Resistance to Dasatinib in primary chronic lymphocytic leukemia lymphocytes involves AMPK-mediated energetic re-programming

Obesity and Leukemia: Biological Mechanisms, Perspectives, and Challenges

PURPOSE OF REVIEW

To examine the epidemiological data on obesity and leukemia; evaluate the effect of obesity on leukemia outcomes in childhood acute lymphoblastic leukemia (ALL) survivors; assess the potential mechanisms through which obesity may increase the risk of leukemia; and provide the effects of obesity management on leukemia. Preventive (diet, physical exercise, obesity pharmacotherapy, bariatric surgery) measures, repurposing drugs, candidate therapeutic agents targeting oncogenic pathways of obesity and insulin resistance in leukemia as well as challenges of the COVID-19 pandemic are also discussed.

RECENT FINDINGS

Obesity has been implicated in the development of 13 cancers, such as breast, endometrial, colon, renal, esophageal cancers, and multiple myeloma. Leukemia is estimated to account for approximately 2.5% and 3.1% of all new cancer incidence and mortality, respectively, while it represents the most frequent cancer in children younger than 5 years. Current evidence indicates that obesity may have an impact on the risk of leukemia. Increased birthweight may be associated with the development of childhood leukemia. Obesity is also associated with worse outcomes and increased mortality in leukemic patients. However, there are several limitations and challenges in meta-analyses and epidemiological studies. In addition, weight gain may occur in a substantial number of childhood ALL survivors while the majority of studies have documented an increased risk of relapse and mortality among patients with childhood ALL and obesity. The main pathophysiological pathways linking obesity to leukemia include bone marrow adipose tissue; hormones such as insulin and the insulin-like growth factor system as well as sex hormones; pro-inflammatory cytokines, such as IL-6 and TNF-α; adipocytokines, such as adiponectin, leptin, resistin, and visfatin; dyslipidemia and lipid signaling; chronic low-grade inflammation and oxidative stress; and other emerging mechanisms. Obesity represents a risk factor for leukemia, being among the only known risk factors that could be prevented or modified through weight loss, healthy diet, and physical exercise. Pharmacological interventions, repurposing drugs used for cardiometabolic comorbidities, and bariatric surgery may be recommended for leukemia and obesity-related cancer prevention.

In-vitro Modulation of mTOR-HIF-1α Axis by TLR7/8 Agonist (Resiquimod) in B-Chronic Lymphocytic Leukemia

Targeting toll-like receptors (TLRs), via TLR agonists, has been implicated in the regulation of immunometabolism. B-chronic lymphocytic leukemia (B-CLL) represents a suitable model for B-cell derived malignancies with shifted metabolic adaptations. Several signaling pathways have been found to be critical in metabolic reprogramming of CLL, including mechanistic target of rapamycin- hypoxia inducible factor-1α (mTOR- HIF-1α) pathway, the main metabolic regulator of glycolysis. Here, we investigated the effect of TLR7/8 agonist (Resiquimod) on the expression of mTOR and HIF-1α in patients with CLL. B cells were purified using Rosettesep Human B cell Enrichment Cocktail (Stem cell Technologies, Vancouver, BC, Canada#15,024) from peripheral venous blood of CLL patients (n = 20) and healthy individuals (n = 15). Isolated B cells were then cultured in both presence and absence of Resiquimod. Gene expression of mTOR and HIF-1α were assessed using qRT-PCR. Resiquimod significantly decreased mTOR and HIF-1α gene expression in both CLL (p < 0.001and p < 0.001, respectively) and Normal B cells (p = 0.004 and p = 0.001, respectively). Resiquimod may reprogram immunometabolism of malignant B-CLL cells via down-regulation of key glycolytic metabolic actors, mTOR and HIF-1α genes. Accordingly, Resiquimod may be an adjuvant as a therapeutic tool for CLL, which needs to be studied further.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12288-023-01649-y.

Emerging Therapies in CLL in the Era of Precision Medicine

Over the past decade, the treatment landscape of CLL has vastly changed from the conventional FC (fludarabine and cyclophosphamide) and FCR (FC with rituximab) chemotherapies to targeted therapies, including inhibitors of Bruton tyrosine kinase (BTK) and phosphatidylinositol 3-kinase (PI3K) as well as inhibitors of BCL2. These treatment options dramatically improved clinical outcomes; however, not all patients respond well to these therapies, especially high-risk patients. Clinical trials of immune checkpoint inhibitors (PD-1, CTLA4) and chimeric antigen receptor T (CAR T) or NK (CAR NK) cell treatment have shown some efficacy; still, long-term outcomes and safety issues have yet to be determined. CLL remains an incurable disease. Thus, there are unmet needs to discover new molecular pathways with targeted or combination therapies to cure the disease. Large-scale genome-wide whole-exome and whole-genome sequencing studies have discovered genetic alterations associated with disease progression, refined the prognostic markers in CLL, identified mutations underlying drug resistance, and pointed out critical targets to treat the disease. More recently, transcriptome and proteome landscape characterization further stratified the disease and revealed novel therapeutic targets in CLL. In this review, we briefly summarize the past and present available single or combination therapies, focusing on potential emerging therapies to address the unmet clinical needs in CLL.

Metabolism in Hematopoiesis and Its Malignancy

Hematopoietic stem cells (HSCs) are multipotent stem cells that can self-renew and generate all blood cells of different lineages. The system is under tight control in order to maintain a precise equilibrium of the HSC pool and the effective production of mature blood cells to support various biological activities. Cell metabolism can regulate different molecular activities, such as epigenetic modification and cell cycle regulation, and subsequently affects the function and maintenance of HSC. Upon malignant transformation, oncogenic drivers in malignant hematopoietic cells can remodel the metabolic pathways for supporting the oncogenic growth. The dysregulation of metabolism results in oncogene addiction, implying the development of malignancy-specific metabolism-targeted therapy. In this chapter, we will discuss the significance of different metabolic pathways in hematopoiesis, specifically, the distinctive metabolic dependency in hematopoietic malignancies and potential metabolic therapy.

Gankyrin and TIGAR cooperatively accelerate glucose metabolism toward the PPP and TCA cycle in hepatocellular carcinoma

Oncogene-derived metabolic reprogramming is important for anabolic growth of cancer cells, which is now considered to be not simply rely on glycolysis. Pentose phosphate pathway and tricarboxylic acid cycle also play pivotal roles in helping cancer cells to meet their anabolic and energy demands. The present work focused on gankyrin, a relatively specific oncogene in hepatocellular carcinoma (HCC), and its impact on glycolysis and mitochondrial homeostasis. Metabolomics, RNA-seq analysis, and subsequent conjoint analysis illustrated that gankyrin regulated the pentose phosphate pathway (PPP), tricarboxylic acid (TCA) cycle, and mitochondrial function and homeostasis, which play pivotal roles in tumor development. Mechanistically, gankyrin was found to modulate HCC metabolic reprogramming via TIGAR. Gankyrin positively regulated the transcription of TIGAR through Nrf2, which bound to the antioxidant response elements (AREs) in the promoter of TIGAR. Interestingly, TIGAR feedback regulated the transcription of Nrf2 and subsequently gankyrin by promoting nuclear importation of PGC1α. The loop between gankyrin, Nrf2, and TIGAR accelerated glucose metabolism toward the PPP and TCA cycle, which provided vital building blocks, such as NADPH, ATP, and ribose of tumor and further facilitated the progression of HCC.

Single-Cell Metabolomics in Hematopoiesis and Hematological Malignancies

Aberrant metabolism contributes to tumor initiation, progression, metastasis, and drug resistance. Metabolic dysregulation has emerged as a hallmark of several hematologic malignancies. Decoding the molecular mechanism underlying metabolic rewiring in hematological malignancies would provide promising avenues for novel therapeutic interventions. Single-cell metabolic analysis can directly offer a meaningful readout of the cellular phenotype, allowing us to comprehensively dissect cellular states and access biological information unobtainable from bulk analysis. In this review, we first highlight the unique metabolic properties of hematologic malignancies and underscore potential metabolic vulnerabilities. We then emphasize the emerging single-cell metabolomics techniques, aiming to provide a guide to interrogating metabolism at single-cell resolution. Furthermore, we summarize recent studies demonstrating the power of single-cell metabolomics to uncover the roles of metabolic rewiring in tumor biology, cellular heterogeneity, immunometabolism, and therapeutic resistance. Meanwhile, we describe a practical view of the potential applications of single-cell metabolomics in hematopoiesis and hematological malignancies. Finally, we present the challenges and perspectives of single-cell metabolomics development.

Metformin and Thymoquinone Synergistically Inhibit Proliferation of Imatinib-Resistant Human Leukemic Cells

Chemotherapy resistance is one of the major challenges in cancer treatment, including leukemia. A massive array of research is evaluating combinations of drugs directed against different intracellular signaling molecules to overcome cancer resistance, increase therapy effectiveness, and decrease its adverse effects. Combining chemicals with proven safety profiles, such as drugs already used in therapy and active substances isolated from natural sources, could potentially have superior effects compared to monotherapies. In this study, we evaluated the effects of metformin and thymoquinone (TQ) as monotherapy and combinatorial treatments in chronic myeloid leukemia (CML) cell lines sensitive and resistant to imatinib therapy. The effects were also evaluated in primary monocytic acute myeloid leukemia (AML) and chronic lymphocytic leukemia (CLL) cells. Both compounds induced a dose- and time-dependent decrease of viability and proliferation in tested cells. Metformin had similar IC₅₀ values in imatinib-sensitive and imatinib-resistant cell lines. IC₅₀ values of TQ were significantly higher in imatinib-resistant cells, but with a limited resistance index (2.4). Synergistic effects of combinatorial treatments were observed in all tested cell lines, as well as in primary cells. The strongest synergistic effects were observed in the inhibition of imatinib-resistant cell line proliferation. Metformin and TQ inhibited the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) signaling and induced apoptosis in tested cell lines and primary cells. The enhanced effects of combinatorial treatments on the induction of apoptosis were more dominant in imatinib-resistant compared to imatinib-sensitive CML cells. Primary cells were more sensitive to combinatorial treatments compared to cell lines. A combination of 1.25 mM metformin and 0.625 µM TQ increased the levels of cleaved poly (ADP-ribose) polymerase (PARP), decreased the levels of proliferation regulatory proteins, and inhibited protein kinase B (Akt) and NF-κB signaling in primary CLL cells. This study demonstrates that combinatorial treatments of imatinib-resistant malignant clones with metformin and TQ by complementary intracellular multi-targeting represents a promising approach in future studies.

In vivo, ex vivo and in vitro dasatinib activity in chronic lymphocytic leukemia

Dasatinib inhibits the breakpoint cluster region-Abelson murine leukemia 1 (BCR-ABL1) gene along with other kinases known to be overexpressed and abnormally active in patients with chronic lymphocytic leukemia (CLL). The current study used primary leukemic cells obtained from 53 patients with CLL that were treated with dasatinib. A 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay and Annexin V staining was performed to assess the cytotoxic effects of dasatinib treatment. The XTT assay revealed that the median cytotoxicity of dasatinib was 8.30% (range, 0.00–77.89%). Due to high dispersion of dasatinib activity, patients were divided into sensitive (n=27; 50.94%; median cytotoxicity, 22.81%) and resistant groups (n=26; 49.06%; median cytotoxicity, 0.00%). A median cytotoxicity of 8.30% was selected as a cut off value. Using Annexin V staining and flow cytometry on exemplary sensitive and resistant CLL samples, it was revealed that 17.71 and 1.84% of cells were apoptotic, respectively. The current study presented a case of a patient with concomitant occurrence of CLL and chronic myeloid leukemia (CML) with a major molecular response after dasatinib treatment. A simultaneous reduction of circulating CLL cells indicated in vivo anti-CLL activity induced by dasatinib. After an in vitro culture of the patient's mononuclear cells with subsequent dasatinib treatment, a higher percentage of CLL cells undergoing apoptosis was obsevered when compared with untreated samples (38.19 vs. 21.99%, respectively). Similarly, the percentage of CLL apoptotic cells (ΔΨm^low) measured by chloromethyl-X-rosamine was higher after incubation with dasatinib (7.28%) than in the negative control (2.86%). In conclusion, dasatinib induced antileukemic effects against CML and CLL cells. The results of the current study indicated that dasatinib may induce apoptosis ex vivo, in vitro and in vivo in CLL.

Inhibition of InsP3R with Xestospongin B Reduces Mitochondrial Respiration and Induces Selective Cell Death in T Cell Acute Lymphoblastic Leukemia Cells

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy whose chemoresistance and relapse persist as a problem despite significant advances in its chemotherapeutic treatments. Mitochondrial metabolism has emerged as an interesting therapeutic target given its essential role in maintaining bioenergetic and metabolic homeostasis. T-ALL cells are characterized by high levels of mitochondrial respiration, making them suitable for this type of intervention. Mitochondrial function is sustained by a constitutive transfer of calcium from the endoplasmic reticulum to mitochondria through the inositol 1,4,5-trisphosphate receptor (InsP3R), making T-ALL cells vulnerable to its inhibition. Here, we determine the bioenergetic profile of the T-ALL cell lines CCRF-CEM and Jurkat and evaluate their sensitivity to InsP3R inhibition with the specific inhibitor, Xestospongin B (XeB). Our results show that T-ALL cell lines exhibit higher mitochondrial respiration than non-malignant cells, which is blunted by the inhibition of the InsP3R. Prolonged treatment with XeB causes T-ALL cell death without affecting the normal counterpart. Moreover, the combination of XeB and glucocorticoids significantly enhanced cell death in the CCRF-CEM cells. The inhibition of InsP3R with XeB rises as a potential therapeutic alternative for the treatment of T-ALL.

Berberine affects mitochondrial activity and cell growth of leukemic cells from chronic lymphocytic leukemia patients

B-cell chronic lymphocytic leukemia (CLL) results from accumulation of leukemic cells that are subject to iterative re-activation cycles and clonal expansion in lymphoid tissues. The effects of the well-tolerated alkaloid Berberine (BRB), used for treating metabolic disorders, were studied on ex-vivo leukemic cells activated in vitro by microenvironment stimuli. BRB decreased expression of survival/proliferation-associated molecules (e.g. Mcl-1/Bcl-xL) and inhibited stimulation-induced cell cycle entry, irrespective of TP53 alterations or chromosomal abnormalities. CLL cells rely on oxidative phosphorylation for their bioenergetics, particularly during the activation process. In this context, BRB triggered mitochondrial dysfunction and aberrant cellular energetic metabolism. Decreased ATP production and NADH recycling, associated with mitochondrial uncoupling, were not compensated by increased lactic fermentation. Antioxidant defenses were affected and could not correct the altered intracellular redox homeostasis. The data thus indicated that the cytotoxic/cytostatic action of BRB at 10–30 μM might be mediated, at least in part, by BRB-induced impairment of oxidative phosphorylation and the associated increment of oxidative damage, with consequent inhibition of cell activation and eventual cell death. Bioenergetics and cell survival were instead unaffected in normal B lymphocytes at the same BRB concentrations. Interestingly, BRB lowered the apoptotic threshold of ABT-199/Venetoclax, a promising BH3-mimetic whose cytotoxic activity is counteracted by high Mcl-1/Bcl-xL expression and increased mitochondrial oxidative phosphorylation. Our results indicate that, while CLL cells are in the process of building their survival and cycling armamentarium, the presence of BRB affects this process.

The Effect of TIGAR Knockdown on Apoptotic and Epithelial-Mesenchymal Markers Expression in Doxorubicin-Resistant Non-Small Cell Lung Cancer A549 Cell Lines

Resistance to chemotherapeutic drugs is a critical problem in cancer therapy, but the underlying mechanism has not been fully elucidated. TP53-induced glycolysis regulatory phosphatase (TIGAR), an important glycolysis and apoptosis regulator, plays a crucial role in cancer cell survival by protecting cells against oxidative stress-induced apoptosis. In the present study, we investigated whether TIGAR is involved in epithelial-mesenchymal transition (EMT) in doxorubicin (DOX)-resistant human non-small cell lung cancer (NSCLC), A549/DOX cells. We found that the expression of TIGAR was significantly higher in A549/DOX cells than in the parent A549 cell lines. siRNA-mediated TIGAR knockdown reduced migration, viability and colony survival of doxorubicin-resistant lung cancer cells. Also, TIGAR knockdown decreased pro-survival protein Bcl-2 and increased pro-apoptotic Bax and cleaved poly (ADP-ribose) polymerase (PARP). Moreover, TIGAR depletion significantly up-regulated both caspase-3 and caspase-9 expression. Furthermore, TIGAR depletion up-regulated the expression of E-cadherin and down-regulated the expression of vimentin. These results indicate that TIGAR knockdown may inhibit EMT in doxorubicin (DOX)-resistant human NSCLC and may represent a therapeutic target for a non-small lung cancer cells chemoresistance.

Metabolic Reprogramming in Metastatic Melanoma with Acquired Resistance to Targeted Therapies: Integrative Metabolomic and Proteomic Analysis

Treatments of metastatic melanoma underwent an impressive development over the past few years, with the emergence of small molecule inhibitors targeting mutated proteins, such as BRAF, NRAS, or cKIT. However, since a significant proportion of patients acquire resistance to these therapies, new strategies are currently being considered to overcome this issue. For this purpose, melanoma cell lines with mutant BRAF, NRAS, or cKIT and with acquired resistances to BRAF, MEK, or cKIT inhibitors, respectively, were investigated using both ¹H-NMR-based metabonomic and protein microarrays. The ¹H-NMR profiles highlighted a similar go and return pattern in the metabolism of the BRAF, NRAS, and cKIT mutated cell lines. Indeed, melanoma cells exposed to mutation-specific inhibitors underwent metabolic disruptions following acute exposure but partially recovered their basal metabolism in long-term exposure, most likely acquiring resistance skills. The protein microarrays inquired about the potential cellular mechanisms used by the resistant cells to escape drug treatment, by showing decreased levels of proteins linked to the drug efficacy, especially in the downstream part of the MAPK signaling pathway. Integrating metabonomic and proteomic findings revealed some metabolic pathways (i.e., glutaminolysis, choline metabolism, glutathione production, glycolysis, oxidative phosphorylation) and key proteins (i.e., EPHA2, DUSP4, and HIF-1A) as potential targets to discard drug resistance.

IND.216: a phase II study of buparlisib and associated biomarkers, raptor and p70S6K, in patients with relapsed and refractory chronic lymphocytic leukemia

Buparlisib is an orally available pan-Class I PI3K inhibitor, that is more potent than idelalisib in vitro. Its distinct toxicities include hyperglycemia, hypertension, and mood disturbance. IND216 is a single arm phase II trial of buparlisib in Relapsed/refractory (R/R) chronic lymphocytic leukemia (CLL). Fourteen patients were enrolled, 13 were evaluable for response and toxicity. Six of 13 patients had a partial response (46%) with a median duration of response of 15.5 months, all 11 patients with tumor assessment experienced tumor shrinkage. The most common adverse events (≥15%) were hyperglycemia, fatigue, anxiety, and gastrointestinal toxicities; all were < grade 3 except for fatigue. Three patients stopped therapy for alterations in mood. Lower levels of raptor were significantly associated with greater tumor shrinkage, suggesting that raptor could be a biomarker for response. This requires further validation in a larger CLL patient cohort. The clinical activity of buparlisib is comparable to other phosphatidylinositol-3-kinase inhibitors, with a different toxicity profile.Novelty and impactBuparlisib, an oral, pan PI3 kinase inhibitor, is associated with a 46% partial response rate among patients with relapse chronic lymphocytic leukemia (CLL). This is a similar clinical activity to other phosphatidylinositol-3-kinase inhibitors tested. However, buparlisib has a distinct toxicity profile, characterized by hyperglycemia, hypertension, and mood alteration. In agreement with our previous preclinical study, our results suggest that basal raptor expression in CLL correlates with clinical response to buparlisib.

mTOR Regulation of Metabolism in Hematologic Malignancies

Neoplastic cells rewire their metabolism, acquiring a selective advantage over normal cells and a protection from therapeutic agents. The mammalian Target of Rapamycin (mTOR) is a serine/threonine kinase involved in a variety of cellular activities, including the control of metabolic processes. mTOR is hyperactivated in a large number of tumor types, and among them, in many hematologic malignancies. In this article, we summarized the evidence from the literature that describes a central role for mTOR in the acquisition of new metabolic phenotypes for different hematologic malignancies, in concert with other metabolic modulators (AMPK, HIF1α) and microenvironmental stimuli, and shows how these features can be targeted for therapeutic purposes.

Cardio-Oncology: Vascular and Metabolic Perspectives: A Scientific Statement From the American Heart Association

Cardio-oncology has organically developed as a new discipline within cardiovascular medicine as a result of the cardiac and vascular adverse sequelae of the major advances in cancer treatment. Patients with cancer and cancer survivors are at increased risk of vascular disease for a number of reasons. First, many new cancer therapies, including several targeted therapies, are associated with vascular and metabolic complications. Second, cancer itself serves as a risk factor for vascular disease, especially by increasing the risk for thromboembolic events. Finally, recent data suggest that common modifiable and genetic risk factors predispose to both malignancies and cardiovascular disease. Vascular complications in patients with cancer represent a new challenge for the clinician and a new frontier for research and investigation. Indeed, vascular sequelae of novel targeted therapies may provide insights into vascular signaling in humans. Clinically, emerging challenges are best addressed by a multidisciplinary approach in which cardiovascular medicine specialists and vascular biologists work closely with oncologists in the care of patients with cancer and cancer survivors. This novel approach realizes the goal of providing superior care through the creation of cardio-oncology consultative services and the training of a new generation of cardiovascular specialists with a broad understanding of cancer treatments.

Metabolic dependencies and vulnerabilities in leukemia

In this Review, Rashkovan et al. discuss the role of cancer metabolic circuitries feeding anabolism and redox potential in leukemia development and recent progress in translating these important findings to the clinic.

Leukemia cell proliferation requires up-regulation and rewiring of metabolic pathways to feed anabolic cell growth. Oncogenic drivers directly and indirectly regulate metabolic pathways, and aberrant metabolism is central not only for leukemia proliferation and survival, but also mediates oncogene addiction with significant implications for the development of targeted therapies. This review explores leukemia metabolic circuitries feeding anabolism, redox potential, and energy required for tumor propagation with an emphasis on emerging therapeutic opportunities.

The Metabolic Profiles in Hematological Malignancies

Leukemia is one of the most aggressive hematological malignancies. Leukemia stem cells account for the poor prognosis and relapse of the disease. Decades of investigations have been performed to figure out how to eradicate the leukemia stem cells. It has also been known that cancer cells especially solid cancer cells use energy differently than most of the cell types. The same thing happens to leukemia. Since there are metabolic differences between the hematopoietic stem cells and their immediate descendants, we aim at manipulating the energy sources with which that could have an effect on leukemia stem cells while sparing the normal blood cells. In this review we summarize the metabolic characteristics of distinct leukemias such as acute myeloid leukemia, chronic myeloid leukemia, T cell lymphoblastic leukemia, B-cell lymphoblastic leukemia, chronic lymphocytic leukemia and other leukemia associated hematological malignancies such as multiple myeloma and myelodysplastic syndrome. A better understanding of the metabolic profiles in distinct leukemias might provide novel perspectives and shed light on novel metabolic targeting strategies towards the clinical treatment of leukemias.

Strategies For Targeting Chronic Myeloid Leukaemia Stem Cells

Chronic Myeloid Leukaemia is a myeloproliferative disorder driven by the t(9;22) chromosomal translocation coding for the chimeric protein BCR-ABL. CML treatment represents the paradigm of molecular therapy of cancer. Since the development of the tyrosine kinase inhibitor of the BCR-ABL kinase, the clinical approach to CML has dramatically changed, with a stunning improvement in the quality of life and response rates of patients. However, it remains clear that tyrosine kinase inhibitors (TKIs) are unable to target the most immature cellular component of CML, the CML stem cell. This review summarizes new insights into the mechanisms of resistance to TKIs.

Bruton's tyrosine kinase is at the crossroads of metabolic adaptation in primary malignant human lymphocytes

In this work we explored metabolic aspects of human primary leukemic lymphocytes that hold a potential impact on the treatment of Bruton tyrosine kinase (BTK)-driven diseases. Our results suggest that there is crosstalk between Bruton tyrosine kinase (BTK) signaling and bioenergetic stress responses. In primary chronic lymphocytic leukemia (CLL) lymphocytes, pharmacological interference with mitochondrial ATP synthesis or glucose metabolism affects BTK activity. Conversely, an inhibitor of BTK used clinically (ibrutinib) induces bioenergetic stress responses that in turn affect ibrutinib resistance. Although the detailed molecular mechanisms are still to be defined, our work shows for the first time that in primary B cells, metabolic stressors enhance BTK signaling and suggest that metabolic rewiring to hyperglycemia affects ibrutinib resistance in TP53 deficient chronic lymphocytic leukemia (CLL) lymphocytes.

Targeting the unfolded protein response in head and neck and oral cavity cancers

Many FDA-approved anti-cancer therapies, targeted toward a wide array of molecular targets and signaling networks, have been demonstrated to activate the unfolded protein response (UPR). Despite a critical role for UPR signaling in the apoptotic execution of cancer cells by many of these compounds, the authors are currently unaware of any instance whereby a cancer drug was developed with the UPR as the intended target. With the essential role of the UPR as a driving force in the genesis and maintenance of the malignant phenotype, a great number of pre-clinical studies have surged into the medical literature describing the ability of dozens of compounds to induce UPR signaling in a myriad of cancer models. The focus of the current work is to review the literature and explore the role of the UPR as a mediator of chemotherapy-induced cell death in squamous cell carcinomas of the head and neck (HNSCC) and oral cavity (OCSCC), with an emphasis on preclinical studies.

Metabolic rewiring beyond Warburg in chronic lymphocytic leukemia: How much do we actually know?

Chronic Lymphocytic Leukemia (CLL) is the most common adult leukemia in the western world. CLL consists of the accumulation of malignant B-cells in the blood stream and homing tissues. Although treatable, this disease is not curable, and resistance or relapse is often present. In many cancers, the study of metabolic reprograming has uncovered novel targets that are already being exploited in the clinic. However, CLL metabolism is still poorly understood. The ability of CLL lymphocytes to adapt to diverse microenvironments is accompanied by modifications in cell metabolism, revealing the challenge of targeting the CLL lymphocytes present in all different compartments. Despite this, the study of CLL metabolism led to an ongoing clinical trial using glucose uptake and mitochondrial respiration inhibitors. In contrast, glutamine and fatty acid metabolism remain to be further exploited in CLL. Here, we summarize the present knowledge of CLL metabolism, as well as the metabolic influence of Myc, ATM and p53 on CLL lymphocytes.

The diverse role of TIGAR in cellular homeostasis and cancer

TP53-induced glycolysis and apoptosis regulator (TIGAR) is a p53 target protein that plays critical roles in glycolysis and redox balance. Accumulating evidence shows that TIGAR is highly expressed in cancer. TIGAR redirects glycolysis and promotes carcinoma growth by providing metabolic intermediates and reductive power derived from pentose phosphate pathway (PPP). The expression of TIGAR in cancer is positively associated with chemotherapy resistance, suggesting that TIGAR could be a novel therapeutic target. In this review, we briefly presented the function of TIGAR in metabolic homeostasis in normal and cancer cells. Finally, we discussed the future directions of TIGAR research in cancer.

Ibrutinib Resistance Is Reduced by an Inhibitor of Fatty Acid Oxidation in Primary CLL Lymphocytes

Chronic Lymphocytic Leukemia (CLL) is an incurable disease, characterized by the accumulation of malignant B-lymphocytes in the blood stream (quiescent state) and homing tissues (where they can proliferate). In CLL, the targeting of B-cell receptor signaling through a Burton's tyrosine kinase inhibitor (ibrutinib) has rendered outstanding clinical results. However, complete remission is not guaranteed due to drug resistance or relapse, revealing the need for novel approaches for CLL treatment. The characterization of metabolic rewiring in proliferative cancer cells is already being applied for diagnostic and therapeutic purposes, but our knowledge of quiescent cell metabolism—relevant for CLL cells—is still fragmentary. Recently, we reported that glutamine metabolism in primary CLL cells bearing the del11q deletion is different from their del11q negative counterparts, making del11q cells especially sensitive to glutaminase and glycolysis inhibitors. In this work, we used our primary CLL lymphocyte bank and compounds interfering with central carbon metabolism to define metabolic traits associated with ibrutinib resistance. We observe a differential basal metabolite uptake linked to ibrutinib resistance, favoring glutamine uptake and catabolism. Upon ibrutinib treatment, the redox balance in ibrutinib resistant cells is shifted toward NADPH accumulation, without an increase in glutamine uptake, suggesting alternative metabolic rewiring such as the activation of fatty acid oxidation. In accordance to this idea, the curtailing of fatty acid oxidation by CPT1 inhibition (etomoxir) re-sensitized resistant cells to ibrutinib. Our results suggest that fatty acid oxidation could be explored as a target to overcome ibrutinib resistance.

Effect of metformin on the survival of patients with ALL who express high levels of the ABCB1 drug resistance gene

BACKGROUND

In acute lymphoblastic leukemia (ALL), high ABCB1 gene expression has been associated with treatment resistance, which affects patient prognosis. Many preclinical reports and retrospective population studies have shown an anti-cancer effect of metformin. Therefore, the objective of this study was to assess the effect of metformin on the treatment regimen in patients with ALL who exhibited high levels of ABCB1 gene expression and to determine its impact on overall survival.

METHODS

A total of 102 patients with ALL were recruited; one group (n = 26) received metformin, and the other received chemotherapy (n = 76). Measurement of ABCB1 transcript expression was performed using qRT-PCR prior to treatment initiation. Survival analysis was performed using Kaplan-Meier curves. The impact of both the type of treatment and the level of expression on the response (remission or relapse) was analyzed by calculating the odds ratio.

RESULTS

The survival of patients with high ABCB1 expression was lower than those with low or absent ABCB1 gene expression (p = 0.030). In the individual analysis, we identified a benefit to adding metformin in the group of patients with high ABCB1 gene expression (p = 0.025). In the metformin user group, the drug acted as a protective factor against both therapeutic failure (odds ratio [OR] 0.07, 95% confidence interval [CI] 0.0037-1.53) and early relapse (OR 0.05, 95% CI 0.0028-1.153).

CONCLUSION

The combined use of metformin with chemotherapy is effective in patients with elevated levels of ABCB1 gene expression. Trial registration NCT 03118128: NCT.

Oxidative Phosphorylation as an Emerging Target in Cancer Therapy

Cancer cells have upregulated glycolysis compared with normal cells, which has led many to the assumption that oxidative phosphorylation (OXPHOS) is downregulated in all cancers. However, recent studies have shown that OXPHOS can be also upregulated in certain cancers, including leukemias, lymphomas, pancreatic ductal adenocarcinoma, high OXPHOS subtype melanoma, and endometrial carcinoma, and that this can occur even in the face of active glycolysis. OXPHOS inhibitors could therefore be used to target cancer subtypes in which OXPHOS is upregulated and to alleviate therapeutically adverse tumor hypoxia. Several drugs including metformin, atovaquone, and arsenic trioxide are used clinically for non-oncologic indications, but emerging data demonstrate their potential use as OXPHOS inhibitors. We highlight novel applications of OXPHOS inhibitors with a suitable therapeutic index to target cancer cell metabolism. Clin Cancer Res; 24(11); 2482-90. ©2018 AACR.

Down-regulation of PKM2 enhances anticancer efficiency of THP on bladder cancer

Pyruvate kinase M2 (PKM2) regulates the final step of glycolysis levels that are correlated with the sensitivity of anticancer chemotherapeutic drugs. THP is one of the major drugs used in non‐muscle‐invasive bladder cancer instillation chemotherapy. However, low response ratio of THP (19.7%) treatment to human genitourinary tumours using collagen gel matrix has been observed. This study aims to investigate the effect of down‐regulation of PKM2 on THP efficiency. Via inhibitor or siRNA, the effects of reduced PKM2 on the efficiency of THP were determined in 2 human and 1 murine bladder cancer cell lines, using MTT, cologenic and fluorescence approaches. Molecular mechanisms of PKM2 on THP sensitization were explored by probing p‐AMPK and p‐STAT3 levels via WB. Syngeneic orthotopic bladder tumour model was applied to evaluate this efficiency in vivo, analysed by Kaplan‐Meier survival curves, body and bladder weights plus immunohistochemistric tumour biomarkers. PKM2 was overexpressed in bladder cancer cells and tissues, and down‐regulation of PKM2 enhanced the sensitivity of THP in vitro. Activation of AMPK is essential for THP to exert anti‐bladder cancer activities. On the other hand, down‐regulating PKM2 activates AMPK and inhibits STAT3, correlated with THP sensitivity. Compared with THP alone (400 μmol L⁻¹, 50 μL), the combination with metformin (60 mmol L⁻¹, 50 μL) stopped growth of bladder cancer completely in vivo (combination group VS normal group P = .078). Down‐regulating the expression of PKM2 enhances the anticancer efficiency of THP. This study provides a new insight for improving the chemotherapeutic effect of THP.

Altered glutamine metabolism in platinum resistant ovarian cancer

Ovarian cancer is characterized by an increase in cellular energy metabolism, which is predominantly satisfied by glucose and glutamine. Targeting metabolic pathways is an attractive approach to enhance the therapeutic effectiveness and to potentially overcome drug resistance in ovarian cancer. In platinum-sensitive ovarian cancer cell lines the metabolism of both, glucose and glutamine was initially up-regulated in response to platinum treatment. In contrast, platinum-resistant cells revealed a significant dependency on the presence of glutamine, with an upregulated expression of glutamine transporter ASCT2 and glutaminase. This resulted in a higher oxygen consumption rate compared to platinum-sensitive cell lines reflecting the increased dependency of glutamine utilization through the tricarboxylic acid cycle. The important role of glutamine metabolism was confirmed by stable overexpression of glutaminase, which conferred platinum resistance. Conversely, shRNA knockdown of glutaminase in platinum resistant cells resulted in re-sensitization to platinum treatment. Importantly, combining the glutaminase inhibitor BPTES with platinum synergistically inhibited platinum sensitive and resistant ovarian cancers in vitro. Apoptotic induction was significantly increased using platinum together with BPTES compared to either treatment alone. Our findings suggest that targeting glutamine metabolism together with platinum based chemotherapy offers a potential treatment strategy particularly in drug resistant ovarian cancer.

Metformin, an Anti-diabetic Drug to Target Leukemia

Metformin, a widely used anti-diabetic molecule, has attracted a strong interest in the last 10 years as a possible new anti-cancer molecule. Metformin acts by interfering with mitochondrial respiration, leading to an activation of the AMPK tumor-suppressive pathway to promote catabolic-energy saving reactions and block anabolic ones that are associated with abnormal cell proliferation. Metformin also acts at the organism level. In type 2 diabetes patients, metformin reduces hyperglycemia and increases insulin sensitivity by enhancing insulin-stimulated glucose uptake in muscles, liver, and adipose tissue and by reducing glucose output by the liver. Lowering insulin and insulin-like growth factor 1 (IGF-1) levels that stimulate cancer growth could be important features of metformin's mode of action. Despite continuous progress in treatments with the use of targeted therapies and now immunotherapies, acute leukemias are still of very poor prognosis for relapse patients, demonstrating an important need for new treatments deriving from the identification of their pathological supportive mechanisms. In the last decade, it has been realized that if cancer cells modify and reprogram their metabolism to feed their intense biochemical needs associated with their runaway proliferation, they develop metabolic addictions that could represent attractive targets for new therapeutic strategies that intend to starve and kill cancer cells. This Mini Review explores the anti-leukemic potential of metformin and its mode of action on leukemia metabolism.

B-cell Receptor Signaling Regulates Metabolism in Chronic Lymphocytic Leukemia

Peripheral blood chronic lymphocytic leukemia (CLL) cells are quiescent but have active transcription and translation processes, suggesting that these lymphocytes are metabolically active. Based on this premise, the metabolic phenotype of CLL lymphocytes was investigated by evaluating the two intracellular ATP-generating pathways. Metabolic flux was assessed by measuring glycolysis as extracellular acidification rate (ECAR) and mitochondrial oxidative phosphorylation as oxygen consumption rate (OCR) and then correlated with prognostic factors. Further, the impact of B-cell receptor signaling (BCR) on metabolism was determined by genetic ablation and pharmacological inhibitors. Compared with proliferative B-cell lines, metabolic fluxes of oxygen and lactate were low in CLL cells. ECAR was consistently low, but OCR varied considerably in human patient samples (n = 45). Higher OCR was associated with poor prognostic factors such as ZAP 70 positivity, unmutated IGHV, high β2M levels, and higher Rai stage. Consistent with the association of ZAP 70 and IGHV unmutated status with active BCR signaling, genetic ablation of BCR mitigated OCR in malignant B cells. Similarly, knocking out PI3Kδ, a critical component of the BCR pathway, decreased OCR and ECAR. In concert, PI3K pathway inhibitors dramatically reduced OCR and ECAR. In harmony with a decline in metabolic activity, the ribonucleotide pools in CLL cells were reduced with duvelisib treatment. Collectively, these data demonstrate that CLL metabolism, especially OCR, is linked to prognostic factors and is curbed by BCR and PI3K pathway inhibition.Implications: This study identifies a relationship between oxidative phosphorylation in CLL and prognostic factors providing a rationale to therapeutically target these processes. Mol Cancer Res; 15(12); 1692-703. ©2017 AACR.

Metformin combined with sodium dichloroacetate promotes B leukemic cell death by suppressing anti-apoptotic protein Mcl-1

Metformin and the mitochondrial targeting dichloroacetate (DCA) have recently received attention due to their ability to inhibit anaerobic glycolysis, which renders most cancer cells resistant to apoptosis induction. We observed that Metformin alone exhibited a dose-dependent anti-leukemic activity in both B leukemic cell lines and primary B-chronic lymphocytic leukemia (B-CLL) patients' cells and its anti-leukemic activity was enhanced when used in combination with DCA. In order to overcome the problems of poor bioavailability and cellular uptake, which limit DCA efficacy, we have designed and synthetized cocrystals consisting of Metformin and DCA (Met-DCA) at different stoichiometric ratios. Of note, the MetH(2)(++)•2DCA(-) cocrystal exhibited enhanced in vitro anti-leukemic activity, with respect to the treatment with the mix consisting of Metformin plus DCA. In particular, the treatment with the cocrystal MetH(2)(++)•2DCA(-) induced a synergistic apoptotic cell death coupled to a marked down-modulation of the anti-apoptotic Mcl-1 protein. Taken together, our data emphasize that innovative compounds based on Metformin-DCA combination merit to be further evaluated as chemotherapeutic agents for the treatment of B-CLL.

ROS homeostasis and metabolism: a critical liaison for cancer therapy

Evidence indicates that hypoxia and oxidative stress can control metabolic reprogramming of cancer cells and other cells in tumor microenvironments and that the reprogrammed metabolic pathways in cancer tissue can also alter the redox balance. Thus, important steps toward developing novel cancer therapy approaches would be to identify and modulate critical biochemical nodes that are deregulated in cancer metabolism and determine if the therapeutic efficiency can be influenced by changes in redox homeostasis in cancer tissues. In this review, we will explore the molecular mechanisms responsible for the metabolic reprogramming of tumor microenvironments, the functional modulation of which may disrupt the effects of or may be disrupted by redox homeostasis modulating cancer therapy.

Metformin inhibits cell cycle progression of B-cell chronic lymphocytic leukemia cells

B-cell chronic lymphocytic leukemia (CLL) was believed to result from clonal accumulation of resting apoptosis-resistant malignant B lymphocytes. However, it became increasingly clear that CLL cells undergo, during their life, iterative cycles of re-activation and subsequent clonal expansion. Drugs interfering with CLL cell cycle entry would be greatly beneficial in the treatment of this disease.

1, 1-Dimethylbiguanide hydrochloride (metformin), the most widely prescribed oral hypoglycemic agent, inexpensive and well tolerated, has recently received increased attention for its potential antitumor activity. We wondered whether metformin has apoptotic and anti-proliferative activity on leukemic cells derived from CLL patients.

Metformin was administered in vitro either to quiescent cells or during CLL cell activation stimuli, provided by classical co-culturing with CD40L-expressing fibroblasts.

At doses that were totally ineffective on normal lymphocytes, metformin induced apoptosis of quiescent CLL cells and inhibition of cell cycle entry when CLL were stimulated by CD40-CD40L ligation. This cytostatic effect was accompanied by decreased expression of survival- and proliferation-associated proteins, inhibition of signaling pathways involved in CLL disease progression and decreased intracellular glucose available for glycolysis.

In drug combination experiments, metformin lowered the apoptotic threshold and potentiated the cytotoxic effects of classical and novel antitumor molecules.

Our results indicate that, while CLL cells after stimulation are in the process of building their full survival and cycling armamentarium, the presence of metformin affects this process.

High-content screening identifies kinase inhibitors that overcome venetoclax resistance in activated CLL cells

Novel agents such as the Bcl-2 inhibitor venetoclax (ABT-199) are changing treatment paradigms for chronic lymphocytic leukemia (CLL) but important problems remain. Although some patients exhibit deep and durable responses to venetoclax as a single agent, other patients harbor subpopulations of resistant leukemia cells that mediate disease recurrence. One hypothesis for the origin of resistance to venetoclax is by kinase-mediated survival signals encountered in proliferation centers that may be unique for individual patients. An in vitro microenvironment model was developed with primary CLL cells that could be incorporated into an automated high-content microscopy-based screen of kinase inhibitors (KIs) to identify agents that may improve venetoclax therapy in a personalized manner. Marked interpatient variability was noted for which KIs were effective; nevertheless, sunitinib was identified as the most common clinically available KI effective in overcoming venetoclax resistance. Examination of the underlying mechanisms indicated that venetoclax resistance may be induced by microenvironmental signals that upregulate antiapoptotic Bcl-xl, Mcl-1, and A1, which can be counteracted more efficiently by sunitinib than by ibrutinib or idelalisib. Although patient-specific drug responses are common, for many patients, combination therapy with sunitinib may significantly improve the therapeutic efficacy of venetoclax.

Adaptive metabolic rewiring to chronic SFK inhibition

Src family kinases (SFK) are key regulators of cellular proliferation, differentiation, survival, motility and angiogenesis. As such, SFK inhibitors are being tested in clinical trials to prevent metastasis as an alternative to current treatment regimens for a variety of cancers including breast cancer. To contribute to the development of molecular tools improving SFK-targeted therapies, we used the SFK inhibitor dasatinib and a well characterized triple negative breast cancer cell line (BT20). Comparison of the response of BT20 cells with acquired resistance to dasatinib and its’ parental counterpart suggest that chronic exposure to SFK inhibition results in increased dependency on TGFβ signaling for proliferation, both in the absence or the presence of dasatinib. In addition, we found that acquired (but not de novo) resistance to dasatinib was reduced by non-cytotoxic concentrations compounds hindering on PI3K, mTORC1 signaling, endoplasmic reticulum stress or autophagy.

The Warburg effect and drug resistance

: The Warburg effect describes the increased utilization of glycolysis rather than oxidative phosphorylation by tumour cells for their energy requirements under physiological oxygen conditions. This effect has been the basis for much speculation on the survival advantage of tumour cells, tumourigenesis and the microenvironment of tumours. More recently, studies have begun to reveal how the Warburg effect could influence drug efficacy and how our understanding of tumour energetics could be exploited to improve drug development. In particular, evidence is emerging demonstrating how better modelling of the tumour metabolic microenvironment could lead to a better prediction of drug efficacy and the identification of new combination strategies. This review will provide details of the current understanding of the complex interplay between glucose metabolism and pharmacology and discuss opportunities for utilizing the Warburg effect in future drug development.

Metabolism pathways in chronic lymphocytic leukemia

Alterations in chronic lymphocytic leukemia (CLL) cell metabolism have been studied by several investigators. Unlike normal B lymphocytes or other leukemia cells, CLL cells, like adipocytes, store lipids and utilize free fatty acids (FFA) to produce chemical energy. None of the recently identified mutations in CLL directly affects metabolic pathways, suggesting that genetic alterations do not directly contribute to CLL cells' metabolic reprogramming. Conversely, recent data suggest that activation of STAT3 or downregulation of microRNA-125 levels plays a crucial role in the utilization of FFA to meet the CLL cells' metabolic needs. STAT3, known to be constitutively activated in CLL, increases the levels of lipoprotein lipase (LPL) that mediates lipoprotein uptake and shifts the CLL cells' metabolism towards utilization of FFA. Herein, we review the evidence for altered lipid metabolism, increased mitochondrial activity and formation of reactive oxygen species (ROS) in CLL cells, and discuss the possible therapeutic strategies to inhibit lipid metabolism pathways in patient with CLL.

Involvement of metformin and AMPK in the radioresponse and prognosis of luminal versus basal-like breast cancer treated with radiotherapy

Metformin is under evaluation as a potential anticancer agent. Expression of total and phospho(Thr172)-adenosine monophosphate-activated kinase-α (AMPKα and pAMPKα(Thr172) respectively), a main metformin target, was examined in radiotherapy treated breast cancers and metformin's ability to modulate Trx system expression and breast cancer radiosensitivity evaluated in vitro.

AMPKα and pAMPKα(Thr172) expression was assessed using a discovery (n=166) and validation cohort (n=609). Metformin's role in regulating radioresponse, and Trx family expression, was examined via clonogenic assays and Western blots. Intracellular reactive oxygen species (ROS) levels, cell cycle progression and apoptosis were assessed by flow cytometry.

High AMPKα expression associated with improved local recurrence-free (P=0.019), relapse-free (P=0.016) and breast cancer-specific survival (P=0.000065) and was, from multivariate analysis, an independent prognostic factor from the discovery cohort. From the validation cases AMPKα expression associated with relapse-free and breast cancer-specific survival in luminal breast cancers. Metformin substantially increased radiosensitivity, intracellular ROS levels and reduced Trx expression, in luminal breast cancer cells, but had little effect on basal phenotype cells.

In conclusion, high AMPKα expression associates with improved prognosis, especially in luminal breast cancer. Metformin preferentially radiosensitises luminal breast cancer cells, potentially due to alterations to intracellular ROS levels via modulation of Trx family protein expression.

Adipose tissue dysfunction and its effects on tumor metabolism

Growing by an alarming rate in the Western world, obesity has become a condition associated with a multitude of diseases such as diabetes, metabolic syndrome and various cancers. Generally viewed as an abnormal accumulation of hypertrophied adipocytes, obesity is also a poor prognostic factor for recurrence and chemoresistance in cancer patients. With more than two-thirds of the adult population in the United States considered clinically overweight or obese, it is critical that the relationship between obesity and cancer is further emphasized and elucidated. Adipocytes are highly metabolically active cells, which, through release of adipokines and cytokines and activation of endocrine and paracrine pathways, affect processes in neighboring and distant cells, altering their normal homeostasis. This work will examine specifically how adipocyte-derived factors regulate the cellular metabolism of malignant cells within the tumor niche. Briefly, tumor cells undergo metabolic pressure towards a more glycolytic and hypoxic state through a variety of metabolic regulators and signaling pathways, i.e., phosphoinositol-3 kinase (PI3K), hypoxia-inducible factor-1 alpha (HIF-1α), and c-MYC signaling. Enhanced glycolysis and high lactate production are hallmarks of tumor progression largely because of a process known as the Warburg effect. Herein, we review the latest literature pertaining to the body of work on the interactions between adipose and tumor cells, and underlining the changes in cancer cell metabolism that have been targeted by the currently available treatments.

Drugs acting on homeostasis: challenging cancer cell adaptation

Cancer treatment aims to exploit properties that define malignant cells. In recent years, it has become apparent that malignant cells often survive cancer treatment and ensuing cell stress by switching on auxiliary turnover pathways, changing cellular metabolism and, concomitantly, the gene expression profile. The changed profile impacts the material exchange of cancer cells with affected tissues. Herein, we show that pathways of proteostasis and energy generation regulate common transcription factors. Namely, when one pathway of intracellular turnover is blocked, it triggers alternative turnover mechanisms, which induce transcription factor proteins that control expression of cytokines and regulators of apoptosis, cell division, differentiation, metabolism, and response to hormones. We focus on several alternative turnover mechanisms that can be blocked by drugs already used in clinical practice for the treatment of other non-cancer related diseases. We also discuss paradigms on the challenges posed by cancer cell adaptation mechanisms.

Transcriptomic analysis reveals inhibition of androgen receptor activity by AMPK in prostate cancer cells

Metabolic alterations contribute to prostate cancer development and progression; however, the role of the central metabolic regulator AMP-activated protein kinase (AMPK) remains controversial. The androgen receptor (AR), a key driver of prostate cancer, regulates prostate cancer cell metabolism by driving the expression of a network of metabolic genes and activates AMPK through increasing the expression of one of its upstream kinases. To more clearly define the role of AMPK in prostate cancer, we performed expression profiling following pharmacologic activation of this kinase. We found that genes down-regulated upon AMPK activation were over-expressed in prostate cancer, consistent with a tumour suppressive function of AMPK. Strikingly, we identified the AR as one of the most significantly enriched transcription factors mediating gene expression changes downstream of AMPK signalling in prostate cancer cells. Activation of AMPK inhibited AR transcriptional activity and reduced androgen-dependent expression of known AR target genes. Conversely, knock-down of AMPK increased AR activity. Modulation of AR expression could not explain these effects. Instead, we observed that activation of AMPK reduced nuclear localisation of the AR. We thus propose the presence of a negative feedback loop in prostate cancer cells whereby AR activates AMPK and AMPK feeds back to limit AR-driven transcription.

Metformin sensitizes anticancer effect of dasatinib in head and neck squamous cell carcinoma cells through AMPK-dependent ER stress

Head and neck squamous cell carcinoma (HNSCC) is an important endemic disease in Taiwan with aggressive course and dismal outcome. Dasatinib is a Bcr-bl and Src kinase inhibitor that has potential against HNSCC. We recently disclosed that EGFR degradation is critical for dasatinib-induced apoptosis. Here, we further demonstrate that AMPK-dependent ER stress is responsible for this event. Dasatinib induced ER stress which mediated EGFR degradation in a c-cbl-dependent manner. AMPK activation induced by dasatinib might be due to ATP decrease through the up-regulation of pyruvate dehydrogenase kinase 4 (PDK4). Furthermore, activation of AMPK by metformin sensitized dasatinib-induced in vitro and in vivo anti-cancer effect. The correlation of AMPK activation and EGFR expression was seen in HNSCC cells and human tumor specimens. Our results disclose that AMPK-dependent ER stress plays a crucial role in the anti-cancer effect of dasatinib in HNSCC and further activation of AMPK by metformin might enhance dasatinib efficacy.

Genomic quantitative real-time PCR proves residual disease positivity in more than 30% samples with negative mRNA-based qRT-PCR in Chronic Myeloid Leukemia

Imatinib mesylate (IM) is the first line therapy against Chronic Myeloid Leukemia, effectively prolonging overall survival. Because discontinuation of treatment is associated with relapse, IM is required indefinitely to maintain operational cure. To assess minimal residual disease, cytogenetic analysis is insensitive in a high background of normal lymphocytes. The qRT-PCR provides highly sensitive detection of BCR-ABL1 transcripts, but mRNA levels are not directly related to the number of leukemic cells, and undetectable results are difficult to interpret. We developed a sensitive approach to detect the number of leukemic cells by a genomic DNA (gDNA) Q-PCR assay based on the break-point sequence, with a formula to calculate the number of Ph-positive cells. We monitored 8 CML patients treated with IM for more than 8 years. We tested each samples by patient specific gDNA Q-PCR in parallel by the conventional techniques. In all samples positive for chimeric transcripts we showed corresponding chimeric gDNA by Q-PCR, and in 32.8% (42/128) of samples with undetectable levels of mRNA we detected the persistence of leukemic cells. The gDNA Q-PCR assay could be a new diagnostic tool used in parallel to conventional techniques to support the clinician's decision to vary or to STOP IM therapy.

Acquired resistance to metformin in breast cancer cells triggers transcriptome reprogramming toward a degradome-related metastatic stem-like profile

Therapeutic interventions based on metabolic inhibitor-based therapies are expected to be less prone to acquired resistance. However, there has not been any study assessing the possibility that the targeting of the tumor cell metabolism may result in unforeseeable resistance. We recently established a pre-clinical model of estrogen-dependent MCF-7 breast cancer cells that were chronically adapted to grow (> 10 months) in the presence of graded, millimolar concentrations of the anti-diabetic biguanide metformin, an AMPK agonist/mTOR inhibitor that has been evaluated in multiple in vitro and in vivo cancer studies and is now being tested in clinical trials. To assess what impact the phenomenon of resistance might have on the metformin-like "dirty" drugs that are able to simultaneously hit several metabolic pathways, we employed the ingenuity pathway analysis (IPA) software to functionally interpret the data from Agilent whole-human genome arrays in the context of biological processes, networks, and pathways. Our findings establish, for the first time, that a "global" targeting of metabolic reprogramming using metformin certainly imposes a great selective pressure for the emergence of new breast cancer cellular states. Intriguingly, acquired resistance to metformin appears to trigger a transcriptome reprogramming toward a metastatic stem-like profile, as many genes encoding the components of the degradome (KLK11, CTSF, FREM1, BACE-2, CASP, TMPRSS4, MMP16, HTRA1), cancer cell migration and invasion factors (TP63, WISP2, GAS3, DKK1, BCAR3, PABPC1, MUC1, SPARCL1, SEMA3B, SEMA6A), stem cell markers (DCLK1, FAK), and key pro-metastatic lipases (MAGL and Cpla2) were included in the signature. Because this convergent activation of pathways underlying tumor microenvironment interactions occurred in low-proliferative cancer cells exhibiting a notable downregulation of the G 2/M DNA damage checkpoint regulators that maintain genome stability (CCNB1, CCNB2, CDC20, CDC25C, AURKA, AURKB, BUB1, CENP-A, CENP-M) and pro-autophagic features (i.e., TRAIL upregulation and BCL-2 downregulation), it appears that the unique mechanism of acquired resistance to metformin has opposing roles in growth and metastatic dissemination. While refractoriness to metformin limits breast cancer cell growth, likely due to aberrant mitotic/cytokinetic machinery and accelerated autophagy, it notably increases the potential of metastatic dissemination by amplifying the number of pro-migratory and stemness inputs via the activation of a significant number of proteases and EMT regulators. Future studies should elucidate whether our findings using supra-physiological concentrations of metformin mechanistically mimic the ultimate processes that could paradoxically occur in a polyploid, senescent-autophagic scenario triggered by the chronic metabolic stresses that occur during cancer development and after treatment with cancer drugs.