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Biomedicine & Pharmacotherapy =... Aug 2020Pancreatic stellate cells (PSCs) are the main effector cells in the development of pancreatic fibrosis. Finding substances that inhibit PSC activation is an important...
Pancreatic stellate cells (PSCs) are the main effector cells in the development of pancreatic fibrosis. Finding substances that inhibit PSC activation is an important approach to inhibiting pancreatic fibrosis. Saikosaponin A (SSa) has numerous pharmacological activities, but its effect on PSCs remains unknown. This study was conducted to explore the effects of SSa on PSC activation in cultured rat PSCs. Cell viability, proliferation, migration and apoptosis were evaluated by MTT assays, the iCELLigence System, Transwell assays and flow cytometry. Markers of PSC activation, autophagy and the NLRP3 inflammasome were measured by real-time PCR, immunofluorescence and western blotting. Rapamycin and phenformin hydrochloride were used to determine the effect of SSa via the AMPK/mTOR pathway. The results showed that SSa suppressed PSC viability, proliferation, and migration and promoted apoptosis. SSa inhibited PSC activation, restrained PSC autophagy and suppressed the NLRP3 inflammasome. In addition, there was interaction between autophagy and the NLRP3 inflammasome during SSa inhibition of PSCs. Moreover, promotion of p-AMPK increased autophagy and the NLRP3 inflammasome. Inhibition of p-mTOR increased autophagy and decreased the NLRP3 inflammasome. Our results indicated that SSa inhibited PSC activation by inhibiting PSC autophagy and the NLRP3 inflammasome via the AMPK/mTOR pathway. These findings provide a theoretical basis for the use of SSa to treat pancreatic fibrosis and further suggest that targeting autophagy and the NLRP3 inflammasome may provide new strategies for the treatment of pancreatic fibrosis.
Topics: AMP-Activated Protein Kinases; Animals; Apoptosis; Autophagy; Cell Movement; Cell Proliferation; Cells, Cultured; Fibrosis; Inflammasomes; NLR Family, Pyrin Domain-Containing 3 Protein; Oleanolic Acid; Pancreatic Stellate Cells; Rats; Saponins; Signal Transduction; TOR Serine-Threonine Kinases
PubMed: 32497863
DOI: 10.1016/j.biopha.2020.110216 -
Cancers May 2020Lung adenocarcinoma cells express high levels of , an enzyme of the one-carbon pathway that catalyzes the conversion of 10-formyltetrahydrofolate into tetrahydrofolate...
Lung adenocarcinoma cells express high levels of , an enzyme of the one-carbon pathway that catalyzes the conversion of 10-formyltetrahydrofolate into tetrahydrofolate and NAD(P)H. In this study, we evaluated the potential of as a therapeutic target by deleting the gene in mice, a model of spontaneous non-small cell lung cancer (NSCLC). Reporter assays revealed KRAS-mediated upregulation of the promoter in human NSCLC cells. mice exhibited a normal phenotype, with a 10% decrease in driven lung tumorigenesis. By contrast, the inhibition of oxidative phosphorylation inhibition using phenformin in ; mice dramatically decreased the number of tumor nodules and tumor area by up to 50%. Furthermore, combined treatment with pan-ALDH inhibitor and phenformin showed a decreased number and area of lung tumors by 70% in the lung cancer model. Consistent with this, previous work showed that the combination of knockdown and phenformin treatment decreased ATP production by as much as 70% in NSCLS cell lines. Taken together, these results suggest that the combined inhibition of ALDH activity and oxidative phosphorylation represents a promising therapeutic strategy for NSCLC.
PubMed: 32481524
DOI: 10.3390/cancers12061382 -
Cell Reports. Medicine May 2020Cancer cells display metabolic plasticity to survive stresses in the tumor microenvironment. Cellular adaptation to energetic stress is coordinated in part by signaling...
Cancer cells display metabolic plasticity to survive stresses in the tumor microenvironment. Cellular adaptation to energetic stress is coordinated in part by signaling through the liver kinase B1 (LKB1)-AMP-activated protein kinase (AMPK) pathway. Here, we demonstrate that miRNA-mediated silencing of LKB1 confers sensitivity of lymphoma cells to mitochondrial inhibition by biguanides. Using both classic (phenformin) and newly developed (IM156) biguanides, we demonstrate that elevated expression in lymphoma cells promotes increased apoptosis to biguanide treatment and . This effect is driven by the -dependent silencing of LKB1, which reduces AMPK activation in response to complex I inhibition. Mechanistically, biguanide treatment induces metabolic stress in lymphoma cells by inhibiting TCA cycle metabolism and mitochondrial respiration, exposing metabolic vulnerability. Finally, we demonstrate a direct correlation between expression and biguanide sensitivity in human cancer cells. Our results identify expression as a potential biomarker for biguanide sensitivity in malignancies.
Topics: AMP-Activated Protein Kinase Kinases; Animals; Antineoplastic Agents; Apoptosis; Biguanides; Drug Resistance, Neoplasm; Drug Synergism; HEK293 Cells; Humans; Lymphoma; Mice; Mice, Nude; Proto-Oncogene Proteins c-myc; RNA, Long Noncoding; Tumor Cells, Cultured; Xenograft Model Antitumor Assays
PubMed: 32478334
DOI: 10.1016/j.xcrm.2020.100014 -
Scientific Reports May 2020One-carbon metabolism fuels the high demand of cancer cells for nucleotides and other building blocks needed for increased proliferation. Although inhibitors of this...
One-carbon metabolism fuels the high demand of cancer cells for nucleotides and other building blocks needed for increased proliferation. Although inhibitors of this pathway are widely used to treat many cancers, their global impact on anabolic and catabolic processes remains unclear. Using a combination of real-time bioenergetics assays and metabolomics approaches, we investigated the global effects of methotrexate on cellular metabolism. We show that methotrexate treatment increases the intracellular concentration of the metabolite AICAR, resulting in AMPK activation. Methotrexate-induced AMPK activation leads to decreased one-carbon metabolism gene expression and cellular proliferation as well as increased global bioenergetic capacity. The anti-proliferative and pro-respiratory effects of methotrexate are AMPK-dependent, as cells with reduced AMPK activity are less affected by methotrexate treatment. Conversely, the combination of methotrexate with the AMPK activator, phenformin, potentiates its anti-proliferative activity in cancer cells. These data highlight a reciprocal effect of methotrexate on anabolic and catabolic processes and implicate AMPK activation as a metabolic determinant of methotrexate response.
Topics: AMP-Activated Protein Kinases; Antineoplastic Agents; Biguanides; Cell Line, Tumor; Cell Proliferation; Cell Respiration; Drug Synergism; Humans; Methotrexate; Mitochondria; Signal Transduction
PubMed: 32398698
DOI: 10.1038/s41598-020-64460-z -
Frontiers in Oncology 2020The treatment of melanoma has remained a difficult challenge. Targeting the tumor stroma has recently attracted attention for developing novel strategies for melanoma...
The treatment of melanoma has remained a difficult challenge. Targeting the tumor stroma has recently attracted attention for developing novel strategies for melanoma therapy. Activating transcription factor 3 (ATF3) plays a crucial role in regulating tumorigenesis and development, but whether the expression of ATF3 in human dermal fibroblasts (HDFs) can affect melanoma development hasn't been studied. Our results show that ATF3 expression is downregulated in stromal cells of human melanoma. HDFs expressing high levels of ATF3 suppressed the growth and migration of melanoma cells in association with downregulation of different cytokines including IL-6 . , HDFs with high ATF3 expression reduced tumor formation. Adding recombinant IL-6 to melanoma cells reversed those and effects, suggesting that ATF3 expression by HDFs regulates melanoma progression through the IL-6/STAT3 pathway. More importantly, HDFs pretreated with cyclosporine A or phenformin to induce ATF3 expression inhibited melanoma cell growth and . In summary, our study reveals that ATF3 suppresses human melanoma growth and that inducing the expression of ATF3 in HDFs can inhibit melanoma growth, a new potential melanoma therapeutic approach.
PubMed: 32373541
DOI: 10.3389/fonc.2020.00624 -
World Academy of Sciences Journal May 2020The mammalian target of rapamycin (mTOR) signaling pathway senses and responds to nutrient availability, energy sufficiency, stress, hormones and mitogens to modulate...
The mammalian target of rapamycin (mTOR) signaling pathway senses and responds to nutrient availability, energy sufficiency, stress, hormones and mitogens to modulate protein synthesis. Rapamycin is a bacterial product that can inhibit mTOR via the PI3K/AKT/mTOR pathway. mTOR signaling is necessary for the development of influenza and modulates the antibody response to provide cross-protective immunity to lethal infection with influenza virus. In one human study, it was found that the treatment of severe H1N1 influenza‑related pneumonia with rapamycin and steroids improved the outcome. However, in other studies, immunosuppression with systemic steroids, and possibly rapamycin as well, was associated with an increased morbidity/mortality and a prolonged viral replication. In order to avoid the systemic side-effects, some investigators have postulated that the inhalation of rapamycin would be desirable. However, the inhalation of rapamycin, with its well-documented lung toxicity, could be contraindicated. Another class of drug, biguanides, can also inhibit mTOR, but have no lung toxicity. Biguanides are widely used small molecule drugs prescribed as oral anti-diabetics that have exhibited considerable promise in oncology. During the 1971 outbreak of influenza, diabetic patients treated with the biguanides, phenformin and buformin, had a lower incidence of infection than diabetics treated with sulfonylureas or insulin. Both buformin and phenformin reduce the mortality of influenza in mice; phenformin is less effective than buformin. The inhalation of buformin or phenformin for influenza may be an effective novel treatment strategy that would limit the risk of systemic side-effects associated with biguanides due to the low inhaled dose. Coronavirus disease 2019 (COVID-19) is an infectious disease caused by SARS-CoV-2, a virus closely related to the SARS virus. The disease is the cause of the 2019-2020 coronavirus outbreak. It is primarily spread between individuals via small droplets emitted from infected individuals when breathing or coughing. PI3K/AKT/mTOR signaling responses play important roles in MERS-CoV infection and may represent a novel drug target for therapeutic intervention strategies. The present review article discusses the effects of biguanides on influenza and coronavirus.
PubMed: 32313883
DOI: 10.3892/wasj.2020.42 -
Pharmaceutics Mar 2020Phenformin and metformin are antihyperglycemic drugs that belong to the class of biguanides. Previously, we demonstrated that metformin elicits renoprotective effects in...
Phenformin and metformin are antihyperglycemic drugs that belong to the class of biguanides. Previously, we demonstrated that metformin elicits renoprotective effects in unilateral ureteral obstructed mice by reducing the infiltration of immune cells into the kidney. Since phenformin is a more potent drug as compared to metformin, we investigated the renoprotective properties of phenformin. We studied the efficacy of both drugs using mice that underwent unilateral ureteral obstruction. Renal damage was evaluated on RNA and protein level by qPCR, Western blotting, and immunohistochemistry. Moreover, we studied immune cell infiltration using flow cytometry. Both biguanides significantly reduced UUO-induced kidney injury, as illustrated by a reduction in KIM-1 protein expression. In addition, both metformin and phenformin impacted the gene expression of several inflammatory markers but to a different extent. Moreover, in contrast to metformin, phenformin did not impact immune cell infiltration into UUO kidneys. In conclusion, we demonstrated that phenformin has similar renoprotective effects as metformin, but the mechanism of action differs, and phenformin is more potent. The beneficial effects of phenformin are probably due to inhibition of the STAT3 pathway and mitochondrial complex I. Further research is needed to unveil the therapeutic potential of phenformin for the treatment of renal injury, either at low, non-toxic concentrations or as part of a combination therapy.
PubMed: 32224876
DOI: 10.3390/pharmaceutics12040301 -
Molecular & Cellular Oncology 2020Metabolic flexibility represents a potential point of attack for novel cancer treatments. We recently described the signaling mechanism inducing a metabolic shift in...
Metabolic flexibility represents a potential point of attack for novel cancer treatments. We recently described the signaling mechanism inducing a metabolic shift in response to metformin and phenformin in leukemia and lymphoma cells. Enhanced glucose utilization was critically dependent on mitochondrial stress signaling/hypoxia-inducible factor-1α representing a therapeutic vulnerability.
PubMed: 32158929
DOI: 10.1080/23723556.2020.1718475 -
International Journal of Molecular... Feb 2020Melanin in the epidermis is known to ultimately regulate human skin pigmentation. Recently, we exploited a phenotypic-based screening system composed of ex vivo human...
Melanin in the epidermis is known to ultimately regulate human skin pigmentation. Recently, we exploited a phenotypic-based screening system composed of ex vivo human skin cultures to search for effective materials to regulate skin pigmentation. Since a previous study reported the potent inhibitory effect of metformin on melanogenesis, we evaluated several biguanide compounds. The unexpected effect of phenformin, once used as an oral anti-diabetic drug, on cutaneous darkening motivated us to investigate its underlying mechanism utilizing a chemical genetics approach, and especially to identify alternatives to phenformin because of its risk of severe lactic acidosis. Chemical pull-down assays with phenformin-immobilized beads were performed on lysates of human epidermal keratinocytes, and subsequent mass spectrometry identified 7-dehydrocholesterol reductase (DHCR7). Consistent with this, AY9944, an inhibitor of DHCR7, was found to decrease autophagic melanosome degradation in keratinocytes and to intensely darken skin in ex vivo cultures, suggesting the involvement of cholesterol biosynthesis in the metabolism of melanosomes. Thus, our results validated the combined utilization of the phenotypic screening system and chemical genetics as a new approach to develop promising materials for brightening/lightening and/or tanning technologies.
Topics: Cholesterol; Female; Humans; Keratinocytes; Male; Melanocytes; Melanosomes; Oxidoreductases Acting on CH-CH Group Donors; Phenformin; Skin Pigmentation; trans-1,4-Bis(2-chlorobenzaminomethyl)cyclohexane Dihydrochloride
PubMed: 32093380
DOI: 10.3390/ijms21041451 -
Cell Reports Feb 2020The antidiabetic drug phenformin displays potent anticancer activity in different tumors, but its mechanism of action remains elusive. Using Shh medulloblastoma as...
The antidiabetic drug phenformin displays potent anticancer activity in different tumors, but its mechanism of action remains elusive. Using Shh medulloblastoma as model, we show here that at clinically relevant concentrations, phenformin elicits a significant therapeutic effect through a redox-dependent but complex I-independent mechanism. Phenformin inhibits mitochondrial glycerophosphate dehydrogenase (mGPD), a component of the glycerophosphate shuttle, and causes elevations of intracellular NADH content. Inhibition of mGPD mimics phenformin action and promotes an association between corepressor CtBP2 and Gli1, thereby inhibiting Hh transcriptional output and tumor growth. Because ablation of CtBP2 abrogates the therapeutic effect of phenformin in mice, these data illustrate a biguanide-mediated redox/corepressor interplay, which may represent a relevant target for tumor therapy.
Topics: Animals; Antineoplastic Agents; Co-Repressor Proteins; Hedgehog Proteins; Humans; Hypoglycemic Agents; Mice; Neoplasms; Phenformin
PubMed: 32049007
DOI: 10.1016/j.celrep.2020.01.024