Down-regulation of RARRES2 in human tumors. (A) RARRES2 expression in melanoma and in normal skin. Public microarray data from the GEO database (accession no. GDS1375) showing the relative expression (calculated signal intensities) of RARRES2 (chemerin). Individual tissue samples are represented as dots. Two-tailed Student’s t test was used to determine statistical significance. (B) Publically available datasets from the GEO database that had direct comparisons of RARRES2 expression in both melanocyte and melanoma primary cultures or cell lines were identified (n = 2; GDS1965 and GDS3012). Data were normalized to GAPDH and pooled and shown as percentage of maximal RARRES2 expression. Significance was determined using the Mann-Whitney test. (A and B) Horizontal bars represent the mean, and vertical bars represent SEM. (C) Kaplan-Meier plot of overall survival for both high and low/absent RARRES2 expression cohorts relative to an idealized threshold, with associated log-rank p-values shown after correction for multiple hypothesis testing using 1,000-fold cross-validation. (D) RARRES2 expression was evaluated in GDS datasets in the GEO database from studies comparing precancerous, primary, or metastatic solid tumors with appropriate normal tissue counterparts. Tumor tissues of prostate cancer (two), colon adenoma, and breast and lung adenocarcinoma (GDS2545, GDS1375, GDS2947, GDS1650, GDS2250, and GDS1439) were examined. Two-tailed Student’s t test was used to determine statistical significance. Individual tissue samples are represented as dots, and bars represent mean. For significant differences, the p-value is noted. (E) Summary of statistical analyses is presented from two clinical datasets (Winnepenninckx et al., 2006; Xu et al., 2008). Statistics are presented for RARRES2 expression when considered as a continuous variable with log-likelihood p-values within a univariate Cox regression model. Therapy represents all possible therapies administered within each cohort. HR, hazard ratio.