Long-chain fatty dihydropyridines: Docking calcium channel studies and antihypertensive activity

Amlodipine inhibits the proliferation and migration of esophageal carcinoma cells through the induction of endoplasmic reticulum stress

BACKGROUND

L-type calcium channels are the only protein channels sensitive to calcium channel blockers, and are expressed in various cancer types. The Cancer Genome Atlas database shows that the mRNA levels of multiple L-type calcium channel subunits in esophageal squamous cell carcinoma tumor tissue are significantly higher than those in normal esophageal epithelial tissue. Therefore, we hypothesized that amlodipine, a long-acting dihydropyridine L-type calcium channel blocker, may inhibit the occurrence and development of esophageal cancer (EC).

AIM

To investigate the inhibitory effects of amlodipine on EC through endoplasmic reticulum (ER) stress.

METHODS

Cav1.3 protein expression levels in 50 pairs of EC tissues and corresponding paracancerous tissues were examined. Subsequently, the inhibitory effects of amlodipine on proliferation and migration of EC cells in vitro were detected using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and Transwell assays. In vivo experiments were performed using murine xenograft model. To elucidate the underlying mechanisms, in vitro cell studies were performed to confirm that ER stress plays a role in inhibition proliferation and migration of EC cells treated with amlodipine.

RESULTS

The expression level of Cav1.3 in esophageal carcinoma was 1.6 times higher than that in paracancerous tissues. Amlodipine treatment decreased the viability of esophageal carcinoma cells in a dose- and time-dependent manner. In vivo animal experiments also clearly indicated that amlodipine inhibited the growth of EC tumors in mice. Additionally, amlodipine reduces the migration of tumor cells by inhibiting epithelial-mesenchymal transition (EMT). Mechanistic studies have demonstrated that amlodipine induces ER stress-mediated apoptosis and suppresses EMT. Moreover, amlodipine-induced autophagy was characterized by an increase in autophagy lysosomes and the accumulation of light chain 3B protein. The combination of amlodipine with the ER stress inhibitor 4-phenylbutyric acid further confirmed the role of the ER stress response in amlodipine-induced apoptosis, EMT, and autophagy. Furthermore, blocking autophagy increases the ratio of apoptosis and migration.

CONCLUSION

Collectively, we demonstrate for the first time that amlodipine promotes apoptosis, induces autophagy, and inhibits migration through ER stress, thereby exerting anti-tumor effects in EC.

Fluorinated dihydropyridines as candidates to block L-type voltage-dependent calcium channels

Voltage-gated calcium (Ca_v) channels malfunction may lead to Alzheimer's and cardiovascular disorders, thus a critical protein target for drug development and treatment against several diseases. Indeed, dihydropyridines (DHPs) as nifedipine and amlodipine are top-selling pharmaceuticals and, respectively, the 121st and 5th most prescribed drugs in the United States that have been used as successful selective blockers for L-type Ca2+ channels (LCC) and may be helpful model structures to compare with new DHP analogs. In this context, we have performed a structure-based drug design (SBDD) study of several fluorinated DHPs by using homology modeling, molecular docking, quantitative structure activity relationship (QSAR) and molecular dynamics calculations. Such approaches combined with molecular mechanics Poisson-Boltzmann surface area (MM/PBSA) interaction energy results and screening of ADMET (absorption, distribution, metabolism, excretion and toxicity) properties indicate that all ligands in this study are potential new candidates to be tested experimentally for inhibition of LCC and may have higher affinities than the commonly used drugs, being convenient synthetic routes proposed for 11-16, which are among the ligands that showed the best theoretical results concerning LCC inhibition. Furthermore, the ligand interactions with the binding site were carefully examined using the topological noncovalent interactions (NCI) method, which highlighted specifically responsible amino acid residues that increase the spontaneity of the new proposed DHP ligands.Communicated by Ramaswamy H. Sarma.