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Biochemistry Sep 2017Metformin is the most commonly prescribed treatment for type II diabetes and related disorders; however, molecular insights into its mode(s) of action have been limited...
Metformin is the most commonly prescribed treatment for type II diabetes and related disorders; however, molecular insights into its mode(s) of action have been limited by an absence of structural data. Structural considerations along with a growing body of literature demonstrating its effects on one-carbon metabolism suggest the possibility of folate mimicry and anti-folate activity. Motivated by the growing recognition that anti-diabetic biguanides may act directly upon the gut microbiome, we have determined structures of the complexes formed between the anti-diabetic biguanides (phenformin, buformin, and metformin) and Escherichia coli dihydrofolate reductase (ecDHFR) based on nuclear magnetic resonance, crystallographic, and molecular modeling studies. Interligand Overhauser effects indicate that metformin can form ternary complexes with p-aminobenzoyl-l-glutamate (pABG) as well as other ligands that occupy the region of the folate-binding site that interacts with pABG; however, DHFR inhibition is not cooperative. The biguanides competitively inhibit the activity of ecDHFR, with the phenformin inhibition constant being 100-fold lower than that of metformin. This inhibition may be significant at concentrations present in the gut of treated individuals, and inhibition of DHFR in intestinal mucosal cells may also occur if accumulation levels are sufficient. Perturbation of folate homeostasis can alter the pyridine nucleotide redox ratios that are important regulators of cellular metabolism.
Topics: Biguanides; Binding Sites; Crystallization; Escherichia coli; Folic Acid Antagonists; Hypoglycemic Agents; Models, Molecular; Molecular Structure; Protein Conformation; Structure-Activity Relationship; Tetrahydrofolate Dehydrogenase
PubMed: 28766937
DOI: 10.1021/acs.biochem.7b00619 -
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 -
Biomedicine & Pharmacotherapy =... Mar 2022Cancer is one of the main causes of human mortality and brain tumors, including invasive pituitary adenomas, medulloblastomas and glioblastomas are common brain... (Review)
Review
Cancer is one of the main causes of human mortality and brain tumors, including invasive pituitary adenomas, medulloblastomas and glioblastomas are common brain malignancies with poor prognosis. Therefore, the development of innovative management strategies for refractory cancers and brain tumors is important. In states of mitochondrial dysfunction - commonly encountered in malignant cells - cells mostly shift to anaerobic glycolysis by increasing the expression of LDHA (Lactate Dehydrogenase-A) gene. Oxamate, an isosteric form of pyruvate, blocks LDHA activity by competing with pyruvate. By blocking LDHA, it inhibits protumorigenic cascades and also induces ROS (reactive oxygen species)-induced mitochondrial apoptosis of cancer cells. In preclinical studies, oxamate blocked the growth of invasive pituitary adenomas, medulloblastomas and glioblastomas. Oxamate also increases temozolomide and radiotherapy sensitivity of glioblastomas. Oxamate is highly polar, which may preclude its clinical utilization due to low penetrance through cell membranes. However, this obstacle could be overcome with nanoliposomes. Moreover, different oxamate analogs were developed which inhibit LDHC4, an enzyme also involved in cancer progression and germ cell physiology. Lastly, phenformin, an antidiabetic agent, exerts anticancer effects via complex I inhibition in the mitochondria and leading the overproduction of ROS. Oxamate combination with phenformin reduces the lactic acidosis-causing side effect of phenformin while inducing synergistic anticancer efficacy. In sum, oxamate as a single agent and more efficiently with phenformin has high potential to slow the progression of aggressive cancers with special emphasis to brain tumors.
Topics: Animals; Brain Neoplasms; Cell Line, Tumor; Glycolysis; Humans; L-Lactate Dehydrogenase; Mitochondria; Neoplasms; Oxamic Acid; Phenformin; Radiation Tolerance; Reactive Oxygen Species; Temozolomide
PubMed: 35124385
DOI: 10.1016/j.biopha.2022.112686 -
Redox Biology Jul 2019Drug resistance invariably limits the response of oncogene-addicted cancer cells to targeted therapy. The upregulation of signal transducer and activator of... (Review)
Review
Drug resistance invariably limits the response of oncogene-addicted cancer cells to targeted therapy. The upregulation of signal transducer and activator of transcription 3 (STAT3) has been implicated as a mechanism of drug resistance in a range of oncogene-addicted cancers. However, the development of inhibitors against STAT3 has been fraught with challenges such as poor delivery or lack of specificity. Clinical experience with small molecule STAT3 inhibitors has seen efficacy signals, but this success has been tempered by drug limiting toxicities from off-target adverse events. It has emerged in recent years that, contrary to the Warburg theory, certain tumor types undergo metabolic reprogramming towards oxidative phosphorylation (OXPHOS) to satisfy their energy production. In particular, certain drug-resistant oncogene-addicted tumors have been found to rely on OXPHOS as a mechanism of survival. Multiple cellular signaling pathways converge on STAT3, hence the localization of STAT3 to the mitochondria may provide the link between oncogene-induced signaling pathways and cancer cell metabolism. In this article, we review the role of STAT3 and OXPHOS as targets of novel therapeutic strategies aimed at restoring drug sensitivity in treatment-resistant oncogene-addicted tumor types. Apart from drugs which have been re-purposed as OXPHOS inhibitors for-anti-cancer therapy (e.g., metformin and phenformin), several novel compounds in the drug-development pipeline have demonstrated promising pre-clinical and clinical activity. However, the clinical development of OXPHOS inhibitors remains in its infancy. The further identification of compounds with acceptable toxicity profiles, alongside the discovery of robust companion biomarkers of OXPHOS inhibition, would represent tangible early steps in transforming the therapeutic landscape of cancer cell metabolism.
Topics: Animals; Drug Resistance, Neoplasm; Humans; Mitochondria; Neoplasms; Oncogenes; Oxidative Phosphorylation; STAT3 Transcription Factor
PubMed: 30594485
DOI: 10.1016/j.redox.2018.101073 -
Seminars in Nephrology May 2023The good old days were not good, at least in terms of treating patients with type 2 diabetes. In the 1960s, the development of a radioimmunoassay for insulin permitted... (Review)
Review
The good old days were not good, at least in terms of treating patients with type 2 diabetes. In the 1960s, the development of a radioimmunoassay for insulin permitted determination of the distinguishing features of type 1 and type 2 diabetes. The latter was treated with sulfonylureas and then phenformin, although the mechanisms of action at the time were unknown. The University Group Diabetes Program was a randomized controlled trial experienced by my medical generation, and the results were dramatic, both medically and legally. Next came the thiazolidinediones. All compounds were associated with weight gain and any end point benefits were uncertain. Nevertheless, basic science explained how glucose is sensed and even found a home for sulfonylureas in some patients. Next came the boom in renin-angiotensin-aldosterone system blockade, sacred ground for many, albeit the benefits were less than astounding. Other wonder drugs came and went. Over the decades, great strides were made in defining the pathology of diabetic renal disease, which is appropriate because the condition has become a primary cause of end-stage renal failure. Nonetheless, recent advances have turned around a depressing situation and are reasons for optimism. We now have compounds that actually could help patients with type 2 diabetes. One hundred years after insulin's introduction, it is high time.
Topics: Humans; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Renin-Angiotensin System; Kidney Failure, Chronic; Insulins; Randomized Controlled Trials as Topic
PubMed: 37862743
DOI: 10.1016/j.semnephrol.2023.151426 -
International Journal of Oral Science May 2024The efficient clinical treatment of oral squamous cell carcinoma (OSCC) is still a challenge that demands the development of effective new drugs. Phenformin has been...
The efficient clinical treatment of oral squamous cell carcinoma (OSCC) is still a challenge that demands the development of effective new drugs. Phenformin has been shown to produce more potent anti-tumor activities than metformin on different tumors, however, not much is known about the influence of phenformin on OSCC cells. We found that phenformin suppresses OSCC cell proliferation, and promotes OSCC cell autophagy and apoptosis to significantly inhibit OSCC cell growth both in vivo and in vitro. RNA-seq analysis revealed that autophagy pathways were the main targets of phenformin and identified two new targets DDIT4 (DNA damage inducible transcript 4) and NIBAN1 (niban apoptosis regulator 1). We found that phenformin significantly induces the expression of both DDIT4 and NIBAN1 to promote OSCC autophagy. Further, the enhanced expression of DDIT4 and NIBAN1 elicited by phenformin was not blocked by the knockdown of AMPK but was suppressed by the knockdown of transcription factor ATF4 (activation transcription factor 4), which was induced by phenformin treatment in OSCC cells. Mechanistically, these results revealed that phenformin triggers endoplasmic reticulum (ER) stress to activate PERK (protein kinase R-like ER kinase), which phosphorylates the transitional initial factor eIF2, and the increased phosphorylation of eIF2 leads to the increased translation of ATF4. In summary, we discovered that phenformin induces its new targets DDIT4 and especially NIBAN1 to promote autophagic and apoptotic cell death to suppress OSCC cell growth. Our study supports the potential clinical utility of phenformin for OSCC treatment in the future.
Topics: Phenformin; Endoplasmic Reticulum Stress; Humans; Mouth Neoplasms; Autophagy; Carcinoma, Squamous Cell; Cell Proliferation; Cell Line, Tumor; Transcription Factors; Mice; Apoptosis Regulatory Proteins; Apoptosis; AMP-Activated Protein Kinases; Animals; Blotting, Western
PubMed: 38719825
DOI: 10.1038/s41368-024-00297-w -
Molecules (Basel, Switzerland) Oct 2021The results presented in this paper confirm the beneficial role of an easy-to-use and low-cost thin-layer chromatography (TLC) technique for describing the retention... (Comparative Study)
Comparative Study
The results presented in this paper confirm the beneficial role of an easy-to-use and low-cost thin-layer chromatography (TLC) technique for describing the retention behavior and the experimental lipophilicity parameter of two biguanide derivatives, metformin and phenformin, in both normal-phase (NP) and reversed-phase (RP) TLC systems. The retention parameters (R, R) obtained under different chromatographic conditions, i.e., various stationary and mobile phases in the NP-TLC and RP-TLC systems, were used to determine the lipophilicity parameter (R) of metformin and phenformin. This study confirms the poor lipophilicity of both metformin and phenformin. It can be stated that the optimization of chromatographic conditions, i.e., the kind of stationary phase and the composition of mobile phase, was needed to obtain the reliable value of the chromatographic lipophilicity parameter (R) in this study. The fewer differences in the R values of both biguanide derivatives were ensured by the RP-TLC system composed of RP2, RP18, and RP18W plates and the mixture composed of methanol, propan-1-ol, and acetonitrile as an organic modifier compared to the NP-TLC analysis. The new calculation procedures for logP of drugs based on topological indices χ, χ, χ, M, and M may be a certain alternative to other algorithms as well as the TLC procedure performed under optimized chromatographic conditions. The knowledge of different lipophilicity parameters of the studied biguanides can be useful in the future design of novel and more therapeutically effective metformin and phenformin formulations for antidiabetic and possible anticancer treatment. Moreover, the topological indices presented in this work may be further used in the QSAR study of the examined biguanides.
Topics: Chromatography, Reverse-Phase; Chromatography, Thin Layer; Hydrophobic and Hydrophilic Interactions; Metformin; Molecular Structure; Phenformin
PubMed: 34771022
DOI: 10.3390/molecules26216613 -
American Journal of Translational... 2021Sorafenib is a first-line drug to treat advanced hepatocellular carcinoma (HCC), which can prolong the median overall survival of patients by approximately 3 months....
Sorafenib is a first-line drug to treat advanced hepatocellular carcinoma (HCC), which can prolong the median overall survival of patients by approximately 3 months. Phenformin is a biguanide derivative that has been shown to exhibit antitumor activity superior to that of metformin. We herein explored the ability of phenformin to enhance the anti-cancer activity of sorafenib against HCC and the mechanisms underlying such synergy. The Hep-G2 and SMMC-7721 HCC cell lines were treated with sorafenib and/or phenformin, after which the proliferation of these cells was evaluated via MTT and colony formation assays, while invasion and apoptotic cell death were evaluated via Transwell and flow cytometry assays, respectively. In addition, protein levels were assessed by Western blotting, drug synergy was assessed with the CompuSyn software, and xenograft models were established by implanting Hep-G2 cells into nude mice and then assessing drug antitumor efficacy. Sorafenib and phenformin exhibited a synergistic ability to suppress HCC cell proliferation, migration, and survival. Phenformin further bolstered the ability of sorafenib to inhibit the CRAF/ERK and PI3K/AKT/mTOR pathways. Strikingly, the combination of these two drugs achieved better efficacy in a murine model system, without causing significant weight loss or hepatorenal toxicity. Sorafenib and phenformin can synergistically suppress CRAF/ERK and PI3K/AKT/mTOR pathway activation in HCC cells, and may thus represent a promising approach to treating this deadly cancer.
PubMed: 34377232
DOI: No ID Found -
Cells Aug 2022The treatment of many skin inflammation diseases, such as psoriasis and atopic dermatitis, is still a challenge and inflammation plays important roles in multiple stages...
The treatment of many skin inflammation diseases, such as psoriasis and atopic dermatitis, is still a challenge and inflammation plays important roles in multiple stages of skin tumor development, including initiation, promotion and metastasis. Phenformin, a biguanide drug, has been shown to play a more efficient anti-tumor function than another well-known biguanide drug, metformin, which has been reported to control the expression of pro-inflammatory cytokines; however, little is known about the effects of phenformin on skin inflammation. This study used a mouse acute inflammation model, ex vivo skin organ cultures and in vitro human primary keratinocyte cultures to demonstrate that phenformin can suppress acute skin inflammatory responses induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in vivo and significantly suppresses the pro-inflammatory cytokines IL-1β, IL-6 and IL-8 in human primary keratinocytes in vitro. The suppression of pro-inflammatory cytokine expression by phenformin was not directly through regulation of the MAPK or NF-κB pathways, but by controlling the expression of c-Myc in human keratinocytes. We demonstrated that the overexpression of c-Myc can induce pro-inflammatory cytokine expression and counteract the suppressive effect of phenformin on cytokine expression in keratinocytes. In contrast, the down-regulation of c-Myc produces effects similar to phenformin, both in cytokine expression by keratinocytes in vitro and in skin inflammation in vivo. Finally, we showed that phenformin, as an AMPK activator, down-regulates the expression of c-Myc through regulation of the AMPK/mTOR pathways. In summary, phenformin inhibits the expression of pro-inflammatory cytokines in keratinocytes through the down-regulation of c-Myc expression to play an anti-inflammation function in the skin.
Topics: AMP-Activated Protein Kinases; Animals; Cytokines; Dermatitis, Atopic; Humans; Inflammation; Keratinocytes; Mice; Phenformin; Proto-Oncogene Proteins c-myc
PubMed: 35954273
DOI: 10.3390/cells11152429