Amlodipine, a Ca2+ channel blocker, suppresses phosphorylation of epidermal growth factor receptor in human epidermoid carcinoma A431 cells

Calcium channel blockers improve the prognosis of patients with intrahepatic cholangiocarcinoma after resection

BACKGROUND

Intrahepatic cholangiocarcinoma is the second most common primary cancer of the liver. It is highly malignant and its prognosis is very poor. Although there have been various reports on the effects of calcium channel blockers on cancer, the effects of calcium channel blockers on intrahepatic cholangiocarcinoma have not been reported so far.

METHODS

Seventy-nine patients diagnosed with intrahepatic cholangiocarcinoma by hepatectomy between January 2002 and May 2019 were retrospectively evaluated. We compared prognosis and time to recurrence between patients treated with calcium channel blockers (CCBs) (n = 29) and those not treated with CCBs (n = 50). Propensity score matching reduced confounding biases and yielded 25 matched patient pairs. Survival between groups was compared using Kaplan-Meier analyses, logrank tests, and Cox proportional hazard regression models.

RESULTS

Overall survival and recurrence-free survival of the CCBs group were significantly longer than those of the non-CCBs group OS in the original cohort and matched cohort (98 months vs 45 months, p = 0.010; 96 months vs 22 months, p = 0.020, respectively). Multivariate analyses showed that CCBs treatment was independently associated with overall survival (HR, 0.37; 95% CI 0.16-0.85; p = 0.019) and recurrence-free survival (HR, 0.39; 95% CI 0.17-0.90; p = 0.020) in the original cohort and matched cohort, respectively.

CONCLUSION

CCBs treatment might improve prognosis of patients with intrahepatic cholangiocarcinoma.

Anticancer Effects of Amlodipine Alone or in Combination With Gefitinib in Non-Small Cell Lung Cancer

Amlodipine is a Ca²⁺ channel blocker commonly used to cardiovascular diseases such as hypertension and angina; however, its anticancer effects in lung cancer A549 cells remain unknown. In the present study, we explored the antitumor effects and molecular mechanisms underlying the action of amlodipine in non-small cell lung cancer (NSCLC) A549 cells in vitro and in vivo. We observed that amlodipine suppressed the proliferation of A549 lung cancer cells by arresting the tumor cell cycle. Mechanistically, our results revealed that amlodipine could attenuate the phosphoinositide 3 kinase (PI3K)/Akt and Raf/MEK/extracellular signal-regulated kinase (ERK) pathways through epidermal growth factor receptor (EGFR) and modulated cell cycle-related proteins such as cyclin D1, p-Rb, p27, and p21. Subsequently, amlodipine combined with gefitinib could synergistically inhibit cell proliferation by arresting the cell cycle. Moreover, amlodipine combined with gefitinib effectively attenuated the growth of A549 lung cancer xenografts when compared with monotherapy, affording an excellent therapeutic effect. Collectively, our results indicate that amlodipine alone or combined with the novel anticancer drug gefitinib might be a potential therapeutic strategy for NSCLC patients with wild-type EGFR.

The Use of Antihypertensive Drugs as Coadjuvant Therapy in Cancer

Cancer is a complex group of diseases that constitute the second largest cause of mortality worldwide. The development of new drugs for treating this disease is a long and costly process, from the discovery of the molecule through testing in phase III clinical trials, a process during which most candidate molecules fail. The use of drugs currently employed for the management of other diseases (drug repurposing) represents an alternative for developing new medical treatments. Repurposing existing drugs is, in principle, cheaper and faster than developing new drugs. Antihypertensive drugs, primarily belonging to the pharmacological categories of angiotensin-converting enzyme inhibitors, angiotensin II receptors, direct aldosterone antagonists, β-blockers and calcium channel blockers, are commonly prescribed and have well-known safety profiles. Additionally, some of these drugs have exhibited pharmacological properties useful for the treatment of cancer, rendering them candidates for drug repurposing. In this review, we examine the preclinical and clinical evidence for utilizing antihypertensive agents in the treatment of cancer.

The cytotoxic effects of VE-3N, a novel 1,4-dihydropyridine derivative, involve the mitochondrial bioenergetic disruption via uncoupling mechanisms

Several 1,4-dihydropyridine derivatives overcome the multidrug resistance in tumors, but their intrinsic cytotoxic mechanisms remain unclear. Here we addressed if mitochondria are involved in the cytotoxicity of the novel 1,4-dihydropyridine derivative VE-3N [ethyl 6-chloro-5-formyl-2-methyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3-carboxylate] towards cancer cells by employing hepatic carcinoma (HepG2) cells and isolated rat liver mitochondria. In HepG2 cells, VE-3N induced mitochondrial membrane potential dissipation, ATP depletion, annexin V/propidium iodide double labeling, and Hoechst staining; events indicating apoptosis induction. In isolated rat liver mitochondria, VE-3N promoted mitochondrial uncoupling by exerting protonophoric actions and by increasing membrane fluidity. Mitochondrial uncoupling was evidenced by an increase in resting respiration, dissipation of mitochondrial membrane potential, inhibition of Ca²⁺ uptake, stimulation of Ca²⁺ release, decrease in ATP synthesis, and swelling of valinomycin-treated organelles in hyposmotic potassium acetate media. Furthermore, uncoupling concentrations of VE-3N in the presence of Ca²⁺ plus ruthenium red induced the mitochondrial permeability transition process. These results indicate that mitochondrial uncoupling is potentially involved in the VE-3N cytotoxic actions towards HepG2 cells. Considering that hepatocellular carcinoma is the most common form of liver cancer, our findings may open a new avenue for the development of VE-3N-based cancer therapies, and help to unravel the cytotoxic mechanisms of 1,4-dihydropyridines towards cancer cells.

Microparticle-Induced Activation of the Vascular Endothelium Requires Caveolin-1/Caveolae

Microparticles (MPs) are small membrane fragments shed from normal as well as activated, apoptotic or injured cells. Emerging evidence implicates MPs as a causal and/or contributing factor in altering normal vascular cell phenotype through initiation of proinflammatory signal transduction events and paracrine delivery of proteins, mRNA and miRNA. However, little is known regarding the mechanism by which MPs influence these events. Caveolae are important membrane microdomains that function as centers of signal transduction and endocytosis. Here, we tested the concept that the MP-induced pro-inflammatory phenotype shift in endothelial cells (ECs) depends on caveolae. Consistent with previous reports, MP challenge activated ECs as evidenced by upregulation of intracellular adhesion molecule-1 (ICAM-1) expression. ICAM-1 upregulation was mediated by activation of NF-κB, Poly [ADP-ribose] polymerase 1 (PARP-1) and the epidermal growth factor receptor (EGFR). This response was absent in ECs lacking caveolin-1/caveolae. To test whether caveolae-mediated endocytosis, a dynamin-2 dependent process, is a feature of the proinflammatory response, EC’s were pretreated with the dynamin-2 inhibitor dynasore. Similar to observations in cells lacking caveolin-1, inhibition of endocytosis significantly attenuated MPs effects including, EGFR phosphorylation, activation of NF-κB and upregulation of ICAM-1 expression. Thus, our results indicate that caveolae play a role in mediating the pro-inflammatory signaling pathways which lead to EC activation in response to MPs.

Knockdown of stromal interaction molecule 1 (STIM1) suppresses store-operated calcium entry, cell proliferation and tumorigenicity in human epidermoid carcinoma A431 cells

Store-operated calcium (Ca(2+)) entry (SOCE) is important for cellular activities such as gene transcription, cell cycle progression and proliferation in most non-excitable cells. Stromal interaction molecule 1 (STIM1), a newly identified Ca(2+)-sensing protein, monitors the depletion of endoplasmic reticulum (ER) Ca(2+) stores and activates store-operated Ca(2+) channels at the plasma membrane to induce SOCE. To investigate the possible roles of STIM1 in tumor growth in relation to SOCE, we established STIM1 knockdown (KD) clones of human epidermoid carcinoma A431 cells by RNA interference. Thapsigargin, an inhibitor of ER Ca(2+)-ATPase, -induced and phospholipase C-coupled receptor agonist-induced SOCEs were reduced in two STIM1 KD clones compared to a negative control clone. Re-expression of a KD-resistant full-length STIM1, but not a Ca(2+) release-activated Ca(2+) channel activation domain (CAD)-deleted STIM1 mutant, in the KD clone restored the amplitude of SOCE, suggesting the specificity of the STIM1 knockdown. The cell growth of the STIM1 KD clones was slower than that of the negative control clone. DNA synthesis assessed by BrdU incorporation, as well as EGF-stimulated EGF receptor activation, decreased in the STIM1 KD clones. Xenograft growth of the STIM1 KD clones was significantly retarded compared with that of the negative control. Cell migration was attenuated in the STIM1 KD clone and the STIM1 silencing effect was reversed by transient re-expression of the full-length STIM1 but not CAD-deletion mutant. These results indicate that STIM1 plays an important role in SOCE, cell-growth and tumorigenicity in human epidermoid carcinoma A431cells, suggesting the potential use of STIM1-targeting agents for treating epidermoid carcinoma.