Mouse anti-Human p130Cas (pY249) monoclonal antibody, clone K270-868.23.3

Reports that the adhesion-associated molecule p130Cas/BCAR1 promotes resistance to tamoxifen suggested that adhesion-mediated signalling may be altered by tamoxifen treatment. We find that p130Cas/BCAR1 phosphorylation is enhanced in tamoxifen-treated estrogen receptor (ER)positive MCF-7 breast cancer cells. The effects of estrogen and tamoxifen were assessed independently and in combination, and the results demonstrate that tamoxifen antagonizes estrogen regulation of p130Cas/BCAR1 phosphorylation. Phosphorylation correlates with tamoxifen ER antagonist effects, as phosphorylation effects are replicated by the pure antiestrogen ICI 182, 780. Correspondingly, phosphorylation is not changed in ER-negative cells exposed to tamoxifen. We show that deletion of the p130Cas/BCAR1 substrate domain substantially reduces tamoxifen-induced phosphorylation of p130Cas/BCAR1 and confers enhanced sensitivity to tamoxifen. P130Cas/BCAR1 forms a phosphorylation-dependent signalling complex with focal adhesion kinase (FAK) and Src kinase that promotes adhesion-mediated cell survival. Therefore, we examined the kinetics of p130Cas/BCAR1, Src and FAK phosphorylation over a 14-day time course and find sustained phosphorylation of these molecules after 7 days exposure to tamoxifen. Inhibition of Src kinase is shown to reduce tamoxifen-promoted p130Cas/BCAR1 phosphorylation and reduce cell viability. Stimulation of the Src/FAK/p130Cas/BCAR1 adhesion signalling pathway in tamoxifen-treated MCF-7 cells does not cause increased migration; however, there is Src-dependent phosphorylation of the cell survival molecule Akt. Correspondingly, Akt inhibition reduces cell viability in cells treated with tamoxifen. We propose that prolonged activation of adhesion-dependent signalling may confer a survival advantage in response to additional cellular insults or alternatively, may poise cells to develop a migratory phenotype in response to additional cellular cues.

Objective: The purpose of the study was to evaluate clinical presentation of breast cancer anti-estrogen resistance protein 1 (BCAR1, also known as p130cas) expression in pulmonary diseases, and to assess its potential as a molecular marker for diagnosis and prognosis. Methods: Between March 2008 and August 2010, we enrolled a total of 80 patients (group A) with non-small-cell lung cancer (NSCLC), 48 patients (group B) with pulmonary tuberculosis (including 27 cases of tuberculoma and 21 cases of cavitary pulmonary tuberculosis), and 32 patients (group C) with other benign pulmonary mass (hamartoma in 15 cases, inflammatory pseudotumor in 10 cases, fibroid tumor in 7 cases). Additionally, 160 healthy age- and sex-matched volunteers were recruited as healthy controls. Tissue BCAR1 expression was investigated by using tissue microarray and immunohistochemistry. BCAR1 and tumor markers (carcinoma embryonic antigen [CEA] and the cancer antigens CA19-9 and CA 125) in serum were assayed by using ELISA and immunoradiometrics, respectively. Results: BCAR1 expression was detected (either in the nucleus, the cytoplasm, or both) in tumor cells in 79 of the 80 NSCLC cases in group A, and in fibroblasts in 41 of the 48 pulmonary tuberculosis cases in group B. However, it was not detected in the normal adjacent tissue in 70 of the 80 cases in group A and in 47 of the 48 cases in group B. In group C, BCAR1 expression was negative in all 32 cases. Additionally, we investigated adjacent tissue with acute or chronic inflammation in 20 cases from group C, and found no expression of BCAR1. Serum BCAR1 levels were significantly higher in patients with NSCLC than in the control group, increased gradually with the progression of tumor staging, and decreased after removal of the tumors. The levels were significantly lower in bronchioloalveolar carcinoma than in other subtypes of carcinoma (Mann-Whitney U test, Z=-5.089; p < 0.001). Serum BCAR1 levels were significantly higher in patients with pulmonary tuberculosis than in the control group, were positively and significantly correlated with the diameter of the tuberculosis lesion (Spearman's rho, correlation coefficient 0.753; p < 0.001), and decreased after removal of the tuberculosis lesions. The levels were significantly higher in patients with cavitary pulmonary tuberculosis than in those with tuberculoma (517.6 +/- 326.5 vs 282.2 +/- 137.6; Student's t-test, t = -3.387; p = 0.001). In group C, there was no appreciable difference in serum BCAR1 levels compared with the matched controls (222.8 +/- 111.0 vs 201.6 +/- 35.7; Dunnett's T3 test, p = 0.993). The discrimination power of combining BCAR1 and tumor markers in NSCLC versus benign lung diseases was higher than that of sole use of BCAR1 as a marker (maximal sum of sensitivity and specificity: 1.538 vs 1.237). Conclusion: We conclude that a combined assay of serum BCAR1 and traditional tumor markers is potentially applicable for distinguishing NSCLC from benign lung diseases. However, the clinical utility of serum BCAR1 as a molecular marker for prognosis in NSCLC or pulmonary tuberculosis requires further clarification and verification.