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International Neurourology Journal Jun 2021Adenosine monophosphate-activated protein kinase (AMPK) is thought to inhibit cell proliferation or promote cell death, but the details remain unclear. In this study, we...
Hypoxia-Induced Suppression of Antiapoptotic Bcl-2 Expression in Human Bladder Tumor Cells Is Regulated by Caveolin-1-Dependent Adenosine Monophosphate-Activated Protein Kinase Activity.
PURPOSE
Adenosine monophosphate-activated protein kinase (AMPK) is thought to inhibit cell proliferation or promote cell death, but the details remain unclear. In this study, we propose that AMPK inhibits the expression of anti-apoptotic B-cell lymphoma 2 (Bcl-2) by relying on the hypoxia-inducible factor 1 alpha (HIF-1α)-induced caveolin-1 (Cav-1) expression pathway in noninvasive human bladder tumor (RT4) cells.
METHODS
In cells exposed to a hypoxic environment (0.5% oxygen), the levels of expression and phospho-activity of the relevant signaling enzymes were examined via Western blots and reverse transcription-polymerase chain reaction. Cell proliferation was assessed using a Cell Counting Kit-8 assay.
RESULTS
The level of expression of Cav-1 was very low or undetectable in RT4 cells. Hypoxia was associated with significantly decreased cell growth, along with marked induction of HIF-1α and Cav-1 expression; additionally, it suppressed the expression of the antiapoptotic marker Bcl-2 while leaving AMPK activity unchanged. Under hypoxic conditions, HIF-1α acts as a transcription factor for Cav-1 mRNA gene expression. The cell growth and Bcl-2 expression suppressed under hypoxia were reversed along with decreases in the induced HIF-1α and Cav-1 levels by AMPK activation with metformin (1mM) or phenformin (0.1mM). In addition, pretreatment with AMPK small interfering RNA not only increased the hypoxia-induced expression of HIF-1α and Cav-1, but also reversed the suppression of Bcl-2 expression. These results suggest that HIF-1α and Cav-1 expression in hypoxic environments is regulated by basal AMPK activity; therefore, the inhibition of Bcl-2 expression cannot be expected when AMPK activity is suppressed, even if Cav-1 expression is elevated.
CONCLUSION
For the first time, we find that AMPK activation can regulate HIF-1α induction as well as HIF-1α-induced Cav1 expression, and the hypoxia-induced inhibitory effect on the antiapoptotic pathway in RT4 cells is due to Cav-1-dependent AMPK activity.
PubMed: 33752282
DOI: 10.5213/inj.2040444.222 -
FEBS Open Bio May 2021Inhibitors of ataxia-telangiectasia mutated (ATM), such as KU-55933 (Ku), represent a promising class of novel anticancer drugs. In addition, the biguanide derivative...
Inhibitors of ataxia-telangiectasia mutated (ATM), such as KU-55933 (Ku), represent a promising class of novel anticancer drugs. In addition, the biguanide derivative phenformin exhibits antitumor activity superior to that of the AMPK activator metformin. Herein, we assessed the potential combinatorial therapeutic efficacy of phenformin and Ku when used to inhibit the growth of liver cancer cells, and we assessed the mechanisms underlying such efficacy. The Hep-G2 and SMMC-7721 liver cancer cell lines were treated with phenformin and Ku either alone or in combination, after which the impact of these drugs on cellular proliferation was assessed via 3-(4,5-dimethylthiazol) 2, 5-diphenyltetrazolium and colony formation assays, whereas Transwell assays were used to gauge cell migratory activity. The potential synergy between these two drugs was assessed using the CompuSyn software, while flow cytometry was employed to evaluate cellular apoptosis. In addition, western blotting was utilized to measure p-ATM, p-AMPK, p-mTOR, and p-p70s6k expression, while mitochondrial functionality was monitored via morphological analyses, JC-1 staining, and measurements of ATP levels. Phenformin and Ku synergistically impacted the proliferation, migration, and apoptotic death of liver cancer cells. Together, these compounds were able to enhance AMPK phosphorylation while inhibiting the phosphorylation of mTOR and p70s6k. These data also revealed that phenformin and Ku induced mitochondrial dysfunction as evidenced by impaired ATP synthesis, mitochondrial membrane potential, and abnormal mitochondrial morphology. These findings suggest that combination treatment with phenformin and Ku may be an effective approach to treating liver cancer via damaging mitochondria within these tumor cells.
Topics: AMP-Activated Protein Kinases; Apoptosis; Ataxia Telangiectasia; Ataxia Telangiectasia Mutated Proteins; Carcinoma, Hepatocellular; Cell Line, Tumor; Cell Movement; Cell Proliferation; China; Drug Synergism; Drug Therapy, Combination; Humans; Liver Neoplasms; Mitochondria; Morpholines; Phenformin; Phosphorylation; Pyrones; Ribosomal Protein S6 Kinases, 70-kDa; TOR Serine-Threonine Kinases
PubMed: 33742560
DOI: 10.1002/2211-5463.13152 -
Theranostics 2021The activity of aldehyde dehydrogenase 7A1 (ALDH7A1), an enzyme that catalyzes the lipid peroxidation of fatty aldehydes was found to be upregulated in pancreatic...
The activity of aldehyde dehydrogenase 7A1 (ALDH7A1), an enzyme that catalyzes the lipid peroxidation of fatty aldehydes was found to be upregulated in pancreatic ductal adenocarcinoma (PDAC). knockdown significantly reduced tumor formation in PDAC. We raised a question how ALDH7A1 contributes to cancer progression. To answer the question, the role of ALDH7A1 in energy metabolism was investigated by knocking down and knockdown gene in mouse model, because the role of ALDH7A1 has been reported as a catabolic enzyme catalyzing fatty aldehyde from lipid peroxidation to fatty acid. Oxygen consumption rate (OCR), ATP production, mitochondrial membrane potential, proliferation assay and immunoblotting were performed. In study, two human PDAC cell lines were used for pre-clinical xenograft model as well as spontaneous PDAC model of KPC mice was also employed for anti-cancer therapeutic effect. knockdown significantly reduced tumor formation with reduction of OCR and ATP production, which was inversely correlated with increase of 4-hydroxynonenal. This implies that ALDH7A1 is critical to process fatty aldehydes from lipid peroxidation. Overall survival of PDAC is doubled by cross breeding of KPC () and mice. Inhibitions of ALDH7A1 and oxidative phosphorylation using gossypol and phenformin resulted in a regression of tumor formation in xenograft mice model and KPC mice model.
Topics: Aldehyde Dehydrogenase; Aldehydes; Animals; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Movement; Cell Proliferation; Gene Expression Regulation, Neoplastic; Gossypol; Homeodomain Proteins; Humans; Lipid Peroxidation; Mice; Mice, Knockout; Mice, Nude; Oxidative Phosphorylation; Pancreatic Neoplasms; Phenformin; Proto-Oncogene Proteins p21(ras); Signal Transduction; Survival Analysis; Trans-Activators; Tumor Suppressor Protein p53; Xenograft Model Antitumor Assays
PubMed: 33537098
DOI: 10.7150/thno.53935 -
Oxidative Medicine and Cellular... 2021Nephrotoxicity is a common complication of cisplatin chemotherapy and, thus, limits the clinical application of cisplatin. In this work, the effects of catalpol (CAT), a...
Nephrotoxicity is a common complication of cisplatin chemotherapy and, thus, limits the clinical application of cisplatin. In this work, the effects of catalpol (CAT), a bioactive ingredient extracted from Rehmannia glutinosa, on cisplatin-induced nephrotoxicity and antitumor efficacy were comprehensively investigated. Specifically, the protective effect of CAT on cisplatin-induced injury was explored in mice and HK-2 cells. , CAT administration strikingly suppressed cisplatin-induced renal dysfunction, morphology damage, apoptosis, and inflammation. , CAT induced activation of adenosine 5'-monophosphate- (AMP-) activated protein kinase (AMPK), improved mitochondrial function, and decreased generation of cellular reactive oxygen species (ROS), leading to a reduction in inflammation and apoptosis, which ultimately protected from cisplatin-induced injury. However, the beneficial effects of CAT were mostly blocked by coincubation with compound C. Furthermore, molecular docking results indicated that CAT had a higher affinity for AMPK than other AMPK activators such as danthron, phenformin, and metformin. Importantly, CAT possessed the ability to reverse drug resistance without compromising the antitumor properties of cisplatin. These findings suggest that CAT exerts positive effects against cisplatin-induced renal injury through reversing drug resistance via the mitochondrial-dependent pathway without affecting the anticancer activity of cisplatin.
Topics: AMP-Activated Protein Kinases; Animals; Antineoplastic Agents; Cisplatin; Enzyme Activation; Iridoid Glucosides; Kidney Diseases; Male; Mice; Mitochondria
PubMed: 33510841
DOI: 10.1155/2021/7467156 -
Nanog maintains stemness of Lkb1-deficient lung adenocarcinoma and prevents gastric differentiation.EMBO Molecular Medicine Mar 2021Growing evidence supports that LKB1-deficient KRAS-driven lung tumors represent a unique therapeutic challenge, displaying strong cancer plasticity that promotes lineage...
Growing evidence supports that LKB1-deficient KRAS-driven lung tumors represent a unique therapeutic challenge, displaying strong cancer plasticity that promotes lineage conversion and drug resistance. Here we find that murine lung tumors from the Kras ; Lkb1 (KL) model show strong plasticity, which associates with up-regulation of stem cell pluripotency genes such as Nanog. Deletion of Nanog in KL model initiates a gastric differentiation program and promotes mucinous lung tumor growth. We find that NANOG is not expressed at a meaningful level in human lung adenocarcinoma (ADC), as well as in human lung invasive mucinous adenocarcinoma (IMA). Gastric differentiation involves activation of Notch signaling, and perturbation of Notch pathway by the γ-secretase inhibitor LY-411575 remarkably impairs mucinous tumor formation. In contrast to non-mucinous tumors, mucinous tumors are resistant to phenformin treatment. Such therapeutic resistance could be overcome through combined treatments with LY-411575 and phenformin. Overall, we uncover a previously unappreciated plasticity of LKB1-deficient tumors and identify the Nanog-Notch axis in regulating gastric differentiation, which holds important therapeutic implication for the treatment of mucinous lung cancer.
Topics: AMP-Activated Protein Kinase Kinases; Adenocarcinoma of Lung; Animals; Cell Differentiation; Disease Models, Animal; Humans; Lung Neoplasms; Mice; Nanog Homeobox Protein; Neoplastic Stem Cells; Protein Serine-Threonine Kinases; Signal Transduction
PubMed: 33439550
DOI: 10.15252/emmm.202012627 -
Molecules (Basel, Switzerland) Jan 2021Resident cancer cells with stem cell-like features induce drug tolerance, facilitating survival of glioblastoma (GBM). We previously showed that strategies targeting...
Combinatorial Therapeutic Effect of Inhibitors of Aldehyde Dehydrogenase and Mitochondrial Complex I, and the Chemotherapeutic Drug, Temozolomide against Glioblastoma Tumorspheres.
Resident cancer cells with stem cell-like features induce drug tolerance, facilitating survival of glioblastoma (GBM). We previously showed that strategies targeting tumor bioenergetics present a novel emerging avenue for treatment of GBM. The objective of this study was to enhance the therapeutic effects of dual inhibition of tumor bioenergetics by combination of gossypol, an aldehyde dehydrogenase inhibitor, and phenformin, a biguanide compound that depletes oxidative phosphorylation, with the chemotherapeutic drug, temozolomide (TMZ), to block proliferation, stemness, and invasiveness of GBM tumorspheres (TSs). Combination therapy with gossypol, phenformin, and TMZ induced a significant reduction in ATP levels, cell viability, stemness, and invasiveness compared to TMZ monotherapy and dual therapy with gossypol and phenformin. Analysis of differentially expressed genes revealed up-regulation of genes involved in programmed cell death, autophagy, and protein metabolism and down-regulation of those associated with cell metabolism, cycle, and adhesion. Combination of TMZ with dual inhibitors of tumor bioenergetics may, therefore, present an effective strategy against GBM by enhancing therapeutic effects through multiple mechanisms of action.
Topics: Aldehyde Dehydrogenase; Antineoplastic Combined Chemotherapy Protocols; Brain Neoplasms; Electron Transport Complex I; Enzyme Inhibitors; Glioblastoma; Humans; Neoplasm Proteins; Spheroids, Cellular; Temozolomide
PubMed: 33429981
DOI: 10.3390/molecules26020282 -
The Journal of Investigative Dermatology Jan 2021The results in the article by Zhou et al. (2020) demonstrate that the antidiabetic drug phenformin inhibits skin tumor growth and promotes keratinocyte differentiation,...
The results in the article by Zhou et al. (2020) demonstrate that the antidiabetic drug phenformin inhibits skin tumor growth and promotes keratinocyte differentiation, and an underlying mechanism is also defined. In this commentary, additional potential mechanisms through which phenformin may exert its antitumorigenic effect are described. Thus, the proposed repurposing of phenformin to treat skin cancer has merit.
Topics: Adenosine Monophosphate; Drug Repositioning; Humans; Hypoglycemic Agents; Neoplasms; Phenformin
PubMed: 33342506
DOI: 10.1016/j.jid.2020.06.008 -
Cell Reports. Medicine Nov 2020Mitochondrial respiration (oxidative phosphorylation, OXPHOS) is an emerging target in currently refractory cancers such as pancreatic ductal adenocarcinoma (PDAC)....
Mitochondrial respiration (oxidative phosphorylation, OXPHOS) is an emerging target in currently refractory cancers such as pancreatic ductal adenocarcinoma (PDAC). However, the variability of energetic metabolic adaptations between PDAC patients has not been assessed in functional investigations. In this work, we demonstrate that OXPHOS rates are highly heterogeneous between patient tumors, and that high OXPHOS tumors are enriched in mitochondrial respiratory complex I at protein and mRNA levels. Therefore, we treated PDAC cells with phenformin (complex I inhibitor) in combination with standard chemotherapy (gemcitabine), showing that this treatment is synergistic specifically in high OXPHOS cells. Furthermore, phenformin cooperates with gemcitabine in high OXPHOS tumors in two orthotopic mouse models (xenografts and syngeneic allografts). In conclusion, this work proposes a strategy to identify PDAC patients likely to respond to the targeting of mitochondrial energetic metabolism in combination with chemotherapy, and that phenformin should be clinically tested in appropriate PDAC patient subpopulations.
Topics: Animals; Carcinoma, Pancreatic Ductal; Cell Line, Tumor; Cell Proliferation; Cell Respiration; Deoxycytidine; Drug Resistance, Neoplasm; Electron Transport Complex I; Female; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Nude; Mitochondria; Oxidative Phosphorylation; PC-3 Cells; Pancreatic Neoplasms; Phenformin; Xenograft Model Antitumor Assays; Gemcitabine
PubMed: 33294863
DOI: 10.1016/j.xcrm.2020.100143 -
Cancer Research Feb 2021Lung cancer is a prevalent and lethal cancer type that leads to more deaths than the next four major cancer types combined. Metastatic cancer spread is responsible for...
Lung cancer is a prevalent and lethal cancer type that leads to more deaths than the next four major cancer types combined. Metastatic cancer spread is responsible for most cancer-related deaths but the cellular changes that enable cancer cells to leave the primary tumor and establish inoperable and lethal metastases remain poorly understood. To uncover genes that are specifically required to sustain metastasis survival or growth, we performed a genome-scale pooled lentiviral-shRNA library screen in cells that represent nonmetastatic and metastatic states of lung adenocarcinoma. Mitochondrial ribosome and mitochondria-associated genes were identified as top gene sets associated with metastasis-specific lethality. Metastasis-derived cell lines and metastases analyzed from an autochthonous lung cancer mouse model had lower mitochondrial membrane potential and reduced mitochondrial functionality than nonmetastatic primary tumors. Electron microscopy of metastases uncovered irregular mitochondria with bridging and loss of normal membrane structure. Consistent with these findings, compounds that inhibit mitochondrial translation or replication had a greater effect on the growth of metastasis-derived cells. Finally, mice with established tumors developed fewer metastases upon treatment with phenformin . These results suggest that the metastatic cell state in lung adenocarcinoma is associated with a specifically altered mitochondrial functionality that can be therapeutically exploited. SIGNIFICANCE: This study characterizes altered mitochondria functionality of the metastatic cell state in lung cancer and opens new avenues for metastasis-specific therapeutic targeting.
Topics: Adenocarcinoma; Animals; Cell Line, Tumor; Disease Models, Animal; Gene Expression Profiling; Gene Expression Regulation, Neoplastic; Genome-Wide Association Study; Humans; Lung Neoplasms; Mice, Knockout; Mice, Transgenic; Mitochondria; Neoplasm Metastasis; RNA Interference; Mice
PubMed: 33239425
DOI: 10.1158/0008-5472.CAN-20-1865 -
Science Advances Nov 2020Mitochondria-derived reactive oxygen species (mROS) are required for the survival, proliferation, and metastasis of cancer cells. The mechanism by which mitochondrial...
Mitochondria-derived reactive oxygen species (mROS) are required for the survival, proliferation, and metastasis of cancer cells. The mechanism by which mitochondrial metabolism regulates mROS levels to support cancer cells is not fully understood. To address this, we conducted a metabolism-focused CRISPR-Cas9 genetic screen and uncovered that loss of genes encoding subunits of mitochondrial complex I was deleterious in the presence of the mitochondria-targeted antioxidant mito-vitamin E (MVE). Genetic or pharmacologic inhibition of mitochondrial complex I in combination with the mitochondria-targeted antioxidants, MVE or MitoTEMPO, induced a robust integrated stress response (ISR) and markedly diminished cell survival and proliferation in vitro. This was not observed following inhibition of mitochondrial complex III. Administration of MitoTEMPO in combination with the mitochondrial complex I inhibitor phenformin decreased the leukemic burden in a mouse model of T cell acute lymphoblastic leukemia. Thus, mitochondrial complex I is a dominant metabolic determinant of mROS-dependent cellular fitness.
PubMed: 33148642
DOI: 10.1126/sciadv.abb7272