AMP-Activated Protein Kinase:Friend or Foe in Cancer

The AMP-activated protein kinase (AMPK) is activated by energy stress and restores homeostasis by switching on catabolism, while switching off cell growth and proliferation. Findings that AMPK acts downstream of the tumor suppressor LKB1 have suggested that AMPK might also suppress tu-morigenesis. In mouse models of B and T cell lymphoma in which genetic loss of AMPK occurred before tumor initiation, tumorigenesis was accelerated , confirming that AMPK has tumor-suppressor functions. However, when loss of AMPK in a T cell lymphoma model occurred after tumor initiation , or simultaneously with tumor initiation in a lung cancer model, the disease was ameliorated. Thus, once tumorigenesis has occurred, AMPK switches from tumor suppression to tumor promotion. Analysis of alterations in AMPK genes in human cancers suggests similar dichotomies, with some genes being frequently amplified while others are mutated. Overall, while AMPK-activating drugs might be effective in preventing cancer, in some cases AMPK inhibitors might be required to treat it

Genotoxic Damage Activates the AMPK-α1 Isoform in the Nucleus via Ca2+/CaMKK2 Signaling to Enhance Tumor Cell Survival

2017 American Association for Cancer Research. Many genotoxic cancer treatments activate AMP-activated protein kinase (AMPK), but the mechanisms of AMPK activation in response to DNA damage, and its downstream consequences, have been unclear. In this study, etoposide activates the a1 but not the a2 isoform of AMPK, primarily within the nucleus. AMPK activation is independent of ataxia-telangiectasia mutated (ATM), a DNA damage-activated kinase, and the principal upstream kinase for AMPK, LKB1, but correlates with increased nuclear Ca2þ and requires the Ca2þ/calmodulin-dependent kinase, CaMKK2. Intriguingly, Ca2þ-dependent activation of AMPK in two different LKB1-null cancer cell lines caused G1-phase cell-cycle arrest, and enhanced cell viability/ survival after etoposide treatment, with both effects being abolished by knockout of AMPK-a1 and a2. The CDK4/6 inhibitor palbociclib also caused G1 arrest in G361 but not HeLa cells and, consistent with this, enhanced cell survival after etoposide treatment only in G361 cells. These results suggest that AMPK activation protects cells against etoposide by limiting entry into S-phase, where cells would be more vulnerable to genotoxic stress. Implications: These results reveal that the a1 isoform of AMPK promotes tumorigenesis by protecting cells against genotoxic stress, which may explain findings that the gene encoding AMPK-a1 (but not -a2) is amplified in some human cancers. Furthermore, a1-selective inhibitors might enhance the anticancer effects of genotoxic-based therapies

TBIO-14. Characterisation of the arginine pathway enzymes in paediatric brain tumours to determine susceptibility to therapeutic arginine depletion

INTRODUCTIONExtracellular arginine dependency (auxotrophy) is increasingly being recognised in several tumours. This is due to the inability of cancer cells to recycle or synthesise intracellular arginine through the urea cycle pathway compared to normal cells. Whilst adult glioblastoma is known to exhibit this, the expression of the arginine pathway enzymes has not been delineated in paediatric brain tumours.METHODSWe used immunohistochemical methods to stain for arginine pathway enzymes in Paediatric High grade glioma (pHGG), low grade glioma (pLGG) and medulloblastoma (MB) tumour tissue microarrays (TMAs). The antibodies detected protein expression of the metaboliser Arginase (Arg2), recycling enzymes ornithine transcarbamoylase (OTC), Arginosuccinate synthetase (ASS1) and arginosuccinate lyase (ASL) as well as the transporter SLC7A1.RESULTSDeficiency of OTC, ASS1 and ASL were seen in 92%, 98% and 93% of pHGG samples (n=156) respectively, with deficiency defined as low

EPCT-03. Working together to accelerate the preclinical to clinical translation of drug delivery systems for children’s brain tumours

Children's brain tumours are the biggest cancer killer in children and young adults. Several techniques, such as intra-cerebrospinal fluid chemotherapy, ultrasound-mediated blood-brain barrier disruption, convection enhanced delivery, polymer delivery systems, electric field therapy, and intra-arterial and intra-nasal chemotherapy, have the potential to transform the treatment of brain tumours in children. However, there have been very few clinical trials to evaluate these. In 2021, the CBTDDC (Children’s Brain Tumour Drug Delivery Consortium) and the ITCC (Innovative Therapies for Children with Cancer) brain tumour group established a Clinical Trials Working Group comprising international researchers and clinicians to address this issue. This partnership highlighted the main challenges in preclinical to clinical translation of paediatric CNS drug delivery as: (1) a lack of specific funding for prototype development and/or scale-up for clinical trials; (2) difficulties in navigating the regulatory landscape; (3) lack of accurate preclinical models; and (4) increased need for multi-centric working. In response to this, we ran a hybrid workshop in November 2021 on ‘Clinical Trial Readiness for CNS Drug Delivery’. At this workshop, around 50 delegates (comprising clinicians, researchers, trial regulatory experts, policy makers, and representatives from funding organisations, brain tumour charities and industry) came together to discuss issues around funding, preclinical models and regulatory processes. We have established speciality-specific working groups to build on the workshop discussions, with the aim of producing recommendations around the use of preclinical models and drug delivery techniques according to brain tumour type. We have also used the workshop presentations and discussions to create a ‘Roadmap’ document for preclinical to clinical translation, which will be freely shared with the neuro-oncology research community. We continue to liaise with funders and regulatory bodies to address the changes that are needed in these areas. If you would like to join our network, contact: [email protected]

EPEN-21. Developing a sensitive method for detection of minimal residual disease in ependymoma using metabolomic analysis of cerebrospinal fluid

Ependymoma (EPN) is the second most common malignant paediatric brain tumour with poor survival and significant neuro-cognitive impairment from current treatments (surgery and radiotherapy). Relapse occurs in 50% of patients within 2 years, despite no evidence of tumour on MRI. This suggests that they have minimal residual disease (MRD) at the end of treatment. Developing an accurate MRD detection method could help select patients who would benefit from further continuation chemotherapy, thereby improving survival. There is also an unmet need for an accurate test to diagnose relapse early when the disease could be more treatable. METHODS: Pilot untargeted liquid chromatography-mass spectrometry (LC-MS) analysis was carried out in cerebrospinal fluid (CSF) samples from patients with ependymoma. CSF from patients in remission from leukemia were used as controls. RESULTS: Pilot data from analysis of CSF using LC-MS demonstrates that this is a feasible approach to characterise CSF metabolomic profile. Also, EPN CSF profile is significantly different from control CSF, with significant elevation of few key metabolites (Vitamin D derivatives and betaine) in EPN CSF compared to control CSF. Immunohistochemical analysis of EPN tumour tissue microarrays confirms the expression of betaine / one-carbon pathway enzymes such as methionine synthase and betaine—homocysteine S-methyltransferase. Further validation of CSF profile with tumour metabolomic profile and serial CSF sample profiling is currently underway. Subgroup-specific differences and targeted analysis to develop a panel of biomarkers is also being explored. CONCLUSION: Early results suggest that CSF-based metabolite profiling using LC-MS is feasible and could help detect minimal residual disease in ependymoma. Further validation is required to analyse subgroup-specific differences and correlate quantitative changes in metabolites with changing disease burden

Phenformin, but not metformin, delays development of T-cell acute lymphoblastic leukemia/lymphoma via cell-autonomous AMPK activation

Summary: AMPK acts downstream of the tumor suppressor LKB1, yet its role in cancer has been controversial. AMPK is activated by biguanides, such as metformin and phenformin, and metformin use in diabetics has been associated with reduced cancer risk. However, whether this is mediated by cell-autonomous AMPK activation within tumor progenitor cells has been unclear. We report that T-cell-specific loss of AMPK-α1 caused accelerated growth of T cell acute lymphoblastic leukemia/lymphoma (T-ALL) induced by PTEN loss in thymic T cell progenitors. Oral administration of phenformin, but not metformin, delayed onset and growth of lymphomas, but only when T cells expressed AMPK-α1. This differential effect of biguanides correlated with detection of phenformin, but not metformin, in thymus. Phenformin also enhanced apoptosis in T-ALL cells both in vivo and in vitro. Thus, AMPK-α1 can be a cell-autonomous tumor suppressor in the context of T-ALL, and phenformin may have potential for the prevention of some cancers. : The roles of AMPK in cancer and of biguanides in its prevention or treatment are controversial. Vara-Ciruelos et al. now report that genetic loss of AMPK in T cells accelerates T cell acute lymphoblastic leukemia/lymphoma, whereas the biguanide phenformin, but not metformin, protects against its development in a cell-autonomous, AMPK-dependent manner. Keywords: AMP-activated protein kinase, AMPK, biguanides, metformin, phenformin, T-ALL, T cell acute lymphoblastic leukemia/lymphom

Characterisation of Aberrant Metabolic Pathways in Hepatoblastoma Using Liquid Chromatography and Tandem Mass Spectrometry (LC-MS/MS)

Hepatoblastoma (HB) is a rare childhood tumour with an evolving molecular landscape. We present the first comprehensive metabolomic analysis using untargeted and targeted liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-MS/MS) of paired tumour and non-tumour surgical samples in HB patients (n = 8 pairs). This study demonstrates that the metabolomic landscape of HB is distinct from that of non-tumour (NT) liver tissue, with 35 differentially abundant metabolites mapping onto pathways such as fatty acid transport, glycolysis, the tricarboxylic acid (TCA) cycle, branched-chain amino acid degradation and glutathione synthesis. Targeted metabolomics demonstrated reduced short-chain acylcarnitines and a relative accumulation of branched-chain amino acids. Medium- and long-chain acylcarnitines in HB were similar to those in NT. The metabolomic changes reported are consistent with previously reported transcriptomic data from tumour and non-tumour samples (49 out of 54 targets) as well as metabolomic data obtained using other techniques. Gene set enrichment analysis (GSEA) from RNAseq data (n = 32 paired HB and NT samples) demonstrated a downregulation of the carnitine metabolome and immunohistochemistry showed a reduction in CPT1a (n = 15 pairs), which transports fatty acids into the mitochondria, suggesting a lack of utilisation of long-chain fatty acids in HB. Thus, our findings suggest a reduced metabolic flux in HB which is corroborated at the gene expression and protein levels. Further work could yield novel insights and new therapeutic targets

Multicentre service evaluation of presentation of newly diagnosed cancers and type 1 diabetes in children in the UK during the COVID-19 pandemic

Background: The COVID-19 pandemic led to changes in patterns of presentation to emergency departments. Child health professionals were concerned that this could contribute to the delayed diagnosis of life-threatening conditions, including childhood cancer (CC) and type 1 diabetes (T1DM). Our multicentre, UK-based service evaluation assessed diagnostic intervals and disease severity for these conditions.Methods: We collected presentation route, timing and disease severity for children with newly diagnosed CC in three principal treatment centres and T1DM in four centres between 1 January and 31 July 2020 and the corresponding period in 2019. Total diagnostic interval (TDI), patient interval (PI), system interval (SI) and disease severity across different time periods were compared.Results: For CCs and T1DM, the route to diagnosis and severity of illness at presentation were unchanged across all time periods. Diagnostic intervals for CCs during lockdown were comparable to that in 2019 (TDI 4.6, PI 1.1 and SI 2.1 weeks), except for an increased PI in January–March 2020 (median 2.7 weeks). Diagnostic intervals for T1DM during lockdown were similar to that in 2019 (TDI 16 vs 15 and PI 14 vs 14 days), except for an increased PI in January–March 2020 (median 21 days).Conclusions: There is no evidence of diagnostic delay or increased illness severity for CC or T1DM, during the first phase of the pandemic across the participating centres. This provides reassuring data for children and families with these life-changing conditions

Evaluation of Pathway to Diagnosis of Pediatric Brain Tumors in Tamil Nadu, India

PurposeDelayed diagnosis and poor awareness are significant barriers to the early intervention of pediatric brain tumors. This multicenter observational study aimed to evaluate the baseline routes and time to diagnosis for pediatric brain tumors in Tamil Nadu (TN), with the goal of promoting early diagnosis and timely referrals in the future.MethodsA standard proforma was used to retrospectively collect information on demographics, diagnosis, referral pathways, and symptoms of incident pediatric brain tumor cases between January 2018 and October 2020 across eight tertiary hospitals in TN. Dates of symptom onset, first presentation of health care, and diagnosis were used to calculate total diagnostic interval (TDI), patient interval (PI), and diagnostic interval (DI).ResultsA total of 144 cases (mean age, 6.64 years; range, 0-15.1 years) were included in the analysis. Among those, 94% (135/144) were from city/district areas, 40% (55/144) were self-referred, and 90% (129/144) had one to three health care professional visits before diagnosis. Median TDI, PI, and DI were 3.5 (IQR, 1-9.3), 0.6 (IQR, 0.1-4.6), and 0.6 (IQR, 0-3.3) weeks, respectively. Low-grade gliomas had the longest median TDI (6.6 weeks), followed by medulloblastomas (4.6 weeks) and high-grade gliomas (3.3 weeks). Average number of symptoms recorded was 1.7 at symptom onset and 1.9 at diagnosis.ConclusionAlthough there are some similarities with data from the United Kingdom, many low-grade and optic pathway tumors were unaccounted for in our study. DIs were relatively short, which suggests that infrastructure may not be a problem in this cohort. Increased training and establishment of proper cancer registries, combined with proper referral pathways, could enhance early diagnosis for these children