MicroRNA-590-5p functions as a tumor suppressor in breast cancer conferring inhibitory effects on cell migration, invasion, and epithelial-mesenchymal transition by downregulating the Wnt-ß-catenin signaling pathway.

Breast cancer remains one of the foremost primary causes of female morbidity and mortality worldwide. During the current study, the effect of miR-590-5p and paired-like homeodomain transcription factor 2 (PITX2) on proliferation, invasion, migration, and epithelial-mesenchymal transition (EMT) of human breast cancer via the Wnt-ß-catenin signaling pathway was investigated. Breast cancer-related genes and related signaling pathways were obtained from KEGG database. The PITX2 regulatory microRNA was predicted. To define the contributory role by which miR-590-5p influences the progression of breast cancer, the interaction between miR-590-5p and PITX2 was explored; the proliferation, invasion, and migration abilities as well as the tumor growth and metastasis in nude mice were detected following the overexpression or silencing of miR-590-5p. PITX2 was determined to share a correlation with breast cancer and miR-590-5p was selected for further analysis. PITX2, Wnt-1, ß-catenin, N-cadherin, and vimentin all displayed higher levels, while miR-590-5p and E-cadherin expression were lower among breast cancer tissues than in the adjacent normal tissue. After overexpression of miR-590-5p or si-PITX2, the expression of E-cadherin was markedly increased, decreases in the expression of Wnt-1, ß-catenin, N-cadherin, and vimentin, as well as inhibited cell proliferation, invasion, migration, metastasis, and EMT were observed. This study provides evidence suggesting that the transfection of overexpressed miR-590-5p can act to alleviate the effects of breast cancer demonstrating an ability to inhibit the processes of cell proliferation, migration, and invasion as well as EMT by suppressing the expression of PITX2 and activation of the Wnt-ß-catenin pathway.

Downregulated GBX2 gene suppresses proliferation, invasion and angiogenesis of breast cancer cells through inhibiting the Wnt/ß-catenin signaling pathway.

OBJECTIVE: Gastrulation brain homeobox 2 (GBX2), a gene involved in mid/hindbrain region, has been revealed as one of the oncogene associated with certain cancers, as an example being prostate cancer. However, despite years of worldwide research, the underlying mechanism of GBX2 as well as its significance in breast cancer still remains unclear. Therefore, the present study evaluates the abilities of GBX gene silencing providing for the proliferation, invasion and angiogenesis of breast cancer cells by way of the Wnt/ß-catenin signaling pathway. METHODS: We employed a microarray analysis to screen out differentially expressed genes relative to breast cancer. Moreover, we retrieved GBX2 expression in breast cancer to find out the relationship between GBX2 expression and prognosis in breast cancer. We performed RT-qPCR to screen out cell lines with high GBX2 expression. Subsequently, both RT-qPCR and western blot analysis were employed so as to measure the combination of the mRNA and protein expressions of GBX2, ß-catenin, vascular endothelial growth factor (VEGF), matrix metalloproteinase (MMP)-2, and MMP-9. The effect that GBX2 gene silencing and the Wnt/ß-catenin signaling pathway had on cell proliferation, invasion, angiogenesis, and tumorigenic ability were evaluated. RESULTS: GBX2 gene was also identified having played a role in breast cancer development due to its association with the Wnt/ß-catenin signaling pathway. GBX2 gene silencing was found to be an inhibitor for the mRNA and protein expressions regulating ß-catenin, VEGF, MMP-2, and MMP-9. Cell proliferation, invasion, angiogenesis, as well as tumorigenic ability in breast cancer were investigated and found to have been suppressed by the GBX2 gene silencing or inactivation of the Wnt/ß-catenin signaling pathway. CONCLUSION: The study has made an attempt to provide evidence to the idea that GBX2 gene silencing has an inhibition effect on the proliferation, invasion and angiogenesis of the breast cancer cells by inhibiting the activation of the Wnt/ß-catenin signaling pathway.

MiR-133a Is Functionally Involved in Doxorubicin-Resistance in Breast Cancer Cells MCF-7 via Its Regulation of the Expression of Uncoupling Protein 2.

The development of novel targeted therapies holds promise for conquering chemotherapy resistance, which is one of the major hurdles in current breast cancer treatment. Previous studies indicate that mitochondria uncoupling protein 2 (UCP-2) is involved in the development of chemotherapy resistance in colon cancer and lung cancer cells. In the present study we found that lower level of miR133a is accompanied by increased expression of UCP-2 in Doxorubicin-resistant breast cancer cell cline MCF-7/Dox as compared with its parental cell line MCF-7. We postulated that miR133a might play a functional role in the development of Doxorubicin-resistant in breast cancer cells. In this study we showed that: 1) exogenous expression of miR133a in MCF-7/Dox cells can sensitize their reaction to the treatment of Doxorubicin, which is coincided with reduced expression of UCP-2; 2) knockdown of UCP-2 in MCF-7/Dox cells can also sensitize their reaction to the treatment of Doxorubicin; 3) intratumoral delivering of miR133a can restore Doxorubicin treatment response in Doxorubicin-resistant xenografts in vivo, which is concomitant with the decreased expression of UCP-2. These findings provided direct evidences that the miR133a/UCP-2 axis might play an essential role in the development of Doxorubicin-resistance in breast cancer cells, suggesting that the miR133a/UCP-2 signaling cohort could be served as a novel therapeutic target for the treatment of chemotherapy resistant in breast cancer.

Correlation between polymorphisms of nicotine acetylcholine acceptor subunit CHRNA3 and lung cancer susceptibility.

Both environmental and genetic factors participate in the pathogenesis of lung cancer. The aim of this study was to explore the association between CHRNA3 polymorphisms of the nicotinic acetylcholine receptor gene and lung cancer risk in a hospital-based, case-controlled study. Single nucleotide polymorphisms (SNPs) in CHRNA3 rs3743073 (A>G) were determined using the TaqMan-MGB probe technique in 600 lung cancer cases and 600 normal controls. The differences in genotype and allele frequency were compared between groups and their association with lung cancer. The genotype frequency of rs3743073 (A>G) demonstrated Hardy-Weinberg equilibrium (P<0.05). The genotype and allele frequencies were significantly different between the cancer and control groups (P<0.05). Compared with patients with the TT genotype, lung cancer incidence was increased in patients with the TG and GG genotypes (OR=1.68; 95% CI, 1.30-2.19; P<0.05; OR=1.30; 95% CI, 1.05-1.61; P<0.05, respectively). Patients with rs3743073G variant alleles (TG and GG) were at greater risk (OR=0.65; 95% CI, 0.50-0.84; P<0.05) of developing lung cancer. Increased risk associated with rs3743073G variant alleles was observed in male smokers over the age of 60 (P<0.05). In this cohort, the CHRNA3 gene rs3743073G variant genotype significantly increased lung cancer risk, especially in male smokers over the age of 60.

Polymorphisms of the ribonucleotide reductase M1 gene and sensitivity to platin-based chemotherapy in non-small cell lung cancer.

Ribonucleotide reductase catalyzes the rate limiting step of deoxyribonucleotide formation, a crucially important step in DNA synthesis and repair. The regulatory subunit M1 of ribonucleotide reductase (RRM1) is the necessary part of the RR function and controls substrate specificity and global on/off enzyme activity. Despite recent research progress, the role of RRM1 in lung cancer sensitivity to chemotherapeutics remains to be elucidated. This study was to investigate the relationship between polymorphisms of the RRM1 gene and sensitivity to platinum-based chemotherapy in non-small cell lung cancer (NSCLC). Genomic DNA samples from 214 NSCLC patients treated with platinum-based chemotherapy were used to determine the RRM1 promoter allelotypes. The RR37CC-RR524TT was the most frequent allelotype (38.50%), followed by RR37AC-RR524CT (26.76%) and RR37CC-RR524CT (14.95%). The average response rate for chemotherapy was 44.4%. The response rates to the treatment regimens in the RR37CC-RR524TT, RR37AC-RR524CT and RR37CC-RR524CT allelotypes were 43.9%, 52.6%, and 51.6%, respectively. The response rates to therapy among patients with RRM1 (-)524 allelotypes were significantly different (p=0.046), whereas that among patients with RRM1 (-)37 allelotypes were not significant. Further analysis showed that the response rate in the patients with RR524CT allelotype (52.3%) was the highest, compared with that with RR37CC-RR524TT allelotype (43.9%, p=0.28), or the Others (RR524CC and RR37AC-RR524TT, 30.2%, p=0.02). Our results suggest that the RR524CT allelotype may be associated with an increased sensitivity to platinum-based chemotherapy in NSCLC. Further research on determining RR524CT as a clinical marker for predicting response to platinum-based therapy in NSCLC patients is warranted.