P5-13-02: Prediction of Dasatinib Sensitivity of Breast Cancer Based on a Novel Tyrosine Kinase-Activity Profiling Assay

• Published in: Cancer research (Chicago, Ill.) Vol. 71; no. 24_Supplement; pp. P5 - P5-13-02
• Main Authors: Kawai, M, Torikoshi, Y, Notoya, M, Gohda, K, Ueno, NT, Ishihara, H
• Format: Journal Article
• Language: English
• Published: 15.12.2011
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/0008-5472.SABCS11-P5-13-02

Abstract Background: Receptor tyrosine kinases and other membrane-associated tyrosine kinases are frequently overexpressed, activated, or mutated in cancer cells and cause aberrant signal transduction, which leads to cellular proliferation, angiogenesis, metastasis, and antiapoptosis. Blockage of these signals is considered an efficient strategy in cancer therapy, and to date, several tyrosine kinase inhibitors (TKIs) and antibody drugs targeting such kinases have been developed and are routinely used in clinics. However, the efficacy rates of the drugs are, unfortunately, limited. To provide optimum care for individual patients, an accurate prediction method for drug efficacy is now strongly demanded. Recent studies have shown that alteration of multiple kinases is involved in both primary and acquired drug resistance. Advantages of multi-targeted TKIs have also been reported. These findings indicate the need for a comprehensive evaluation of multiple kinases for predicting drug response. To achieve this, we developed a novel method of comprehensively profiling kinase activity. Materials and methods: We characterized the membranous tyrosine kinases of breast cancer cell lines using a newly established profiling assay. Briefly, crude membrane fractions were prepared and directly subjected to the assay with nonspecific substrate (Poly(Glu4-Tyr)). The profile of the kinases in the crude membrane fraction was obtained by inhibiting the total activity with 13 selected kinds of adenosine triphosphate antagonists, independently. The residual activity (RA) of membranous kinases was defined as the percentage of activity with/without TKI. Results: Nineteen breast cancer cell lines were classified as “sensitive” (n = 6) and “resistant” (n = 13) to dasatinib according to the definition in the publication (Cancer Res., 67 2226–38. 2007). The RA of tyrosine kinases targeted by different types of TKIs was determined by our assay, and we found that two RAs (src inhibitor 1 and PP1) showed statistically significant differences between the “sensitive” and “resistant” groups (p=0.017, and p=0.002, respectively, Student's t-test). The RA of the two TKIs were also significant predictors for dasatinib sensitivity in a receiver operating characteristic curve analysis (area under the curve: 0.846 for src inhibitor 1 and 0.910 for PP1). Since the major target of dasatinib are src family kinases, protein expressions of the src family of the cell lines were quantified by a Western blotting and compared between the groups. We found that the protein expression is not a statistically significant predictor of dasatinib sensitivity. Conclusion: We have shown that a comprehensive tyrosine kinase activity profiling assay of cancer cells can predict dasatinib sensitivity. We plan to validate this assay prospectively in patients with breast cancer who receive dasatinib. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-02.