Antwi, Kwasi

Abstract Quiescin-sulfhydryl oxidase (QSOX1) oxidizes sulfhydryl groups to form disulfide bonds in proteins. We previously mapped a peptide in plasma from pancreatic ductal adenocarcinoma patients back to an overexpressed QSOX1 parent protein in tumor cells. It is not known why, or in what capacity, pancreatic tumors overexpress QSOX1. To begin to address this question, we first showed through immunohistochemistry that QSOX1 is overexpressed in patients diagnosed with pancreatic cancer, while it is not expressed in adjacent normal tissue or infiltrating lymphocytes. To determine the potential advantages QSOX1 might provide to tumor cells we knocked down QSOX1 using shRNA that suppressed both short and long isoforms of the protein. Loss of QSOX1 expression suppressed cell growth over time, while changes in cell cycle and apoptotic markers were minimal. However, QSOX1 shRNA dramatically inhibited the abilities of BxPC3 and Panc-1 pancreatic tumor cells to invade through Matrigel in a modified Boyden chamber assay. Mechanistically, gelatin zymography indicated that QSOX1 may play an important role in intracellular processing and extracellular activation of MMP-2 and MMP-9. Taken together, our results suggest that pancreatic tumors that express QSOX1 demonstrate an invasive phenotype through MMP activation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr B60.

Abstract Quiescin sulfhydryl oxidase 1 (QSOX1) oxidizes sulfhydryl groups to form disulfide bonds in proteins. We previously mapped a peptide in plasma from pancreatic ductal adenocarcinoma (PDA) patients back to an overexpressed QSOX1 parent protein. In addition to overexpression in pancreatic cancer cell lines, 29 of 37 patients diagnosed with PDA expressed QSOX1 protein in tumor cells, but QSOX1 was not detected in normal adjacent tissues or in a transformed, but nontumorigenic cell line. To begin to evaluate the advantage QSOX1 might provide to tumors, we suppressed QSOX1 protein expression using short hairpin (sh) RNA in two pancreatic cancer cell lines. Growth, cell cycle, apoptosis, invasion, and matrix metalloproteinase (MMP) activity were evaluated. QSOX1 shRNA suppressed both short and long isoforms of the protein, showing a significant effect on cell growth, cell cycle, and apoptosis. However, QSOX1 shRNA dramatically inhibited the abilities of BxPC-3 and Panc-1 pancreatic tumor cells to invade through Matrigel in a modified Boyden chamber assay. Mechanistically, gelatin zymography indicated that QSOX1 plays an important role in activation of MMP-2 and MMP-9. Taken together, our results suggest that the mechanism of QSOX1-mediated tumor cell invasion is by activation of MMP-2 and MMP-9. Mol Cancer Res; 9(12); 1621–31. ©2011 AACR.