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Altered subcellular localization and low frequency of mutations of ING1 in human brain tumors.

PURPOSE: Clinical and experimental evidence suggest that the p33ING1b candidate tumor suppressor functionally cooperates with p53 in controlling biochemical and biological functions. Because p53 is frequently mutated in brain tumors and the ING1 locus maps to a site of which the loss is associated with gliomas, we analyzed the mutation and expression profiles of ING1B in human brain tumors. Here we present the first report of ING1 expression and mutation analyses in human brain tumor samples and malignant glioma cell lines. EXPERIMENTAL DESIGN: Expression and mutation analyses of ING1B together with subcellular localization studies of ING1 proteins were performed on 29 brain tumor specimens and 6 human glioma cell lines. RESULTS: A single point mutation (3.5%) was detected in the 29 brain tumor specimens analyzed. This missense mutation occurred in a sequence reported previously to confer nuclear translocation properties to p33ING1b. Interestingly, overexpression and subcellular mislocalization of p33ING1b were observed in all 29 of the brain tumor specimens and some glioma cell lines. In tumor samples, ING1 proteins aberrantly localized to the cytoplasm, and to a lesser extent, to the nucleus of glioma cells. CONCLUSIONS: Our data indicate that although mutations of ING1 seem to be infrequent in human brain tumors, deregulated expression and mislocalization of ING1 proteins, particularly the p33ING1b isoform, are common events in gliomas and glioblastomas.

Astrocytoma↗

Distinct clinicopathologic and genetic profiles in sporadic gastric cancer with different mutator phenotypes.

A subset of sporadic gastric cancers (GC) exhibits microsatellite instability (MSI). To define the precise role of MSI in GC, a total of 100 patients with sporadic GC were classified into three groups, i.e., high-frequency MSI (MSI-H), low-frequency MSI (MSI-L), and microsatellite stable (MSS), based on 10 microsatellite markers. Mutational analyses of TGFbetaRII, IGFIIR, BAX, MSH3, MSH6, E2F4, MSH2, MLH1, and TP53 genes, and methylation and protein expression of MLH1 and MSH2 were performed and correlated. Twenty-seven percent of GC showed MSI at least in one locus and could be further graded as MSI-H (14%) and MSI-L (13%). No clinicopathologic difference was noted between GC with MSI-L and MSS. Compared with GC with MSI-L or MSS, GC with MSI-H had a significantly higher frequency of antral location, intestinal subtype, H. pylori seropositivity, but a lower incidence of lymph node metastasis, and displayed a higher frequency of frameshift mutations of TGFbetaRII, IGFIIR, BAX, MSH3, and E2F4 genes but a lower incidence of TP53 mutations. Furthermore, hypermethylation of the MLH1 promoter was responsible for the loss of protein function in 13 of 14 MSI-H tumors. It was concluded that a specific phenotype and a distinct profile of genetic alterations exist in MSI-H GC. We speculate that epigenetic inactivation of MLH1 by methylation plays a crucial role in initiating such a pathway of carcinogenesis. In contrast, GCs with MSS and MSI-L exhibit clinicopathologic features that are distinct from MSI-H tumors and have a higher frequency of TP53 mutations, suggesting that they may evolve through an entirely different pathway.

Adaptor Proteins, Signal Transducing↗

Emerging concepts in glioma biology: implications for clinical protocols and rational treatment strategies.

Glioblastoma multiforme (GBM), the most common primary central nervous system neoplasm, is a complex, heterogeneous disease. The recent identification of stem cells in murine tumor xenografts that were capable of recapitulating the tumor phenotype adds a new dimension of complexity to the already challenging treatment of patients with GBMs. Although specific cellular and genetic changes are commonly associated with GBM, the mechanism by which those changes occur may have a significant impact on treatment outcome. Of the many bioinformatics techniques developed in recent years, gene expression profiling has become a commonly used research tool for investigating tumor characteristics, and the development of rationally targeted molecular therapies has also accelerated following the initial success of specifically designed inhibitors in the treatment of malignancies. Despite these advances in research techniques and targeted molecular therapies, however, limited clinical impact has been achieved in the treatment of infiltrative malignancies such as GBMs. Thus, further extension in survival of patients with GBMs may require use of multiple analyses of tumors to develop tailored therapies that reflect the inter- and intratumoral heterogeneity of this disease. In this review, the authors briefly consider the potential use of expression profiling combined with mutation analysis in the development of treatment modalities to address the heterogeneity of this complex tumor phenotype.

Animals↗

Comparative study of genotype B and C hepatitis B virus-induced chronic hepatitis in relation to the basic core promoter and precore mutations.

BACKGROUND: The clinicopathological profiles and outcome of chronic hepatitis B can differ by hepatitis B virus (HBV) genotypes. In Japan, genotype B and C are two major HBV genotypes. The basic core promoter and precore mutations are other known viral factors for disease activity, although the relationship between HBV genotypes and these mutations is not fully understood. METHODS: The HBV genotypes in 90 patients with chronic hepatitis B were determined using an ELISA. Obtained data were correlated with clinicopathological parameters, basic core promoter, precore and the nucleotide 1858 mutations of the HBV genome. RESULTS: Among 90 cases, 20 (22.2%) had genotype B and 70 (77.8%) had genotype C HBV. Genotype B patients were older than genotype C patients (44.0 +/- 13.9 vs 34.7 +/- 11.0 P = 0.0022). The HBeAg was more prevalent in genotype C than B patients (P = 0.0008) while anti-HBe was more common in genotype B than C patients (P = 0.0002). Serum aspartate aspartate aminotransferase/alanine aminotransferase levels (B: 220.7 +/- 612.8/257.0 +/- 498.0 IU/L vs C: 111.3 +/- 122.8/201.6 +/- 229.4 IU/L, P = 0.16/0.48) and HBV viral loads in blood (B: 6.1 +/- 3.1 log genome equivalent [LGE]/mL vs C: 6.7 +/- 2.3 LGE/mL, P = 0.42) were equivalent. The seroconversion from HBeAg to anti-HBe occurred significantly earlier in genotype B than C patients (62 +/- 53 months vs 136 +/- 54 months, P = 0.0028) during the mean observation period of 149 +/- 82 months even under various therapeutic modalities. The categories III and IV of the histological activity index in genotype C were higher (III: P < 0.005, IV: P < 0.05, n = 68) than that in B patients whereas category II was higher in genotype B than C patients (P < 0.05). The double mutation (1762T/1764A) in the basic core promoter was more frequently found in genotype C than in B HBV (P = 0.0068), whereas the precore mutation (1896A) was more common in genotype B than C HBV (P = 0.0233). The incidence of 1858C that was complementary to the precore mutation site in the stem-loop structure in, was equally rare in both genotype B and C HBV. CONCLUSIONS: Genotype B patients were older, had earlier HBeAg seroconversion and exhibited more severe lobular necroinflammation, less portal inflammation and fibrosis than genotype C patients. This genotypic difference is related to the basic core promoter and precore mutations irrespective of 1858C. (c) 2004 Blackwell Publishing Asia Pty Ltd.

Adult↗

Cognitive-behavioral profiles of females with the fragile X mutation.

The fragile X (FRAXA) mutation is typically manifested as either a full mutation (FM) or premutation (PM), and is often associated with some form of learning impairment. The study by Lachiewicz et al. in this issue suggests that females with the FM or PM exhibit a specific profile of strengths in verbal abilities and significant weaknesses in quantitative skills. We examined 17 females with either the FM or PM using a standard cognitive-behavioral battery consisting of the Stanford-Binet (4th Edition; SBFE) and the Vineland Adaptive Behavior Scale (VABS). Although we found the expected differences in composite IQ scores and adaptive behavior composite scores (DQ) between FM and PM females, we found no significant differences between verbal and quantitative reasoning in either group.

Adaptation, Psychological↗

Functional annotation of mouse mutations in embryonic stem cells by use of expression profiling.

Expression profiling offers a potential high-throughput phenotype screen for mutant mouse embryonic stem (ES) cells. We have assessed the ability of expression arrays to distinguish among heterozygous mutant ES cell lines and to accurately reflect the normal function of the mutated genes. Two ES cell lines hemizygous for overlapping regions of mouse Chromosome (Chr) 5 differed substantially from the wildtype parental line and from each other. Expression differences included frequent downregulation of hemizygous genes and downstream effects on genes mapping to other chromosomes. Some genes were affected similarly in each deletion line, consistent with the overlap of the deletions. To determine whether such downstream effects reveal pathways impacted by a mutation, we examined ES cell lines heterozygous for mutations in either of two well-characterized genes. A heterozygous mutation in the gene encoding the cell cycle regulator, cyclin D kinase 4 ( Cdk4), affected expression of many genes involved in cell growth and proliferation. A heterozygous mutation in the ATP binding cassette transporter family A, member 1 ( Abca1) gene, altered genes associated with lipid homeostasis, the cytoskeleton, and vesicle trafficking. Heterozygous Abca1 mutation had similar effects in liver, indicating that ES cell expression profile reflects changes in fundamental processes relevant to mutant gene function in multiple cell types.

ATP Binding Cassette Transporter 1↗

Mutational analysis of the human dihydropyrimidine dehydrogenase gene by denaturing high-performance liquid chromatography.

Mutations in the DPYD gene, which encodes dihydropyrimidine dehydrogenase (DPD), the rate-limiting enzyme in the catabolism of pyrimidines, are responsible for an inborn error of metabolism associated with thymine-uraciluria and neurological symptoms. Because the antimetabolite 5-fluorouracil (5-FU) is metabolized by the same enzyme, deficient DPYD alleles may also constitute a risk factor for severe toxicity following treatment with this anticancer drug. The aim of this study was to develop a comprehensive and rapid method to detect sequence variations within the DPYD gene. Using polymerase chain reaction (PCR) amplification and denaturing high-performance liquid chromatography (DHPLC), we established a protocol that makes it possible to screen all 23 exons of the DPYD gene and their exon-intron boundaries for both known and unknown mutations under identical conditions. A novel one-step PCR mutagenesis procedure was developed to generate heterozygous mutant amplicons as positive controls to optimize DHPLC detection of any sequence variation. DHPLC analysis was shown to result in mutation-specific elution profiles and to be able to distinguish different base changes within the same exon or different heterozygous combinations of mutations within the same exon. By analyzing the DPYD gene in 16 affected individuals, a total of 47 base changes were detected, representing eight known mutations and three novel intronic base changes. Sequence analysis confirmed all base changes detected. This method will be useful in identifying patients at risk for toxicity prior to 5-FU treatment, as well as in the analysis of individual patients with thymine-uraciluria.

Alleles↗

Growth factor signaling and resistance to cancer chemotherapy.

Multiple mechanisms contribute to chemoresistance, eventually leading to failure of cancer chemotherapy. Deregulated growth factor signaling pathways promote cell proliferation and render cancer cells resistant to apoptosis, a common mechanism of chemoresistance. Therefore, inhibitors of growth factor signaling, including antibodies and small molecules, are promising drug candidates for chemotherapy, either given alone or as adjuvants to overcome general drug resistance. While dramatic responses have been attained in some cases, innate or acquired resistance to these novel anticancer drugs is common and limits broad applicability. Treatment failure may arise from complexity of growth factor signaling, with numerous parallel pathways and diverse downstream events. This review discusses the use of pharmacogenomics, assessing multiple growth factor signaling pathways and complex chemoresistance mechanisms. Monitoring expression profiles and activating mutations in growth factor receptors holds promise for the design of individualized therapy with a combination of drugs.

Drug Resistance, Neoplasm↗

The Wsh and Ph mutations affect the c-kit expression profile: c-kit misexpression in embryogenesis impairs melanogenesis in Wsh and Ph mutant mice.

The receptor tyrosine kinases (RTKs) c-kit and platelet-derived growth factor receptor alpha chain (PDG-FRa) are encoded at the white spotting (W) and patch (Ph) loci on mouse chromosome 5. While W mutations affect melanogenesis, gametogenesis, and hematopoiesis, the Ph mutation affects melanogenesis and causes early lethality in homozygotes. W-sash (Wsh) is an expression mutation and blocks c-kit expression in certain cell types and enhances c-kit expression in others, including at sites important for early melanogenesis. We have determined the effect of Ph on c-kit expression during embryogenesis in Ph heterozygotes. Immunohistochemical analysis revealed enhanced c-kit expression in several cell types, including sites important for early melanogenesis. We propose that in both Wsh and Ph mutant mice c-kit misexpression affects early melanogenesis and is responsible for the pigment deficiency. Moreover, we have defined the organization of the RTKs in the W/Ph region on chromosome 5 and characterized the Wsh mutation by using pulsed-field gel electrophoresis. Whereas the order of the RTK genes was determined as Pdgfra-c-kit-flk1, analysis of the Wsh mutation revealed that the c-kit and Pdgfra genes are unlinked in Wsh, presumably because of an inversion of a small segment of chromosome 5. The Ph mutation consists of a deletion including Pdgfra and the 3' deletion endpoint of Ph lies between Pdgfra and c-kit. Therefore, positive 5' upstream elements controlling c-kit expression in mast cells and some other cell types are affected by the Wsh mutation and negative elements are affected by both the Wsh and the Ph mutation.

Animals↗

Identification of 14-3-3sigma mutation causing cutaneous abnormality in repeated-epilation mutant mouse.

Repeated-epilation (Er) mutation in the mouse is inherited as an autosomal and semidominant mutation. Major defects in heterozygous adults and homozygous fetuses were associated with skin and were caused by abnormal ectodermal differentiation. Heterozygous mice are characterized by repeated hair loss and regrowth, and homozygous fetuses die at birth with severe abnormality in skin, limb, tail, and face. To identify the gene causing Er mutation, we have performed gene-expression profiles of skins and mouse embryonic fibroblasts from WT and mutant Er mice by using Affymetrix (Santa Clara, CA) chip analysis. By analyzing the candidate genes generated from gene-expression profiling, we identified a Sfn mutation in Er mice. A single nucleotide insertion in the Sfn (Stratifin, also called 14-3-3sigma) coding region results in a truncated protein lacking 40 amino acid residues at the C terminus. The mutation is linked with phenotypes of Er-heterozygous and -homozygous mice. Ectopic overexpression of WT 14-3-3sigma in Er/Er keratinocytes rescues defects in keratinocyte differentiation. Our study demonstrates that 14-3-3sigma is a crucial regulator for skin proliferation and differentiation.

14-3-3 Proteins↗

Paclitaxel-resistant cells have a mutation in the paclitaxel-binding region of beta-tubulin (Asp26Glu) and less stable microtubules.

Resistance to paclitaxel-based therapy is frequently encountered in the clinic. The mechanisms of intrinsic or acquired paclitaxel resistance are not well understood. We sought to characterize the resistance mechanisms that develop upon chronic exposure of a cancer cell line to paclitaxel in the presence of the P-glycoprotein reversal agent, CL-347099. The epidermoid tumor line KB-3-1 was exposed to increasing concentrations of paclitaxel and 5 micromol/L CL-347099 for up to 1 year. Cells grown in 15 nmol/L paclitaxel plus CL-347099 (KB-15-PTX/099) developed 18-fold resistance to paclitaxel and were dependent upon paclitaxel for maximal growth. They grew well and retained resistance to paclitaxel when grown in athymic mice. Cross-resistance (3- to 5-fold) was observed in tissue culture to docetaxel, the novel taxane MAC-321, and epothilone B. Collateral sensitivity (approximately 3-fold) was observed to the depolymerizing agents vinblastine, dolastatin-10, and HTI-286. KB-15-PTX/099-resistant cells did not overexpress P-glycoprotein nor did they have an alteration of [14C]paclitaxel accumulation compared with parental cells. However, a novel point mutation (T to A) resulting in Asp26 to glutamate substitution in class I (M40) beta-tubulin was found. Based on an electron crystallography structure of Zn-stabilized tubulin sheets, the phenyl ring of C-3' NHCO-C6H5 of paclitaxel makes contact with Asp26 of beta-tubulin, suggesting a ligand-induced mutation. Optimized model complexes of paclitaxel, docetaxel, and MAC-321 in beta-tubulin show a novel hydrogen bonding pattern for the glutamate mutant and rationalize the observed resistance profiles. However, a mutation in the paclitaxel binding pocket does not explain the phenotype completely. KB-15-PTX/099 cells have impaired microtubule stability as determined by a reduced percentage of tubulin in microtubules and reflected by less acetylated tubulin. These results suggest that a mutation in tubulin might affect microtubule stability as well as drug binding and contribute to the observed resistance profile.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Brachydactyly type C caused by a homozygous missense mutation in the prodomain of CDMP1.

Brachydactyly type C (BDC) is characterized by shortening of the middle phalanges of the index, middle, and little finger with hyperphalangy, usually of the index and middle finger. Heterozygous mutations of the cartilage derived morphogenetic protein-1 (CDMP1) resulting in a loss of function have been reported in BDC. We here describe a large kindred with a semi-dominant form of BDC and pronounced ulnar deviation of the second and third digits. In this family a novel homozygous missense mutation was identified (517A > G) changing methionine to valine at amino acid position 173. The mutation is located within a highly conserved seven amino acid region of the prodomain of CDMP1. Hand radiographs of heterozygous mutation carriers showed mild shortening of the metacarpals IV and V; a finding confirmed by the analysis of their metacarpophalangeal profiles (MCPPs). The mutation described here points toward an important function of the prodomain for the folding, secretion, and availability of biologically active CDMP1.

Adolescent↗

TSC angiofibroma and ungual fibroma have different mutation signatures, with recurrent mutations in KMT2C.

PURPOSE: Tuberous sclerosis complex (TSC) is an autosomal dominant tumor suppressor syndrome characterized by tumors affecting multiple tissues, including skin, due to inactivating TSC1/TSC2 variants. Genome-wide profiling of somatic mutations in a unique collection of angiofibroma (FAF) and ungual fibroma (UF) TSC skin tumors was performed. METHODS: Genome sequencing was performed on 9 samples, comprising 4 FAF and 5 UF, along with 6 matched normal samples from 6 individuals with TSC. RESULTS: TSC-FAF and TSC-UF skin tumors have different mutation signatures, with a predominance of UV-related single-nucleotide variant (SNV; SBS7a and SBS7b) and dinucleotide variant (DNV; DBS1) signatures in FAF, and aging-related SNV (SBS1 and SBS5) signatures in UF. We also identified a novel DNV signature for TSC-UF, with frequent TG>CA and TT>GG substitutions. Furthermore, 3 inactivating somatic mutations in KMT2C were observed in 2 of 4 TSC-FAF and 5 mutations in other cancer genes. CONCLUSION: The distinct SNV mutation signatures seen in TSC-FAF and UF indicate that they develop through distinct pathogenic mechanisms, UV-induced mutagenesis in FAF, and aging-related mutagenesis in UF. The mechanism of the novel DNV signature in UFs merits further investigation. Our observation on the occurrence of KMT2C mutations suggests that KMT2C inactivation contributes to the pathogenesis of TSC-FAF.

Humans↗

Role of phosphatidylinositol-linked proteins in paroxysmal nocturnal hemoglobinuria pathogenesis.

Patients with paroxysmal nocturnal hemoglobinuria have one or more mutant hematopoietic stem cell clones deficient in glycosylphosphatidylinositol (GPI)-anchor synthesis owing to somatic mutations in the X-linked gene PIG-A. The progeny of mutant stem cells dominates the peripheral blood. The presence of a large number of GPI-anchor deficient, complement-sensitive erythrocytes leads to hemolytic anemia. The somatic mutations in PIG-A are small, various, and widely distributed in the coding regions and splice sites, indicating they occur randomly. Profiles of the mutations vary geographically, suggesting the presence of mutagen-induced mutations. The clonal dominance by the mutants does not seem to be solely due to the PIG-A mutation but may be caused either by autonomous expansion of the mutants due to a combination of the PIG-A mutation and some other genetic change(s) or by selection that preferentially suppresses normal stem cells.

Erythrocytes↗

Inherited frontotemporal dementia in nine British families associated with intronic mutations in the tau gene.

Genetic screening of 171 patients with frontotemporal lobar degeneration disclosed 14 patients, across nine pedigrees, with mutations in the intron to exon 10 in the tau gene, a region regulating the splicing of exon 10 via a stem loop mechanism. Thirteen of these patients had the +16 splice site mutation and one had the +13 splice site mutation. Affected members of all nine families presented with changes in behaviour and social conduct that were prototypical of frontotemporal dementia (FTD). In all patients with the +16 splice site mutation, the behavioural profile was characterized by disinhibition, restless overactivity, a fatuous affect, puerile behaviour and verbal and motor stereotypies. The single patient with the +13 mutation presented a contrasting picture of apathy and inertia. In addition, all patients had evidence of semantic loss. Pathologically, five of the six patients so far autopsied shared frontotemporal atrophy with involvement of the substantia nigra. The underlying histology was that of microvacuolar-type cortical degeneration with a few swollen cells. Tau pathology was widespread throughout the brain and present in neurones and glial cells, mostly in the frontal and temporal cortical regions. This was in the form of neurofibrillary tangles and amorphous tau deposits (pre-tangles); Pick bodies were not observed. Ultrastructurally, the tau filaments had a twisted, ribbon-like morphology distinct from the paired helical filaments of Alzheimer's disease. One patient died from an unrelated illness whilst in the early clinical stages of FTD. In this patient, cortical microvacuolar and astrocytic changes were absent, though there were scattered neurones and glial cells, immunoreactive to tau, throughout the cortical and subcortical regions. The disease process underlying the neurodegeneration within these inherited forms of FTD may therefore stem directly from early, primary alterations in the function of tau. All eight families with the +16 mutation seem to be part of a common extended pedigree, possibly originating from a founder member residing within the North Wales region of Great Britain.

Age of Onset↗

Apolipoprotein A-IFIN (Leu159-->Arg) mutation affects lecithin cholesterol acyltransferase activation and subclass distribution of HDL but not cholesterol efflux from fibroblasts.

We showed earlier that the apolipoprotein A-I Leu159-->Arg mutation (apoA-IFin) results in dominantly inherited hypoalphalipoproteinemia. In the present study we investigated the effect of the apoA-IFin mutation on lipoprotein profile, apoA-I kinetics, lecithin:cholesterol acyltransferase (LCAT) activation, and cholesterol efflux in vitro. Carriers (n = 9) of the apoA-IFin mutation exhibited several lipoprotein abnormalities. The serum HDL cholesterol level was diminished to 20% of normal, and nondenaturing gradient gel electrophoresis of HDL showed disappearance of particles at the 9.0- to 12-nm size range (HDL2-type) and the presence of small 7.8- to 8.9-nm (mostly HDL3-type) particles only. HDL3-type particles from both the mutation carriers and nonaffected family members were similarly converted to large, HDL2-type particles by phospholipid transfer protein in vitro. Studies on apoA-I kinetics in four affected subjects favored accelerated catabolism of apoA-I. Experiments with reconstituted proteoliposomes showed that the capacity of apoA-IFin protein to activate LCAT was reduced to 40% of that of the wild-type apoA-I. The impact of the apoA-IFin protein on cholesterol efflux was examined in vitro using [3H]cholesterol-loaded human fibroblasts and three different cholesterol acceptors: (1) total HDL, (2) total apoA-I combined with phospholipid, and (3) apoA-I isoform (apoA-IFin or wild-type apoA-I isoform 1) combined with phospholipid. ApoA-IFin did not impair phospholipid binding or cholesterol efflux from fibroblasts to any of the acceptors used. Only one of the nine apoA-IFin carriers appears to have evidence of clinically manifested atherosclerosis. In conclusion, although the apoA-IFin mutation does not alter the properties of apoA-I involved in promotion of cholesterol efflux, its ability to activate LCAT in vitro is defective. In vivo, apoA-IFin was found to be associated with several lipoprotein composition rearrangements and increased catabolism of apoA-I.

Adolescent↗

Ehlers-Danlos syndrome type IV: unusual congenital anomalies in a mother and son with a COL3A1 mutation and a normal collagen III protein profile.

A mother and son with Ehlers-Danlos syndrome (EDS) type IV and unusual congenital anomalies are described. The congenital anomalies include, in the mother, amniotic band-like constrictions on one hand, a unilateral clubfoot, and macrocephaly owing to normal-pressure hydrocephaly and, in the son, an esophageal atresia and hydrocephaly. Protein analysis of collagen III in cultured fibroblasts of the mother showed no abnormalities. However, DNA analysis of the COL3A1 gene revealed a pathogenic mutation (388G-->T) in both the mother and the son. The possible relationship between the observed congenital anomalies and EDS IV are discussed. We stress that DNA analysis of COL3A1 should be performed in all patients when there is a strong suspicion of EDS IV, despite negative findings in a collagen protein analysis.

Collagen Type III↗

Differentially expressed proteins in gastrointestinal stromal tumors with KIT and PDGFRA mutations.

Most gastrointestinal stromal tumors (GIST) have activating mutations in either KIT or PDGFRA. However, a small subset of GIST lacks either mutation. To investigate the molecular characteristics of GIST according to mutation type, protein expression profiles in 12 GIST (2 cases with PDGFRA mutations, 8 cases with KIT mutations and 2 cases lacking either mutation) were analyzed using 2-DE and MALDI-TOF-MS. Comparative analysis of the respective spot patterns using 2-DE showed that 15 proteins were differently expressed according to the mutation status. Expression levels of septin and heat shock protein (HSP) 27 were increased in GIST with KIT mutations and annexin V was overexpressed in GIST lacking either mutation. Among the 15 proteins, overexpression of 5 proteins [annexin V, high mobility group protein 1 (HMGB1), C13orf2, glutamate dehydrogenase 1 and fibrinogen beta chain] and decreased expression of RoXaN correlated with a higher tumor grade. These findings suggest that differential protein expression can be used as a diagnostic biomarker. Moreover, it may play a role in the development and progression of GIST according to activating mutation type, as these proteins have been shown to be involved in tumor metastasis, apoptosis and immune response.

Electrophoresis, Gel, Two-Dimensional↗