Targeting Isocitrate Dehydrogenase (IDH) in Solid Tumors: Current Evidence and Future Perspectives.

The isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) enzymes are involved in key metabolic processes in human cells, regulating differentiation, proliferation, and oxidative damage response. IDH mutations have been associated with tumor development and progression in various solid tumors such as glioma, cholangiocarcinoma, chondrosarcoma, and other tumor types and have become crucial markers in molecular classification and prognostic assessment. The intratumoral and serum levels of D-2-hydroxyglutarate (D-2-HG) could serve as diagnostic biomarkers for identifying IDH mutant (IDHmut) tumors. As a result, an increasing number of clinical trials are evaluating targeted treatments for IDH1/IDH2 mutations. Recent studies have shown that the focus of these new therapeutic strategies is not only the neomorphic activity of the IDHmut enzymes but also the epigenetic shift induced by IDH mutations and the potential role of combination treatments. Here, we provide an overview of the current knowledge about IDH mutations in solid tumors, with a particular focus on available IDH-targeted treatments and emerging results from clinical trials aiming to explore IDHmut tumor-specific features and to identify the clinical benefit of IDH-targeted therapies and their combination strategies. An insight into future perspectives and the emerging roles of circulating biomarkers and radiomic features is also included.

Evaluations of Biomarkers CDX1 and CDX2 in Gastric Cancer Prognosis: A Meta-analysis.

CDX1 and CDX2 are homeobox-type transcription factors that are potential biomarkers and are associated with prognostic significance in intestinal-type gastric cancer early disease before lymph node metastasis is associated with better prognosis. In addition, the genes IDH 1 and IDH 2 previously known to be involved in brain cancer are implicated in cancer-related molecular signatures as a result new targeted personalized therapies may be possible. Our retrospective study determined the correlation between CDX markers and clinicopathologic data including survival in patients with gastric cancer. This study included studies from 1997 to December 2022 a meta-analysis to provide odds ratios (ORs) and relative risks (RRs). We discussed in detail the impact of IDH 1/2 on the prognosis of gastric cancer outcomes and potential therapeutic strategies. Our meta-analysis included 20 studies identifying 11,163 patients with gastric cancer. We found that CDX 1 overexpression was associated with better overall survival (pooled HR: 1.28) and CDX 2 expression and better 3-year survival (pooled HR: 1.64) and 5-year survival was the pooled HR was correlated 1 94 with both showing statistical correlation. Evidence suggests that IDH 1/2 mutations and CDX 1/2 overexpression are closely associated with metabolic abnormalities epigenetic changes and mutations evidence suggests the potential for novel targeted therapies in gastric cancer. CDX 1/2 overexpression is associated with a favorable prognosis in gastric cancer cases. Further studies are needed to explore the clinical significance of IDH 1/2 mutations and CDX 1/2 expression.

IDH2 mutation accelerates TPO-induced myelofibrosis with enhanced S100a8/a9 and NFκB signaling in vivo.

Introduction: IDH2 mutation is an unfavorable prognostic factor in patients with primary myelofibrosis (PMF) but its effect on myelofibrosis (MF) remains largely unclear. Methods: In this study, we aimed to elucidate the roles of IDH2 mutation in the development and progression of MF by transcriptomic and molecular techniques using the Idh2 R172K transgenic mice. Results: We found that thrombopoietin (TPO)-overexpressed Idh2 R172K (Idh2 R172K + TPO) mice had accelerated progression to MF, compared with TPO-overexpressed Idh2-wild (WT + TPO) mice, showing activation of multiple inflammatory pathways, among which nuclear factor κB (NFκB) was the most significantly enhanced. Single-cell transcriptomes of the marrow cells in early MF showed that S100a8/a9 expression was mainly confined to neutrophil progenitors in the WT + TPO mice, but highly expressed in several types of myeloid precursor cells, including the megakaryocyte progenitors in the Idh2 R172K + TPO group. Furthermore, Idh2 R172K mice at age of 18 months had larger spleens, increased S100a8/a9-Tlr4 expression, and elevated serum S100a8/a9 levels compared with WT mice. PMF patients with IDH2 mutations had higher bone marrow plasma S100A8/A9 levels than those without IDH2 mutations. Conclusion: Overall, our findings showed that IDH2 mutation induced proinflammatory effects, which further exacerbated MF, as evidenced by the increase in S100a8/a9 levels and NFκB hyperactivation in Idh2 R172K + TPO mice.

Circ_0028826 Promotes Growth and Metastasis of NSCLC via Acting as a Sponge of miR-758-3p to Derepress IDH2 Expression.

BACKGROUND: Non-small cell lung cancer (NSCLC) is one of the cancers with the highest mortality and morbidity in the world. Circular RNAs (circRNAs) are newly identified players in carcinogenesis and development of various cancers. This study is aimed at exploring the functional effects and mechanism of circ_0028826 in the development of NSCLC. METHODS: Real-time quantitative PCR (RT-qPCR) was used to detect the expression levels of circ_0028826, IDH2 mRNA, and miR-758-3p. IDH2, Bcl2, Bax, and E-cadherin protein levels were detected using a western blot. Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine (EdU), flow cytometry, wound healing, and transwell assays were used to assess the capacities of proliferation, apoptosis, migration, and invasion. Interaction between miR-758-3p and circ_0028826 or IDH2 was validated using a dual-luciferase reporter assay. The role of circ_0028826 in vivo was checked based on a xenograft tumor model. RESULTS: Circ_0028826 was elevated in NSCLC, and its absence inhibited NSCLC cell proliferation, migration, invasion, and induced apoptosis. In terms of mechanism, circ_0028826 increased IDH2 expression by targeting miR-758-3p. In addition, circ_0028826 knockdown also regulated IDH2 by targeting miR-758-3p to inhibit tumor growth in vivo. CONCLUSION: Circ_0028826 promoted the development of NSCLC via regulation of the miR-758-3p/IDH2 axis, providing a new strategy for NSCLC treatment.

Genomic characterization of AML with aberrations of chromosome 7: a multinational cohort of 519 patients.

BACKGROUND: Deletions and partial losses of chromosome 7 (chr7) are frequent in acute myeloid leukemia (AML) and are linked to dismal outcome. However, the genomic landscape and prognostic impact of concomitant genetic aberrations remain incompletely understood. METHODS: To discover genetic lesions in adult AML patients with aberrations of chromosome 7 [abn(7)], 60 paired diagnostic/remission samples were investigated by whole-exome sequencing in the exploration cohort. Subsequently, a gene panel including 66 genes and a SNP backbone for copy-number variation detection was designed and applied to the remaining samples of the validation cohort. In total, 519 patients were investigated, of which 415 received intensive induction treatment, typically containing a combination of cytarabine and anthracyclines. RESULTS: In the exploration cohort, the most frequently mutated gene was TP53 (33%), followed by epigenetic regulators (DNMT3A, KMT2C, IDH2) and signaling genes (NRAS, PTPN11). Thirty percent of 519 patients harbored ≥ 1 mutation in genes located in commonly deleted regions of chr7-most frequently affecting KMT2C (16%) and EZH2 (10%). KMT2C mutations were often subclonal and enriched in patients with del(7q), de novo or core-binding factor AML (45%). Cancer cell fraction analysis and reconstruction of mutation acquisition identified TP53 mutations as mainly disease-initiating events, while del(7q) or -7 appeared as subclonal events in one-third of cases. Multivariable analysis identified five genetic lesions with significant prognostic impact in intensively treated AML patients with abn(7). Mutations in TP53 and PTPN11 (11%) showed the strongest association with worse overall survival (OS, TP53: hazard ratio [HR], 2.53 [95% CI 1.66-3.86]; P < 0.001; PTPN11: HR, 2.24 [95% CI 1.56-3.22]; P < 0.001) and relapse-free survival (RFS, TP53: HR, 2.3 [95% CI 1.25-4.26]; P = 0.008; PTPN11: HR, 2.32 [95% CI 1.33-4.04]; P = 0.003). By contrast, IDH2-mutated patients (9%) displayed prolonged OS (HR, 0.51 [95% CI 0.30-0.88]; P = 0.0015) and durable responses (RFS: HR, 0.5 [95% CI 0.26-0.96]; P = 0.036). CONCLUSION: This work unraveled formerly underestimated genetic lesions and provides a comprehensive overview of the spectrum of recurrent gene mutations and their clinical relevance in AML with abn(7). KMT2C mutations are among the most frequent gene mutations in this heterogeneous AML subgroup and warrant further functional investigation.

IDH1 and IDH2 Gene Mutations in Omani Patients with Acute Myeloid Leukemia: Prognostic Significance and Clinic-pathologic Features.

Objectives: We sought to define the prevalence of isocitrate dehydrogenase (IDH) mutations, evaluate the clinicopathologic impact of IDH mutations, assess the effect of IDH mutations on the response to the currently offered treatment for acute myeloid leukemia (AML) cases, and determine the impact of other common concurrent mutations with IDH. Methods: A single-center retrospective cohort study was conducted at Sultan Qaboos University Hospital (SQUH) from October 2009 to October 2019. We included all Omani patients (pediatric and adult) treated at SQUH with the standard therapy, for whom DNA extraction was performed at diagnosis. The target mutations in both IDH1 and IDH2 genes were screened using the direct polymerase chain reaction product sequencing method. Statistical analysis was conducted using SPSS software. Survival differences were estimated using the log-rank test. Continuous variables were presented as median (IQRs), while categorical variables were presented as frequency. Results: A total of 61 patients treated, for whom DNA extraction was performed at diagnosis were evaluated. The median age was 40 (range = 25.5-65.5). The prevalence of IDH1 R132, IDH2 R140, and IDH2 R172 mutations among the study group was 6.6%, 3.3%, and 1.6%, respectively. Clinicopathologic characteristics associated with IDH mutations at diagnosis included older age, lower white blood cell count, higher median platelet counts, normal karyotype AML, and cytogenetics intermediate-risk group. The overall survival (OS) in patients harboring IDH mutations was poor, with a median OS of nine months. This analysis confirms that the response rate and OS for both IDH-mutated and IDH wild-type AML patients were comparable. This will provide contemporary data to be used for comparison with the results of novel investigational (e.g., selective IDH inhibitor) strategies. Conclusions: The current study results were consistent with the other international studies of IDH mutations in AML and demonstrate the poor prognosis associated with IDH mutations. Clinicopathologic features associated with IDH mutations included older age, lower white blood cell count, higher median platelet counts, normal karyotype AML, and cytogenetics intermediate-risk group.

Epigenetic dysregulation in cancers by isocitrate dehydrogenase 2 (IDH2).

Recent advances in genome-wide studies have revealed numerous epigenetic regulations brought about by genes involved in cellular metabolism. Isocitrate dehydrogenase (IDH), an essential enzyme, that converts isocitrate into -ketoglutarate (KG) predominantly in the tricarboxylic acid (TCA) cycle, has gained particular importance due to its cardinal role in the metabolic pathway in cells. IDH1, IDH2, and IDH3 are the three isomeric IDH enzymes that have been shown to regulate cellular metabolism. Of particular importance, IDH2 genes are associated with several cancers, including gliomas, oligodendroglioma, and astrocytomas. These mutations lead to the production of oncometabolite D-2-hydroxyglutarate (D-2-HG), which accumulates in cells promoting tumor growth. The enhanced levels of D-2-HG competitively inhibit α-KG dependent enzymes, inhibiting cell TCA cycle, upregulating the cell growth and survival relevant HIF-1α pathway, promoting DNA hypermethylation related epigenetic activity, all of which synergistically contribute to carcinogenesis. The present review discusses epigenetic mechanisms inIDH2 regulation in cells and further its clinical implications.

Synthetic lethality between toxic amino acids, RTG-target genes and chaperones in Saccharomyces cerevisiae.

The toxicity of non-proteinogenic amino acids has been known for decades. Numerous reports describe their antimicrobial/anticancer potential. However, these molecules are often toxic to the host as well; thus, a synthetic lethality approach that reduces the dose of these toxins while maintaining toxicity can be beneficial. Here we investigate synthetic lethality between toxic amino acids, the retrograde pathway, and molecular chaperones. In Saccharomyces cerevisiae, mitochondrial retrograde (RTG) pathway activation induces transcription of RTG-target genes to replenish alpha-ketoglutarate and its downstream product glutamate; both metabolites are required for arginine and lysine biosynthesis. We previously reported that tolerance of canavanine, a toxic arginine derivative, requires an intact RTG pathway, and low-dose canavanine exposure reduces the expression of RTG-target genes. Here we show that only a few of the examined chaperone mutants are sensitive to sublethal doses of canavanine. To predict synthetic lethality potential between RTG-target genes and chaperones, we measured the expression of RTG-target genes in canavanine-sensitive and canavanine-tolerant chaperone mutants. Most RTG-target genes were induced in all chaperone mutants starved for arginine; the same trend was not observed under lysine starvation. Canavanine exposure under arginine starvation attenuated and even reversed RTG-target-gene expression in the tested chaperone mutants. Importantly, under nearly all tested genetic and pharmacological conditions, the expression of IDH1 and/or IDH2 was induced. In agreement, idh1 and idh2 mutants are sensitive to canavanine and thialysine and show synthetic growth inhibition with chaperone mutants. Overall, we show that inhibiting molecular chaperones, RTG-target genes, or both can sensitize cells to low doses of toxic amino acids.

Methylation-Based Characterization of a New IDH2 Mutation in Sinonasal Undifferentiated Carcinoma.

Mutations affecting codon 172 of the isocitrate dehydrogenase 2 (IDH2) gene define a subgroup of sinonasal undifferentiated carcinomas (SNUCs) with a relatively favorable prognosis and a globally hypermethylated phenotype. They are also recurrent (along with IDH1 mutations) in gliomas, acute myeloid leukemia, and intrahepatic cholangiocarcinoma. Commonly reported mutations, all associated with aberrant IDH2 enzymatic activity, include R172K, R172S, R172T, R172G, and R172M. We present a case of SNUC with a never-before-described IDH2 mutation, R172A. Our report compares the methylation pattern of our sample to other cases from the Gene Expression Omnibus database. Hierarchical clustering suggests a strong association between our sample and other IDH-mutant SNUCs and a clear distinction between sinonasal normal tissues and tumors. Principal component analysis (PCA), using 100 principal components explaining 94.5% of the variance, showed the position of our sample to be within 1.02 standard deviation of the other IDH-mutant SNUCs. A molecular modeling analysis of the IDH2 R172A versus other R172 variants provides a structural explanation to how they affect the protein active site. Our findings thus suggest that the R172A mutation in IDH2 confers a gain of function similar to other R172 mutations in IDH2, resulting in a similar hypermethylated profile.

Identifying Targetable Vulnerabilities to Circumvent or Overcome Venetoclax Resistance in Diffuse Large B-Cell Lymphoma.

Clinical trials with single-agent venetoclax/ABT-199 (anti-apoptotic BCL2 inhibitor) revealed that diffuse large B-cell lymphoma (DLBCL) is not solely dependent on BCL2 for survival. Gaining insight into pathways/proteins that increase venetoclax sensitivity or unique vulnerabilities in venetoclax-resistant DLBCL would provide new potential treatment avenues. Therefore, we generated acquired venetoclax-resistant DLBCL cells and evaluated these together with intrinsically venetoclax-resistant and -sensitive DLBCL lines. We identified resistance mechanisms, including alterations in BCL2 family members that differed between intrinsic and acquired venetoclax resistance and increased dependencies on specific pathways. Although combination treatments with BCL2 family member inhibitors may overcome venetoclax resistance, RNA-sequencing and drug/compound screens revealed that venetoclax-resistant DLBCL cells, including those with TP53 mutation, had a preferential dependency on oxidative phosphorylation. Mitochondrial electron transport chain complex I inhibition induced venetoclax-resistant, but not venetoclax-sensitive, DLBCL cell death. Inhibition of IDH2 (mitochondrial redox regulator) synergistically overcame venetoclax resistance. Additionally, both acquired and intrinsic venetoclax-resistant DLBCL cells were similarly sensitive to inhibitors of transcription, B-cell receptor signaling, and class I histone deacetylases. These approaches were also effective in DLBCL, follicular, and marginal zone lymphoma patient samples. Our results reveal there are multiple ways to circumvent or overcome the diverse venetoclax resistance mechanisms in DLBCL and other B-cell lymphomas and identify critical targetable pathways for future clinical investigations.

Rationale design of novel substituted 1,3,5-triazine candidates as dual IDH1(R132H)/ IDH2(R140Q) inhibitors with high selectivity against acute myeloid leukemia: In vitro and in vivo preclinical investigations.

In this study, novel substituted 1,3,5-triazine candidates (4a-d, 5a-j, and 6a-d) were designed as second-generation small molecules to act as dual IDH1 and IDH2 inhibitors according to the pharmacophoric features of both vorasidenib and enasidenib. Compounds 6a and 6b for leukemia cell lines showed from low to sub-micromolar GI50. Moreover, compounds 4c, 5f, and 6b described the frontier antitumor activity against THP1 and Kasumi Leukemia cancer cells with IC50 values of (10 and 12), (10.5 and 7), and (6.2 and 5.9) µg/mL, which were superior to those of cisplatin (25 and 28) µg/mL, respectively. Interestingly, compounds 4c, 6b, and 6d represented the best dual IDH1(R132H)/IDH2(R140Q) inhibitory potentials with IC50 values of (0.72 and 1.22), (0.12 and 0.93), and (0.50 and 1.28) µg/mL, respectively, compared to vorasidenib (0.02 and 0.08) µg/mL and enasidenib (0.33 and 1.80) µg/mL. Furthermore, the most active candidate (6b) has very promising inhibitory potentials towards HIF-1α, VEGF, and SDH, besides, a marked increase of ROS was observed as well. Besides, compound 6b induced the upregulation of P53, BAX, Caspases 3, 6, 8, and 9 proteins by 3.70, 1.99, 2.06, 1.73, 1.75, and 1.85-fold changes, respectively, and the downregulation for the BCL-2 protein by 0.55-fold change compared to the control. Besides, the in vivo behavior of compound 6b as an antitumor agent was evaluated in female mice bearing solid Ehrlich carcinoma tumors. Notably, compound 6b administration resulted in a prominent decrease in the weight and volume of the tumors, accompanied by improvements in biochemical, hematological, and histological parameters.

Enasidenib-induced hepatitis in an individual with Type II D2-hydroxyglutaric aciduria.

Type II D-2-Hydroxyglutaric aciduria (T2D2HGA) is caused by a gain-of-function pathogenic variant in Isocitrate Dehydrogenase 2 (IDH2). Patients with T2D2HGA commonly present with developmental delay, seizures, cardiomyopathy, and arrhythmias. The recently approved IDH2-inhibitor Enasidenib targets the p.Arg140Gln pathogenic IDH2 variant and decreases production of D2HGA. We present a 7-year-old female with T2D2HGA due to the p.Arg140Gln variant. She was diagnosed at 3-years-old after presenting with global developmental delay, leukoencephalopathy, communicating hydrocephalus, seizures, and dilated cardiomyopathy. At age 3 years 11 months, 50 mg Enasidenib daily was initiated. Primary outcomes included seizure frequency, hospital admissions, development, and cardiac structure. Laboratories were monitored biweekly for common Enasidenib side effects. Our patient tolerated Enasidenib well. Urine 2-HGA decreased significantly from 244 mg/g creatinine to undetectable within 2 weeks of treatment. Inpatient admissions decreased from 8 during the 2 years preceding treatment to 1 during treatment. She has been seizure-free since Enasidenib initiation. Echocardiography showed improvement in dilated cardiomyopathy with normal left ventricular systolic function. Developmental assessment demonstrated improvements in gross motor, fine motor, language, and socialization domains. Treatment was complicated by mild elevations in alanine transaminase (118 IU/L, range 0-28) and creatine kinase (334 U/L, range 45-198) that resolved by decreasing Enasidenib dosing frequency to three times weekly. Enasidenib is a viable treatment for Type II D2HGA with benefits including developmental gains, fewer acute medical interventions, and cardiomyopathy improvement. While drug-induced hepatitis is a novel adverse effect of Enasidenib, it can be ameliorated by decreasing dose frequency.

A comprehensive case study on successful multimodal therapy in philadelphia chromosome-positive acute myeloid leukemia with NPM1 and IDH2 mutations.

A 67-year-old female came to Tampa General Hospital with Philadelphia chromosome-positive (Ph+) acute myeloid leukemia (AML) featuring an intriguing combination of mutations, including NPM1 and IDH2 mutations. Novel combination therapy with azacitidine, venetoclax and ponatinib allowed her to successfully achieve a complete response (CR) and undergo an allogeneic hematopoietic stem cell transplant (HSCT). This case report provides an overview of her clinical course, emphasizing the significance of integrated therapy and the challenges associated with balancing treatment for AML. It also underscores the importance of a multidisciplinary approach and careful monitoring of patients with complex hematologic conditions.

Evaluation of the rapid Idylla IDH1-2 mutation assay in FFPE glioma samples.

IDH1 and IDH2 mutational status is a critical biomarker with diagnostic, prognostic, and treatment implications in glioma. Although IDH1 p.R132H-specific immunohistochemistry is available, it is unable to identify other mutations in IDH1/2. Next-generation sequencing can accurately determine IDH1/2 mutational status but suffers from long turnaround time when urgent treatment planning and initiation is medically necessary. The Idylla assay can detect IDH1/2 mutational status from unstained formalin-fixed paraffin-embedded (FFPE) slides in as little as a few hours. In a clinical validation, we demonstrate clinical accuracy of 97% compared to next-generation sequencing. Sensitivity studies demonstrated a limit of detection of 2.5-5% variant allele frequency, even at DNA inputs below the manufacturer's recommended threshold. Overall, the assay is an effective and accurate method for rapid determination of IDH1/2 mutational status.

Somatic gene mutation patterns and burden influence outcomes with enasidenib in relapsed/refractory IDH2-mutated AML.

Limited treatment options are available for patients with relapsed/refractory acute myeloid leukemia (R/R AML). We recently reported results from the phase 3 IDHENTIFY trial (NCT02577406) showing improved response rates and event-free survival with enasidenib monotherapy compared with conventional care regimens (CCR) in heavily pretreated, older patients with late-stage R/R AML bearing IDH2 mutations. Here we investigated the prognostic impact of mutational burden and different co-mutation patterns at study entry within the predominant IDH2 variant subclasses, IDH2-R140 and IDH2-R172. The prognostic relevance of these variants is well documented in newly diagnosed AML, but data are lacking in R/R AML. In this large R/R AML patient cohort, targeted next-generation sequencing at baseline (screening) revealed distinct co-mutation patterns and mutational burden between subgroups bearing different IDH2 variants: variant IDH2-R140 was associated with greater mutational burden and was enriched predominantly with poor-risk mutations, including FLT3, RUNX1, and NRAS, while variant IDH2-R172 was associated with lower mutational burden and was preferentially co-mutated with DNMT3A. In multivariable analyses, RAS and RTK pathway mutations were significantly associated with decreased overall survival, after adjusting for treatment arm, IDH2 variant, and mutational burden. Importantly, enasidenib-mediated survival benefit was more pronounced in patients with IDH2-R172 variants.

A personalized medicine approach identifies enasidenib as an efficient treatment for IDH2 mutant chondrosarcoma.

BACKGROUND: Sarcomas represent an extensive group of malignant diseases affecting mesodermal tissues. Among sarcomas, the clinical management of chondrosarcomas remains a complex challenge, as high-grade tumours do not respond to current therapies. Mutations in the isocitrate dehydrogenase (IDH) 1 and 2 genes are among the most common mutations detected in chondrosarcomas and may represent a therapeutic opportunity. The presence of mutated IDH (mIDH) enzymes results in the accumulation of the oncometabolite 2-HG leading to molecular alterations that contribute to drive tumour growth. METHODS: We developed a personalized medicine strategy based on the targeted NGS/Sanger sequencing of sarcoma samples (n = 6) and the use of matched patient-derived cell lines as a drug-testing platform. The anti-tumour potential of IDH mutations found in two chondrosarcoma cases was analysed in vitro, in vivo and molecularly (transcriptomic and DNA methylation analyses). FINDINGS: We treated several chondrosarcoma models with specific mIDH1/2 inhibitors. Among these treatments, only the mIDH2 inhibitor enasidenib was able to decrease 2-HG levels and efficiently reduce the viability of mIDH2 chondrosarcoma cells. Importantly, oral administration of enasidenib in xenografted mice resulted in a complete abrogation of tumour growth. Enasidenib induced a profound remodelling of the transcriptomic landscape not associated to changes in the 5 mC methylation levels and its anti-tumour effects were associated with the repression of proliferative pathways such as those controlled by E2F factors. INTERPRETATION: Overall, this work provides preclinical evidence for the use of enasidenib to treat mIDH2 chondrosarcomas. FUNDING: Supported by the Spanish Research Agency/FEDER (grants PID2022-142020OB-I00; PID2019-106666RB-I00), the ISC III/FEDER (PI20CIII/00020; DTS18CIII/00005; CB16/12/00390; CB06/07/1009; CB19/07/00057); the GEIS group (GEIS-62); and the PCTI (Asturias)/FEDER (IDI/2021/000027).

Isocitrate dehydrogenase 2 regulates the proliferation of triple-negative breast cancer through the ferroptosis pathway.

Triple-negative breast cancer (TNBC) is currently the type of breast cancer with the worst prognosis; it lacks specific treatments, such as ER/PR antagonistic endocrine and anti-HER2 targeted therapies. Although immunotherapy with immune checkpoints has shown some efficacy in many solid tumors, clinical data in TNBC suggest significant limitations. The essence of ferroptosis is the impaired metabolism of intracellular lipid oxides, which in turn causes the activation and abnormalities of the immune system, including ROS, and not only plays an important role in liver injury and organ aging but also a large amount of data points to the close correlation between the ferroptosis process and tumor development. In this study, through the analysis of large-throughput biological data of breast tumors, combined with the characteristics of the biological process of ferroptosis, the specific gene IDH2 was found to be significantly highly expressed in TNBC and functionally correlated with ferroptosis. Through clinical specimens validated at the gene and protein levels, in vitro tumor cell line validation, and in vivo mouse models, we found that the high expression of IDH2 in TNBC has a role in inhibiting the ferroptosis process in TNBC, thus promoting the proliferation of TNBC cells and other malignant features.

Aggressive renal cell carcinoma with biphasic papillary and solid clear cell features harboring IDH2 (R172M) mutation.

Renal cell carcinoma (RCC) is fundamentally a metabolic disease, and RCC associated with mutation of the Krebs cycle enzyme genes include fumarate hydratase-deficient and succinate dehydrogenase-deficient RCC. Most recently, the mutation of isocitrate dehydrogenase 2 (IDH2) has been suggested as the third Krebs cycle enzyme alteration to be associated with oncometabolite-induced RCC tumorigenesis. Herein, we report the second case of RCC harboring an IDH2 (R127M) mutation identified by targeted next-generation sequencing and further confirmed by reverse transcription polymerase chain reaction and Sanger sequencing. This tumor demonstrated a distinctive biphasic morphology, characterized by mixture of a clear cells solid component and an eosinophilic papillary component. These two components were intermingled and formed variably sized nodular or nested structures. Unfavorable histologic features, including infiltration into the perirenal and renal sinus adipose tissues, high nuclei grade, rhabdoid tumor cells, and focal tumor necrosis, were observed. The patient had local lymph nodes metastases at diagnosis and developed brain metastases 3 months after the surgery. This peculiar case provides further insights into RCCs harboring IDH2 mutations.

LINC00571 drives tricarboxylic acid cycle metabolism in triple-negative breast cancer through HNRNPK/ILF2/IDH2 axis.

BACKGROUND: Triple-negative breast cancer is a complex breast malignancy subtype characterized by poor prognosis. The pursuit of effective therapeutic approaches for this subtype is considerably challenging. Notably, recent research has illuminated the key role of the tricarboxylic acid cycle in cancer metabolism and the complex landscape of tumor development. Concurrently, an emerging body of evidence underscores the noteworthy role that long non-coding RNAs play in the trajectory of breast cancer development. Despite this growing recognition, the exploration of whether long non-coding RNAs can influence breast cancer progression by modulating the tricarboxylic acid cycle has been limited. Moreover, the underlying mechanisms orchestrating these interactions have not been identified. METHODS: The expression levels of LINC00571 and IDH2 were determined through the analysis of the public TCGA dataset, transcriptome sequencing, qRT‒PCR, and Western blotting. The distribution of LINC00571 was assessed using RNA fluorescence in situ hybridization. Alterations in biological effects were evaluated using CCK-8, colony formation, EdU, cell cycle, and apoptosis assays and a tumor xenograft model. To elucidate the interaction between LINC00571, HNRNPK, and ILF2, RNA pull-down, mass spectrometry, coimmunoprecipitation, and RNA immunoprecipitation assays were performed. The impacts of LINC00571 and IDH2 on tricarboxylic acid cycle metabolites were investigated through measurements of the oxygen consumption rate and metabolite levels. RESULTS: This study revealed the complex interactions between a novel long non-coding RNA (LINC00571) and tricarboxylic acid cycle metabolism. We validated the tumor-promoting role of LINC00571. Mechanistically, LINC00571 facilitated the interaction between HNRNPK and ILF2, leading to reduced ubiquitination and degradation of ILF2, thereby stabilizing its expression. Furthermore, ILF2 acted as a transcription factor to enhance the expression of its downstream target gene IDH2. CONCLUSIONS: Our study revealed that the LINC00571/HNRNPK/ILF2/IDH2 axis promoted the progression of triple-negative breast cancer by regulating tricarboxylic acid cycle metabolites. This discovery provides a novel theoretical foundation and new potential targets for the clinical treatment of triple-negative breast cancer.

D-mannose promotes the degradation of IDH2 through upregulation of RNF185 and suppresses breast cancer.

BACKGROUND: D-mannose, an epimer of glucose, which is abundant in some fruits, such as cranberry, has been previously reported to inhibit urinary tract infection. In recent years, the potential function of D-mannose has been broadened into the regulation of other inflammation diseases and cancer. It was reported that D-mannose can increase reactive oxygen species (ROS) production, while IDH2 is important for the generation of NADPH, the crucial reducing factor. These findings prompted us to determine whether D-mannose can regulate IDH2 and IDH2-mediated NADPH production in tumor. METHODS: The breast cancer cell line MDA-MB-231 was cultured and treated with 100mM D-mannose. IDH2 expression was detected by Western Blot and qRT-PCR. RNA-seq was conducted to identify the differentially expressed genes. BioGRID database was used to find the IDH2 interactors. Tumor cells were collected to measure the NADPH production using the NADP+/NADPH detection Kit. Colony formation assay and CCK-8 assay were conducted to evaluate the proliferation of cells. RESULTS: D-mannose can promote IDH2 protein degradation through ubiquitination-proteasome pathway. Mechanistically, D-mannose treatment upregulated the expression of an E3 ligase - RNF185, which can interact with IDH2 and promotes its proteasomal degradation. Consequently, IDH2-mediated NADPH production was inhibited by D-mannose, the proliferation of breast cancer cells was retarded, and the sensitivity to pro-oxidant of breast cancer cells was elevated. CONCLUSIONS: Our study demonstrated that D-mannose can degrade IDH2 and inhibit the production of NADPH to suppress the proliferation of breast cancer cells and render the breast cancer cells more sensitive to pro-oxidant treatment. Furthermore, we illustrated the E3 ligase RNF185 plays an important role in D-mannose-mediated proteasomal degradation of IDH2.