Cancer Biomarker Discovery via Selective Tissue Proteome Enrichment

Cheng S. Lee

Department of Chemistry and Biochemistry

University of Maryland

Abstract:

The greatest bioanalytical challenge facing comprehensive proteomic analysis, particularly in the identification of low abundance proteins, is related to the large variation of protein relative abundances. One obvious approach to increase the detection capability of low abundant proteins is to significantly raise the sample loading along with additional fractionation/separation procedures, and therefore is impractical for proteomic studies of small populations of tumor cells microdissected from limited tissue samples. Since the sizes of human tissue biopsies are becoming significantly smaller due to the advent of minimally-invasive methods and early detection and treatment of lesions, our research efforts therefore aim to develop a more effective discovery-based proteomic technology to enable comparative and sensitive studies of protein profiles that will have diagnostic and therapeutic relevance.

Results of oncoproteomic studies of paired primary and recurrent (post-chemotherapy) ovarian high grade serous carcinomas from nine ovarian cancer patients will be presented. Low abundance proteins, such as IL-6 and STAT3 as well as many other proteins known to participate in the IL-6 signaling pathway, are identified and compared for their expression levels within primary and recurrent ovarian carcinomas. For example, RELA and STAT5B are identified as the major over-expressed and carboplatin-resistant proteins in recurrent ovarian carcinoma. Based on shRNA screening for the upregulated genes in in vitro carboplatin-resistant cells, simultaneous knockdown of RELA and STAT5B is most effective in sensitizing tumor cells for carboplatin treatment. Similarly, the use of small molecule inhibitors for RELA and STAT5B significantly enhances cell sensitivity to carboplatin and benefits patients with carboplatin-resistant recurrent ovarian carcinoma.