Verapamil-induced autophagy-like process in colon adenocarcinoma COLO 205 cells; the ultrastructural studies

Follicle inhibition at the primordial stage without increasing apoptosis, with a combination of everolimus, verapamil

The aim of the present study was to test whether inhibition of ovarian primordial follicles and subsequent activation can be achieved by transient mTOR inhibition. In this preclinical investigation, forty-five female immature Wistar rats were randomized in 5 groups. The control group received subcutaneous saline injections. The other groups received Everolimus, Everolimus plus Verapamil, Everolimus plus Fisetin, and Fisetin alone. Primary and secondary outcomes were measured in the left ovary after a treatment period of 8 weeks. Ten days later, animals received 35 IU FSH for 4 days and 35 IU of hCG on the 5th day. The same parameters were examined in the right ovary. AMH, estradiol, and progesterone levels were assessed at the end of both interventions. Significantly, more primordial and less atretic follicles were observed in the Everolimus plus Verapamil group. AMH and progesterone levels were substantially lower in the Everolimus group. Interestingly, after ovarian stimulation higher levels of AMH and progesterone were observed in the Everolimus plus Verapamil group. Immunoblot analysis of ovarian extracts revealed that the administration of Everolimus led to a significant reduction in the mTORC1-mediated phosphorylation of the 70-kDa ribosomal protein S6 kinase 1. This decrease was reversed in the presence of FSH after stopping drug administration. The expression of the anti-apoptotic molecule Bcl2 as well as of LC3-II and ATG12 was increased after removal of the Everolimus plus Verapamil combination, indicating reduced apoptosis and increased autophagy, whereas the levels of the proliferation marker PCNA in the granulosa cells were elevated, consistent with initiation of follicular growth.Thus, the combination of Everolimus plus Verapamil is capable of increasing the number of competent primordial follicles while reducing atresia.

High drug efflux pump capacity and low DNA damage response induce doxorubicin resistance in canine hemangiosarcoma cell lines

Canine hemangiosarcoma (HSA) is an aggressive malignant endothelial tumor in dogs and characterized by poor prognosis because of its high invasiveness, high metastatic potential, and poor responsiveness to anti-cancer drugs. Although doxorubicin-based chemotherapy is regularly conducted after surgical treatment, its effects on survival rates are limited. Acquisition of drug resistance is one of the causes of this problem, but the underlying mechanisms remain unclear. In the present study, we aimed to identify the drug-resistance mechanism in canine HSA by establishing doxorubicin-resistant (DR) HSA cell lines. HSA cell lines were exposed to doxorubicin at gradually increasing concentrations. When the cells were able to grow in the presence of a 16-fold higher doxorubicin concentration compared with the initial culture, they were designated DR-HSA cell lines. Characterization of these DR-HSA cell lines revealed higher drug efflux pump capacity compared with the parental cell lines. Furthermore, the DR-HSA cell lines did not show activation of the DNA damage response despite carrying high DNA damage burdens, meaning that apoptosis was not strongly induced. In conclusion, canine HSA cell lines acquired doxorubicin resistance by increasing their drug efflux pump capacity and decreasing the DNA damage response. This study provides useful findings to promote further research on the drug-resistance mechanisms in canine HSA.

Modulation of autophagy in human diseases strategies to foster strengths and circumvent weaknesses

Autophagy is central to the maintenance of intracellular homeostasis across species. Accordingly, autophagy disorders are linked to a variety of diseases from the embryonic stage until death, and the role of autophagy as a therapeutic target has been widely recognized. However, autophagy-associated therapy for human diseases is still in its infancy and is supported by limited evidence. In this review, we summarize the landscape of autophagy-associated diseases and current autophagy modulators. Furthermore, we investigate the existing autophagy-associated clinical trials, analyze the obstacles that limit their progress, offer tactics that may allow barriers to be overcome along the way and then discuss the therapeutic potential of autophagy modulators in clinical applications.

Verapamil treatment induces cytoprotective autophagy by modulating cellular metabolism

Verapamil, an L-type calcium channel blocker, has been used successfully to treat cardiovascular diseases. Interestingly, we have recently shown that treatment of cancer cells with verapamil causes an effect on autophagy. As autophagy is known to modulate chemotherapy responses, this prompted us to explore the impact of verapamil on autophagy and cell viability in greater detail. We report here that verapamil causes an induction of autophagic flux in a number or tumor cells and immortalized normal cells. Moreover, we found that inhibition of autophagy in COLO 205 cells, via treatment with the chloroquine (CQ) or by CRISPR/Cas9-mediated disruption of the autophagy genes Atg7 and Atg5, causes an upregulation of apoptotic markers in response to verapamil. In search of a mechanism for this effect and because autophagy can often mitigate metabolic stress, we examined the impact of verapamil on cellular metabolism. This revealed that in normal prostate cells, verapamil diminishes glucose and glycolytic intermediate levels leading to adenosine 5'-triphosphate (ATP) depletion. In contrast, in COLO 205 cells it enhances aerobic glycolysis and maintains ATP. Importantly, we found that the autophagic response in these cells is related to the activity of l-lactate dehydrogenase A (LDHA, EC 1.1.1.27), as inhibition of LDHA reduces both basal and verapamil-induced autophagy and consequently decreases cell viability. In summary, these findings not only identify a novel mechanism of cytoprotective autophagy induction but they also highlight the potential of using verapamil together with inhibitors of autophagy for the treatment of malignant disease. ENZYMES: l-lactate dehydrogenase (LDHA, EC 1.1.1.27).

The hypertension drug, verapamil, activates Nrf2 by promoting p62-dependent autophagic Keap1 degradation and prevents acetaminophen-induced cytotoxicity

Nuclear factor erythroid 2-related factor 2 (Nrf2) provides a cellular defense against oxidative stress by inducing the expression of antioxidant and detoxification enzymes. The calcium antagonist, verapamil, is an FDA-approved drug prescribed for the treatment of hypertension. Here, we show that verapamil acts as a potent Nrf2 activator without causing cytotoxicity, through degradation of Kelch-like ECH-associated protein 1 (Keap1), a Nrf2 repressor. Furthermore, verapamil-induced Keap1 degradation is prominently mediated by a p62-dependent autophagic pathway. Correspondingly, verapamil protects cells from acetaminophen-induced oxidative damage through Nrf2 activation. These results demonstrated the underlying mechanisms for the protective role of verapamil against acetaminophen-induced cytotoxicity.

Metformin induces degradation of mTOR protein in breast cancer cells

Activation of mTOR is implicated in the development and progression of breast cancer. mTOR inhibition exhibited promising antitumor effects in breast cancer; however, its effect is compromised by several feedback mechanisms. One of such mechanisms is the upregulation of mTOR pathway in breast cancer cells. Despite the established role of mTOR activation in breast cancer, the status of total mTOR protein and its impact on the tumor behavior and response to treatment are poorly understood. Besides, the mechanisms underlying mTOR protein degradation in normal and cancer breast cells are still largely unknown. We and others found that total mTOR protein level is elevated in breast cancer cells compared to their nonmalignant counterparts. We have detected defective proteolysis of mTOR protein in breast cancer cells, which could, at least in part, explain the high level of mTOR protein in these cells. We show that metformin treatment in MCF‐7 breast cancer cells induced degradation of mTOR and sequestration of this protein in a perinuclear region. The decrease in mTOR protein level in these cells correlated positively with a concomitant inhibition of proliferation and migration potentials of these cells. These findings provided a novel mechanism for the metformin action in breast cancer treatment. Understanding the proteolytic mechanism responsible for mTOR level in breast cancer may pave the way for improving the efficacy of breast cancer treatment regimens and mitigating drug resistance as well as providing a basis for potential novel therapeutic modalities for breast cancer.

Autophagy-related proteins are functionally active in human spermatozoa and may be involved in the regulation of cell survival and motility

Macroautophagy (hereafter autophagy) is an evolutionarily highly conserved cellular process that participates in the maintenance of intracellular homeostasis through the degradation of most long-lived proteins and entire organelles. Autophagy participates in some reproductive events; however, there are not reports regarding the role of autophagy in the regulation of sperm physiology. Hence, the aim of this study was to investigate whether autophagy-related proteins are present and functionally active in human spermatozoa. Proteins related to autophagy/mitophagy process (LC3, Atg5, Atg16, Beclin 1, p62, m-TOR, AMPKα 1/2, and PINK1) were present in human spermatozoa. LC3 colocalized with p62 in the middle piece of the spermatozoa. Autophagy activation induced a significant increase in motility and a decrease in PINK1, TOM20 expression and caspase 3/7 activation. In contrast, autophagy inhibition resulted in decreased motility, viability, ATP and intracellular calcium concentration whereas PINK1, TOM20 expression, AMPK phosphorylation and caspase 3/7 activation were significantly increased. In conclusion our results show that autophagy related proteins and upstream regulators are present and functional in human spermatozoa. Modification of mitochondrial proteins expression after autophagy activation/inhibition may be indicating that a specialized form of autophagy named mitophagy may be regulating sperm function such as motility and viability and may be cooperating with apoptosis.

Comprehensive cytotoxic evaluation of morin, a bioflavonoid against verapamil on rat gastrointestinal epithelium for novel pharmaceutical application involving P-glycoprotein inhibition

OBJECTIVE

In this study, a comprehensive and comparative cytotoxic evaluation of morin against verapamil on rat intestinal epithelium as P-gp inhibitors through in-vitro gastrointestinal short-term toxicity assays involving permeability studies for safety evaluation was investigated.

METHODS

In this study, the effect of morin (1 mM or 10 mM) or verapamil (1 mM or 10 mM) or sodium deoxycholate (10 mM) was investigated on intestinal epithelium and isolated brush border membrane using biomarker assays. Cytotoxicity was determined using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay. The nutrients transport was assessed using everted sacs studies. Paracellular permeability was measured using Lucifer yellow, followed by morphometric analysis of intestinal sacs.

KEY FINDINGS

Our results indicated that morin was effective in maintaining cell viability with no significant changes (P > 0.05) in the activity of intestinal brush border markers, membrane integrity and morphometric analysis as compared with control. On the contrary, dramatic (P < 0.01) changes were noticed in the release of membrane markers, cell viability and surface characteristics of intestinal segments when treated with verapamil or sodium deoxycholate as compared with control or morin.

CONCLUSIONS

Our findings confirm that morin is non-toxic to rat intestinal epithelium against verapamil demonstrating the potential use of bioflavonoid as safe and novel pharmaceutical adjuvant as P-gp inhibitor.

Calcium homeostasis and ER stress in control of autophagy in cancer cells

Autophagy is a basic catabolic process, serving as an internal engine during responses to various cellular stresses. As regards cancer, autophagy may play a tumor suppressive role by preserving cellular integrity during tumor development and by possible contribution to cell death. However, autophagy may also exert oncogenic effects by promoting tumor cell survival and preventing cell death, for example, upon anticancer treatment. The major factors influencing autophagy are Ca²⁺ homeostasis perturbation and starvation. Several Ca²⁺ channels like voltage-gated T- and L-type channels, IP3 receptors, or CRAC are involved in autophagy regulation. Glucose transporters, mainly from GLUT family, which are often upregulated in cancer, are also prominent targets for autophagy induction. Signals from both Ca²⁺ perturbations and glucose transport blockage might be integrated at UPR and ER stress activation. Molecular pathways such as IRE 1-JNK-Bcl-2, PERK-eIF2α-ATF4, or ATF6-XBP 1-ATG are related to autophagy induced through ER stress. Moreover ER molecular chaperones such as GRP78/BiP and transcription factors like CHOP participate in regulation of ER stress-mediated autophagy. Autophagy modulation might be promising in anticancer therapies; however, it is a context-dependent matter whether inhibition or activation of autophagy leads to tumor cell death.

The induction of apoptosis and autophagy by Wasabia japonica extract in colon cancer

PURPOSE

Wasabia japonica (wasabi) has been shown to exhibit properties of detoxification, anti-inflammation and the induction of apoptosis in cancer cells. This study aimed to investigate the molecular mechanism of the cytotoxicity of wasabi extract (WE) in colon cancer cells to evaluate the potential of wasabi as a functional food for chemoprevention.

METHODS

Colo 205 cells were treated with different doses of WE, and the cytotoxicity was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide. Apoptosis and autophagy were detected by 4',6-diamidino-2-phenylindole, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethyl-imidacarbo-yanine iodide and staining for acidic vascular organelles (AVOs), along with Western blotting.

RESULTS

The results demonstrated that WE induced the extrinsic pathway and mitochondrial death machinery through the activation of TNF-α, Fas-L, caspases, truncated Bid and cytochrome C. WE also induced autophagy by decreasing the phosphorylation of Akt and mTOR and promoting the expression of microtubule-associated protein 1 light chain 3-II and AVO formation. An in vivo xenograft model verified that tumor growth was delayed by WE treatment.

CONCLUSION

Our studies revealed that WE exhibits anti-colon cancer properties through the induction of apoptosis and autophagy. These results provide support for the application of WE as a chemopreventive functional food and as a prospective treatment of colon cancer.