Case report of a rare purine synthesis disorder due to 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase (AICAR) deficiency.

BACKGROUND: AICA (5-aminoimidazole-4-carboxamide) ribosiduria is an inborn error in purine biosynthesis caused due to biallelic pathogenic variants in the 5-aminoimidazole-4-carboxamide ribonucleotide-formyltransferase/imp cyclohydrolase (ATIC) gene located on chromosome 2q35. ATIC codes for a bifunctional enzyme, AICAR transformylase and inosine monophosphate (IMP) cyclohydrolase, which catalyse the last two steps of de novo purine synthesis. This disorder has been previously reported in only 4 cases worldwide, and herein, we report the first from India. CASE REPORT: The proband presented with global developmental delay, developmental hip dysplasia (DDH), acyanotic heart disease and nystagmoid eye movements. Whole exome sequencing (WES) identified compound heterozygous pathogenic variants in the ATIC. A novel splice site variant; c.1321-2A > G and a previously reported missense variant; c.1277A > G (p.Lys426Arg) were identified. Segregation analysis of parents showed the father to be a heterozygous carrier for the splice site variant and the mother, a heterozygous carrier for the missense variant. CONCLUSION: This case of a rare genetic disorder of purine biosynthesis of ATIC deficiency is the first case reported from India. Early diagnosis lead to early interventional therapy and genetic counselling.

ATIC facilitates cell growth and migration by upregulating Myc expression in lung adenocarcinoma.

5-Aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC), a catalysing enzyme in the de novo purine biosynthetic pathway, has been previously reported to be upregulated and to participate in myeloma and hepatocellular carcinoma progression. In the present study, by using bioinformatics technology, a higher ATIC expression was identified in lung adenocarcinoma (LUAD) tissues than in normal tissues, and ATIC expression was found to be positively associated with Myc expression in LUAD tissues. In addition, the role of ATIC in modulating the growth and migration of LUAD cells was explored and the involvement of Myc was revealed. ATIC expression in 56 paired LUAD and tumour adjacent non-cancerous tissues was assessed using reverse transcription-quantitative PCR and western blot analysis. Pearson's correlation analysis was applied to evaluate the correlation between ATIC and Myc expression levels in LUAD tissues. A rescue experiment was performed to explore the role of ATIC/Myc in regulating the growth, migration and invasion of HCC827 and NCI-H1435 cells. It was demonstrated that ATIC was overexpressed in LUAD tissues, particularly in advanced-stage LUAD, and was predicted to be associated with an advanced TNM stage, a higher lymph node metastasis rate, poor tissue differentiation and a lower overall survival rate. ATIC overexpression promoted cell growth, migratory and invasive capacities, whereas this effect was abrogated by Myc knockdown in the HCC827 and NCI-H1435 cells. On the whole, the present study demonstrates that ATIC promotes LUAD cell growth and migration by increasing Myc expression.

Hypoxia drives the assembly of the multienzyme purinosome complex.

The purinosome is a dynamic metabolic complex composed of enzymes responsible for de novo purine biosynthesis, whose formation has been associated with elevated purine demand. However, the physiological conditions that govern purinosome formation in cells remain unknown. Here, we report that purinosome formation is up-regulated in cells in response to a low-oxygen microenvironment (hypoxia). We demonstrate that increased purinosome assembly in hypoxic human cells requires the activation of hypoxia inducible factor 1 (HIF-1) and not HIF-2. Hypoxia-driven purinosome assembly was inhibited in cells lacking 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/IMP cyclohydrolase (ATIC), a single enzyme in de novo purine biosynthesis, and in cells treated with a small molecule inhibitor of ATIC homodimerization. However, despite the increase in purinosome assembly in hypoxia, we observed no associated increase in de novo purine biosynthesis in cells. Our results indicate that this was likely due to a reduction in mitochondrial one-carbon metabolism, resulting in reduced mitochondrion-derived one-carbon units needed for de novo purine biosynthesis. The findings of our study further clarify and deepen our understanding of purinosome formation by revealing that this process does not solely depend on cellular purine demand.

Coexistence of a novel CCNY-ALK and ATIC-ALK double-fusion in one patient with ALK-positive NSCLC and response to crizotinib: a case report.

Anaplastic lymphoma kinase (ALK) rearrangement, one of the common oncogene rearrangements in the mutational history of lung adenocarcinoma, occurs in approximately 5% of non-small cell lung cancer (NSCLC) patients who could be effectively treated with ALK tyrosine kinase inhibitors (TKIs). The earlier phase III PROFILE 1014 study has shown that crizotinib, a first-generation ALK-TKI, significantly improved progression-free survival (PFS) compared with platinum-based chemotherapy in patients with previously untreated advanced ALK-positive NSCLC. Thus, clinicians must screen potential candidates for this driver alteration to guide ALK inhibitor therapy with a molecular testing platform capable of capturing all ALK fusions. Echinoderm microtubule-associated proteins, including the EML4 gene, are the most common ALK rearrangement partner. With the widespread use of the next-generation sequencing (NGS) techniques, which could approach enable the simultaneous screening of multiple genetic alterations, increasingly ALK rearrangement partners have been documented. However, the concurrent two ALK rearrangements within the same patient have rarely previously been reported. Here, we describe a novel CCNY-ALK (C1:A20) and ATIC-ALK (A7:A20), coexisting in the same case with poorly differentiated NSCLC and providing evidence of its sensitivity to ALK inhibitors. The newly identified rearrangement partners can be added to the list of ALK rearrangements that occurred in ALK-positive NSCLC, as it could lead to prolonged disease control. Also, while different ALK rearrangement variants might bring differing clinical outcomes, we discuss the impact of the co-mutations of these two ALK rearrangements on the sensitivity to ALK inhibitors. However, the impact of co-mutations on the pathogenesis of NSCLC should be further studied to supply more theoretical insight that co-mutations present for personalized anti-cancer therapy.

Early Treatment of AICAR Protects Hypoxia-ischemia Brain Injury in Neonatal Rats / 医药导报

Objective To investigate the neuroprotective effects and mechanisms of 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/ IMP cyclohydrolase(AICAR) supplement (AMPK activator) in different stages of neonatal rats sufferring from hypoxia-ischemia encephalopathy ( HIE). Methods Neonatal rat hypoxia-ischemia brain injury model was employed in this study. A total of 160 neonatal rats were distributed into five groups: sham, model control,AICAR30 min, AICAR24 h and AICAR72 h. The neuroprotective effects of AICAR supplement (30 min, 24 h, 72 h post operation) were compared by cresyl violet staining; Expressions of P-AMPK,AMPK in the brain tissue were measured by Western blotting.Foot-faults method was used to evaluate the long-term prognosis of the rats. Results Compared with the sham group, the survival of rats brain in model control group was significantly decreased [(100.0± 0.1)% and (45.3± 6.3)%, P0.05). Compared with the sham group, the expression of P-AMPK significantly increased about three times, while ATP level decreased close to the same. Conclusion Early AICAR treatment can protect hypoxia-ischemia brain injury by increasing AMPK-ATP level.