Synthetic Diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates Induce Apoptosis.

BACKGROUND: The Hantzsch ester, diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5- dicarboxylate, has been used as a hydride donor and its various biological effects have been reported. To identify chemotherapeutic agents with apoptotic effects, 21 diethyl 2,6-dimethyl-1,4- dihydropyridine-3,5-dicarboxylates were designed and synthesized; they have not been reported as apoptosis inducers thus far. Their structure-cytotoxicity relationships were investigated. Further biological experiments were performed on the title compound. METHODS: The cytotoxicities of the current synthetic compounds were measured using a clonogenic assay in HCT116 human colon cancer cells. An annexin V staining assay was used to confirm if the title compound induced apoptosis. To identify the synthetic compounds, Nuclear Magnetic Resonance (NMR) spectroscopy and high-resolution mass spectrometry (HR-MS) were conducted. As molecular symmetry was observed in the NMR spectroscopic data, the three dimensional structures were determined from ab initio calculations and X-ray crystallography. RESULTS: The results obtained from NMR spectroscopy, ab initio calculations, and X-ray crystallography revealed that the diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylate derivatives synthesized in this research have symmetric structures. The cytotoxicities of the 21 derivatives were tested in the HCT116 human colon cancer cell lines, and their half-maximal cell growth inhibitory concentrations ranged between 16.29 and 68.88 µM. Structure-cytotoxicity relationships demonstrated that bulky substitutions were preferred, para-positioned substituents tended to have better cytotoxic values, and the polarity may have a function as well. The cytotoxicity of the title compound in HCT116 colon cancer cells was mediated through apoptotic cell death. CONCLUSION: To obtain chemotherapeutic agents that induce apoptosis, 21 diethyl 2,6-dimethyl- 1,4-dihydropyridine-3,5-dicarboxylates were designed and synthesized. NMR spectroscopy, ab initio calculations, and X-ray crystallography demonstrated that the diethyl 2,6-dimethyl-1,4- dihydropyridine-3,5-dicarboxylate derivatives synthesized in this research had symmetric structures. Even if the half-maximal cell growth inhibitory concentrations of the 21 derivatives did not show dramatic inhibitory activity against HCT116 human colon cancer cells, small changes in the structure affected the anticancer activities. Treatment with diethyl 4-(4-chlorophenyl)-2,6- dimethyl-1,4-dihydropyridine-3,5-dicarboxylate substantially reduced the cell viability and the cytotoxicity against HCT116 colon cancer cells was mediated through apoptotic cell death. As the ability of diethyl 2,6-dimethyl-1,4-dihydropyridine-3,5-dicarboxylates to induce apoptosis has not been previously reported, we have now reported their design, synthesis, cytotoxicity, and structureactivity relationships.

Benzoflavonoids Structure Hinders Human Colon Cancer Clonogenicity.

BACKGROUND: Since flavonoids fused by benzene have been known for their potent chemopreventive effects, in this study, we examined the relationship between the structures and activities of benzoflavones, benzoflavanones, benzochalcones, and benzochalcone derivatives bearing the pyrazole moiety against human colon cancer cells. METHODS: We investigated the effect of 34 benzoflavonoids on the inhibition of colon cancer cells based on the clonogenicity. The biological activity values used for the quantitative structure-activity relationship (QSAR) calculations were obtained from the cell growth inhibition on the basis of clonogenicity. 3D-QSAR calculations were performed using comparative molecular field analyses (CoMFA) and comparative molecular similarity index analyses (CoMSIA). RESULTS: Of several CoMFA and CoMSIA models, the best models showing the highest cross validated correlation coefficient were selected and validated. The cell growth inhibition values were calculated using the above models. The structural conditions to show good cell growth inhibitory effects on human colon cancer cells were analyzed by CoMFA and CoMSIA contour maps. The contribution of steric fields remarkably decreased without any change in the contribution of the electrostatic field, which means that electrostatic contribution is more crucial than the steric contribution in the modification of benzoflavonoids. Furthermore, the increase in the hydrogen bond donor contribution was approximately proportional to the decrease in steric field contribution. CONCLUSION: This study demonstrated that benzoflavonoids structure hinders colon cancer clonogenicity. Most of the benzoflavonoids structures comprised a C-3 linkage between the naphthalene and phenyl moieties, which contained diverse functional moieties such as oxygen-fused rings, double bonds, pyrazole rings, and sulfur constituents, and were able to exhibit great potential in diverse anticancer effects. Also, the positions of the hydroxyl group close to the naphthalene and phenyl rings were crucial for activity against colon cancer. The structural conditions obtained here may help us design potent benzoflavonoids against colon cancer cells and predict their activities.

Transdifferentiation-inducing HCCR-1 oncogene.

BACKGROUND: Cell transdifferentiation is characterized by loss of some phenotypes along with acquisition of new phenotypes in differentiated cells. The differentiated state of a given cell is not irreversible. It depends on the up- and downregulation exerted by specific molecules. RESULTS: We report here that HCCR-1, previously shown to play an oncogenic role in human cancers, induces epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) in human and mouse, respectively. The stem cell factor receptor CD117/c-Kit was induced in this transdifferentiated (EMT) sarcoma tissues. This MET occurring in HCCR-1 transfected cells is reminiscent of the transdifferentiation process during nephrogenesis. Indeed, expression of HCCR-1 was observed during the embryonic development of the kidney. This suggests that HCCR-1 might be involved in the transdifferentiation process of cancer stem cell. CONCLUSIONS: Therefore, we propose that HCCR-1 may be a regulatory factor that stimulates morphogenesis of epithelia or mesenchyme during neoplastic transformation.