Anti-cancer synergy of dichloroacetate and EGFR tyrosine kinase inhibitors in NSCLC cell lines

Dichloroacetate for Cancer Treatment: Some Facts and Many Doubts

Rarely has a chemical elicited as much controversy as dichloroacetate (DCA). DCA was initially considered a dangerous toxic industrial waste product, then a potential treatment for lactic acidosis. However, the main controversies started in 2008 when DCA was found to have anti-cancer effects on experimental animals. These publications showed contradictory results in vivo and in vitro such that a thorough consideration of this compound's in cancer is merited. Despite 50 years of experimentation, DCA's future in therapeutics is uncertain. Without adequate clinical trials and health authorities' approval, DCA has been introduced in off-label cancer treatments in alternative medicine clinics in Canada, Germany, and other European countries. The lack of well-planned clinical trials and its use by people without medical training has discouraged consideration by the scientific community. There are few thorough clinical studies of DCA, and many publications are individual case reports. Case reports of DCA's benefits against cancer have been increasing recently. Furthermore, it has been shown that DCA synergizes with conventional treatments and other repurposable drugs. Beyond the classic DCA target, pyruvate dehydrogenase kinase, new target molecules have also been recently discovered. These findings have renewed interest in DCA. This paper explores whether existing evidence justifies further research on DCA for cancer treatment and it explores the role DCA may play in it.

Targeting pyruvate dehydrogenase kinase 1 overcomes EGFR C797S mutation-driven osimertinib resistance in non-small cell lung cancer

Osimertinib, a selective third-generation epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), effectively targets the EGFR T790M mutant in non-small cell lung cancer (NSCLC). However, the newly identified EGFR C797S mutation confers resistance to osimertinib. In this study, we explored the role of pyruvate dehydrogenase kinase 1 (PDK1) in osimertinib resistance. Patients exhibiting osimertinib resistance initially displayed elevated PDK1 expression. Osimertinib-resistant cell lines with the EGFR C797S mutation were established using A549, NCI-H292, PC-9, and NCI-H1975 NSCLC cells for both in vitro and in vivo investigations. These EGFR C797S mutant cells exhibited heightened phosphorylation of EGFR, leading to the activation of downstream oncogenic pathways. The EGFR C797S mutation appeared to increase PDK1-driven glycolysis through the EGFR/AKT/HIF-1α axis. Combining osimertinib with the PDK1 inhibitor leelamine helped successfully overcome osimertinib resistance in allograft models. CRISPR-mediated PDK1 knockout effectively inhibited tumor formation in xenograft models. Our study established a clear link between the EGFR C797S mutation and elevated PDK1 expression, opening new avenues for the discovery of targeted therapies and improving our understanding of the roles of EGFR mutations in cancer progression.

Recent advances in pyruvate dehydrogenase kinase inhibitors: Structures, inhibitory mechanisms and biological activities

Metabolism is reprogrammed in a variety of cancer cells to ensure their rapid proliferation. Cancer cells prefer to utilize glycolysis to produce energy as well as to provide large amounts of precursors for their division. In this process, cancer cells inhibit the activity of pyruvate dehydrogenase complex (PDC) by upregulating the expression of pyruvate dehydrogenase kinases (PDKs). Inhibiting the activity of PDKs in cancer cells can effectively block this metabolic transition in cancer cells, while also activating mitochondrial oxidative metabolism and promoting apoptosis of cancer cells. To this day, the study of PDKs inhibitors has become one of the research hotspots in the field of medicinal chemistry. Novel structures targeting PDKs are constantly being discovered, and some inhibitors have entered the clinical research stage. Here, we reviewed the research progress of PDKs inhibitors in recent years and classified them according to the PDKs binding sites they acted on, aiming to summarize the structural characteristics of inhibitors acting on different binding sites and explore their clinical application value. Finally, the shortcomings of some PDKs inhibitors and the further development direction of PDKs inhibitors are discussed.

Natural Product-Based Glycolysis Inhibitors as a Therapeutic Strategy for Epidermal Growth Factor Receptor-Tyrosine Kinase Inhibitor-Resistant Non-Small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is a leading cause of cancer-related deaths worldwide. Targeted therapy against the epidermal growth factor receptor (EGFR) is a promising treatment approach for NSCLC. However, resistance to EGFR tyrosine kinase inhibitors (TKIs) remains a major challenge in its clinical management. EGFR mutation elevates the expression of hypoxia-inducible factor-1 alpha to upregulate the production of glycolytic enzymes, increasing glycolysis and tumor resistance. The inhibition of glycolysis can be a potential strategy for overcoming EGFR-TKI resistance and enhancing the effectiveness of EGFR-TKIs. In this review, we specifically explored the effectiveness of pyruvate dehydrogenase kinase inhibitors and lactate dehydrogenase A inhibitors in combating EGFR-TKI resistance. The aim was to summarize the effects of these natural products in preclinical NSCLC models to provide a comprehensive understanding of the potential therapeutic effects. The study findings suggest that natural products can be promising inhibitors of glycolytic enzymes for the treatment of EGFR-TKI-resistant NSCLC. Further investigations through preclinical and clinical studies are required to validate the efficacy of natural product-based glycolytic inhibitors as innovative therapeutic modalities for NSCLC.

Combined inhibition of pyruvate dehydrogenase kinase 1 and hexokinase 2 induces apoptsis in non-small cell lung cancer cell models

Many cancer cells exhibit enhanced glycolysis, which is seen as one of the hallmark metabolic alterations, known as Warburg effect. Substantial evidence shows that upregulated glycolytic enzymes are often linked to malignant growth. Using glycolytic inhibitors for anticancer treatment has become appealing in recent years for therapeutic intervention in cancers with highly glycolytic characteristic, including non-small cell lung cancer (NSCLC). In this work, we studied the anticancer effects and the underlying mechanisms of combination of benzerazide hydrocholoride (Benz), a hexokinase 2 (HK2) inhibitor and 64, a pyruvate dehydrogenase kinase 1 (PDK1) inhibitor, in several NSCLC cell lines. We found that combination of Benz and 64 exhibited strong synergistic anticancer effects in NCI-H1975, HCC827, NCI-H1299 and SK-LU-1 cell lines. With this combination treatment, we observed changes of certain mechanistic determinants associated with metabolic stress caused by glycolysis restriction, such as mitochondrial membrane potential depolarization, overproduction of reactive oxygen species [1], activation of AMPK and down-regulation of mTOR, which contributed to enhanced apoptosis. Moreover, Benz and 64 together significantly suppressed the tumor growth in HCC827 cell mouse xenograft model. Taken together, our study may suggest that combined inhibition of HK2 and PDK1 using Benz and 64 could be a viable anticancer strategy for NSCLC.

From signalling pathways to targeted therapies: unravelling glioblastoma's secrets and harnessing two decades of progress

Glioblastoma, a rare, and highly lethal form of brain cancer, poses significant challenges in terms of therapeutic resistance, and poor survival rates for both adult and paediatric patients alike. Despite advancements in brain cancer research driven by a technological revolution, translating our understanding of glioblastoma pathogenesis into improved clinical outcomes remains a critical unmet need. This review emphasises the intricate role of receptor tyrosine kinase signalling pathways, epigenetic mechanisms, and metabolic functions in glioblastoma tumourigenesis and therapeutic resistance. We also discuss the extensive efforts over the past two decades that have explored targeted therapies against these pathways. Emerging therapeutic approaches, such as antibody-toxin conjugates or CAR T cell therapies, offer potential by specifically targeting proteins on the glioblastoma cell surface. Combination strategies incorporating protein-targeted therapy and immune-based therapies demonstrate great promise for future clinical research. Moreover, gaining insights into the role of cell-of-origin in glioblastoma treatment response holds the potential to advance precision medicine approaches. Addressing these challenges is crucial to improving outcomes for glioblastoma patients and moving towards more effective precision therapies.

Dichloroacetophenone biphenylsulfone ethers as anticancer pyruvate dehydrogenase kinase inhibitors in non-small cell lung cancer models

Pyruvate dehydrogenase kinase 1 (PDK1) is an important metabolic enzyme which is often overexpressed in many types of cancers, including non-small-cell lung cancers (NSCLC). Targeting PDK1 appears to be an attractive anticancer strategy. Based on a previously reported moderate potent anticancer PDK1 inhibitor, 64, we developed three dichloroacetophenone biphenylsulfone ethers, 30, 31 and 32, which showed strong PDK1 inhibitions of 74%, 83% and 72% at 10 μM, respectively. Then we investigated the anticancer effects of 31 in two NSCLC cell lines, namely, NCI-H1299 and NCI-H1975. It was found that 31 exhibited sub-micromolar cancer cell IC50_s, suppressed colony formation, induced mitochondrial membrane potential depolarization, triggered apoptosis, altered cellular glucose metabolism, with concomitant reductions in extracellular lactate levels and enhanced the generation of reactive oxygen species in NSCLC cells. Moreover, 31 significantly suppressed the tumor growth in an NCI-H1975 mouse xenograft model, outperforming the anticancer effects of 64. Taken together our results suggested that inhibition of PDK1 via dichloroacetophenone biphenylsulfone ethers may provide a novel direction leading to an alternative treatment option in NSCLC therapy.

Targeting glucose metabolism to develop anticancer treatments and therapeutic patents

INTRODUCTION

One of the most distinctive hallmarks of cancer cells is increased glucose consumption for aerobic glycolysis which is named the Warburg effect. In recent decades, extensive research has been carried out to exploit this famous phenomenon, trying to detect promising targetable vulnerabilities in altered metabolism to fight cancer. Targeting aberrant glucose metabolism can perturb cancer malignant proliferation and even induce programmed cell death.

AREAS COVERED

This review covered the recent patents which focused on targeting key glycolytic enzymes including hexokinase, pyruvate dehydrogenase kinases and lactate dehydrogenase for cancer treatment.

EXPERT OPINION

Compared with the conventional cancer treatment, specifically targeting the well-known Achilles heel Warburg effect has attracted considerable attention. Although there is still no single glycolytic agent for clinical cancer treatment, the combination of glycolytic inhibitor with conventional anticancer drug or the combined use of multiple glycolytic inhibitors are being investigated extensively in recent years, which could emerge as attractive anticancer strategies.

Impact of Sodium Dichloroacetate Alone and in Combination Therapies on Lung Tumor Growth and Metastasis

Metabolic reprogramming has been recognized as an essential emerging cancer hallmark. Dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), has been reported to have anti-cancer effects by reversing tumor-associated glycolysis. This study was performed to explore the anti-cancer potential of DCA in lung cancer alone and in combination with chemo- and targeted therapies using two non-small cell lung cancer (NSCLC) cell lines, namely, A549 and LNM35. DCA markedly caused a concentration- and time-dependent decrease in the viability and colony growth of A549 and LNM35 cells in vitro. DCA also reduced the growth of tumor xenografts in both a chick embryo chorioallantoic membrane and nude mice models in vivo. Furthermore, DCA decreased the angiogenic capacity of human umbilical vein endothelial cells in vitro. On the other hand, DCA did not inhibit the in vitro cellular migration and invasion and the in vivo incidence and growth of axillary lymph nodes metastases in nude mice. Treatment with DCA did not show any toxicity in chick embryos and nude mice. Finally, we demonstrated that DCA significantly enhanced the anti-cancer effect of cisplatin in LNM35. In addition, the combination of DCA with gefitinib or erlotinib leads to additive effects on the inhibition of LNM35 colony growth after seven days of treatment and to synergistic effects on the inhibition of A549 colony growth after 14 days of treatment. Collectively, this study demonstrates that DCA is a safe and promising therapeutic agent for lung cancer.

Assessment of elementary derivatives of 1,5-benzodiazepine as anticancer agents with synergy potential

Herein, we designed and synthesized 1,5-benzodiazepines as a lead molecule for anticancer activity and as potent synergistic activity with drug Methotrexate. Working under the framework of green chemistry principles, series of 1,5-benzodiazepine derivatives (3a-3a¹) were synthesized using biocatalyst i.e. thiamine hydrochloride under solvent free neat heat conditions. These compounds were screened for in vitro anti cancer activity against couple of cancer cell lines (HeLa and HEPG2) and normal human cell line HEK-293 via MTT assay. The IC₅₀ values for the compounds were in the range 0.067 to 0.35 µM, better than Paclitaxel and compatible with the drug Methotrexate. Compound 3x was found to be influential against both the cell lines with IC₅₀ values of 0.067 ± 0.002 µM against HeLa and 0.087 ± 0.003 µM against HEPG2 cell line, having activity as compatible to the standard drug Methotrexate. Bioinformatic analysis showed that these compounds are good tyrosine kinase inhibitors which was then proved using enzyme inhibition assay. The studies of apoptosis revealed late apoptotic mode of cell death for the compounds against HEPG2 cancer cell line using flow cytometry method. Synergistic studies of compound 3x and drug Methotrexate showed that the combination was highly active against cancer HeLa and HEPG2 cell line with IC50 value 0.046 ± 0.002 µM and 0.057 ± 0.002 µM respectively, which was well supported by apoptosis pathway. Further the compounds proved its scope as DNA intercalating agents, as its molecular docking and DNA binding studies revealed that the compounds would fit well into the DNA strands.

Non-Canonical Role of PDK1 as a Negative Regulator of Apoptosis through Macromolecular Complexes Assembly at the ER-Mitochondria Interface in Oncogene-Driven NSCLC

Simple Summary

Co-targeting of glucose metabolism and oncogene drivers in patients with non-small cell lung cancer (NSCLC) has been proposed as a potentially effective therapeutic strategy. Here, we demonstrate that downregulation of pyruvate dehydrogenase kinase 1 (PDK1), an enzyme of glycolytic cascade, enhances maximal respiration of cancer cells by upregulating mitochondrial complexes of oxidative phosphorylation (OXPHOS) and improves tumor response to tyrosine kinase inhibitors by promoting apoptosis. Furthermore, we provided consistent evidence that PDK1 drives the formation of macromolecular complexes at the ER–mitochondria interface involving PKM2, Bcl-2 and Bcl-xL and serves as an indirect anchorage of anti-apoptotic proteins to the mitochondrial membrane. Our findings taken together highlighted a non-canonical role of PDK1 as a negative regulator of apoptosis, thus coupling the glycolytic phenotype to drug resistance. The major translational relevance of this study is to provide a rational basis for combined therapeutic strategies targeting PDK1 and oncogene drivers in NSCLC patients.

Abstract

Here, we tested whether co-targeting of glucose metabolism and oncogene drivers may enhance tumor response to tyrosine kinase inhibitors (TKIs) in NSCLC. To this end, pyruvate dehydrogenase kinase 1 (PDK1) was stably downregulated in oncogene-driven NSCLC cell lines exposed or not to TKIs. H1993 and H1975 cells were stably transfected with scrambled (shCTRL) or PDK1-targeted (shPDK1) shRNA and then treated with MET inhibitor crizotinib (1 µM), double mutant EGFR^L858R/T790M inhibitor WZ4002 (1 µM) or vehicle for 48 h. The effects of PDK1 knockdown on glucose metabolism and apoptosis were evaluated in untreated and TKI-treated cells. PDK1 knockdown alone did not cause significant changes in glycolytic cascade, ATP production and glucose consumption, but it enhanced maximal respiration in shPDK1 cells when compared to controls. When combined with TKI treatment, PDK1 downregulation caused a strong enhancement of OXPHOS and a marked reduction in key glycolytic enzymes. Furthermore, increased levels of apoptotic markers were found in shPDK1 cells as compared to shCTRL cells after treatment with TKIs. Co-immunoprecipitation studies showed that PDK1 interacts with PKM2, Bcl-2 and Bcl-xL, forming macromolecular complexes at the ER–mitochondria interface. Our findings showed that downregulation of PDK1 is able to potentiate the effects of TKIs through the disruption of macromolecular complexes involving PKM2, Bcl-2 and Bcl-xL.

Hypoxia in Lung Cancer Management: A Translational Approach

Simple Summary

Hypoxia is a common feature of lung cancers. Nonetheless, no guidelines have been established to integrate hypoxia-associated biomarkers in patient management. Here, we discuss the current knowledge and provide translational novel considerations regarding its clinical detection and targeting to improve the outcome of patients with non-small-cell lung carcinoma of all stages.

Abstract

Lung cancer represents the first cause of death by cancer worldwide and remains a challenging public health issue. Hypoxia, as a relevant biomarker, has raised high expectations for clinical practice. Here, we review clinical and pathological features related to hypoxic lung tumours. Secondly, we expound on the main current techniques to evaluate hypoxic status in NSCLC focusing on positive emission tomography. We present existing alternative experimental approaches such as the examination of circulating markers and highlight the interest in non-invasive markers. Finally, we evaluate the relevance of investigating hypoxia in lung cancer management as a companion biomarker at various lung cancer stages. Hypoxia could support the identification of patients with higher risks of NSCLC. Moreover, the presence of hypoxia in treated tumours could help clinicians predict a worse prognosis for patients with resected NSCLC and may help identify patients who would benefit potentially from adjuvant therapies. Globally, the large quantity of translational data incites experimental and clinical studies to implement the characterisation of hypoxia in clinical NSCLC management.

Dichloroacetate and PX-478 exhibit strong synergistic effects in a various number of cancer cell lines

Background

One key approach for anticancer therapy is drug combination. Drug combinations can help reduce doses and thereby decrease side effects. Furthermore, the likelihood of drug resistance is reduced. Distinct alterations in tumor metabolism have been described in past decades, but metabolism has yet to be targeted in clinical cancer therapy. Recently, we found evidence for synergism between dichloroacetate (DCA), a pyruvate dehydrogenase kinase inhibitor, and the HIF-1α inhibitor PX-478. In this study, we aimed to analyse this synergism in cell lines of different cancer types and to identify the underlying biochemical mechanisms.

Methods

The dose-dependent antiproliferative effects of the single drugs and their combination were assessed using SRB assays. FACS, Western blot and HPLC analyses were performed to investigate changes in reactive oxygen species levels, apoptosis and the cell cycle. Additionally, real-time metabolic analyses (Seahorse) were performed with DCA-treated MCF-7 cells.

Results

The combination of DCA and PX-478 produced synergistic effects in all eight cancer cell lines tested, including colorectal, lung, breast, cervical, liver and brain cancer. Reactive oxygen species generation and apoptosis played important roles in this synergism. Furthermore, cell proliferation was inhibited by the combination treatment.

Conclusions

Here, we found that these tumor metabolism-targeting compounds exhibited a potent synergism across all tested cancer cell lines. Thus, we highly recommend the combination of these two compounds for progression to in vivo translational and clinical trials.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08186-9.

Altered glycolysis results in drug-resistant in clinical tumor therapy

Cancer cells undergo metabolic reprogramming, including increased glucose metabolism, fatty acid synthesis and glutamine metabolic rates. These enhancements to three major metabolic pathways are closely associated with glycolysis, which is considered the central component of cancer cell metabolism. Increasing evidence suggests that dysfunctional glycolysis is commonly associated with drug resistance in cancer treatment, and aberrant glycolysis plays a significant role in drug-resistant cancer cells. Studies on the development of drugs targeting these abnormalities have led to improvements in the efficacy of tumor treatment. The present review discusses the changes in glycolysis targets that cause drug resistance in cancer cells, including hexokinase, pyruvate kinase, pyruvate dehydrogenase complex, glucose transporters, and lactate, as well the underlying molecular mechanisms and corresponding novel therapeutic strategies. In addition, the association between increased oxidative phosphorylation and drug resistance is introduced, which is caused by metabolic plasticity. Given that aberrant glycolysis has been identified as a common metabolic feature of drug-resistant tumor cells, targeting glycolysis may be a novel strategy to develop new drugs to benefit patients with drug-resistance.

Expression and prognostic significance of pyruvate dehydrogenase kinase 1 in bladder urothelial carcinoma

Muscular infiltrating bladder urothelial carcinoma (MIBC) is a highly malignant disease with a poor prognosis. Radical cystectomy is the standard treatment. However, due to surgery and postoperative complications, the quality of life of patients is seriously affected. Therefore, it is increasingly important to find prognostic markers and new therapeutic targets for MIBC. Here, we investigated the expression of PDK1, a key regulator of glucose metabolism, in bladder urothelial carcinoma (BLCA) and its effect on prognosis. The expression pattern of PDK1 was examined by bioinformatics analysis and immunohistochemistry. A total of 101 cases of BLCA were selected for tissue microarrays (TMAs) that contained both tumour and paired normal tissues. We demonstrated that PDK1 expression was correlated with tumour grade and Ki67expression in our TMA cohort (all p values < 0.05). Kaplan-Meier survival analysis showed that patients with MIBC with high PDK1 expression had a worse prognosis than patients with low PDK1 expression (p = 0.016). Multifactor risk analysis showed that increased PDK1 expression was an independent prognostic factor affecting the overall survival of MIBC patients. GSEA showed that the mTOR pathway, HIF pathway, glycolysis, PI3K/AKT/mTOR signalling, etc. were differentially enriched in the PDK1 high expression phenotype. Hence, PDK1 may be a prognostic and therapeutic target for MIBC.

Vitamin K2 promotes PI3K/AKT/HIF-1α-mediated glycolysis that leads to AMPK-dependent autophagic cell death in bladder cancer cells

Vitamin K2 has been shown to exert remarkable anticancer activity. However, the detailed mechanism remains unclear. Here, our study was the first to show that Vitamin K2 significantly promoted the glycolysis in bladder cancer cells by upregulating glucose consumption and lactate production, whereas inhibited TCA cycle by reducing the amounts of Acetyl-CoA. Moreover, suppression of PI3K/AKT and HIF-1α attenuated Vitamin K2-increased glucose consumption and lactate generation, indicating that Vitamin K2 promotes PI3K/AKT and HIF-1α-mediated glycolysis in bladder cancer cells. Importantly, upon glucose limitation, Vitamin K2-upregulated glycolysis markedly induced metabolic stress, along with AMPK activation and mTORC1 pathway suppression, which subsequently triggered AMPK-dependent autophagic cell death. Intriguingly, glucose supplementation profoundly abrogated AMPK activation and rescued bladder cancer cells from Vitamin K2-triggered autophagic cell death. Furthermore, both inhibition of PI3K/AKT/HIF-1α and attenuation of glycolysis significantly blocked Vitamin K2-induced AMPK activation and subsequently prevented autophagic cell death. Collectively, these findings reveal that Vitamin K2 could induce metabolic stress and trigger AMPK-dependent autophagic cell death in bladder cancer cells by PI3K/AKT/HIF-1α-mediated glycolysis promotion.

Competitive glucose metabolism as a target to boost bladder cancer immunotherapy

Bladder cancer - the tenth most frequent cancer worldwide - has a heterogeneous natural history and clinical behaviour. The predominant histological subtype, urothelial bladder carcinoma, is characterized by high recurrence rates, progression and both primary and acquired resistance to platinum-based therapy, which impose a considerable economic burden on health-care systems and have substantial effects on the quality of life and the overall outcomes of patients with bladder cancer. The incidence of urothelial tumours is increasing owing to population growth and ageing, so novel therapeutic options are vital. Based on work by The Cancer Genome Atlas project, which has identified targetable vulnerabilities in bladder cancer, immune checkpoint inhibitors (ICIs) have arisen as an effective alternative for managing advanced disease. However, although ICIs have shown durable responses in a subset of patients with bladder cancer, the overall response rate is only ~15-25%, which increases the demand for biomarkers of response and therapeutic strategies that can overcome resistance to ICIs. In ICI non-responders, cancer cells use effective mechanisms to evade immune cell antitumour activity; the overlapping Warburg effect machinery of cancer and immune cells is a putative determinant of the immunosuppressive phenotype in bladder cancer. This energetic interplay between tumour and immune cells leads to metabolic competition in the tumour ecosystem, limiting nutrient availability and leading to microenvironmental acidosis, which hinders immune cell function. Thus, molecular hallmarks of cancer cell metabolism are potential therapeutic targets, not only to eliminate malignant cells but also to boost the efficacy of immunotherapy. In this sense, integrating the targeting of tumour metabolism into immunotherapy design seems a rational approach to improve the therapeutic efficacy of ICIs.

Novel Therapeutic Anti-ADAM17 Antibody A9(B8) Enhances EGFR-TKI-Mediated Anticancer Activity in NSCLC

Epidermal growth factor receptor (EGFR) mutations were found in 30%-40% of non-small cell lung cancer (NSCLC) patients, who often responded well to EGFR tyrosine kinase inhibitors (EGFR-TKIs) as exemplified by erlotinib and gefitinib in the past decades. However, EGFR mutation-led drug resistance usually occurred upon prolonged treatment with EGFR-TKI. Herein, we study the anticancer effects of EGFR-TKI in combination with a newly developed antibody, A9(B8), to target a disintegrin and metalloprotease (ADAM) 17 that was overexpressed in NSCLC patients. NSCLC cell lines with different EGFR mutations were used to evaluate the drug combination. We have found that the EGFR-TKI-A9(B8) combination exhibited enhanced anticancer effects in NCI-H1975 cells harboring L858R and T790M mutations, which were due to simultaneous suppression of extracellular signal-regulated kinases phosphorylation. Our results suggested that targeting ADAM17 could potentiate the anticancer effects of EGFR-TKI against NSCLC and overcome drug resistance due to EGFR mutations.

Metabolic Flexibility in Cancer: Targeting the Pyruvate Dehydrogenase Kinase:Pyruvate Dehydrogenase Axis

Cancer cells use alterations of normal metabolic processes to sustain proliferation indefinitely. Transcriptional and posttranscriptional control of the pyruvate dehydrogenase kinase (PDK) family is one way in which cancer cells alter normal pyruvate metabolism to fuel proliferation. PDKs can phosphorylate and inactivate the pyruvate dehydrogenase complex (PDHC), which blocks oxidative metabolism of pyruvate by the mitochondria. This process is thought to enhance cancer cell growth by promoting anabolic pathways. Inhibition of PDKs induces cell death through increased PDH activity and subsequent increases in ROS production. The use of PDK inhibitors has seen widespread success as a potential therapeutic in laboratory models of multiple cancers; however, gaps still exist in our understanding of the biology of PDK regulation and function, especially in the context of individual PDKs. Efforts are currently underway to generate PDK-specific inhibitors and delineate the roles of individual PDK isozymes in specific cancers. The goal of this review is to understand the regulation of the PDK isozyme family, their role in cancer proliferation, and how to target this pathway therapeutically to specifically and effectively reduce cancer growth.

Inhibiting two cellular mutant epidermal growth factor receptor tyrosine kinases by addressing computationally assessed crystal ligand pockets

Aim: Blocking receptor tyrosine kinases is a useful strategy for inhibiting the overexpression of EGFR. However, the quality of crystal pocket is an essential issue for virtually identifying new leads for surviving resistance cancer cells. Results: With the examinating crystal pocket quality by the self-docking root-mean-square deviation (RMSD) calculation, we used the two best kinase pockets of mutant EGFR kinases, T790M/L858R and G719S, for virtual screening. After sorting all the docking poses of the 57,177 library compounds by consensus scores, three evidently blocked cellular EGFR phosphorylation in the H1975 and SW48 cell lines. Conclusion: The computationally assessed qualities of crystal pockets of crystal EGFR kinases can help identify new cellular active and target-specific ligands rapidly and at low cost.

Inhibition of pyruvate dehydrogenase kinase 1 enhances the anti-cancer effect of EGFR tyrosine kinase inhibitors in non-small cell lung cancer

Although epidermal growth factor receptor (EGFR) inhibitors have been used to treat non-small cell lung cancer (NSCLC) for decades with great success in patients with EGFR mutations, acquired-resistance inevitably occurs after long-term exposure to the treatment of EGFR inhibitors. Glycolysis is a predominant process for most cancer cells to utilize glucose, which referred to as the Warburg Effect. Targeting critical enzymes, such as pyruvate dehydrogenase kinase 1 (PDK1) that inversely regulating the process of glycolysis could be a promising approach to work alone or in combination with other treatments for cancer therapy. The purpose of this study is to evaluate whether PDK1 inhibition could enhance the anti-cancer effects of EGFR-TKi. Herein, we utilized a recently reported PDK1 inhibitor 2,2-Dichloro-1-(4-isopropoxy-3-nitrophenyl)ethan-1-one (Cpd64), which was more potent and selective than dichloroacetate (DCA) and/or dichloroacetophenone (DAP), to study the mechanism of PDK1 inhibition in TKi-mediated anti-cancer activity. We found that the introduction of Cpd64 in EGFR-TKi therapy enhanced the anti-proliferative effects in EGFR-mutant NSCLC cells under hypoxia. In particular, Cpd64 was shown to increase the activity of pyruvate dehydrogenase (PDH) and improved XPHOS, such as elevated mitochondrial respiration, and increased ATP generation, which effectively modulated the upregulation of PDK1 by EGFR-TKi treatment. We have observed that Cpd64 effectively enhanced the tumor growth inhibition induced by erlotinib in a NCI-H1975 xenograft mouse model. Collectively, our results suggested that combined use of selective PDK inhibitor and EGFR-TKi could be a potential strategy for NSCLC therapy.

Combination Strategies Using EGFR-TKi in NSCLC Therapy: Learning from the Gap between Pre-Clinical Results and Clinical Outcomes

Although epidermal growth factor receptor (EGFR) inhibitors have been used to treat non-small cell lung cancer (NSCLC) for decades with great success in patients with EGFR mutations, acquired resistance inevitably occurs after long-term exposure. More recently, combination therapy has emerged as a promising strategy to overcome this issue. Several experiments have been carried out to evaluate the synergism of combination therapy both in vitro and in vivo. Additionally, many clinical studies have been carried out to investigate the feasibility of treatment with EGFR-tyrosine kinase inhibitors (TKi) combined with other NSCLC treatments, including radiotherapy, cytotoxic chemotherapies, targeted therapies, and emerging immunotherapies. However, a significant gap still exists when applying pre-clinical results to clinical scenarios, which hinders the development and use of these strategies. This article is a literature review analysing the rationalities and controversies in the transition from pre-clinical investigation to clinical practice associated with various combination strategies. It also highlights clues and challenges regarding future combination therapeutic options in NSCLC treatment.

Inhibition of HIF1α and PDK Induces Cell Death of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common and aggressive form of brain tumors. GBMs, like other tumors, rely relatively less on mitochondrial oxidative phosphorylation (OXPHOS) and utilize more aerobic glycolysis, and this metabolic shift becomes augmented under hypoxia. In the present study, we investigated the physiological significance of altered glucose metabolism and hypoxic adaptation in the GBM cell line U251 and two newly established primary GBMs (GBM28 and GBM37). We found that these three GBMs exhibited differential growth rates under hypoxia compared to those under normoxia. Under normoxia, the basal expressions of HIF1α and the glycolysis-associated genes, PDK1, PDK3, and GLUT1, were relatively low in U251 and GBM28, while their basal expressions were high in GBM37. Under hypoxia, the expressions of these genes were enhanced further in all three GBMs. Treatment with dichloroacetate (DCA), an inhibitor of pyruvate dehydrogenase kinase (PDK), induced cell death in GBM28 and GBM37 maintained under normoxia, whereas DCA effects disappeared under hypoxia, suggesting that hypoxic adaptation dominated DCA effects in these GBMs. In contrast, the inhibition of HIF1α with chrysin suppressed the expression of PDK1, PDK3, and GLUT1 and markedly promoted cell death of all GBMs under both normoxia and hypoxia. Interestingly, however, GBMs treated with chrysin under hypoxia still sustained higher viability than those under normoxia, and chrysin and DCA co-treatment was unable to eliminate this hypoxia-dependent resistance. Together, these results suggest that hypoxic adaptation is critical for maintaining viability of GBMs, and targeting hypoxic adaptation can be an important treatment option for GBMs.

Combined Inhibitions of Glycolysis and AKT/autophagy Can Overcome Resistance to EGFR-targeted Therapy of Lung Cancer

Efficacy of EGFR-targeted tyrosine kinase inhibitors (TKIs), such as erlotinib, to treat human non-small cell lung cancers (NSCLCs) with activating mutations in EGFR is not persistent due to drug resistance. Reprogramming in energy (especially glucose) metabolism plays an important role in development and progression of acquired resistance in cancer cells. We hypothesize that glucose metabolism in EGFR-TKI sensitive HCC827 cells and erlotinib-resistant sub-line of HCC827 (which we name it as erlotinib-resistant 6, ER6 cells in this study) is different and targeting glucose metabolism might be a treatment strategy for erlotinib-resistant NSCLCs. In this study, we found increased glucose uptakes, significant increase in glycolysis rate and overexpression of glucose transporter 1 in ER6 cells compared to its parental cells HCC827. We also found AKT and autophagy of ER6 cells were more activated than HCC827 cells after glucose starvation. Combining glucose deprivation and AKT or autophagy inhibitor could synergize and overcome the acquired resistance against EGFR-targeted therapy for NSCLCs. Our data suggest that the combinations of inhibitors of AKT or autophagy together with glucose deprivation could be novel treatment strategies for NSCLC with acquired resistance to targeted therapy.

Pharmacological synergism of 2,2-dichloroacetophenone and EGFR-TKi to overcome TKi-induced resistance in NSCLC cells

Combination treatment has been used as one of the therapeutic approaches for patients suffering from lung cancer, either to cope with the issue of acquired drug resistance due to prolong the use of a particular EGFR-TKi treatment, or to decrease the doses of each compound in order to reduce potential toxicity. 2,2-dichloroacetophenone (DAP) was reported as a PDK inhibitor recently, which is much more potent than dichloroacetate (DCA) in anti-cancer therapy. In this study, we applied DAP in combined with EGFR-TKis, erlotinib or gefitinib in NSCLC cell lines and NSCLC xenograft model. Synergistic anti-cancer effects in two NSCLC cell lines with EGFR mutation, NCI-H1975 and NCI-H1650, as well as in NCI-H1975 xenograft model were observed. In comparison with either DAP or EGFR-TKi applied alone, the combination treatment not only further suppressed the EGFR signaling in vitro and in vivo, but also significantly promoted cell apoptosis. Interestingly, this synergistic anti-cancer effect was also observed in NCI-H1975 gefitinib induced-resistant cell line. Taken together, our results suggested that the combined use of DAP and EGFR-TKi exhibited anti-cancer synergy which may offer an additional treatment option for patients with EGFR-TKi induced-resistance.