPT treatment. This indicates that treatment with CPT leads to the disruption of subsequent phosphorylation events after IL 6 treatment.

Collectively our results suggest that CPT affects multiple pathways leading to diminution of kinase activities. Clinicopathologic features of cancer patients luciferase reporter assay luciferase reporter assay To see if we could correlate our cell based studies with the colon cancer patient clinical outcome we examined a TMA of 140 patients. The mean age of the patients at initial surgery was 74. 3 years, 66 men and 74 women were included in the study. The mean duration of follow up was 76. 6 months. All the tumors were Stage II with 25 cases of high grade and 115 cases of low grade based on the latest American Joint Committee of Cancer tumor stage. There were 13 tumors with LVI and 127 tumors without LVI. The clinicopathologic features of the patients are summarized in Table 1.

Expression of phosphorylated RKIP in colon cancer and its prognostic value The staining pattern for pRKIP is mixed, both cytoplasmic and nuclear. The cytoplasmic staining intensity was graded 3 in 66 cases, 2 in 46 cases, 1 in 14 cases and 0 in 2 cases. The nuclear stain ing intensity was graded 3 in one case, 2 in 26 cases, 1 in 84 cases, and 0 in 18 cases. Kaplan Meier survival analysis of a limited number of patients indicated a decrease in survival of patients with elevated pRKIP. The percent of patients with low levels of pRKIP and no LVI was much greater than the population with LVI. Cytoplasmic and nuclear pRKIP have opposite associ ation with two important prognostic markers, tumor grade and lymphovascular invasion.

Twenty six percentage cytoplasmic pRKIP low tumors are high grade compared with 11% cytoplasmic pRKIP high tumors being high grade. Similarly 11% cyto plasmic pRKIP low tumors have LVI while 6% cytoplasmic pRKIP high tumors have LVI. Thus, low expression of cytoplasmic pRKIP is associated with high tumor grade and presence of LVI, i. e. worse selleck chemicals Wortmannin prognosis. In contrast, 19% of nuclear pRKIP high tumors are high grade as opposed to 11% of nuclear pRKIP low tumors being high grade. Similarly, 10% of nuclear pRKIP high tumors have LVI while 0% of nuclear pRKIP low tumors have LVI.