Molecules linked to Ras signaling as therapeutic targets in cardiac pathologies

The Ras family of small Guanosine Triphosphate (GTP)-binding proteins (G proteins) represents one of the main components of intracellular signal transduction required for normal cardiac growth, but is also critically involved in the development of cardiac hypertrophy and heart failure. The present review provides an update on the role of the H-, K- and N-Ras genes and their related pathways in cardiac diseases. We focus on cardiac hypertrophy and heart failure, where Ras has been studied the most. We also review other cardiac diseases, like genetic disorders related to Ras. The scope of the review extends from fundamental concepts to therapeutic applications. Although the three Ras genes have a nearly identical primary structure, there are important functional differences between them: H-Ras mainly regulates cardiomyocyte size, whereas K-Ras regulates cardiomyocyte proliferation. N-Ras is the least studied in cardiac cells and is less associated to cardiac defects. Clinically, oncogenic H-Ras causes Costello syndrome and facio-cutaneous-skeletal syndromes with hypertrophic cardiomyopathy and arrhythmias. On the other hand, oncogenic K-Ras and alterations of other genes of the Ras-Mitogen-Activated Protein Kinase (MAPK) pathway, like Raf, cause Noonan syndrome and cardio-facio-cutaneous syndromes characterized by cardiac hypertrophy and septal defects. We further review the modulation by Ras of key signaling pathways in the cardiomyocyte, including: (i) the classical Ras-Raf-MAPK pathway, which leads to a more physiological form of cardiac hypertrophy; as well as other pathways associated with pathological cardiac hypertrophy, like (ii) The SAPK (stress activated protein kinase) pathways p38 and JNK; and (iii) The alternative pathway Raf-Calcineurin-Nuclear Factor of Activated T cells (NFAT). Genetic alterations of Ras isoforms or of genes in the Ras-MAPK pathway result in Ras-opathies, conditions frequently associated with cardiac hypertrophy or septal defects among other cardiac diseases. Several studies underline the potential role of H- and K-Ras as a hinge between physiological and pathological cardiac hypertrophy, and as potential therapeutic targets in cardiac hypertrophy and failure. Highlights - The Ras (Rat Sarcoma) gene family is a group of small G proteins - Ras is regulated by growth factors and neurohormones affecting cardiomyocyte growth and hypertrophy - Ras directly affects cardiomyocyte physiological and pathological hypertrophy - Genetic alterations of Ras and its pathways result in various cardiac phenotypes? - Ras and its pathway are differentially regulated in acquired heart disease - Ras modulation is a promising therapeutic target in various cardiac conditions.

Study on Association between an H-RAS Gene Polymorphism and Gastric Cancer Development / 대한소화기학회지

BACKGROUND/AIMS: Oncogenic RAS gene mutations have been frequently observed in many tumor types, and their associations with various cancers were reported. This study was conducted to evaluate the association between H-RAS T81C polymorphism and gastric cancer development. METHODS: H-RAS T81C polymorphism was genotyped in 321 chronic gastritis (ChG) and 151 gastric cancer (GC) patients using GoldenGate(R) Assay kit. Logistic regression analysis adjusted for age and gender was performed to identify the differences of genotype and allele distributions between the each group. RESULTS: All ChG and GC patients were in Hardy-Weinberg equilibrium. When the frequencies of H-RAS T81C genotype in each group were compared, the homozygous type of major allele TT was more frequent in GC group (62.9%) than ChG group (57.3%), while the frequencies of heterozygous type TC and homozygous type of minor allele CC were higher in ChG group than GC group (39.3% vs. 33.8%, 3.4% vs. 3.3%, respectively). In the results of logistic regression analyses adjusted for age and gender, the odds ratios were 0.845 (0.604-1.182), 0.799 (0.556-1.147), 0.741 (0.493-1.114) and 1.094 (0.366-3.270) for allele, codominant, dominant and recessive models, respectively. However, significant difference was not observed between two groups in any models. CONCLUSIONS: H-RAS T81C polymorphism was not associated with gastric cancer development in a Korean population.

Detección de mutaciones en los genes K-ras, H-ras y EGFR en muestras de plasma sanguíneo y cepillado cervical de pacientes con neoplasia intraepitelial cervical (NIC) III y cáncer de cuello uterino / Detection of genes mutations in the K-RAS, H-RAS and EGFR in samples of blood plasma and cervical smears for patients with cervical intraepithelial neoplasia III and cervical cancer

Introducción: El cáncer cervical es el segundo cáncer más importante en mujeres a nivel mundial y la segunda causa de muerte en mujeres por cáncer. Se ha demostrado que el proceso de carcinogénesis cervical presenta componentes tanto genéticos, epigenéticos y medio ambientales. En la actualidad, muchos estudios se encaminan en la búsqueda de marcadores moleculares como mutaciones en oncogenes y/o genes tumor supresor que se asocien con la progresión de esta entidad. Los genes candidatos más estudiados en cáncer cervical en distintas poblaciones han sido H-ras, K-ras, EGFR entre otros. Objetivos: Se identificó el virus de papiloma humano (VPH) genérico y específico en el ADN libre de plasma y de cepillado cervical de pacientes con cáncer cervical invasivo y con neoplasia intraepitelial cervical (NIC) III además de evaluar alteraciones genéticas, como mutaciones en los genes H-ras, K-ras y EGFR. Metodología: Para ello se detectó el VPH genérico mediante PCR con los iniciadores GP5+/GP6+, y específico para VPH 16 y 18 en la región E6/E7. Para detectar las mutaciones en el codón 12 de H-ras, codones 12 y 13 de K-Ras y el exón 21 de EGFR se realizó mediante secuenciación directa de los productos de PCR de estos fragmentos génicos. Resultados: Obteniendo una buena correlación entre las muestras de plasma sanguíneo y los cepillados cervicales, tanto para los hallazgos de VPH p=0.0374 como para las mutaciones evaluadas p=0. En general, para EGFR en el exón 21 no se encontraron mutaciones, al igual que para los codones 12 y 13 en K-ras y codón 12 en H-ras. Conclusión: El uso del ADN presente en el plasma puede ser relevante para el análisis de mutaciones y de la presencia de marcadores tumorales cuando no se dispone de otras muestras.

Introduction: Cervical cancer is the second most important cancer in women worldwide, and the second cause of cancer death in women. It has been shown that the process of cervical carcinogenesis presents as genetic and epigenetic components as environmental issues. At present, many studies are addressed in searching for molecular markers such as mutations in oncogenes and/or tumor suppressor genes that are associated with the progression of this disease, the most studied candidate genes in cervical cancer in different populations have been H-ras, K-ras, EGFR among others. Objective: The present study identified human papilloma virus (HPV) generic and specific in DNA-free plasma and cervical smears of invasive cervical cancer patients and patients with cervical intraepithelial neoplasia (CIN) III in addition to assessing genetic alterations, such as mutations in the genes H-ras, EGFR and K-ras. Methods: To do so generic HPV was detected by PCR with primers GP5+/GP6+, and specific HPV 16 and 18 in E6/E7 region; to detect mutations in codon 12 of  H-ras, codons 12 and 13 of K-ras and EGFR exon 21 was conducted by direct sequencing of PCR products of these gene fragments. Results: Getting a good correlation between samples of blood plasma and cervical smears for both; the findings of HPV p=0.0374 and evaluated mutations p=0. In general, for EGFR in exon 21 mutations were not found, as for codons 12 and 13 in K-ras and codon 12 in H-ras. Conclusion: The use of DNA in plasma may be relevant to the analysis of mutations and the presences of tumor markers are not available from other samples.

Prediction Model for the Cellular Immortalization and Transformation Potentials of Cell Substrates

The establishment of DNA microarray technology has enabled high-throughput analysis and molecular profiling of various types of cancers. By using the gene expression data from microarray analysis we are able to investigate diagnostic applications at the molecular level. The most important step in the application of microarray technology to cancer diagnostics is the selection of specific markers from gene expression profiles. In order to select markers of immortalization and transformation we used c-myc and H-ras(V12) oncogene-transfected NIH3T3 cells as our model system. We have identified 8751 differentially expressed genes in the immortalization/transformation model by multivariate permutation F-test (95% confidence, FDR <0.01). Using the support vector machine algorithm, we selected 13 discriminative genes which could be used to predict immortalization and transformation with perfect accuracy. We assayed H-ras(V12)-transfected "transformed" cells to validate our immortalization/transformation classification system. The selected molecular markers generated valuable additional information for tumor diagnosis, prognosis and therapy development.

ras Gene Mutations in Malignant Fibrous Histiocytoma

BACKGROUND: ras gene mutations have been described in various human malignancies, suggesting that their activation may play a role in oncogenesis. However, there are few reports concerning ras gene alterations in malignant fibrous histiocytomas. We therefore designed a study to determine the prevalence and type of mutations in the first exons of H-ras and K-ras genes in these tumors. METHODS: Twenty-seven malignant fibrous histiocytomas were investigated by direct sequencing analysis with the automated DNA sequencing of polymerase chain reaction-amplified ras sequences. RESULTS: Twenty-four mutations were found in 18 (67%) of the tumors: GGC to GAC transition mutations at codon 13 of K-ras (coding for aspartic acid instead of glycine) in 18 of the samples and GGC to GTC transversions at codon 12 of H-ras (coding for valine instead of glycine) in six of the lesions. CONCLUSIONS: Our data suggest an involvement of the ras gene mutation in conjunction with other yet unknown events in the tumorigenesis and/or progression of malignant fibrous histiocytomas. The K-ras gene activation predominated in these tumors by a mutation at codon 13. It is noteworthy that H-ras mutations were detected only in association with the lesions containing K-ras mutated genes, the significance of which remains to be determined.

Occurrence and Specific Type of p53 and H-ras Mutations Based on Polymorphisms of NAT2 and GSTM1 in Human Bladder Cancer / 대한비뇨기과학회지

PURPOSE: Cancer development depends on not only activation of oncogene or inactivation of tumor suppressor gene but also activities of enzymes involved in the metabolism of various carcinogenic xenobiotics, such as arylamine N-acetyltrasferase 2(NAT 2) and glutathione S-transferase (GSTM1). We analyzed whether genetic polymorphisms of NAT2 and GSTM1 were correlated with the mutation patterns of p53 and H-ras genes in bladder tumor tissues. MATERIALS AND METHODS: In 49 bladder cancer patients, we performed direct DNA sequencing for the detection of mutations of p53 and H-ras gene in bladder tumor tissues, and adopted PCR and PCR-RFLP techniques for the analysis of genetic polymorphisms of NAT2 and GSTM1 using patients` blood samples, respectively. RESULTS: In 18 cases, mutations in p53 were detected whereas 1 case carried two mutations; thus total of 19 mutations were detected. Sixteen of these were point mutations including 13 of transversions and 3 of transitions, and others were 1 of frameshift and 2 of microdeletions-insertions. Among 33 patients, H-ras mutations were detected in 5 cases with 2 of transitions and 3 of transversions. The frequencies of slow, intermediate, and rapid acetylator in NAT2 genotyping analysis, were 10.2%, 40.8%, and 49.0%, respectively, and GSTM1 deletions were observed in 73.5%. We could not find any significant correlations between NAT2 or GSTM1 polymorphisms and the occurence of p53(p=0.614, p=0.310) or H-ras(p=0.500, p=0.582) mutations. Also, no apparent associations were seen for specific type of p53 and H-ras mutations according to polymorphisms of NAT2(p=0.456, p=0.600) and GSTM1(p=0.378, p=0.400). CONCLUSIONS: The polymorphisms of NAT2 and GSTM1, conjugating enzymes of foreign compound metabolism, were not considered to influence occurrence and type of mutations in p53 and H-ras in human bladder cancer.

Patterns of p53 and H-ras Mutations related to Invasiveness and Differentiation of Transitional Cell Carcinoma in Human bladder / 대한비뇨기과학회지

PURPOSE: To characterize the patterns of p53 & H-ras mutations related to invasiveness and differentiation of transitional cell carcinoma in human bladder. MATERIALS AND METHODS: Tissues from 52 patients diagnosed as transitional cell carcinoma in the Chungbuk National University Hospital from 1992 to 1997 were used. Direct DNA sequencing was performed to detect the presence of mutated p53 and H-ras genes and to determine the types of mutations. RESULTS: 40.4%(21/52) and 11.5%(6/52) exhibited mutations in p53 and H-ras genes, respectively. In p53 gene, 26 mutations were detected in 21 specimens; 16 point mutations and 10 microdeletions-insertions in exon 7, 8, and 10, but not in exon 9. Three specimens showed mutations more than one, i.e., a triple point mutation, and two point mutation with microdeletions-insertions in p53 gene. ATG-->AAG point mutation at codon 243 was found most frequently(38.1%). Concerning the mutation of H-ras gene, 8 point mutations were detected from 6 specimens. Only one specimen showed triple point mutation. AGT-->AGA point mutation at codon 17 was the most frequent(50%). The mutation of H-ras was statistically correlated with differentiation but not with invasiveness, whereas the mutation of p53 was not statistically correlated with any of them. Mutation of both genes had correlations to differentiation(p=0.045). CONCLUSIONS: From theses results, the mutation of H-ras gene might be a useful factor to expect the progression of transitional cell carcinoma. However, the mutation of p53 gene was insufficient as a prognostic factor of transitional cell carcinoma.

A PCR-RFLP method for the detection of activated H-ras oncogene with a point mutation at codon 12 and 61

To investigate the incidence of the H-ras gene activation in bladder tumor and the feasibility of using urinary washout samples for screening, a series of 33 human bladder tumors and their preoperatively collected urinary washout samples were screened using a mutant specific PCR-RFLP (polymerase chain-restriction fragment length polymorphism) to detect a point mutation of the H-ras gene. Five tumors were found to harbor H-ras mutations where two tumors had a glycine to valine (G-->T) change in codon 12 and three tumors had a glutamine to lysine (C-->A) change in codon 61, respectively. Moreover, we could also detect the same point mutations of the H-ras gene in corresponding urine washout samples. The incidence of H-ras mutation in Korean bladder cancer was estimated at approximately 15.2%. In conclusion, a mutant specific PCR-RFLP method for the detection of H-ras gene mutation is useful for screening or postoperative follow-up of bladder tumor due to its simplicity and high specificity even in urinary samples.

Effects of docosahexaenoic acid (DHA) compound on H-Ras and p16 mRNA transcription in gastric adenocarcinoma / 中国海洋药物

Objective To study the antitumor mechanism of DHA compound. Methods RT-PCR was used to investigate the effects of DHA compound on H-Ras and pl6 mRNA transcription in gastric adenocarcinoma. Results Compared with control, the content of H-Ras mRNA was decreased and the content of p16 mRNA was increased in gastric adenocarcinoma significantly after treated with DHA compound. Conclusion The transcription of H-Ras gene was decreased and the transcription of pl6 gene was increased in gastric adenocarcinoma after treated with DHA compound and thus the cancer cell growth was inhibited.

Identification of mutagenic site of c-H-ras oncogene damaged by N-acetoxyacetylaminofluorene(AAAF)

A molecularly cloned human cellular H-ras (c-H-ras) oncogene(pbc N1 plasmid) was treated with N-acetoxyacetylaminofluorene (AAAF) in vitro and subcloned into E.coli. This was done to identify the mutational changes at specific codons of the gene. Guanine nucleotides were identified as the major AAAF binding site of the DNA adduct formed. Base changes in codons 12 and 61 were determined by the analysis of restriction fragment length polymorphism (RFLP) and site specific oligonucleotide hybridization. RFLP was observed due to the loss of the Hpall recognition site at codon 11 and 12 of AAAF-treated c-H-ras gene. Hybridization of AAAF treated c-H-ras with 32P-labeled oligonucleotide probes for the mutant alleles of codon 61 showed no substitutions at codon 61. From these results, it is assumed that AAAF treatment in vitro caused mutation at codon 12 but not at codon 61 of the c-H-ras oncogene and that codon 12 is the primary target of mutation by AAAF