Synthesis, interaction with DNA and antiproliferative activities of two novel Cu(II) complexes with norcantharidin and benzimidazole derivatives.

Two novel complexes [Cu(L)2(Ac)2]·3H2O (1) (L=N-2-methyl benzimidazole demethylcantharate imide, C16H15N3O3, Ac=acetate, C2H3O2) and [Cu(bimz)2(DCA)] (2) (bimz=benzimidazole, C7H6N2; DCA=demethylcantharate, C8H8O5) were synthesized and characterized by elemental analysis, infrared spectra and X-ray diffraction techniques. Cu(II) ion was four-coordinated in complex 1, Cu(II) ion was five-coordinated in complex 2. A large amount of intermolecular hydrogen-bonding and π-π stacking interactions were observed in these complex structures. The DNA-binding properties of these complexes were investigated using electronic absorption spectra, fluorescence spectra, viscosity measurements and agarose gel electrophoresis. The interactions between the complexes and bovine serum albumin (BSA) were investigated by fluorescence spectra. The antiproliferative activities of the complexes against human hepatoma cells (SMMC7721) were tested in vitro. And the results showed that these complexes could bind to DNA in moderate intensity via partial intercalation, and complexes 1 and 2 could cleave plasmid DNA through hydroxyl radical mechanism. Title complexes could effectively quench the fluorescence of BSA through static quenching. Meanwhile, title complexes had stronger antiproliferative effect compared to L and Na2(DCA) within the tested concentration range. And complex 1 possessed more antiproliferative active than complex 2.

Expression of E-cadherin and nm23 is associated with the clinicopathological factors of human non-small cell lung cancer in China.

E-cadherin, a calcium-dependent cell-cell adhesion molecule, functions as maintenance of epithelial integrity. nm23, encoded by non-metastatic 23 gene, plays a key role in differentiation of many kinds of epithelium. Loss or dysfunction of E-cadherin and nm23 was frequently identified in many types of human cancers and is considered to correlate with invasive/metastatic phenotype. We previously reported that defective expression of E-cadherin might play a role in the development of the malignant phenotype in non-small cell lung cancer (NSCLC) [Q.Y. Fei, H.T. Zhang, X.F. Chen, et al., Defected expression of Ecadherin in non-small cell lung cancer, Lung Cancer 37 (2002) 147-152]. In an attempt to evaluate the significance of E-cadherin and nm23 in human non-small cell lung cancer, we performed mRNA expression and genetic structure analyses of the E-cadherin and nm23 genes in 54 NSCLCs and 46 normal lung tissues. The mRNA expression was determined by semi-quantitative RT-PCR, and genetic structure was examined through PCR-SSCP followed by sequencing. Although no mutation of the E-cadherin and nm23 genes was detected, the results obtained in the present study showed that reduction of E-cadherin and nm23 mRNA expression remarkably correlated with low histological differentiation, increasing stage as well as lymph node metastases (P<0.05). These data provide us with support for the idea that dysfunction of E-cadherin and nm23 has a role in progression of NSCLC and that the examination of E-cadherin and nm23 expression can provide experimental evidence for clinical treatment.

Defective expression of transforming growth factor beta receptor type II is associated with CpG methylated promoter in primary non-small cell lung cancer.

PURPOSE: Reduced expression of the transforming growth factor beta receptor type II (TGF beta RII), a key inhibitor of epithelial cell growth and tumor suppressor gene, was reported frequently in many types of tumors including non-small cell lung cancer (NSCLC). This study explored the significance of the TGF beta RII gene in NSCLC carcinogenesis. EXPERIMENTAL DESIGN: With 43 independent pairs of tumor and paracarcinoma tissue samples from patients with primary NSCLC, we carried out PCR-denaturing gradient gel electrophoresis screening for DNA variants over the coding sequence of the TGF beta RII gene, immunohistochemical assay of TGF beta RII expression, methylation-specific PCR analysis, and semiquantitative reverse transcription-PCR. RESULTS: The PCR-denaturing gradient gel electrophoresis did not detect variation in the whole coding sequence of the TGF beta RII gene, but the immunohistochemistry experiment revealed reduced or lost expression of the gene in 44% (19 of 43) of the tumor samples. The methylation analysis on the 19 pairs detected the frequent occurrence of methylated TGF beta RII promoter in tumor tissues, whereas most of the paracarcinoma tissues were free of methylation. The reduced TGF beta RII expression was highly significantly associated with the methylation event (P < 10(-4)). The reverse transcription-PCR analysis demonstrated a clear agreement between reduced TGF beta RII expression and decreased mRNA level of the gene in the tumor tissue samples. CONCLUSIONS: TGF beta RII plays an important role as a tumor suppressor in NSCLC carcinogenesis. The defective expression may serve as one of most important molecular mechanisms in explaining progression of the disease. In particular, aberrant 5' CpG methylation of the gene has explained the down-regulation of the gene at a transcriptional level.

Mutational analysis of the transforming growth factor beta receptor type I gene in primary non-small cell lung cancer.

Transforming growth factor-beta receptor-dependent signals are critical for cell growth and differentiation and are often disrupted during tumorigenesis. The entire coding region of TGFbetaRI and flanking intron sequences from 53 primary non-small cell lung cancer (NSCLC) tissues were examined for alterations using SSCP and direct sequencing. No somatic point mutations other than two silent mutations and a polymorphism were found in the TGFbetaRI gene. The two silent mutations located at codon 344 (AAT to AAC) and codon 406 (TTA to CTA), respectively, and the polymorphism was at the 24th base of intron 7 (G to A). To investigate whether the presence of this polymorphism is associated with NSCLC, we determined its allele distribution in all the 53 carcinomas and 89 normal controls. Interestingly, we found that the subjects with homozygous genotype A/A displayed more than 3-fold increased risk of developing NSCLC than the common wild genotype G/G. As the first report, the present study showed that TGFbetaRI gene is not a frequent site of spontaneous mutational inactivation while the detected polymorphism is frequent in the pathogenesis of NSCLC.