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We previously demonstrated that microRNA (miR)-224 expression was significantly reduced in human prostate cancer (PCa) tissues and predicted unfavorable prognosis in patients. However, the underlying mechanisms of miR-224 have not been fully elucidated. In this study, calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2) was identified as a target gene of miR-224. Then, we found that enforced expression of miR-224 could suppress PCa cell proliferation and cell cycle by regulating the expression of CAMKK2 in vitro. In addition, the expression levels of miR-224 in PCa tissues were negatively correlated with those of CAMKK2 mRNA significantly (Spearman's correlation: r = -0.66, P = 0.004). Moreover, combined low miR-224 expression and high CAMKK2 expression (miR-224-low/CAMKK2-high) was closely correlated with advanced clinical stage (P = 0.028). Furthermore, PCa patients with miR-224-low/CAMKK2-high expression more frequently had shorter overall survival than those in groups with other expression patterns of two molecules. In conclusion, our data offer the convincing evidence that miR-224 and its target gene CAMKK2 may synergistically contribute to the malignant progression of PCa. Combined detection of miR-224 and CAMKK2 expressions represents an efficient predictor of patient prognosis and may be a novel marker which can provide additional prognostic information in PCa.

Numerous epidemiological studies have been conducted to investigate the association between Xeroderma pigmentosum complementation group D (XPD) Asp312Asn (rs1799793 G > A) and Lys751Gln (rs13181 A > C) polymorphisms and bladder cancer risk; however, the conclusions remain controversial. With this in mind, we performed this meta-analysis with 11 studies including 3,797 cases and 5,094 controls for Asp312Asn and 21 studies including 6,360 cases and 7,894 controls for Lys751Gln polymorphism. We searched available literatures from PubMed, Embase, and CBM databases. Crude odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the strength of the associations. Moreover, to validate biological plausibility of our findings, the effects of these two polymorphisms on XPD gene expression within three ethnicities was determine by gene expression analysis based on imputed genotypes from HapMap. Overall, the variant allele of Asp312Asn polymorphism was associated with an increased risk of bladder cancer (Asn/Asn vs. Asp/Asp: OR = 1.51, 95% CI = 1.19-1.91; Asp/Asn vs. Asp/Asp: OR = 1.23, 95% CI = 1.12-1.35; recessive model: OR = 1.33, 95% CI = 1.10-1.61; dominant model: OR = 1.32, 95% CI = 1.14-1.52; and allele comparing: OR = 1.26, 95% CI = 1.11-1.42). We found the Lys751Gln was associated with increased bladder cancer risk only under the recessive model (OR = 1.14, 95% CI = 1.01-1.29). Stratification analyses demonstrated an increased risk for Asians and hospital-based studies under all genetic models while only under the dominant model for Caucasians as to the Asp312Asn polymorphism and for Caucasians under the recessive model as to the Lys751Gln polymorphism. We also found the Asp312Asn polymorphism can significantly influence mRNA expression levels among Asians and Caucasians, and the Lys751Gln polymorphism has a similar effect for Caucasians. Despite some limitations, this meta-analysis suggests that polymorphisms in XPD gene may contribute to bladder cancer susceptibility. These findings need further validation by large well-designed prospective studies.

Numerous studies have investigated the association between three polymorphisms (Lys939Gln, Ala499Val and PAT-/+) of Xeroderma pigmentosum group C (XPC) gene and bladder cancer susceptibility; however, the findings are inconclusive. In order to acquire a more precise estimation of the relationship, we performed a meta-analysis based on 10 studies including 3,934 cases and 4,269 controls for Lys939Gln, five studies including 2,113 cases and 2,249 controls for Ala499Val, and seven studies including 2,834 cases and 3,048 controls for PAT-/+ polymorphism. We searched publications from EMBASE, MEDLINE, and Chinese Biomedical. We calculated pooled odds ratio (OR) and 95% confidence interval (CI) by using either fixed-effects or random-effects model according to the between-study heterogeneity. We found that all studied polymorphisms were individually associated with increased overall cancer risks, as shown by ORs (95% CIs) below: the Lys939Gln (Gln/Gln vs. Lys/Lys: OR = 1.39, 95% CI = 1.08-1.79; recessive model: OR = 1.42, 95% CI = 1.11-1.83; and allele comparing: OR = 1.12, 95% CI = 1.003-1.24), the Ala499Val (Val/Val vs. Ala/Ala: OR = 1.82, 95% CI = 1.19-2.79; recessive model: OR = 1.70, 95% CI = 1.18-2.46; and allele comparing: OR = 1.23, 95% CI = 1.01-1.50), and the PAT-/+ (+/+ vs. -/-: OR = 1.36, 95% CI = 1.03-1.79 and recessive model: OR = 1.34, 95% CI = 1.06-1.70). Furthermore, stratification analyses demonstrated an increased risk for Asian populations as to the Lys939Gln and PAT-/+ whereas for Caucasian populations as to the Ala499Val polymorphism in the homozygous and recessive models. Despite some limitations, this meta-analysis suggests that XPC polymorphisms are associated with bladder cancer risk, but this association warrants further validation in well-designed studies with large sample sizes.