Comparative proteomic analysis for the insoluble fractions of colorectal cancer patients

We used label-free quantitative proteomics with the insoluble fractions from colorectal cancer (CRC) patients to gain further insight into the utility of profiling altered protein expression as a potential biomarker for cancer. The insoluble fractions were prepared from paired tumor/normal biopsies from 13 patients diagnosed with CRC (stages I to IV). Fifty-six proteins identified in data pooled from the 13 cases were differentially expressed between the tumor and adjacent normal tissue. The connections between these proteins are involved in reciprocal networks related to tumorigenesis, cancer incidence based on genetic disorder, and skeletal and muscular disorders. To assess their potential utility as biomarkers, the relative expression levels of the proteins were validated using personal proteomics and a heat map to compare five individual CRC samples with five normal tissue samples. Further validation of a panel of proteins (KRT5, JUP, TUBB, and COL6A1) using western blotting confirmed the differential expression. These proteins gave specific network information for CRC, and yielded a panel of novel markers and potential targets for treatment. It is anticipated that the experimental approach described here will increase our understanding of the membrane environment in CRC, which may provide direction for making diagnoses and prognoses through molecular biomarker targeting.

Network analysis of protein expression in membrane fraction of CRC has provided novel information potentially useful for making diagnoses and determining prognoses for chemotherapeutic treatments. Using label-free quantitative proteomics, we identified 56 differentially expressed proteins from 13 CRC patients. Alterations in the expression of these proteins were analyzed to establish connections to cancer incidence. These proteins were applicable to individual proteomics, which supports their potential for use as biomarkers and for discovery of new information relevant to CRC characteristics.Figure optionsDownload high-quality image (297 K)Download as PowerPoint slideHighlights
► We identified differentially expressed 56 candidates between tumor and adjacent normal tissues of 13 CRC patients.
► We checked protein network of the identified proteins with IPA program.
► We performed personal proteomics with patient samples of tumor stage II and III.
► These identified proteins confirmed the expression pattern between CRC and healthy subjects using immunoblotting and immunohistochemistry.