Down-regulated microRNA-375 expression as a predictive biomarker in non-small cell lung cancer brain metastasis and its prognostic significance.

Brain metastases (BM) are common among patients with non-small cell lung cancer (NSCLC) and have been associated with significant morbidity and limited survival. Early and sensitive detection of BM is essential for improving prognosis. Recently, microRNA-375(miR-375) which is specifically expressed in the brain has been found significantly dysregulated in many human cancers. However, there is still no data whether miR-375 is associated with higher risk of BM development in NSCLC. In this study, we detected the miR-375 expression using quantitative real-time PCR (qRT-PCR) and assessed its predictive and prognostic significance. Our result showed that miR-375 expression was significantly down-regulated in NSCLC patients with BM(BM+, N=30) compared with NSCLC without BM(BM-, N=30) (P<0.001). Statistical analysis indicated that low miR-375 expression was linked to advanced disease stage (P<0.001) and brain metastasis (P<0.001) in NSCLC patient. Survival analysis suggested that low-expression group had significantly shorter overall survival than high-expression group in NSCLC patients with BM(log-rank test: P<0.05) as well as the total cases(log-rank test: P<0.01). Multivariate Cox proportional hazards model analysis indicated that low miR-375 expression was independently linked to poor survival of patients with NSCLC (HR=5.48, 95% CI: 1.93-15.56, P=0.001). In addition, we found that VEGF and MMP-9 were over-expressed in down-regulated miR-375 expression cases. Collectively, this study demonstrated that miR-375 may play an important role as a predictive biomarker in brain metastasis and an independent prognostic factor in NSCLC. Over-expression of VEGF and MMP-9 may be the reason for poor prognosis of NSCLC patients with low miR-375 expression.

The clinical significances of the abnormal expressions of Piwil1 and Piwil2 in colonic adenoma and adenocarcinoma.

OBJECTIVE: The objective of the present investigation was to study the clinical significances of the abnormal expressions of Piwil1 and Piwil2 protein in colonic adenoma and adenocarcinoma. METHODS: This study had applied immunohistochemical method to detect 45 cases of tissues adjacent to carcinoma (distance to cancerous tissue was above 5 cm), 41 cases of colonic adenoma and 92 cases of colon cancer tissues, and their Piwil1 and Piwil2 protein expression levels. ANALYSIS: The correlation of both expression and its relationship with clinicopathological features of colon cancer was analyzed. RESULTS: Positive expression rates of Piwil1 in tissues adjacent to carcinoma, colonic adenoma, and colon cancer were 11.1% (5/45), 53.7% (22/41), and 80.4% (74/92), respectively; the expression rates increased, and the comparisons between each two groups were statistically significant (P<0.05). In each group, the positive expression rates of Piwil2 were 24.4% (11/45 cases), 75.6% (31/41 cases), and 92.4% (85/92 cases); expression rates increased, and the comparisons between each two groups were statistically significant (P<0.05). Piwil1 expression and the correlation of the degree of differentiation, TNM stage, and lymph node metastasis were statistically significant (P<0.05). Piwil2 expression and the correlation of the degree of differentiation, tumor node metastasis (TNM) stage, and lymph node metastasis had no statistical significance (P>0.05). In colon cancer tissue, Piwil1 and Piwil2 expressions were positively correlated (r=0.262, P<0.05). CONCLUSION: The results showed that the abnormal expression of Piwil1 and Piwil2 might play an important role in the process of colon cancer development.

[Meiotic recombination hotspots in eukaryotes].

Meiotic recombination may occur more frequently in some regions of the eukaryotic genome. These regions are referred to as meiotic recombination hotspot loci. Genetic studies in the yeast have revealed that these hotspots contain special sites for recombination initiation and result in heterogeneous distribution of recombination (along the chromosome length or across the genome). However, the data for recombination hotspot is so far limited to organisms such as fungi, maize and human. In the present paper, we listed several typical approaches to characterizing recombination hotspots in different organisms, summarizing current progress in mapping of the meiotic recombination hotspots and discussing the factors and mechanisms for activation of eukaryotic meiotic recombination. Some unresolved questions and future prospects were also discussed.