Pitavastatin induces caspase-mediated apoptotic death through oxidative stress and DNA damage in combined with cisplatin in human cervical cancer cell line

Pitavastatin (PITA) is a 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitor to treat hypercholesterolemia and in recent studies is focused that its potential anti-cancer effect. This study was aimed to elucidate the effect of PITA alone and in combination with cisplatin on cervical cancer cells (HeLa) in vitro. Cytotoxicity of PITA (5-200 μM) was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red uptake (NRU) assays for 24, 48, and 72 h. Cell apoptosis and cell cycle analyses were performed in flow cytometry (0.1-100 μM). The evaluation of genotoxic effects and oxidative DNA damage of PITA (2-200 μM) were performed with standard comet assay, formamidopyrimidine glycosylase (fpg)-modified comet assay, and reactive oxygen species (ROS) activation in HeLa cells. PITA alone reduced cell viability in a dose-dependent manner (20-200, 20-200, and 5-200 μM for 24, 48, and 72 h, respectively, in MTT). The combined treatment of PITA with cisplatin resulted in significantly greater inhibition of cell viability. ROS and DNA damage increased significantly at 100 μM for 4 h and 20 μM for 24 h, respectively. PITA-induced apoptosis, an increased proportion of sub G1 cells, was monitored, and also, it increased the expression of active caspase-9 and caspase-3 and upregulated cleaved poly adenosine diphosphate ribose polymerase (PARP) by western blotting and caspase 3/8/9 multiple assay kit. We conclude that PITA can be used to efficiently cervical cancer studies, and promising findings have been obtained for further studies.

Anti-Proliferative Effect of Statins Is Mediated by DNMT1 Inhibition and p21 Expression in OSCC Cells

Statins, also known as HMG-CoA reductase inhibitors, are a class of cholesterol-lowering drugs and their anti-cancer effects have been studied in different types of malignant diseases. In the present study, we investigated the anti-proliferative effects of statins, including cerivastatin and simvastatin, on oral squamous cell carcinoma (OSCC) cells. Our data showed that statins inhibited the proliferation of three OSCC cell lines in a dose-dependent manner and this growth inhibition was confirmed through G0/G1 cell cycle arrest. Accordingly, we found the upregulation of p21 and downregulation of cyclin-dependent kinases, including CDK2, CDK4, and CDK6, in the statin-treated cells. Importantly, we clearly showed that statins were able to inhibit the expression of DNA methyltransferase 1 (DNMT1) and further promote the expression of p21. Taken together, our data demonstrated that the anti-proliferative effect of statins is mediated by suppressing DNMT1 expression, thus promoting p21 expression and leading to G0/G1 cell cycle arrest in OSCC cells.

Pitavastatin induces apoptosis in oral squamous cell carcinoma through activation of FOXO3a

Statins are a class of lipid‐lowering drugs that have recently been used in drug repositioning in the treatment of human cancer. However, the underlying mechanism of statin‐induced cancer cell death has not been clearly defined. In the present study, we evaluated the anticancer effect of pitavastatin on oral squamous cell carcinoma (OSCC), SCC15 and SCC4 cells and found that FOXO3a might be a direct target in pitavastatin‐induced cancer cell death. Our data revealed that pitavastatin selectively suppressed cell viability and induced intrinsic apoptosis in a FOXO3a‐dependent manner in SCC15 cells while no effect was observed in SCC4 cells. Notably, treatment with pitavastatin in SCC15 cells induced the nuclear translocation of FOXO3a via dual regulation of two upstream kinases, AMPK and Akt, resulting in the up‐regulation of PUMA, a transcriptional target gene of FOXO3a. Furthermore, our data revealed that FOXO3a‐mediated PUMA induction plays a role in pitavastatin‐induced intrinsic apoptosis in SCC15 cells. Taken together, our findings suggest that pitavastatin activates the FOXO3a/PUMA apoptotic axis by regulation of nuclear translocation of FOXO3a via Akt/FOXO3a or AMPK/FOXO3a signalling. Therefore, these findings might help to elucidate the underlying mechanism of the anticancer effects of pitavastatin on OSCC.

Preparation and Optimization of In Situ Gel Loaded with Rosuvastatin-Ellagic Acid Nanotransfersomes to Enhance the Anti-Proliferative Activity

The objective of this study was to develop an optimized sustained-release nanotransfersomes (NTS) based in situ gel formulation of rosuvastatin (RO) combined with ellagic acid (EA) antioxidant, to enhance cytotoxic and anti-proliferative activity against tongue carcinoma. The concentrations of lecithin, Tween 80, and d-tocopherol polyethylene glycol succinate (TPGS) were considered as independent variables. Particle size, entrapment, and stability were selected as dependent variables. The obtained formulation containing 25% lecithin, 20% Tween 80, and TPGS 15% fulfilled the prerequisites of the optimum formulation. RO-NTS loaded in situ gel was prepared and optimized for concentrations of Poloxamer 407, and Carbopol, using statistical design. Drug release from in situ gel showed a sustained release profile. The RO IC50 was decreased by half for the in situ gel in comparison to plain RO and RO-EA-NTS. A significant amount of caspase-3 was detected in all the formulation treatments. The studies indicated that EA’s synergistic anti-oxidant effect owing to a high affinity to the PGP efflux transporter and higher penetration in the RO-NTS formulation led to a higher inhibition against human chondrosarcome-3 cancer cell lines. RO-EA NTS–loaded in situ gel had a sustained release that could be significant in localized therapy as an alternative to surgery in the treatment of aggressive tongue carcinoma.

Differential roles of the mevalonate pathway in the development and survival of mouse Purkinje cells in culture

The cerebellum is an important locus for motor learning and higher cognitive functions, and Purkinje cells constitute a key component of its circuit. Biochemically, significant turnover of cholesterol occurs in Purkinje cells, causing the activation of the mevalonate pathway. The mevalonate pathway has important roles in cell survival and development. In this study, we investigated the outcomes of mevalonate inhibition in immature and mature mouse cerebellar Purkinje cells in culture. Specifically, we found that the inhibition of the mevalonate pathway by mevastatin resulted in cell death, and geranylgeranylpyrophosphate (GGPP) supplementation significantly enhanced neuronal survival. The surviving immature Purkinje cells, however, exhibited dendritic developmental deficits. The morphology of mature cells was not affected. The inhibition of squalene synthase by zaragozic acid caused impaired dendritic development, similar to that seen in the GGPP-rescued Purkinje cells. Our results indicate GGPP is required for cell survival and squalene synthase for the cell development of Purkinje cells. Abnormalities in Purkinje cells are linked to motor-behavioral learning disorders such as cerebellar ataxia. Thus, serious caution should be taken when using drugs that inhibit geranylgeranylation or the squalene-cholesterol branch of the pathway in the developing stage.

Bisphosphonate- and statin-induced enhancement of OPG expression and inhibition of CD9, M-CSF, and RANKL expressions via inhibition of the Ras/MEK/ERK pathway and activation of p38MAPK in mouse bone marrow stromal cell line ST2

Osteoclast differentiation is influenced by receptor activator of the NF-κB ligand (RANKL), macrophage colony-stimulating factor (M-CSF), and CD9, which are expressed on bone marrow stromal cells and osteoblasts. In addition, osteoprotegerin (OPG) is known as an osteoclastogenesis inhibitory factor. In this study, we investigated whether bisphosphonates and statins increase OPG expression and inhibit the expression of CD9, M-CSF, and RANKL in the bone marrow-derived stromal cell line ST2. We found that bisphosphonates and statins enhanced OPG mRNA expression and inhibited the expression of CD9, M-CSF, and RANKL mRNA. Futhermore, bisphosphonates and statins decreased the membrane localization of Ras and phosphorylated ERK1/2, and activated the p38MAPK. This indicates that bisphosphonates and statins enhanced OPG expression, and inhibited the expression of CD9, M-CSF, and RANKL through blocking the Ras/ERK pathway and activating p38MAPK. Accordingly, we believe that its clinical applications will be investigated in the future for the development of osteoporosis therapy.

Transcriptome analysis and in vivo activity of fluvastatin versus zoledronic acid in a murine breast cancer metastasis model

Statins and bisphosphonates are two distinct classes of isoprenoid pathway inhibitors targeting downstream enzyme to HMG-CoA reductase (upstream enzyme) and farnesyl-pyrophosphate synthase, respectively. Here, we studied fluvastatin (Fluva) and zoledronate (Zol), representative molecules of each class, respectively. In vivo metastatic potentials of both molecules were assessed. For the first time, we observed a significant reduction in progression of established metastases with Fluva treatment. Treatment with both Zol at 100 μg/kg and Fluva at 15 mg/kg inhibited 80% of the metastasis bioluminescence signal and increased survival of mice. The Zol and Fluva transcriptomic profiles of treated MDA-MB-231 cells revealed analogous patterns of affected genes, but each of them reached with different kinetics. The observable changes in gene expression started after 24 h for Fluva IC(50 72 h) and only after 48 h for Zol IC(50 72 h). To obtain early changes in gene expression of Zol-treated cells, a 3 times higher dose of Zol IC(50 72 h) had to be applied. Combining Fluva and Zol in vivo showed no synergy, but a benefit of several days in survival of mice. This study demonstrated that Zol or Fluva is of potential clinical use for the treatment of established metastasis.

Statin-induced apoptosis via the suppression of ERK1/2 and Akt activation by inhibition of the geranylgeranyl-pyrophosphate biosynthesis in glioblastoma

BACKGROUND

Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase, the rate-limiting enzyme in cholesterol synthesis. The inhibition of this key enzyme in the mevalonate pathway leads to suppression of cell proliferation and induction of apoptosis. However, the molecular mechanism of apoptosis induction by statins is not well understood in glioblastoma. In the present study, we attempted to elucidate the mechanism by which statins induce apoptosis in C6 glioma cells.

METHODS

The cytotoxicity of statins toward the C6 glioma cells were evaluated using a cell viability assay. The enzyme activity of caspase-3 was determined using activity assay kits. The effects of statins on signal transduction molecules were determined by western blot analyses.

RESULTS

We found that statins inhibited cell proliferation and induced apoptosis in these cells. We also observed an increase in caspase-3 activity. The apoptosis induced by statins was not inhibited by the addition of farnesyl pyrophosphate, squalene, ubiquinone, and isopentenyladenine, but by geranylgeranyl-pyrophosphate (GGPP). Furthermore, statins decreased the levels of phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt.

CONCLUSIONS

These results suggest that statins induce apoptosis when GGPP biosynthesis is inhibited and consequently decreases the level of phosphorylated ERK1/2 and Akt. The results of this study also indicate that statins could be used as anticancer agents in glioblastoma.

Unexpected applications of secondary metabolites

Secondary metabolites have been found to have interesting applications over and above their well-known medical uses, e.g., as antimicrobials, etc. These alternative applications include antitumor, cholesterol-lowering, immunosuppressant, antiprotozoal, antihelminth, antiviral and anti-ageing activities. Polyene antibiotics, such as amphotericin B, are of use as antiprion agents, antitumor drugs and against leishmaniasis. Other microbial natural products that show antibiotic activity are used against cancer e.g., doxorubicin, neomycin, β-lactams, bleomycin and rapamycin. Macrolide antibiotics, such as erythromycin, clarithromycin and azithromycin, improve pulmonary function in patients suffering from panbioncholitis. Pigments like prodigiosin and shikonin have antitumor activity, while violacein has anti-ulcer and antitumor activity and also acts as an antiprotozoal agent. Statins, in addition to lowering cholesterol and LDL levels, also decrease elevated C-reactive protein (CRP) levels independent of their cholesterol effects. Immunosuppressants have many alternative effects: (i) Cyclosporin is proving useful in treatment of inflammatory disease such as asthma and muscular dystrophy. (ii) Rapamycin is extremely useful in preventing restenosis of stents grafted in balloon angioplasty. (iii) Tacrolimus and ascomycin help in treating inflammatory skin disease such as allergic contact dermatitis and psoriasis. Artemisinin, an antimalarial agent, is also showing antitumor activity. Other natural products, including those from plants (betulinic acid and shikonin), animals (bryostatins) and microbes (squalestatin and sophorolipids) have a multiplicity of potentially useful actions. Unexpected functions of known secondary metabolites are continuously being unraveled, and are fulfilling some of the needs of present day medicine and show great promise for the future.

Osteopontin is a new target molecule for ovarian clear cell carcinoma therapy

Recent studies have demonstrated overexpression of osteopontin (OPN) in ovarian clear cell carcinoma. Here, we revealed the role of OPN in invasiveness in ovarian clear cell carcinoma. We used immunofluorescence analysis to detect OPN in a total of 160 patient-derived specimens. Ovarian clear cell carcinoma cell lines, RMG-1 and TOV-21G, were used to monitor changes in OPN and integrin levels, and cell invasiveness following treatment with OPN, simvastatin, and transfection with siRNA. Immunofluorescence analysis revealed statistically significant differences among the histological groups, and ovarian clear cell carcinoma expressed a strong OPN signal. The OPN receptors, alpha v and 5, and beta 1 and 3 integrins, were increased after treatment with OPN. Invasion assays indicated that OPN enhanced in vitro extracellular matrix invasion dose-dependently in ovarian clear cell carcinoma. Simvastatin significantly reduced expression of OPN and the integrins, and decreased ECM invasion. RNA interference also suppressed ECM invasion. These results suggest that down- or up-regulation of OPN is involved in carcinoma cell invasion. We thus conclude that OPN regulation could have a crucial role in ovarian clear cell carcinoma therapy.