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PubMed1997

Mutational analysis of a fatty acyl-coenzyme A synthetase signature motif identifies seven amino acid residues that modulate fatty acid substrate specificity.

Fatty acyl-CoA synthetase (fatty acid:CoA ligase, AMP-forming; EC 6.2.1.3) catalyzes the formation of fatty acyl-CoA by a two-step process that proceeds through the hydrolysis of pyrophosphate. In Escherichia coli this enzyme plays a pivotal role in the uptake of long chain fatty acids (C12-C18) and in the regulation of the global transcriptional regulator FadR. The E. coli fatty acyl-CoA synthetase has remarkable amino acid similarities and identities to the family of both prokaryotic and eukaryotic fatty acyl-CoA synthetases, indicating a common ancestry. Most notable in this regard is a 25-amino acid consensus sequence, DGWLHTGDIGXWXPXGXLKIIDRKK, common to all fatty acyl-CoA synthetases for which sequence information is available. Within this consensus are 8 invariant and 13 highly conserved amino acid residues in the 12 fatty acyl-CoA synthetases compared. We propose that this sequence represents the fatty acyl-CoA synthetase signature motif (FACS signature motif). This region of fatty acyl-CoA synthetase from E. coli, 431NGWLHTGDIAVMDEEGFLRIVDRKK455, contains 17 amino acid residues that are either identical or highly conserved to the FACS signature motif. Eighteen site-directed mutations within the fatty acyl-CoA synthetase structural gene (fadD) corresponding to this motif were constructed to evaluate the contribution of this region of the enzyme to catalytic activity. Three distinct classes of mutations were identified on the basis of growth characteristics on fatty acids, enzymatic activities using cell extracts, and studies using purified wild-type and mutant forms of the enzyme: 1) those that resulted in either wild-type or nearly wild-type fatty acyl-CoA synthetase activity profiles; 2) those that had little or no enzyme activity; and 3) those that resulted in lowering and altering fatty acid chain length specificity. Among the 18 mutants characterized, 7 fall in the third class. We propose that the FACS signature motif is essential for catalytic activity and functions in part to promote fatty acid chain length specificity and thus may compose part of the fatty acid binding site within the enzyme.

Amino Acid Sequence↗

PubMed2005

Molecular classification of papillary thyroid carcinoma: distinct BRAF, RAS, and RET/PTC mutation-specific gene expression profiles discovered by DNA microarray analysis.

Thyroid cancer poses a significant clinical challenge, and our understanding of its pathogenesis is incomplete. To gain insight into the pathogenesis of papillary thyroid carcinoma, transcriptional profiles of four normal thyroids and 51 papillary carcinomas (PCs) were generated using DNA microarrays. The tumors were genotyped for their common activating mutations: BRAF V600E point mutation, RET/PTC1 and 3 rearrangement and point mutations of KRAS, HRAS and NRAS. Principal component analysis based on the entire expression data set separated the PCs into three groups that were found to reflect tumor morphology and mutational status. By combining expression profiles with mutational status, we defined distinct expression profiles for the BRAF, RET/PTC and RAS mutation groups. Using small numbers of genes, a simple classifier was able to classify correctly the mutational status of all 40 tumors with known mutations. One tumor without a detectable mutation was predicted by the classifier to have a RET/PTC rearrangement and was shown to contain one by fluorescence in situ hybridization analysis. Among the mutation-specific expression signatures were genes whose differential expression was a direct consequence of the mutation, as well as genes involved in a variety of biological processes including immune response and signal transduction. Expression of one mutation-specific differentially expressed gene, TPO, was validated at the protein level using immunohistochemistry and tissue arrays containing an independent set of tumors. The results demonstrate that mutational status is the primary determinant of gene expression variation within these tumors, a finding that may have clinical and diagnostic significance and predicts success for therapies designed to prevent the consequences of these mutations.

Base Sequence↗

PubMed2005

A unique gene expression signature discriminates familial Alzheimer's disease mutation carriers from their wild-type siblings.

Alzheimer's disease (AD) is a neurodegenerative disease with an insidious onset and progressive course that inevitably leads to death. The current diagnostic tools do not allow for diagnosis until the disease has lead to irreversible brain damage. Genetic studies of autosomal dominant early onset familial AD has identified three causative genes: amyloid precursor protein (APP), presenilin 1 and 2 (PSEN1 and PSEN2). We performed a global gene expression analysis on fibroblasts from 33 individuals (both healthy and demented mutation carriers as well as wild-type siblings) from three families segregating the APP(SWE), APP(ARC) and PSEN1 H163Y mutations, respectively. The mutations cause hereditary progressive cognitive disorder, including typical autosomal dominant AD. Our data show that the mutation carriers share a common gene expression profile significantly different from that of their wild-type siblings. The results indicate that the disease process starts several decades before the onset of cognitive decline, suggesting that presymptomatic diagnosis of AD and other progressive cognitive disorders may be feasible in the near future.

Alzheimer Disease↗

PubMed2003

Mutation causing severe myasthenia reveals functional asymmetry of AChR signature cystine loops in agonist binding and gating.

We describe a highly disabling congenital myasthenic syndrome (CMS) associated with rapidly decaying, low-amplitude synaptic currents, and trace its cause to a valine to leucine mutation in the signature cystine loop (cys-loop) of the AChR alpha subunit. The recently solved crystal structure of an ACh-binding protein places the cys-loop at the junction between the extracellular ligand-binding and transmembrane domains where it may couple agonist binding to channel gating. We therefore analyzed the kinetics of ACh-induced single-channel currents to identify elementary steps in the receptor activation mechanism altered by the alphaV132L mutation. The analysis reveals that alphaV132L markedly impairs ACh binding to receptors in the resting closed state, decreasing binding affinity for the second binding step 30-fold, but attenuates gating efficiency only about twofold. By contrast, mutation of the equivalent valine residue in the delta subunit impairs channel gating approximately fourfold with little effect on ACh binding, while corresponding mutations in the beta and epsilon subunits are without effect. The unique functional contribution of the alpha subunit cys-loop likely owes to its direct connection via a beta strand to alphaW149 at the center of the ligand-binding domain. The overall findings reveal functional asymmetry between cys-loops of the different AChR subunits in contributing to ACh binding and channel gating.

Acetylcholine↗

PubMed2005

Mutations in nucleophosmin (NPM1) in acute myeloid leukemia (AML): association with other gene abnormalities and previously established gene expression signatures and their favorable prognostic significance.

Mutations in nucleophosmin NPM1 are the most frequent acquired molecular abnormalities in acute myeloid leukemia (AML). We determined the NPM1 mutation status in a clinically and molecularly well-characterized patient cohort of 275 patients with newly diagnosed AML by denaturing high-performance liquid chromatography (dHPLC). We show that NPM1 mutations are significantly underrepresented in patients younger than 35 years. NPM1 mutations positively correlate with AML with high white blood cell counts, normal karyotypes, and fms-like tyrosine kinase-3 gene (FLT3) internal tandem duplication (ITD) mutations. NPM1 mutations associate inversely with the occurrence of CCAAT/enhancer-binding protein-alpha (CEBPA) and NRAS mutations. With respect to gene expression profiling, we show that AML cases with an NPM1 mutation cluster in specific subtypes of AML with previously established gene expression signatures, are highly associated with a homeobox gene-specific expression signature, and can be predicted with high accuracy. We demonstrate that patients with intermediate cytogenetic risk AML without FLT3 ITD mutations but with NPM1 mutations have a significantly better overall survival (OS) and event-free survival (EFS) than those without NPM1 mutations. Finally, in multivariable analysis NPM1 mutations express independent favorable prognostic value with regard to OS, EFS, and disease-free survival (DFS).

Acute Disease↗

PubMed2003

Mutation analysis in congenital Long QT Syndrome--a case with missense mutations in KCNQ1 and SCN5A.

Long QT Syndrome (LQTS) is a cardiac disease characterized by a prolonged QT interval on a surface electrocardiogram (ECG) and by clinical symptoms such as seizures, syncope, and cardiac sudden death. At present, causal mutations of LQTS have been identified in five cardiac ion-channel genes. Because a causal mutation is usually unique to a specific family and can be located in any region of any of these five genes, a mutation analysis effort may require screening of the complete coding regions of each of these genes. The causative nature of a detected mutation can then be determined either by family history or by functional studies, such as the electrophysiological signature of the mutation. Here we describe a mutation analysis of an LQTS patient who carries two heterozygous missense mutations in two different LQTS genes. The first mutation identified, A572D in SCN5A, was not linked with clinical LQTS features in the two other mutation carriers in the family; neither was it identified in 90 healthy controls. Therefore, this mutation most likely has either a mild effect on cardiac ion-channel function or represents a very rare polymorphism. The second mutation, V254M in KCNQ1, co-segregated with higher QT intervals and symptoms in other family members, and was previously reported in another LQTS family. Because the clinical LQTS symptoms are most pronounced in the proband, a combined effect of both mutations cannot be excluded, although no functional data are available to support such an hypothesis. We conclude that, for newly presented LQTS cases, a mutation analysis strategy should routinely screen the complete coding region of all LQTS genes, followed by an evaluation of the identified mutation(s) in conjunction with family or functional data.

Child↗

PubMed2000

Frequency of antiretroviral drug resistance mutations in HIV-1 strains from patients failing triple drug regimens. The Terry Beirn Community Programs for Clinical Research on AIDS.

The frequency of protease and reverse transcriptase (RT) gene mutations was determined in HIV-1 strains from 153 patients entering the CPCRA 046 (GART) study who were failing triple-drug regimens consisting of one protease inhibitor (PI) and two RT inhibitors. Population-based sequence analyses showed that nearly all patients had similar RT gene mutations regardless of prior drug exposure, although the M184V mutation was significantly less prevalent in patients not recently treated with lamivudine. Whilst typical inhibitor-specific ('signature') protease gene mutations were found in patients failing their first PI, these mutations were significantly less likely to be found in patients exposed to two or more PIs. Protease gene mutations associated with multi-PI resistance were more likely to be observed in patients treated with more than one PI. These results suggest sequential treatment with PIs select for a relatively limited number of protease gene mutations that likely originated during early PI therapy. These protease gene mutations and a similarly limited set of RT gene mutations appear to be responsible for treatment failure in antiretroviral therapy.

Anti-HIV Agents↗

PubMed2001

UV-induced DNA damage and mutations in Hupki (human p53 knock-in) mice recapitulate p53 hotspot alterations in sun-exposed human skin.

The major etiological agent contributing to human nonmelanoma skin cancer is sunlight. The p53 tumor suppressor gene is usually mutated in these tumors, and the mutations are "UV signature" single or tandem transitions at dipyrimidine sequences in the DNA-binding domain (DBD). Cells that harbor these characteristic mutations are already present in sun-exposed skin areas of healthy individuals, and small epidermal patches that are immunoreactive to anti-p53 antibody accrue as exposure increases. To explore carcinogen-specific human p53 mutation patterns experimentally, we generated a knock-in (Hupki) mouse in which the murine DBD of the p53 gene has been replaced by the homologous human p53 DBD segment; thus, the precise base sequence context frequently targeted by mutagens or endogenous mutagenic processes in human carcinogenesis is present in this strain (J. L. Luo et al., Oncogene, 20: 320-328, 2001). Here we show that when epidermal cells of Hupki mice (p53(ki/ki)) are irradiated in vivo with a single acute dose of UVB light, they accumulate UV photoproducts at the same locations of the p53 gene as human cells. Chronic exposure of Hupki mice (4.5 kJ/m(2) 5x/week for 4 weeks) results in the appearance of cell patches that stain intensely with the anti-p53 antiserum CM1. DNA preparations from 2 cm(2) sections of chronically irradiated Hupki epidermis harbor C to T and CC to TT mutations at two mutation hotspots identified in human skin cancer, one at codons 278-279, and one at codons 247-248; the latter is the most frequent UVB-associated mutation site in humans but not in p53 wild-type mice. Thus, Hupki keratinocytes with these p53 mutations encode an aberrant DBD identical in amino acid sequence to the mutant p53 molecules in human UV-induced tumors. The Hupki mouse model offers a new experimental tool in molecular epidemiology and biomedical research.

Amino Acid Sequence↗

PubMed2003

Detection and assignment of TP53 mutations in tumor DNA using peptide mass signature genotyping.

This report describes the application of a new approach to tumor genotyping called peptide mass signature genotyping (PMSG) that is particularly suited to detecting minority sequences in a DNA sample. Detecting minority sequences is essential for accurate tumor genotyping because tumor resections are generally a mixture of malignant and non-malignant cells, with the mutations of interest often outnumbered by the corresponding wild-type alleles. To explore the suitability of PMSG for tumor genotyping, 25 human squamous cell carcinomas of the head and neck, as well as a set of cell lines derived from those tumors, were analyzed for mutations in exons 5 to 8 of the TP53 gene, the exons that encode the DNA-binding domains of the p53 protein. PMSG identified mutations in 11 tumor DNA samples, whereas dideoxy sequencing of the same samples detected mutations in only four. Currently, PMSG can be used to detect mutations that are present in only 20% of the sample DNA, and we expect that this threshold will be lowered significantly as the PMSG process is improved. Hum Mutat 22:158-165, 2003.

Carcinoma, Squamous Cell↗

PubMed2003

Detection and assignment of mutations and minihaplotypes in human DNA using peptide mass signature genotyping (PMSG): application to the human RDS/peripherin gene.

Peptide mass-signature genotyping (PMSG) is a scanning genotyping method that identifies mutations and polymorphisms by translating the sequence of interest in more than one reading frame and measuring the masses of the resulting peptides by mass spectrometry. PMSG was applied to the RDS/peripherin gene of 16 individuals from a family exhibiting autosomal dominant macular degeneration. The method revealed an A-->T transversion in the 5' splice site of intron 2 that is the likely cause of the disease. It also revealed four different minihaplotypes in exon 3 that represent particular combinations of SNPs at four different locations. This study demonstrates the utility of PMSG for identifying and characterizing point mutations and local minihaplotypes that are not readily analyzed by other approaches.

DNA Mutational Analysis↗

PubMed1997

Characterization of the human multidrug resistance protein containing mutations in the ATP-binding cassette signature region.

A number of mutants with single amino acid replacements were generated in the highly conserved ATP-binding cassette (ABC)-signature region (amino acids 531-543) of the N-terminal half of the human multidrug resistance (MDR1) protein. The cDNA variants were inserted into recombinant baculoviruses and the MDR1 proteins were expressed in Spodoptera frugiperda (Sf9) insect cells. The level of expression and membrane insertion of the MDR1 variants was examined by immunostaining, and MDR1 function was followed by measuring drug-stimulated ATPase activity. We found that two mutations, L531R and G534V, practically eliminated MDR1 expression; thus these amino acid replacements seem to inhibit the formation of a stable MDR1 protein structure. The MDR1 variants G534D and I541R were expressed at normal levels with normal membrane insertion, but showed a complete loss of drug-stimulated ATPase activity, while mutant R538M yielded full protein expression but with greatly decreased ATPase activity. Increasing the ATP concentration did not restore MDR1 ATPase activity in these variants. Some amino acid replacements in the ABC-signature region (K536I, K536R, I541T and R543S) affected neither the expression and membrane insertion nor the ATPase function of MDR1. We found no alteration in the drug-sensitivity of ATP cleavage in any of the MDR1 variants that had measurable ATPase activity. These observations suggest that the ABC-signature region is essential for MDR1 protein stability and function, but alterations in this region do not seem to modulate MDR1-drug interactions directly.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2026

Prognostic value and immune landscape implications of using a novel homologous recombination repair pathway signature in prostate cancer: A retrospective cohort study.

ObjectiveAlthough the homologous recombination repair (HRR) pathway plays a critical role in the treatment of prostate cancer, its prognostic value remains incompletely understood. This study aimed to identify HRR pathway-related biomarkers with clinical utility for prognosis prediction and treatment guidance.MethodsWe analyzed genomic data from The Cancer Genome Atlas and Chinese patients with prostate cancer in a retrospective cohort study using a comprehensive multiomics approach to characterize a novel HRR-related prognostic signature and its immune implications.ResultsIn the Chinese cohort, 25.6% of the patients exhibited homologous recombination deficiency scores >42, whereas 27.3% carried ≥1 HRR gene mutation. We established a prognostic HRR signature (homologous recombination deficiency score >32, HRR gene mutations, and Signature 3) associated with poor outcomes. Compared with The Cancer Genome Atlas data, the Chinese cohort demonstrated a higher prevalence of HRR signature. Patients with HRR signatures demonstrated significantly increased genomic instability markers, including segment number, alteration burden, aneuploidy score, and intratumor heterogeneity. The HRR signature was associated with higher neoantigen load but reduced T cell receptor (TCR) evenness. Immunologically, HRR-positive tumors were associated with computationally inferred immune profiles suggestive of reduced immune activity, characterized by depletion of T-helper 17 cell; downregulation of TLR4/PDCD1LG2 expression; and upregulation of ARG1, IFNG, KIR2DL3, and CXCL9. However, these findings are descriptive and require experimental validation.ConclusionOur findings identify a clinically relevant HRR signature that warrants investigation as a potential predictive biomarker for prostate cancer prognosis and treatment response. This biomarker provides new insights for personalized therapy and may help optimize patient outcomes.

Humans↗

PubMed2003

The ABC-transporter signature motif is required for peptide translocation but not peptide binding by TAP.

The transporter associated with antigen processing (TAP) translocates peptides from their site of generation in the cytosol to the lumen of the endoplasmic reticulum for binding to MHC class I molecules. TAP is a member of the ATP-binding cassette (ABC) transporter family whose members utilize energy from ATP hydrolysis to translocate substrates across membranes. The highly conserved nucleotide-binding domains of ABC transporters couple ATP hydrolysis to substrate translocation by the membrane domains. The conserved 'signature motif' can be identified in the nucleotide-binding domains of all ABC transporters, and may play a role in ATP hydrolysis. Here we show that introduction of mutations into the signature motifs of either TAP1 or TAP2 inhibits the translocation of peptide without affecting binding of either peptide or ATP by TAP. We therefore conclude that the signature motifs in both TAP1 and TAP2 are required after peptide binding to facilitate peptide translocation by TAP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2007

Theory of lethal mutagenesis for viruses.

Mutation is the basis of adaptation. Yet, most mutations are detrimental, and elevating mutation rates will impair a population's fitness in the short term. The latter realization has led to the concept of lethal mutagenesis for curing viral infections, and work with drugs such as ribavirin has supported this perspective. As yet, there is no formal theory of lethal mutagenesis, although reference is commonly made to Eigen's error catastrophe theory. Here, we propose a theory of lethal mutagenesis. With an obvious parallel to the epidemiological threshold for eradication of a disease, a sufficient condition for lethal mutagenesis is that each viral genotype produces, on average, less than one progeny virus that goes on to infect a new cell. The extinction threshold involves an evolutionary component based on the mutation rate, but it also includes an ecological component, so the threshold cannot be calculated from the mutation rate alone. The genetic evolution of a large population undergoing mutagenesis is independent of whether the population is declining or stable, so there is no runaway accumulation of mutations or genetic signature for lethal mutagenesis that distinguishes it from a level of mutagenesis under which the population is maintained. To detect lethal mutagenesis, accurate measurements of the genome-wide mutation rate and the number of progeny per infected cell that go on to infect new cells are needed. We discuss three methods for estimating the former. Estimating the latter is more challenging, but broad limits to this estimate may be feasible.

Antiviral Agents↗

PubMed2005

Functional interactions between nucleotide binding domains and leukotriene C4 binding sites of multidrug resistance protein 1 (ABCC1).

Multidrug resistance protein 1 (MRP1) is a member of the "C" branch of the ATP-binding cassette transporter superfamily. The NH(2)-proximal nucleotide-binding domain (NBD1) of MRP1 differs functionally from its COOH-proximal domain (NBD2). NBD1 displays intrinsic high-affinity ATP binding and little ATPase activity. In contrast, ATP binding to NBD2 is strongly dependent on nucleotide binding by NBD1, and NBD2 is more hydrolytically active. We have demonstrated that occupancy of NBD2 by ATP or ADP markedly decreased substrate binding by MRP1. We have further explored the relationship between nucleotide and substrate binding by examining the effects of various ATP analogs and ADP trapping, as well as mutations in conserved functional elements in the NBDs, on the ability of MRP1 to bind the photoactivatable, high-affinity substrate cysteinyl leukotriene C(4) (LTC(4))(.) Overall, the results support a model in which occupancy of both NBD1 and NBD2 by ATP results in the formation of a low-affinity conformation of the protein. However, nonhydrolyzable ATP analogs (beta,gamma-imidoadenosine 5'-triphosphate and adenylylmethylene diphosphonate) failed to substitute for ATP or adenosine 5'-O-(thiotriphosphate) (ATPgammaS) in decreasing LTC(4) photolabeling. Furthermore, mutations of the signature sequence in either NBD that had no apparent effect on azido-ATP binding abrogated the formation of a low-affinity substrate binding state in the presence of ATP or ATPgammaS. We suggest that the effect of these mutations, and possibly the failure of some ATP analogs to decrease LTC(4) binding, may be attributable to an inability to elicit a conformational change in the NBDs that involves interactions between the signature sequence and the gamma-phosphate of the bound nucleotide.

Amino Acid Sequence↗

PubMed2004

The role of the conserved glycines of ATP-binding cassette signature motifs of MRP1 in the communication between the substrate-binding site and the catalytic centers.

A key element of the structural model of ABC-ATP-ases is the interaction of the two ABC domains. They complement each other's active sites in a way that the ABC signature motif (LSGGQ) of one subunit interacts with the gamma-phosphate of the ATP, bound at the Walker motifs of the opposite subunit. In the present study, the conserved glycines in the fourth position of the LSGGQ motifs of human MRP1 were substituted for aspartic acids (G771D and G1433D), the mutants were expressed in Sf9 insect cells, and the nucleotideas well as the transported substrate-protein interactions were studied. We found that these transport- and ATPase-incompetent mutants showed no nucleotide trapping under any of the conditions examined. However, when measuring the effect of nucleotide and transported substrates on the vanadate-induced cleavage reactions, we found that the effect of substrates on the cleavage reactions was significantly different in the mutant MRP1 proteins than in the wild type. Although the transported substrates (e.g. etoposide + oxidized glutathione) stimulated the formation of the posthydrolytic complex in the wild type, this reaction was inhibited in the signature mutants. Our study also revealed that a similar mutation in the ABC signature of either ABC unit resulted in the same effect. We suggest that the conserved glycine residues in both LSGGQ segments are part of the conformational network, which is responsible for the accelerated hydrolytic activity upon interaction of the protein with its transported substrates. This intramolecular communication between the substrate-binding site and the catalytic centers is assumed to be a general feature of the molecular mechanism of ABC transporters.

Amino Acid Motifs↗

PubMed2025

Genetic and transcriptional insights into immune checkpoint blockade response and survival: lessons from melanoma and beyond.

BACKGROUND: Integration of immune checkpoint inhibitors (ICIs) with non-immune therapies relies on identifying combinatorial biomarkers, which are essential for patient stratification and personalized treatment. METHODS: We analyzed genomic and transcriptomic data from pretreatment tumor samples of 342 melanoma patients treated with ICIs to identify mutations and expression signatures associated with ICI response and survival. External validation and mechanistic exploratory analyses were conducted in two additional datasets to assess generalizability. RESULTS: Responders were more likely to have received anti-PD-1 therapy rather than anti-CTLA-4 and exhibited a higher tumor mutation burden (both P < 0.001). Mutations in the dynein axonemal heavy chain (DNAH) family genes, specifically DNAH2 (P = 0.03), DNAH6 (P < 0.001), and DNAH9 (P < 0.01), were enriched in responders. The combined mutational status of DNAH 2/6/9 effectively stratified patients by progression-free survival (hazard ratio [HR]: 0.69; 95% confidence interval [CI] 0.51-0.92; P = 0.013) and overall survival (HR: 0.58; 95% CI 0.43-0.78; P < 0.001), with consistent association observed in the validation cohort (HR: 0.28; 95% CI 0.12-0.61; P < 0.001). DNAH-altered melanomas exhibited upregulation of chemokine signaling, cytokine-cytokine receptor interaction, and cell cycle-related pathways, along with elevated expression of immune-related signatures in interferon signaling, cytolytic activity, T cell function, and immune checkpoints. Using LASSO logistic regression, we identified a 26-gene composite signature predictive of clinical response, achieving an area under the curve (AUC) of 0.880 (95% CI 0.825-0.936) in the training dataset and 0.725 (95% CI 0.595-0.856) in the testing dataset. High-risk patients, stratified by the expression levels of a 13-gene signature, demonstrated significantly shorter overall survival in both datasets (HR: 3.35; P < 0.001; HR: 2.93; P = 0.002). CONCLUSIONS: This analysis identified potential molecular determinants of response and survival to ICI treatment. Insights from melanoma biomarker research hold significant promise for translation into other malignancies, guiding individualized anti-tumor immunotherapy.

Humans↗

PubMed2006

Gene expression signatures associated with the resistance to imatinib.

Imatinib (imatinib mesylate, STI-571, Gleevec) is a selective BCR-ABL tyrosine kinase inhibitor that has been used as a highly effective chemoagent for treating chronic myelogenous leukemia. However, the initial response to imatinib is often followed by the recurrence of a resistant form of the disease, which is major obstacle to many therapeutic modalities. The aim of this study was to identify the gene expression signatures that confer resistance to imatinib. A series of four resistant K562 sublines was established with different imatinib dosage (200, 400, 600 and 800 nM) and analyzed using microarray technology. The transcripts of the genes showing universal or dose-dependent expression changes across the resistant sublines were identified. The gene sets associated with the imatinib-resistance were also identified using gene set enrichment analysis. In the resistant K562 sublines, the transcription- and apoptosis-related expression signatures were upregulated, whereas those related to the protein and energy metabolism were downregulated. Several genes identified in this study such as IGF1 and RAB11A have the potential to become surrogate markers useful in a clinical evaluation of imatinib-resistant patients without BCR-ABL mutation. The expression signatures identified in this study provide insights into the mechanism of imatinib-resistance and are expected to facilitate the development of an effective diagnostic and therapeutic strategy.

Antineoplastic Agents↗