Mefloquine induces cell death in prostate cancer cells and provides a potential novel treatment strategy in vivo.

Mefloquine (MQ) is currently in clinical use as a prophylactic treatment for malaria. Previous studies have shown that MQ induces oxidative stress in vitro. The present study investigated the anticancer effects of MQ treatment in PC3 cells. The cell viability was evaluated using sulphorhodamine-B (SRB) staining, while annexin V and propidium iodide (PI) were used as an assay for cell death. Reactive oxygen species (ROS) formation was detected with 2',7'-dichlorofluorescein-diacetate (DCFH-DA), a sensitive intracellular probe, and the alteration of cellular status was defined by trypan blue staining. The results of the present study indicated that MQ has a high cytotoxicity that causes cell death in PC3 cells. MQ markedly inhibited the PC3 cells through non-apoptotic cell death. MQ also induced significant ROS production. The MQ treatment mediated G1 cell cycle arrest and cyclin D1 accumulation through p21 upregulation in the PC3 cells. Moreover, the use of MQ improved the survival of the treatment group compared with the control group in the experimental mice. The present study indicates that MQ possesses potential therapeutic efficacy for the treatment of prostate cancer (PCa) in vivo. These findings provide insights that may aid the further optimization and application of new and existing therapeutic options.

Mefloquine exerts anticancer activity in prostate cancer cells via ROS-mediated modulation of Akt, ERK, JNK and AMPK signaling.

Mefloquine (MQ) is a prophylactic anti-malarial drug. Previous studies have shown that MQ induces oxidative stress in vitro. Evidence indicates that reactive oxygen species (ROS) may be used as a therapeutic modality to kill cancer cells. This study investigated whether MQ also inhibits prostate cancer (PCa) cell growth. We used sulforhodamine B (SRB) staining to determine cell viability. MQ has a highly selective cytotoxicity that inhibits PCa cell growth. The antitumor effect was most significant when examined using a colony formation assay. MQ also induces hyperpolarization of the mitochondrial membrane potential (MMP), as well as ROS generation. The blockade of MQ-induced anticancer effects by N-acetyl cysteine (NAC) pre-treatment confirmed the role of ROS. This indicates that the MQ-induced anticancer effects are caused primarily by increased ROS generation. Moreover, we observed that MQ-mediated ROS simultaneously downregulated Akt phosphorylation and activated extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK) and adenosine monophosphate-activated protein kinase (AMPK) signaling in PC3 cells. These findings provide insights for further anticancer therapeutic options.

Aspirin antagonizes the cytotoxic effect of methotrexate in lung cancer cells.

Methotrexate (MTX) has been widely used for the treatment of cancer and rheumatoid arthritis (RA). Aspirin (ASA) is a non-selective cyclooxygenase (COX) inhibitor that contributes to the treatment of inflammatory conditions such as RA. It has been observed that the antitumor effect of ASA can be attributed to inhibition of cell cycle progression, induction of apoptosis and inhibition of angiogenesis. In the present study, we revealed that the treatment with a combination of MTX and ASA resulted in antagonism of the cytotoxic effect as demonstrated by SRB and colony formation assays. ASA alleviated the MTX-mediated S phase accumulation and recovered the G1 phase. MTX-mediated accumulation of the S phase marker cyclin A was also alleviated by ASA. Notably, FAS protein levels were upregulated by MTX in A549 cells. The antagonism of MTX efficacy caused by ASA was accompanied by altered expression of caspase-3, Bcl-2 and FAS but not dihydrofolate reductase (DHFR). This suggests that the alteration of caspase-3, Bcl-2 and FAS was involved in the antagonism between ASA and MTX. Exogenously added folic acid reversed the MTX-mediated DHFR inhibition following either MTX or MTX + ASA treatments. Most importantly, we demonstrated for the first time that the commonly used non-steroidal anti-inflammatory drug for headache ASA and possibly other COX-1/2 inhibitors can produce a strong antagonistic effect on the growth inhibition of lung cancer cells when administered in combination with MTX. The clinical implication of our finding is obvious, i.e., the clinical efficacy of MTX therapy can be compromised by ASA and their concomitant use should be avoided.

Tomatidine inhibits invasion of human lung adenocarcinoma cell A549 by reducing matrix metalloproteinases expression.

Tomatidine is an aglycone of glycoalkaloid tomatine in tomato. Tomatidine is found to possess anti-inflammatory properties and may serve as a chemosensitizer in multidrug-resistant tumor cells. However, the effect of tomatidine on cancer cell metastasis remains unclear. This study examines the effect of tomatidine on the migration and invasion of human lung adenocarcinoma A549 cell in vitro. The data demonstrates that tomatidine does not effectively inhibit the viability of A549 cells. When treated with non-toxic doses of tomatidine, cell invasion is markedly suppressed by Boyden chamber invasion assay, while cell migration is not affected. Tomatidine reduces the mRNA level of matrix metalloproteinase-2 (MMP-2), MMP-9 and increases the expression of reversion-inducing cysteine-rich protein with kazal motifs (RECK), as well as tissue inhibitor of metalloproteinase-1 (TIMP-1). The immunoblotting assays indicate that tomatidine is very effective in suppressing the phosphorylation of Akt and extracellular signal regulating kinase (ERK). In addition, tomatidine significantly decreases the nuclear level of nuclear factor kappa B (NF-κB), which suggests that tomatidine inhibits NF-κB activity. Furthermore, the treatment of inhibitors specific for PI3K/Akt (LY294002), ERK (U0126), or NF-κB (pyrrolidine dithiocarbamate) to A549 cells reduced cell invasion and MMP-2/9 expression. The results suggest that tomatidine inhibits the invasion of A549 cells by reducing the expression of MMPs. It also inhibits ERK and Akt signaling pathways and NF-κB activity. These findings demonstrate a new therapeutic potential for tomatidine in anti-metastatic therapy.

Targeting PML-RARα and Oncogenic Signaling Pathways by Chinese Herbal Mixture Tien-Hsien Liquid in Acute Promyelocytic Leukemia NB4 Cells.

Tien-Hsien Liquid (THL) is a Chinese herbal mixture that has been used worldwide as complementary treatment for cancer patients in the past decade. Recently, THL has been shown to induce apoptosis in various types of solid tumor cells in vitro. However, the underlying molecular mechanisms have not yet been well elucidated. In this study, we explored the effects of THL on acute promyelocytic leukemia (APL) NB4 cells, which could be effectively treated by some traditional Chinese remedies containing arsenic trioxide. The results showed THL could induce G2/M arrest and apoptosis in NB4 cells. Accordingly, the decrease of cyclin A and B1 were observed in THL-treated cells. The THL-induced apoptosis was accompanied with caspase-3 activation and decrease of PML-RARα fusion protein. Moreover, DNA methyltransferase 1 and oncogenic signaling pathways such as Akt/mTOR, Stat3 and ERK were also down-regulated by THL. By using ethyl acetate extraction and silica gel chromatography, an active fraction of THL named as EAS5 was isolated. At about 0.5-1% of the dose of THL, EAS5 appeared to have most of THL-induced multiple molecular targeting effects in NB4 cells. Based on the findings of these multi-targeting effects, THL might be regarding as a complementary and alternative therapeutic agent for refractory APL.

The synergistic anticancer effect of troglitazone combined with aspirin causes cell cycle arrest and apoptosis in human lung cancer cells.

Troglitazone (TGZ) is a synthetic thiazolidinedione drug belonging to a group of potent peroxisome proliferator-activated receptor gamma (PPAR gamma) agonists known to inhibit proliferation, alter cell cycle regulation, and induce apoptosis in various cancer cell types. TGZ is an oral anti-type II diabetes drug that can reverse insulin resistance. For more then 100 yr, aspirin, a nonselective cyclooxygenase (COX) inhibitor, has been successfully used as an anti-inflammatory drug. Recently, Aspirin (ASA) and some other nonsteroidal anti-inflammatory drugs (NSAIDs) have drawn much attention for their protective effects against colon cancer and cardiovascular disease; it has been observed that ASA's anti-tumor effect can be attributed to inhibition of cell cycle progression, induction of apoptosis, and inhibition of angiogenesis. In this report we demonstrate for the first time that, when administered in combination, TGZ and ASA can produce a strong synergistic effect in growth inhibition and G(1) arrest in lung cancer CL1-0 and A549 cells. Examination by colony formation assay revealed an even more profound synergy. In Western blot, combined TGZ and ASA also could downregulate Cdk2, E2F-1, cyclin B1, cyclin D3 protein, and the ratio of phospho-Rb/Rb. Importantly, apoptosis was synergistically induced by the combination treatment, as evidenced by caspase-3 activation and PARP cleavage. The involvement of PI3K/Akt inhibition and p27 upregulation, as well as hypophosphorylation of Rac1 at ser71, were demonstrated. Taken together, these results suggest that clinically achievable concentrations of TGZ and ASA used in combination may produce a strong anticancer synergy that warrants further investigation for its clinical applications.

Proton pumping inorganic pyrophosphatase of endoplasmic reticulum-enriched vesicles from etiolated mung bean seedlings.

Endoplasmic reticulum (ER)-enriched vesicles from etiolated hypocotyls of mung bean seedlings (Vigna radiata) were successfully isolated using Ficoll gradient and two-phase (polyethylene glycol-dextran) partition. The ER-enriched vesicles contained inorganic pyrophosphate (PPi) hydrolysis and its associated proton translocating activities. Antiserum prepared against vacuolar H+-pyrophosphatase (V-PPase, EC 3.6.1.1) did not inhibit this novel pyrophosphatase-dependent proton translocation, excluding the possible contamination of tonoplast vesicles in the ER-enriched membrane preparation. The optimal ratios of Mg2+/PPi (inorganic pyrophosphate) for enzymatic activity and PPi-dependent proton translocation of ER-enriched vesicles were higher than those of vacuolar membranes. The PPi-dependent proton translocation of ER-enriched vesicles absolutely required the presence of monovalent cations with preference for K+, but could be inhibited by a common PPase inhibitor, F-. Furthermore, ER H+-pyrophosphatase exhibited some similarities and differences to vacuolar H+-PPases in cofactor/substrate ratios, pH profile, and concentration dependence of F-, imidodiphosphate (a PPi analogue), and various chemical modifiers. These results suggest that ER-enriched vesicles contain a novel type of proton-translocating PPase distinct from that of tonoplast from higher plants.