Title: Analyses of collagen XXII expression and function in non-small cell lung cancer
Description: Collagen XXIII is a transmembrane collagen previously shown to be upregulated in metastatic prostate cancer. The purpose of this study was to determine the protein expression of collagen XXIII in tumor tissues from a variety of cancers, to assess collagen XXIII's utility as a biomarker for non small-cell lung cancer (NSCLC), and to determine whether collagen XXIII has a functional role in metastasis. A multi-cancer tissue microarray was used for the immunohistochemical examination of collagen XXIII protein expression in a variety of cancers. Subsequently, collagen XXIII expression was analyzed in three separate cohorts using tissue microarrays with representative tumor and control lung tissues from NSCLC patients. In addition, NSCLC patient urine samples were analyzed for the presence of collagen XXIII through Western blot. Collagen XXIII was detected in tissue samples from a variety of cancers Within lung cancer tissues, collagen XXIII staining was enriched in NSCLC subtypes--present in 294 of 333 (88%) lung adenocarcinomas and 97 of 133 (73%) squamous cell carcinomas. High collagen XXIII staining intensity correlated with shorter recurrence- free survival in NSCLC patients. In urine, collagen XXIII was detected in 23 of 29 (79%) NSCLC patient samples but only in 15 of 54 (28%) control samples. This indicates the utility of collagen XXIII as a tissue and urinary biomarker for NSCLC, where positivity in tissue or urine significantly correlates with presence of NSCLC and high staining intensity is a significant recurrence predictor.

For the functional studies, stable H460 cell lines expressing control or collagen XXIII shRNA were examined for behavioral and morphological differences using xenograft models of metastasis as well as in vitro cell adhesion assays and anchorage independence assays. In experimental and spontaneous xenograft models of metastasis, H460 cells expressing collagen XXIII shRNA formed fewer lung metastases than control cells. Loss of collagen XXIII also impaired cell adhesion, anchorage-independent growth, and cell seeding to the lung, but did not affect cell proliferation. The potential role of these processes in metastasis and how collagen XXIII can influence metastasis is discussed.