Protein profiling of tumor tissues by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry to discriminate between localized and metastatic renal cell carcinoma

Abstract

e16098 Background: We previously reported that mRNA of interferon-alpha receptor type 2 (IFNAR2) was upregulated in metastatic and IFN-a resistant renal cell carcinoma (RCC) in comparison to localized RCC or metastatic tumors with good response to IFN-a (BMC Cancer, 2007). We speculated potential different molecular mechanism between above two groups. Protein profiling using human tumor tissues may give insight into cellular pathways leading to carcinogenesis and metastasis in RCC. Methods: We examined mRNAs expression for IFNAR2 in paired tumor and non-tumor samples from the surgical specimens of Japanese patients with RCC using a real-time reverse transcription polymerase chain reaction. Then we selected representative five IFNAR2 upregulated clear cell carcinomas cases with metastatic tumor, five IFNAR2 upregulated metastatic sarcomatoid carcinomas, and five normal expression clear cell carcinomas with localized tumor. We investigated protein profiling in the tumor tissues of above three groups using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) coupled with IMAC-Cu chips. Results: For hierarchical clustering analysis, we used the 25 peaks which revealed significant differences in single-marker analysis in the range from 1,500 to 10,000 m/z. The heat map analysis based on the clustering distinguished completely metastatic tumors with IFNAR2 upregulated groups from localized tumors with IFNAR2 normal expression group. Furthermore, the heat map discriminated metastatic sarcomatoid carcinomas from metastatic clear cell carcinomas with a sensitivity of 100% and a specificity of 80%. Conclusions: SELDI-TOF MS profiling of tumor tissues can be applied to differentiate patients with three types of RCCs. Our findings may reflect different molecular mechanism between localized and metastatic carcinomas, and the different response to immunotherapy with IFN-α. This may shed light on the potential therapeutic strategy for IFN-α treatment. However, further investigation is required to verify the usefulness of this method in clinical practice. No significant financial relationships to disclose.