Low miR-145 and high miR-367 are associated with unfavourable prognosis in resected nonsmall cell lung cancer.

The transcription factors SRY-related HMG box (SOX)2 and octamer-binding transcription factor (OCT)4 regulate the expression of the miR-302-367 cluster. miR-145 regulates SOX2 and OCT4 translation and p53 regulates miR-145 expression. We analysed the expression of the miR-302-367 cluster and miR-145 and the mutational status of p53 in resected nonsmall cell lung cancer (NSCLC) patients and correlated results with time to relapse (TTR). Tumour and paired normal tissue samples were obtained from 70 NSCLC patients. MicroRNA expression was assessed with TaqMan MicroRNA Assays. p53 exons 5 to 8 were sequenced. miR-145 was downregulated (p<0.0001) and miR-367 was upregulated (p<0.0001) in tumour compared with normal tissue. Mean TTR was 18.4 months for patients with low miR-145 levels and 28.2 months for those with high levels (p=0.015). Mean TTR was 29.1 months for patients with low miR-367 levels and 23.4 months for those with high levels (p=0.048). TTR was shorter for patients with both unfavourable variables (p=0.009). Low miR-145 expression (p=0.049), the combination of unfavourable microRNA levels (p=0.02) and the combination of low miR-145 with p53 mutations (p=0.011) were independent markers of shorter TTR. In conclusion, miR-145 and miR-367 expression could be novel markers for relapse in surgically treated NSCLC. p53 may play a role in modulating miR-145 expression in NSCLC.

Intermittent hypoxia increases melanoma metastasis to the lung in a mouse model of sleep apnea.

Obstructive sleep apnea (OSA) has recently been associated with an increased risk of cancer incidence and mortality in humans. Experimental data in mice have also shown that intermittent hypoxia similar to that observed in OSA patients enhances tumor growth. The aim of this study was to test the hypothesis that intermittent hypoxia mimicking OSA enhances lung metastasis. A total of 75 C57BL/6J male mice (10-week-old) were subjected to either spontaneous or induced melanoma lung metastasis. Normoxic animals breathed room air and intermittent hypoxic animals were subjected to cycles of 20s of 5% O2 followed by 40s of room air for 6h/day. Spontaneous and induced lung metastases were studied after subcutaneous and intravenous injection of B16F10 melanoma cells, respectively. Compared with normoxia, intermittent hypoxia induced a significant increase in melanoma lung metastasis. These animal model results suggest that intermittent hypoxia could contribute to cancer metastasis in patients with OSA.

A dual role for KRT81: a miR-SNP associated with recurrence in non-small-cell lung cancer and a novel marker of squamous cell lung carcinoma.

MicroRNAs (miRNAs) play an important role in carcinogenesis through the regulation of their target genes. miRNA-related single nucleotide polymorphisms (miR-SNPs) can affect miRNA biogenesis and target sites and can alter microRNA expression and functions. We examined 11 miR-SNPs, including 5 in microRNA genes, 3 in microRNA binding sites and 3 in microRNA-processing machinery components, and evaluated time to recurrence (TTR) according to miR-SNP genotypes in 175 surgically resected non-small-cell lung cancer (NSCLC) patients. Significant differences in TTR were found according to KRT81 rs3660 (median TTR: 20.3 months for the CC genotype versus 86.8 months for the CG or GG genotype; P = 0.003) and XPO5 rs11077 (median TTR: 24.7 months for the AA genotype versus 73.1 months for the AC or CC genotypes; P = 0.029). Moreover, when patients were divided according to stage, these differences were maintained for stage I patients (P = 0.002 for KRT81 rs3660; P<0.001 for XPO5 rs11077). When patients were divided into sub-groups according to histology, the effect of the KRT81 rs3660 genotype on TTR was significant in patients with squamous cell carcinoma (P = 0.004) but not in those with adenocarcinoma. In the multivariate analyses, the KRT81 rs3660 CC genotype (OR = 1.8; P = 0.023) and the XPO5 rs11077 AA genotype (OR = 1.77; P = 0.026) emerged as independent variables influencing TTR. Immunohistochemical analyses in 80 lung specimens showed that 95% of squamous cell carcinomas were positive for KRT81, compared to only 19% of adenocarcinomas (P<0.0001). In conclusion, miR-SNPs are a novel class of SNPs that can add useful prognostic information on the clinical outcome of resected NSCLC patients and may be a potential key tool for selecting high-risk stage I patients. Moreover, KRT81 has emerged as a promising immunohistochemical marker for the identification of squamous cell lung carcinoma.