COX-2 potentiates cisplatin resistance of non-small cell lung cancer cells by promoting EMT in an AKT signaling pathway-dependent manner.

OBJECTIVE: To elucidate the effect of cyclooxygenase 2 (COX-2) on cisplatin resistance of NSCLC and its molecular mechanisms, with special attention to its pro-EMT (epithelial-mesenchymal transition) properties. MATERIALS AND METHODS: COX-2 levels were compared in two NSCLC cell lines, A549 and H460, by qPCR (quantitative Polymerase Chain Reaction) and Western blot. Cytotoxicity of cisplatin was also determined in the two cell lines using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) assay. The expression of EMT-related proteins and activation of AKT (protein kinase B) signaling were detected in H460 cells with ectopic COX-2 expression. RESULTS: Cisplatin-induced apoptosis was assessed in COX-2 overexpressing H460 cells by FACS. NS398, a COX-2 inhibitor, was also applied to determine EMT status and effect on cisplatin sensitivity in H460 cells. COX-2 levels were positively correlated with cisplatin resistance in both NSCLC cell lines tested. In response to COX-2 overexpression, EMT-related proteins, such as E-cadherin, were inhibited, while vimentin and N-cadherin were upregulated. The AKT signaling pathway was also activated in H460 cells. Ectopic expression of COX-2 potentiated cisplatin resistance of H460 cells, which was accompanied by decreased levels of apoptosis. Notably, NS398 effectively increased the cytotoxicity of cisplatin in A549 cells by inhibiting EMT and the AKT pathway. CONCLUSIONS: COX-2 might promote cisplatin resistance in NSCLC by promoting EMT through the AKT signaling pathway activation.

Correlation between the methylation of LIVIN gene and the pathogenesis of bone tumor.

OBJECTIVE: We investigated the correlation between the methylation of LIVIN gene and the pathogenesis of bone tumor at the molecular level, in order to improve the treatment method and enhance the cure rate of bone tumor. PATIENTS AND METHODS: The expression level of Livin protein was detected using Western blot analysis, and its expressions in control group and patients were detected by immunohistochemistry. The methylation frequency of LIVIN gene was calculated by direct sequencing. Finally, the prognosis of treatment was investigated by follow-up. RESULTS: The experiment found that Livin protein was not expressed in normal cells, while its expression rate was about 71.4% in 112 patients. The methylation frequency of LIVIN gene was gradually decreased with the increase of clinical stage, and had no significant relationship with age and sex. The prognosis experiment indicated that the lower the methylation frequency of LIVIN gene was, the shorter the survival time would be. CONCLUSIONS: The methylation of LIVIN gene was closely related to the pathogenesis of bone tumor, which may be one of the important factors to induce the formation of a bone tumor. In addition, the methylation frequency of LIVIN gene could be used as a biomarker for the prognosis of bone tumor treatment.

Convergent evolution of perenniality in rice and sorghum.

Annual and perennial habit are two major strategies by which grasses adapt to seasonal environmental change, and these distinguish cultivated cereals from their wild relatives. Rhizomatousness, a key trait contributing to perenniality, was investigated by using an F(2) population from a cross between cultivated rice (Oryza sativa) and its wild relative, Oryza longistaminata. Molecular mapping based on a complete simple sequence-repeat map revealed two dominant-complementary genes controlling rhizomatousness. Rhz3 was mapped to the interval between markers OSR16 [1.3 centimorgans (cM)] and OSR13 (8.1 cM) on rice chromosome 4 and Rhz2 located between RM119 (2.2 cM) and RM273 (7.4 cM) on chromosome 3. Comparative mapping indicated that each gene closely corresponds to major quantitative trait loci (QTLs) controlling rhizomatousness in Sorghum propinquum, a wild relative of cultivated sorghum. Correspondence of these genes in rice and sorghum, which diverged from a common ancestor approximately 50 million years ago, suggests that the two genes may be key regulators of rhizome development in many Poaceae. Many additional QTLs affecting abundance of rhizomes in O. longistaminata were identified, most of which also corresponded to the locations of S. propinquum QTLs. Convergent evolution of independent mutations at, in some cases, corresponding genes may have been responsible for the evolution of annual cereals from perennial wild grasses. DNA markers closely linked to Rhz2 and Rhz3 will facilitate cloning of the genes, which may contribute significantly to our understanding of grass evolution, advance opportunities to develop perennial cereals, and offer insights into environmentally benign weed-control strategies.