The synergistic effect of everolimus and chloroquine on endothelial cell number reduction is paralleled by increased apoptosis and reduced autophagy occurrence

The inhibition of autophagy by spautin boosts the anticancer activity of fingolimod in multidrug-resistant hepatocellular carcinoma

The contribution of autophagy to drug resistance has been studied in several cancers. However, there is no clear evidence about the role of autophagy in the resistance to chemotherapy in cancers, such as hepatocellular carcinoma (HCC). HCC is characterized by a poor prognosis and limited therapeutic options. Moreover, the emergence of multidrug-resistance (MDR) hinders successful treatment. Therefore, understanding how autophagy is regulated in resistant HCC is essential for sensitizing this malignancy to chemotherapy. This work demonstrated that basal and induced autophagy differ between parental and resistant Hep3B cells. In optimum growth conditions, the basal level of autophagy was low in resistant Hep3B (Hep3B-R) cells compared to the wild-type Hep3B (Hep3B-P) cells. However, in metabolic or therapeutic stress conditions, the rate of autophagy flux was much faster in the resistant cells. The work also confirmed the pro-survival function of autophagy in HCC. Besides, it demonstrated that the autophagy inhibitor, spautin, acted synergistically with fingolimod (FTY720) to promote cell death. The combination treatment resulted in superior reactive oxygen species (ROS) production and significant induction of apoptosis. In addition, spautin potentiated the effect of FTY720 against cell survival pathways like the Akt and ERK. Interestingly, the results indicated that Hep3B-R cells were more sensitive to autophagy inhibition than their parental counterparts. Collectively, this work revealed that combining spautin with chemotherapeutic agents that induce cytoprotective autophagy such as FTY720 is a promising approach to overcome MDR in HCC.

The Autophagy Inhibitor Chloroquine, Alone or in Combination with mTOR Inhibitors, Displays Anti-Tumor Effects in In Vitro and In Vivo Lung Carcinoid Models

Simple Summary

Neuroendocrine neoplasms of the lung (lung carcinoids) are often diagnosed when they are not surgically curable, and treatment options are limited. One of the approved options for treating inoperable tumors is everolimus, an mTOR inhibitor. Activation of mTOR inhibits autophagy, which is a cell survival mechanism; everolimus may paradoxically encourage cancer cell survival via stimulation of autophagy. Chloroquine, a known antimalarial compound, inhibits autophagy. Our research is focused on the hypothesis that autophagy plays a key role in the development of tumor resistance to everolimus, and that chloroquine addition to an mTOR inhibitor increases their inhibitory effect on tumor growth. In this study, we examined the effects of chloroquine alone or in combination with mTOR inhibitors on lung neuroendocrine tumor models (cell lines and mice). We have shown that chloroquine alone suppresses tumor cells’ viability and proliferation and increases their cytotoxicity and apoptosis; these effects are augmented when chloroquine is added to mTOR inhibitors. Apparently, chloroquine suppresses tumor cell growth in lung neuroendocrine neoplasms models, potentiating the effects of the mTOR inhibitors, and implying that more research is warranted to unravel its possible role in the clinical setting, in patients with advanced lung neuroendocrine neoplasms.

Abstract

(1) Background: Neuroendocrine neoplasms of the lung (LNENs, lung carcinoids) are often diagnosed at an advanced stage when they are not surgically curable, and treatment options are limited. One of the approved options for treating inoperable tumors is everolimus—an mTOR inhibitor (mTORi). Activation of mTOR, among many other effects, inhibits autophagy, which is a cell survival mechanism in general, and in tumor cells in particular. Everolimus may paradoxically encourage cancer cell survival. In practice, the drug inhibits tumor development. Chloroquine (CQ) is a known antimalarial compound that inhibits autophagy. Our research is focused on the hypothesis that autophagy plays a key role in the development of tumor resistance to mTORi, and that the addition of autophagy inhibitors to mTORi exerts a synergistic effect on suppressing tumor cell proliferation. We have recently demonstrated that the combination of CQ with different mTORi increases their potency compared with mTORi alone in both in vitro and in vivo models of pancreatic NENs. In this study, we examined the effects of CQ and mTORi on in vitro and in vivo LNEN models. Aims: Testing the effects of CQ together with mTORi on cell proliferation, apoptosis, and autophagy in in vitro and in vivo LNEN models. (2) Methods: The NCI-H727 LNEN cells were treated with CQ ± mTORi. Cells’ viability and proliferation were measured using XTT and Ki-67 FACS staining. The effects of the treatments on the mTOR pathway and autophagy were examined using Western blotting. Cytotoxicity was measured using a cytotoxicity kit; apoptosis was measured by PI FACS staining and Western blotting. We further established an LNEN subcutaneous murine xenograft model and evaluated the effects of the drugs on tumor growth. (3) Results: CQ alone suppressed LNEN cells’ viability and proliferation and increased their cytotoxicity and apoptosis; these effects were augmented when CQ was added to an mTORi. We also showed the possible mechanisms for these results: on the one hand we could see a decrease in P62 levels and the absence of LC3-II (both inversely related to autophagy) following treatment with the mTORi, and on the other hand we could demonstrate an increase in their levels when CQ was added. The effect was less apparent in the murine xenograft model. (4) Conclusions: By inhibiting autophagy and inducing apoptosis, CQ suppresses tumor cell growth in LNENs. CQ potentiates mTORi effects, implying that further studies are needed in order to elucidate its possible role in tumor inhibition in patients with LNENs.

Emerging Role of Autophagy in the Development and Progression of Oral Squamous Cell Carcinoma

Autophagy is a cellular catabolic process, which is characterized by degradation of damaged proteins and organelles needed to supply the cell with essential nutrients. At basal levels, autophagy is important to maintain cellular homeostasis and development. It is also a stress responsive process that allows the cells to survive when subjected to stressful conditions such as nutrient deprivation. Autophagy has been implicated in many pathologies including cancer. It is well established that autophagy plays a dual role in different cancer types. There is emerging role of autophagy in oral squamous cell carcinoma (OSCC) development and progression. This review will focus on the role played by autophagy in relation to different aspects of cancer progression and discuss recent studies exploring the role of autophagy in OSCC. It will further discuss potential therapeutic approaches to target autophagy in OSCC.

Colorectal Cancer Apoptosis Induced by Dietary δ-Valerobetaine Involves PINK1/Parkin Dependent-Mitophagy and SIRT3

Understanding the mechanisms of colorectal cancer progression is crucial in the setting of strategies for its prevention. δ-Valerobetaine (δVB) is an emerging dietary metabolite showing cytotoxic activity in colon cancer cells via autophagy and apoptosis. Here, we aimed to deepen current knowledge on the mechanism of δVB-induced colon cancer cell death by investigating the apoptotic cascade in colorectal adenocarcinoma SW480 and SW620 cells and evaluating the molecular players of mitochondrial dysfunction. Results indicated that δVB reduced cell viability in a time-dependent manner, reaching IC50 after 72 h of incubation with δVB 1.5 mM, and caused a G2/M cell cycle arrest with upregulation of cyclin A and cyclin B protein levels. The increased apoptotic cell rate occurred via caspase-3 activation with a concomitant loss in mitochondrial membrane potential and SIRT3 downregulation. Functional studies indicated that δVB activated mitochondrial apoptosis through PINK1/Parkin pathways, as upregulation of PINK1, Parkin, and LC3B protein levels was observed (p < 0.0001). Together, these findings support a critical role of PINK1/Parkin-mediated mitophagy in mitochondrial dysfunction and apoptosis induced by δVB in SW480 and SW620 colon cancer cells.

Friend or Foe: Paradoxical Roles of Autophagy in Gliomagenesis

Glioblastoma multiforme (GBM) is the most common and aggressive type of primary brain tumor in adults, with a poor median survival of approximately 15 months after diagnosis. Despite several decades of intensive research on its cancer biology, treatment for GBM remains a challenge. Autophagy, a fundamental homeostatic mechanism, is responsible for degrading and recycling damaged or defective cellular components. It plays a paradoxical role in GBM by either promoting or suppressing tumor growth depending on the cellular context. A thorough understanding of autophagy's pleiotropic roles is needed to develop potential therapeutic strategies for GBM. In this paper, we discussed molecular mechanisms and biphasic functions of autophagy in gliomagenesis. We also provided a summary of treatments for GBM, emphasizing the importance of autophagy as a promising molecular target for treating GBM.

Aflatoxin B1 disrupts blood-testis barrier integrity by reducing junction protein and promoting apoptosis in mice testes

Aflatoxin B₁ (AFB₁) is an unavoidable food and environmental contaminant, which can lead to disorders in spermatogenesis and its mechanism remains unclear. The blood-testis barrier (BTB) is responsible for ensuring normal spermatogenesis in testes. Therefore, we hypothesized that disruption of the BTB was involved in AFB₁-induced spermatogenesis disorders. To confirm our hypothesis, male Kunming mice were orally gavaged AFB₁ (0, 0.375, 0.75, or 1.5 mg/kg) for 30 days. Primarily, we first proved that AFB₁ disrupted the BTB integrity. Then, AFB₁ decreased BTB-related junction protein expression and elevated Sertoli cell apoptosis, which were associated with oxidative stress. Additionally, AFB₁ upregulated the p-p38 MAPK/p38 MAPK ratio. These results collectively indicated that AFB₁ disrupted the BTB via reducing the expression of BTB-related junction protein and promoting apoptosis in mice testes, which were associated with the oxidative stress-mediated p38 MAPK signaling pathway.

EGFR/c-Met and mTOR signaling are predictors of survival in non-small cell lung cancer

BACKGROUND

EGFR/c-Met activation/amplification and co-expression, mTOR upregulation/activation, and Akt/Wnt signaling upregulation have been individually associated with more aggressive disease and characterized as potential prognostic markers for lung cancer patients.

METHODS

Tumors obtained from 109 participants with stage I-IV non-small cell lung cancer (NSCLC) were studied for EGFR/c-Met co-localization as well as for total and active forms of EGFR, c-Met, mTOR, S6K, beta-catenin, and Axin2. Slides were graded by two independent blinded pathologists using a validated scoring system. Protein expression profile correlations were assessed using Pearson correlation and Spearman's rho. Prognosis was assessed using Kaplan-Meier analysis.

RESULTS

Protein expression profile analysis revealed significant correlations between EGFR/p-EGFR (p = 0.0412) and p-mTOR/S6K (p = 0.0044). Co-localization of p-EGFR/p-c-Met was associated with increased p-mTOR (p = 0.0006), S6K (p = 0.0018), and p-S6K (p < 0.0001) expression. In contrast, active beta-catenin was not positively correlated with EGFR/c-Met nor any activated proteins. Axin2, a negative regulator of the Wnt pathway, was correlated with EGFR, p-EGFR, p-mTOR, p-S6K, EGFR/c-Met co-localization, and p-EGFR/p-c-Met co-localization (all p-values <0.03). Kaplan-Meier analysis revealed shorter median survival in participants with high expression of Axin2, total beta-catenin, total/p-S6K, total/p-mTOR, EGFR, and EGFR/c-Met co-localization compared with low expression. After controlling for stage of disease at diagnosis, subjects with late-stage disease demonstrated shorter median survival when exhibiting high co-expression of EGFR/c-Met (8.1 month versus 22.3 month, p = 0.050), mTOR (6.7 month versus 22.3 month, p = 0.002), and p-mTOR (8.1 month versus 25.4 month, p = 0.004) compared with low levels.

CONCLUSIONS

These findings suggest that increased EGFR/c-Met signaling is correlated with upregulated mTOR/S6K signaling, which may in turn be associated with shorter median survival in late-stage NSCLC.

Autophagy inhibition potentiates the anti-angiogenic property of multikinase inhibitor anlotinib through JAK2/STAT3/VEGFA signaling in non-small cell lung cancer cells

BACKGROUND

The efficacy and safety of multikinase inhibitor anlotinib have been confirmed in the treatment of advanced non-small cell lung cancer (NSCLC). However, the direct functional mechanisms of tumor lethality mediated by anlotinib were not fully elucidated, and the underlying mechanisms related to resistance remain largely elusive.

METHODS

Cell viability, colony formation, apoptosis and tumor growth assays were performed to examine the effect of anlotinib on lung cancer cells in vitro and in vivo. The punctate patterns of LC3-I/II were detected by confocal microscopy. HUVECs motility was detected using Transwell and scratch wound-healing assay. To visualize the microvessels, tubular formation assay was performed. The expression of LC3-I/II and beclin-1 and the changes of JAK2/STAT3/VEGFA pathway were detected by western blotting. The VEGFA levels in tumor supernatant were measured by ELISA.

RESULTS

Anlotinib treatment decreased cell viability and induced apoptosis in Calu-1 and A549 cells. Moreover, anlotinib induced human lung cancer cell autophagy in a dose- and time-dependent manner. Blocking autophagy enhanced the cytotoxicity and anti-angiogenic ability of anlotinib as evidenced by HUVECs migration, invasion, and tubular formation assay. Co-administration of anlotinib and chloroquine (CQ) further reduced VEGFA level in the tumor supernatant, compared with that of anlotinib or CQ treatment alone. When autophagy was induced by rapamycin, the JAK2/STAT3 pathway was activated and VEGFA was elevated, which was attenuated after deactivating STAT3 by S3I-201. Further in vivo studies showed that anlotinib inhibited tumor growth, induced autophagy and suppressed JAK2/STAT3/VEGFA pathway, and CQ enhanced this effect.

CONCLUSION

Anlotinib induced apoptosis and protective autophagy in human lung cancer cell lines. Autophagy inhibition further enhanced the cytotoxic effects of anlotinib, and potentiated the anti-angiogenic property of anlotinib through JAK2/STAT3/VEGFA signaling.

Simultaneous activation and inhibition of autophagy sensitizes cancer cells to chemotherapy

While combined chemotherapy (CT) with an autophagy inducer and an autophagy inhibitor appears paradoxical, it may provide a more effective perturbation of autophagy pathways. We used two dissimilar cell lines to test the hypothesis that autophagy is the common denominator of cell fate after CT. HA22T cells are characterized by CT-induced apoptosis and use autophagy to prevent cell death, while Huh7.5.1 cells exhibit sustained autophagic morphology after CT. Combined CT and rapamycin treatment resulted in a better combination index (CI) in Huh7.5.1 cells than combined CT and chloroquine, while the reverse was true in HA22T cells. The combination of 3 drugs (triplet drug treatment) had the best CI. After triplet drug treatment, HA22T cells switched from protective autophagy to mitochondrial membrane permeabilization and endoplasmic reticulum stress response-induced apoptosis, while Huh7.5.1 cells intensified autophagic lethality. Most importantly, both cell lines showed activation of Akt after CT, while the triplet combination blocked Akt activation through inhibition of phospholipid lipase D activity. This novel finding warrants further investigation as a broad chemosensitization strategy.

Chloroquine inhibits tumor growth and angiogenesis in malignant pleural effusion

Malignant pleural effusion (MPE) is associated with a poor prognosis in lung cancer. Currently, no effective cure exists for MPE. Chloroquine (CQ) has been demonstrated to induce vascular normalization and inhibit tumor growth. The aim of this study was to assess whether CQ affects MPE. The xenografts mice were divided into normal saline (NS), CQ, or bevacizumab (BE) group. Tumor growth and microvascular density (MVD) were monitored. We explored the effect of CQ on the proliferation, survival, and proangiogenic signaling of tumor cells in vitro. We further evaluated the effects of CQ on the viability, migration, and tube formation of human umbilical vein endothelial cells (HUVECs). A chicken chorioallantoic membrane (CAM) model was used to elucidate the effects of CQ on angiogenesis. Finally, an MPE mouse model were treated by CQ, BE, or NS. The volume of pleural effusion, tumor foci, and MVD was evaluated. CQ therapy group exhibited decreased tumor volume, tumor weight, and MVD in the mouse xenografts. CQ inhibited the proliferation of the tumor cells. However, the expression of vascular endothelial growth factor was not affected. Additionally, CQ inhibited the proliferation, migration, and tube formation of HUVECs and also restrained angiogenesis in the CAM. Western blot showed that CQ might suppress angiogenesis by downregulating p-Akt, Jagged1, and Ang2 in HUVECs. In MPE mice, the volume of the pleural effusion, the number of pleural tumor foci, and the MVD were significantly reduced in the CQ group. Our work demonstrated that CQ played the role of an efficient treatment for MPE.

Double autophagy modulators reduce 2-deoxyglucose uptake in sarcoma patients

Rationale

According to the metabolic symbiosis model, cancer stromal fibroblasts could be hijacked by surrounding cancer cells into a state of autophagy with aerobic glycolysis to help provide recycled nutrients. The purpose of this study was to investigate whether combined treatment with the autophagy inhibitor: hydroxychloroquine (HCQ) and the autophagy inducer: sirolimus (rapamycin, Rapa) would reduce glucose utilization in sarcoma patients.

Methods

Ten sarcoma patients who failed first-line treatment were enrolled in this study. They were treated with 1 mg of Rapa and 200 mg of HCQ twice daily for two weeks. The standardized uptake values (SUV) from pretreatment and posttreatment [18F]-fluorodeoxyglucose positron emission tomography (FDG PET) scans were reviewed, and changes from the baseline SUVmax were evaluated.

Results

Based on FDG PET response criteria, six patients had a partial response; three had stable disease, and one had progressive disease. Nevertheless, none of them showed a reduction in tumor volume. The mean SUVmax reduction in the 34 lesions evaluated was − 19.6% (95% CI = −30.1% to −9.1%), while the mean volume change was +16.4% (95% CI = +5.8% to + 27%). Only grade 1 toxicities were observed. Elevated serum levels of lactate dehydrogenase were detected after treatment in most metabolic responders.

Conclusions

The results of reduced SUVmax without tumor volume reduction after two weeks of Rapa and HCQ treatment may indicate that non-proliferative glycolysis occurred mainly in the cancer associated fibroblast compartment, and decreased glycolytic activity was evident from Rapa + HCQ double autophagy modulator treatment.

Glutaminolysis and autophagy in cancer

The remarkable metabolic differences between cancer cells and normal cells result in the potential for targeted cancer therapy. The upregulation of glutaminolysis provides energetic advantages to cancer cells. The recently described link between glutaminolysis and autophagy, mediated by MTORC1, may constitute an attractive target for therapeutic strategies. A combination of therapies targeting simultane-ously cell signaling, cancer metabolism, and autophagy can solve therapy resistance and tumor relapse problems, commonly observed in patients treated with most of the current targeted therapies. In this review we summarize the mechanistic link between glutaminolysis and autophagy, and discuss the impacts of these processes on cancer progression and the potential for therapeutic intervention.

Addition of rapamycin and hydroxychloroquine to metronomic chemotherapy as a second line treatment results in high salvage rates for refractory metastatic solid tumors: a pilot safety and effectiveness analysis in a small patient cohort

BACKGROUND

Autophagy is an important oncotarget that can be modulated during anti-cancer therapy. Enhancing autophagy using chemotherapy and rapamycin (Rapa) treatment and then inhibiting it using hydroxychloroquine (HCQ) could synergistically improve therapy outcome in cancer patients. It is still unclear whether addition of Rapa and HCQ to chemotherapy could be used for reversing drug resistance.

PATIENTS AND METHODS

Twenty-five stage IV cancer patients were identified. They had no clinical response to first-line metronomic chemotherapy; the patients were salvaged by adding an autophagy inducer (Rapa, 2 mg/day) and an autophagosome inhibitor (HCQ, 400 mg/day) to their current metronomic chemotherapy for at least 3 months. Patients included 4 prostate, 4 bladder, 4 lung, 4 breast, 2 colon, and 3 head and neck cancer patients as well as 4 sarcoma patients.

RESULTS

Chemotherapy was administered for a total of 137 months. The median duration of chemotherapy cycles per patient was 4 months (95% confidence interval, 3–7 months). The overall response rate to this treatment was of 40%, with an 84% disease control rate. The most frequent and clinically significant toxicities were myelotoxicities. Grade ≥3 leucopenia occurred in 6 patients (24%), grade ≥3 thrombocytopenia in 8 (32%), and anemia in 3 (12%). None of them developed febrile neutropenia. Non-hematologic toxicities were fatigue (total 32%, with 1 patient developing grade 3 fatigue), diarrhea (total 20%, 1 patient developed grade 3 fatigue), reversible grade 3 cardiotoxicity (1 patient), and grade V liver toxicity from hepatitis B reactivation (1 patient).

CONCLUSION

Our results of Rapa, HCQ and chemotherapy triplet combination suggest autophagy is a promising oncotarget and warrants further investigation in phase II studies.

Pharmacological inhibitors of autophagy as novel cancer therapeutic agents

Autophagy is an evolutionarily conserved cellular degradative process in which intracellular components (cellular proteins and organelles) are engulfed in autophagosomes which then fuse with lysosomes to form autolysosome for degradation. Autophagy is closely implicated in various physio-pathological processes and human diseases. Among them, the roles of autophagy in cancer have been extensively studied. Increasing evidence has demonstrated that inhibiting autophagy is a novel and promising approach in cancer therapy, based on the notion that autophagy is a pro-survival mechanism in cancer cells under therapeutic stress, and induction of autophagy is associated with chemoresistance of cancer cells to chemotherapeutic agents. Thus, suppression of autophagy would sensitize resistance tumor cells to cancer therapeutic agents, thereby supporting the clinical application of autophagy inhibitors. In recent years, significant progress has been achieved in developing autophagy inhibitors and testing their therapeutical potential, either as standalone or as adjuvant therapeutic agents, in cell and animal models, and more importantly in clinical trials. In this review, we will discuss some of these recent advances in development of novel small molecules autophagy inhibitors and their mechanisms of action, together with their applications in clinical trials.

MicroRNA-143 enhances chemosensitivity of Quercetin through autophagy inhibition via target GABARAPL1 in gastric cancer cells

MicroRNAs have emerged as fundamental regulators in gene expression through silencing gene expression at the post-transcriptional and translational levels. In this study, miR-143 expression and biological functions in AGS/MNK28 cell lines was investigated. Results indicated that the expression of miR-143 was significantly down-regulated in cancer tissues and in gastric cancer (GC) cell lines. Target prediction algorithms (Target Scan and miRanda) showed that GABARAPL1 was a potential target gene of miR-143. GABARAPL1, also regarded as autophagy-related protein 8 (Atg8) is a ubiquitin-like protein required for the formation of autophagosomal membranes. Then, several different assays were conducted to detect autophagy in AGS/MNK28 after transfected with miR-143. In the present study, miR-143 was firstly identified as a autophagy inhibitor in GC cells via targeting GABARAPL1. Quercetin is one of the most prominent dietary antioxidants in human diet and lately it is grabbing some serious attention as a potentially powerful cancer fighter. However, the effect of Quercetin was unexpected decreased in GC cells on account of the appearance of Quercetin-induced autophagy. Therefore, applicable autophagy inhibitors might enhance the chemosensitivity of Quercetin. Furthermore, the therapeutic response of Quercetin in the combination of miR-143 was evaluated by MTT, Hochest and western blot, results suggesting that the chemosensitivity of Quercetin was enhanced when in combination with miR-143 in AGS/MNK28 cells. In conclusion, we determined miR-143 as a potent inhibitor of autophagy via targeting GABARAPL1 and miR-143 could improve the efficacy of Quercetin though autophagy inhibition in GC cell lines, thus representing a novel potential therapeutic target for gastric cancer.

Activation of p53 by sodium selenite switched human leukemia NB4 cells from autophagy to apoptosis

It was revealed by our previous research that sodium selenite repressed autophagy accompanied by the induction of apoptosis in human leukemia NB4 cells. The inhibition of autophagy exerted a facilitative effect on apoptosis. In the present study, we further explored the mechanisms underlying the switch from autophagy to apoptosis and elucidated p53 played a key role. Selenite induced phosphorylation of p53 at the vital site Ser15 via p38MAPK and ERK. Subsequently p53 dissociated with its inhibitory protein mouse double minute 2 (MDM2). Meanwhile, the nucleolar protein B23 transferred from the nucleolus to the nucleoplasm and associated with MDM2, probably stabilizing p53. The active p53 participated in the decrease of autophagic protein Beclin-1 and LC-3, as well as activation of apoptosis-related caspases. Furthermore, in p53 mutant U937 leukemia cells, selenite could not elicit such a switch from autophagy to apoptosis, laying emphasis on the crucial role p53 played in this process.

The dual PI3K/mTOR inhibitor NVP-BEZ235 prevents epithelial-mesenchymal transition induced by hypoxia and TGF-β1

Epithelial-mesenchymal transition (EMT) is regarded as the most important mechanism behind the initiation of cancer metastasis. Though there has been great interest in developing therapies aimed at impairing the process of EMT, only few molecules have been identified to orchestrate it so far. Here we report that the dual PI3K/mTOR inhibitor NVP-BEZ235 is capable of preventing human ovarian cancer cell line SKOV-3 and prostatic cancer cell line PC-3 from hypoxia- and TGF-β1-induced EMT. The addition of NVP-BEZ235 reverses the EMT-like morphologic changes, down-regulation of E-cadherin, and enhancement of cell migration induced by 1% O2 partially through interfering with the expression and transcriptional activity of Hif-1α via PI3K/mTOR pathway. In addition, NVP-BEZ235 inhibits TGF-β1-induced phosphorylation of Smad2/3 and Akt/GSK-3β, reduces the expression of Snail both in transcriptional and post-translational level, and consequently prevents the repression of E-cadherin expression as well as the increase of cell motility caused by TGF-β1. Moreover, in nude mice bearing SKOV-3 ovarian cancer xenografts, NVP-BEZ235 significantly increases the mRNA level of E-cadherin. Taken together, our study demonstrates, for the first time, NVP-BEZ235 can prevent microenvironment and growth factor induced EMT, which suggests this agent as a potential candidate for cancer metastasis treatment.

Targeting bone metastatic cancer: Role of the mTOR pathway

One of the great challenges of cancer medicine is to develop effective treatments for bone metastatic cancer. Most patients with advanced solid tumors will develop bone metastasis and will suffer from skeletal related events associated with this disease. Although some therapies are available to manage symptoms derived from bone metastases, an effective treatment has not been developed yet. The mammalian target of rapamycin (mTOR) pathway regulates cell growth and survival. Alterations in mTOR signaling have been associated with pathological malignancies, including bone metastatic cancer. Inhibition of mTOR signaling might therefore be a promising alternative for bone metastatic cancer management. This review summarizes the current knowledge on mTOR pathway signaling in bone tissue and provides an overview on the known effects of mTOR inhibition in bone cancer, both in in vitro and in vivo models.

Mtor-Fanconi Anemia DNA Damage Repair Pathway in Cancer

mTOR is a serine/threonine kinase and plays a critical role in mammalian cell growth, survival, and metabolism. mTOR is present in two cellular complexes: mTORC1 and mTORC2. Dysregulation of the mTOR pathway has been related to tumorigenesis, poor prognosis and/or chemotherapy resistance in a variety of malignancies. Inhibition of mTORC1 by Rapamycin and its analogs has been explored to treat a number of tumors. However, the effectiveness of patient response is limited and not all patients respond. Second generation of mTOR inhibitors have recently been developed to target mTOR kinase activity and to suppress both mTORC1 and mTORC2. Dual mTORC1/mTORC2 inhibitors generally are more efficacious in preclinical studies and clinical trials. We and others have recently found that dual mTORC1/mTORC2 inhibitors sensitize T-cell acute lymphocytic leukemia and rhabdomyosarcoma cells to DNA damaging agents by suppression of expression of FANCD2 of the Fanconi anemia pathway, an important DNA repair mechanism that is associated with drug resistance of multiple types of cancer. This review will highlight mTOR and the Fanconi anemia pathway in cancer, with a particular attention to our newly discovered connection between mTOR and the Fanconi anemia pathway.