SEARCH · PubMed Health

Results for “mutational profiling”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,189 records · Page 66Linked to original sources

PubMed2026

Genetic insights into lung squamous cell carcinoma: how TP53 and CSMD3 co-mutations shape prognosis and immune response.

BACKGROUND: Lung squamous cell carcinoma (LUSC) accounts for a significant proportion of lung cancer cases and is often associated with smoking and various environmental factors. The prognostic and immunologic implications of TP53 and CSMD3 co-mutations in LUSC remain poorly understood. This study aimed to investigate the role of TP53/CSMD3 co-mutations in LUSC using comprehensive bioinformatics analyses. METHODS: Data from 487 LUSC patients were obtained from The Cancer Genome Atlas (TCGA) database, with external validation performed using the combined cohort. Patients were stratified into TP53/CSMD3 co-mutation, single-mutation, and wild-type (WT) groups. Prognostic analysis was conducted using Kaplan-Meier survival curves. Tumor mutational burden (TMB) was calculated, and immune cell infiltration was assessed using multiple algorithms. Differentially expressed genes (DEGs) between co-mutated and WT groups were identified, followed by Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. A nomogram incorporating mutation status, gender, age, and tumor stage (T stage) was developed for individualized prognostic prediction. RESULTS: The TP53/CSMD3 co-mutated group exhibited significantly better overall survival (OS) compared to single-mutation and WT groups. TMB scores were markedly higher in co-mutated patients, suggesting potential sensitivity to immune checkpoint inhibitors. Immune infiltration analysis revealed distinct profiles, including elevated CD8 T cells and reduced immunosuppressive components, in the co-mutation group. A total of 403 DEGs were identified between co-mutated and WT groups, with significant enrichment in immune-related pathways. Mechanistically, the co-mutation was associated with distinct downregulation of complement negative regulators (CFH/CFI), indicating complement hyperactivation independent of TMB. The constructed nomogram provided accurate individualized prognostic assessments. CONCLUSIONS: The co-mutation of TP53 and CSMD3 identifies a distinct LUSC subtype with favorable survival, marked by high TMB and an immune-activated microenvironment. Beyond TMB-driven neoantigen generation, the significant downregulation of complement negative regulators (CFH/CFI) reveals an independent complement hyperactivation pathway associated with CSMD3 loss. The constructed nomogram provides accurate individualized survival prediction. These findings establish TP53/CSMD3 co-mutation as a promising prognostic biomarker and offer mechanistic insights for personalized immunotherapy strategies. Future prospective cohorts are warranted to validate its predictive value.

Lung squamous cell carcinoma (LUSC)↗

PubMed2002

Thirteenth annual pezcoller symposium: focusing analytical tools on complexity in cancer.

The physiopathology of cancer cells is the result of very complex signaling networks that represent in many cases distortions of the orderly networks regulating the physiology of normal cells. These networks are the consequence of the expression of, or the lack of expression of, genes, mutated or not, which represent the genomic profile of different types of or of individual cancers. The complex signaling pathways, the cross-talks among them, and the redundancies existing for several of them mediate not only the transmission of signals from the cell environment to the nucleus but also that from the nucleus to the other cellular components whose function is involved in cell proliferation, apoptosis, or differentiation. Modern approaches to cancer therapy and also prevention are aimed at identifying new molecular targets, pivotal to the life of the cancer cell, which would provide for specific sites of intervention. In the face of the enormous complexity of the phenomena on which the life of cancer cells is based, it is both difficult to identify unique specific target for intervention and important to develop analytical tools and approaches capable to identify them for further exploitation. This was the main subject of the Symposium. Consideration was given to: (a) tumor genotypic analysis through expression array evaluation and definition of cancer transcriptomes in studies aimed at identifying determinants of specific characteristics of cancer cells; (b) approaches based on the knowledge gained in this analysis that would lead to the visualization of new targets exploitable for antitumor action; and (c) multifactorial analysis of the complex interactions regulating cancer cells and methods to comprehend the complexity of molecular models and validate their functional relevance.

Animals↗

PubMed2004

Significance of PTEN alterations in endometrial carcinoma: a population-based study of mutations, promoter methylation and PTEN protein expression.

Mutations in the PTEN gene are frequent in endometrial carcinoma. PTEN methylation is an alternative mechanism of gene inactivation. To elucidate different mechanisms of PTEN gene inactivation, we have studied a population-based series of endometrial carcinomas for PTEN mutations in relation to clinicopathologic characteristics, promoter methylation and protein expression. PTEN mutations were found in 54%, mainly in exons 5 and 8; with at least two different mutations in 21%. Presence of PTEN mutation was significantly correlated with young age, low FIGO-stage, endometrioid subtype, low grade, microsatellite instability and favourable prognosis. Previous studies of these tumours have observed PTEN methylation in 18% and low protein expression in 20%. Low expression of PTEN-antibody 6H2.1 was correlated with the presence of mutations in exon 8 among patients with 'two hits'; i.e. > or =2 mutations, or mutation(s) plus methylation (p=0.001). Number of PTEN hits was significantly associated with microsatellite instability, low hMLH1 expression and hMLH1 methylation. Thus, PTEN mutations are frequent in sporadic endometrial carcinoma and define a prognostically favourable subgroup, whereas the relationship with PTEN protein expression is complex. A pathway in endometrial carcinogenesis involving PTEN mutation and microsatellite instability is confirmed, and this study also indicates the importance of PTEN and hMLH1 methylation in this pathway.

Adult↗

PubMed2004

HLA class II genotype and factor VIII inhibitors in mild haemophilia A patients with an Arg593 to Cys mutation.

We evaluated inhibitor formation in a group of patients with mild haemophilia A caused by an Arg593 to Cys mutation. A remarkably high cumulative inhibitor incidence of 14% over 22 years was observed. Three of 49 patients developed transient, low-titre inhibitors, which remained below 2.0 BU mL(-1). Four patients with an Arg593 to Cys mutation developed high-titre inhibitors (>5.0 BU mL(-1)). Three of these patients have been described previously. In this study, we characterized inhibitory antibodies in a fourth patient with high-titre inhibitors. Epitope mapping studies revealed that antibodies were predominantly directed to the A2 domain of factor VIII. We addressed the role of human leucocyte antigen (HLA) class II alleles in inhibitor development in patients with an Arg593 to Cys mutation by HLA genotyping. In the group of inhibitor patients raised frequencies of HLA-DRB1*01 and HLA-DQB1*05 were observed that did not reached statistical significance. Our data suggest that inhibitor development in mild haemophilia A patients with an Arg593 to Cys mutation is not linked to HLA class II profile.

Antibodies↗

PubMed2005

Effort angina in a middle-aged woman with abnormally high levels of serum high-density lipoprotein cholesterol: a case of cholesteryl-ester transfer protein deficiency.

A 54-year-old female was admitted to hospital complaining of oppressive anterior chest pain during exercise. Treadmill exercise ECG testing showed significant ischemic ECG changes, and electron-beam computed tomography demonstrated patchy calcifications in the coronary artery. Coronary angiography revealed a significant stenotic lesion of the right coronary artery. On routine investigations, no classical coronary risk factors were found, although a very high concentration (209 mg/dl) of high-density lipoprotein cholesterol (HDL-C) was detected. The serum concentration of cholesteryl-ester transfer protein (CETP), which plays a central role in the reverse cholesterol transport system, was measured and found to be less than the measurable minimum. The patient showed one of the typical genetic CETP mutations (intone 14 splicing defect), and her lipid profile was improved by administration of probucol for 3 months. A very high concentration of HDL-C with a defect of CETP activity may be a specific biochemical indicator pointing to an increased risk of premature coronary artery disease, and the lipid profile can be improved by use of lipid-lowering drugs.

Angina Pectoris↗

PubMed2026

Genomic and transcriptomic features of relapsed small cell lung cancer.

BACKGROUND: Relapsed small cell lung cancer is characterized by treatment resistance and poor outcomes. Genomic and transcriptomic alterations in relapsed SCLC have not been characterized well. We comprehensively profiled relapsed SCLC samples along with patient-matched treatment-naive samples, when available, using whole-exome (WES), whole-genome (WGS), and RNA-sequencing (RNA-seq) to describe the molecular landscape of relapsed SCLC. Our goal is to identify potential novel pathways for additional functional validation and eventually novel therapeutic options. METHODS: We analyzed 54 relapsed and 27 treatment-naive SCLC samples using WES (with 26 patient-matched paired samples). A subset of the samples was also analyzed by WGS (n=28) and RNA-seq (n=31). Differences in mutational signatures, gene expression, structural variants, splicing, and neoantigen profiles at diagnosis and relapse were investigated. RESULTS: Relapsed SCLC samples demonstrated mutation signatures characteristic of platinum and APOBEC mutagenesis. Furthermore, these samples were characterized by MYC, MYCL and MYCN amplifications. Both treatment-naive and relapsed SCLC samples showed high prevalence of mutation-associated neoantigens (median= 86 in treatment-naive and 90 in relapsed SCLC; p=0.8) and TP53 was the most frequently altered gene to result in a neoantigen (48% of analyzed samples). Potential mechanisms of immune evasion, including amplification of CD24, overexpression of IDO1, increased M2 macrophage presence, and upregulation of HLA-E were also observed in relapse samples. Differences in alternative splicing patterns were observed between treatment-naive and relapsed small cell samples. Retained intron events were significantly enriched in treatment-naive samples and affected genes involved in DNA repair, metabolism, and WNT and MYC pathways. CONCLUSIONS: This study highlights the genomic and transcriptomic features of relapsed SCLC. These samples were characterized by genomic instability, WNT and MYC dysregulation, and splicing aberrations. Additional studies targeting the splicing machinery, WNT signaling, and immune evasion pathways could identify novel therapeutic vulnerabilities in SCLC.

Journal Article↗

PubMed1999

A genotypic study of 217 unrelated probands diagnosed as "genetic hemochromatosis" on "classical" phenotypic criteria.

BACKGROUND/AIMS: The HFE gene is a crucial candidate gene for hemochromatosis. The aims of this study were to assess the HFE genotypic profile in a large series of unrelated probands diagnosed as having phenotypic hemochromatosis, to characterize the sub-group of patients who were not homozygous for the major C282Y mutation, and to report the iron status of the detected HFE-identical siblings. METHODS: In 217 patients, the phenotypic diagnosis of hemochromatosis was based on strict bioclinical and/or histological criteria, and their genotypic profile (C282Y and H63D mutations) was determined. RESULTS: 1) 209 of the 217 probands were C282Y +/+. In 33 cases, an HFE-identical sibling was identified. Two of them had neither a clinical nor a biochemical phenotypic profile of hemochromatosis in the absence of any external factor which might have attenuated this expression. 2) Eight patients (seven males) were not C282Y +/+. Their genotypic profiles were: (C282Y +/-): six cases (four were H63D +/- and two H63D -/-); (C282Y -/-): two cases (one was H63D +/+, one H63D +/-). Phenotypic expression consisted of six cases of mild liver siderosis (among whom were the four compound heterozygotes and one case of alcoholic cirrhosis) and two severe cases of hepatic iron overload (one with alcoholic cirrhosis). Three HFE-identical siblings were identified, none of them presenting with iron excess. CONCLUSIONS: In our population: 1) The classical phenotypic criteria fitted, in 96.3% of cases, with a homogeneous genotypic entity defined by homozygosity for the C282Y mutation. Incomplete penetrance of the homozygous status was shown by the absence of the hemochromatosis phenotypic profile in 6% of the HFE-identical siblings. 2) A minority (3.7%) were not homozygous for C282Y. These were essentially men with mild iron overload, and might present with distinct iron overload entity(ies) as suggested by the presence in three of an HFE-identical sibling with absence of iron overload.

Adult↗

PubMed2004

Evaluation of a DHPLC-based assay for rapid detection of RET germline mutations in Italian patients with medullary thyroid carcinoma.

Causative gain-of-function mutations of the RET tyrosine-kinase receptor gene have been reported in more than 95% of inherited cases of medullary thyroid carcinoma (MTC; OMIM# 155240). Most RET activating mutations are clustered in mutational "hot spots" in exons 10, 11, 13, 14, 15 and 16 and are usually detected by single-strand conformation polymorphism (SSCP) followed by direct sequencing. To improve sensitivity, time and costs of mutational screening we have developed a denaturing high performance chromatography (DHPLC) protocol, based on the detection of heteroduplex molecules by ion-pair reverse-phase liquid chromatography under partially denaturing conditions. The mutational screening of RET exons 10, 11, 13-16 was performed in a total of 111 subjects, including 45 MTC patients and 49 relatives with known RET mutations and 17 individuals, being at risk of hereditary MTC and carrying unknown RET alleles. Heteroduplex peaks with a distinct and reproducible DHPLC elution profile allowed the detection of both rare and common RET mutations. Overall, the DHPLC-based methodology showed a high level of sensitivity and accuracy, nearing 100%. Furthermore, our protocol showed the ability to identify: 1) all the mutated codons of RET located in the "hot spots" domain; 2) the different point mutations occurring in the same codon of RET gene; 3) less frequent or rare mutations; 4) polymorphisms. As such, it can be proposed as a relatively simple and highly accurate method for a rapid genetic testing for members of MTC families.

Carcinoma, Medullary↗

PubMed2026

Personalizing endometrial cancer care beyond histology: clinical applications and limits of molecular classification.

Endometrial cancer is a biologically heterogeneous disease whose management has been reshaped by molecular classification. This review summarizes the current evidence supporting the integration of molecular subgroups into prognostic assessment and treatment personalization across stages of disease. The Cancer Genome Atlas classification and its clinically applicable surrogates identify four major molecular categories: POLE-mutated, mismatch repair-deficient, p53-abnormal, and no specific molecular profile tumors. These groups differ substantially in biology, prognosis, treatment sensitivity, and areas of unmet need. POLE-mutated tumors have an excellent prognosis and represent the clearest candidates for adjuvant treatment de-escalation, particularly in early-stage disease. Mismatch repair-deficient tumors show intermediate prognosis but strong sensitivity to immune checkpoint inhibition, which has transformed the management of advanced and recurrent disease and is now being tested in earlier settings. p53-abnormal tumors represent the highest-risk subgroup, requiring multimodal treatment and offering opportunities for biomarker-driven strategies including HER2-directed therapy and DNA damage repair targeting. No specific molecular profile tumors remain the most heterogeneous category, increasingly refined by estrogen receptor status, grade, L1 cell adhesion molecule overexpression, and other biomarkers. Mismatch repair-proficient advanced/recurrent disease should be interpreted as a composite clinical trial population rather than a molecular class. Molecular classification should be integrated with traditional clinicopathologic factors, emerging biomarkers, and local implementation strategies to support equitable, biologically informed treatment selection in endometrial cancer.

Humans↗

PubMed2006

TFIIA plays a role in the response to oxidative stress.

To characterize the role of the general transcription factor TFIIA in the regulation of gene expression by RNA polymerase II, we examined the transcriptional profiles of TFIIA mutants of Saccharomyces cerevisiae using DNA microarrays. Whole-genome expression profiles were determined for three different mutants with mutations in the gene coding for the small subunit of TFIIA, TOA2. Depending on the particular mutant strain, approximately 11 to 27% of the expressed genes exhibit altered message levels. A search for common motifs in the upstream regions of the pool of genes decreased in all three mutants yielded the binding site for Yap1, the transcription factor that regulates the response to oxidative stress. Consistent with a TFIIA-Yap1 connection, the TFIIA mutants are unable to grow under conditions that require the oxidative stress response. Underexpression of Yap1-regulated genes in the TFIIA mutant strains is not the result of decreased expression of Yap1 protein, since immunoblot analysis indicates similar amounts of Yap1 in the wild-type and mutant strains. In addition, intracellular localization studies indicate that both the wild-type and mutant strains localize Yap1 indistinguishably in response to oxidative stress. As such, the decrease in transcription of Yap1-dependent genes in the TFIIA mutant strains appears to reflect a compromised interaction between Yap1 and TFIIA. This hypothesis is supported by the observations that Yap1 and TFIIA interact both in vivo and in vitro. Taken together, these studies demonstrate a dependence of Yap1 on TFIIA function and highlight a new role for TFIIA in the cellular mechanism of defense against reactive oxygen species.

Amino Acid Sequence↗

PubMed1997

The PAH mutation analysis consortium database: update 1996.

A website (http://www.mcgill.ca/pahdb ) is maintained by the curators for a Consortium (88 investigators, 28 countries) and all other users; it serves a relational database for human locus-specific genetic variation in a defined DNA sequence (GenBank U49897); (100 kb on human chromosome 12q24.1, gene symbol PAH). The intragenic nucleotide variation is both rare (Q< 0.01), extensive (>320 different mutations) and phenotype modifying, causing hyperphenylalaninemia by impairing phenylalanine hydroxylase function (see OMIM 261600), as well as polymorphic and neutral, the latter providing informative locus-specific haplotypes (>1200 different mutation/haplotype associations). The PAH database contains both offline core components (mutations, population associations and data source information) and several accessory online components: (i) relative frequencies of mutations by populations/regions (expanding file); (ii) data on genotype- phenotype correlations both in vitro and in vivo (new file); (iii) polymorphic haplotype structures (new file); (iv) intron sequence data (new file for design of primers); (v) description of mouse homologues (new file for mutations and phenotypes); (vi) the predicted PAH gene mutability profile (improved graphic); (vii) a clinical field for patient use (new interface with database). The website home page has been revised and a counter is recording >15 visits per day. Linkages to other mutation databases and an alliance of mutation database curators (new) are expanding. The primary 'electronic publication' reports now vastly exceed print reports. PAHdb serves as a prototype for obtaining, storing and distributing records of human genetic variation.

Animals↗

PubMed1995

Relating aromatic hydrocarbon-induced DNA adducts and c-H-ras mutations in mouse skin papillomas: the role of apurinic sites.

Mouse skin tumors contain activated c-H-ras oncogenes, often caused by point mutations at codons 12 and 13 in exon 1 and codons 59 and 61 in exon 2. Mutagenesis by the noncoding apurinic sites can produce G-->T and A-->T transversions by DNA misreplication with more frequent insertion of deoxyadenosine opposite the apurinic site. Papillomas were induced in mouse skin by several aromatic hydrocarbons, and mutations in the c-H-ras gene were determined to elucidate the relationship among DNA adducts, apurinic sites, and ras oncogene mutations. Dibenzo[a,l]pyrene (DB[a,l]P), DB[a,l]P-11,12-dihydrodiol, anti-DB[a,l]P-11,12-diol-13,14-epoxide, DB[a,l]P-8,9-dihydrodiol, 7,12-dimethylbenz[a]anthracene (DMBA), and 1,2,3,4-tetrahydro-DMBA consistently induced a CAA-->CTA mutation in codon 61 of the c-H-ras oncogene. Benzo[a]pyrene induced a GGC-->GTC mutation in codon 13 in 54% of tumors and a CAA-->CTA mutation in codon 61 in 15%. The pattern of mutations induced by each hydrocarbon correlated with its profile of DNA adducts. For example, both DB[a,l]P and DMBA primarily form DNA adducts at the N-3 and/or N-7 of deoxyadenosine that are lost from the DNA by depurination, generating apurinic sites. Thus, these results support the hypothesis that misreplication of unrepaired apurinic sites generated by loss of hydrocarbon-DNA adducts is responsible for transforming mutations leading to papillomas in mouse skin.

Animals↗

PubMed2026

Genetic mutations in metastatic adenocarcinoma of unknown primary.

INTRODUCTION: Although several genomic alterations have been reported in adenocarcinoma of unknown primary (ACUP), molecularly targeted therapies are not yet clinically established, and comprehensive genomic profiling (CGP) is rarely used in daily practice. AIM: We aimed to clarify the molecular landscape and prognostic impact of key mutations in recurrent or metastatic ACUP. MATERIALS AND METHODS: Data from 480 consecutive ACUP patients registered in Japan's National Cancer Center (C-CAT) between June 2019 and August 2025 were analyzed. Somatic mutations were identified using the FoundationOne CDx platform. Overall survival (OS) was assessed by Kaplan-Meier analysis, log-rank tests, and multivariate Cox proportional hazards modeling. RESULTS: The most frequent alterations were TP53 (59.4%), KRAS (31.5%), CDKN2A (26.3%), KMT2D (22.3%), LTK (17.9%), NOTCH3 (16.9%), STK11 (16.3%), CDKN2B (15.8%), ERBB2 (15.4%), and GNAS (15.2%). Patients harbored an average of 17.3 9.9 mutations. Mutations in GNAS (p = 0.046) and PIK3CA (p = 0.025) were associated with better OS, whereas ARID1A (p = 0.049) and NOTCH1 (p = 0.038) predicted worse OS. In Cox analysis, hazard ratios (HR [95% CI]) were 0.57 (0.36-0.92, p = 0.020) for GNAS, 0.57 (0.33-0.96, p = 0.033) for PIK3CA, 1.98 (1.27-3.09, p = 0.0024) for ARID1A, and 1.84 (1.17-2.91, p = 0.0090) for NOTCH1. CONCLUSIONS: GNAS and PIK3CA mutations were linked to favorable outcomes, while ARID1A and NOTCH1 alterations indicated poor prognosis in ACUP. These results highlight the prognostic significance of specific genomic alterations and support integrating CGP into the clinical management of ACUP.

Humans↗

PubMed2022

Feasibility of a novel non-invasive swab technique for serial whole-exome sequencing of cervical tumors during chemoradiation therapy.

BACKGROUND: Clinically relevant genetic predictors of radiation response for cervical cancer are understudied due to the morbidity of repeat invasive biopsies required to obtain genetic material. Thus, we aimed to demonstrate the feasibility of a novel noninvasive cervical swab technique to (1) collect tumor DNA with adequate throughput to (2) perform whole-exome sequencing (WES) at serial time points over the course of chemoradiation therapy (CRT). METHODS: Cervical cancer tumor samples from patients undergoing chemoradiation were collected at baseline, at week 1, week 3, and at the completion of CRT (week 5) using a noninvasive swab-based biopsy technique. Swab samples were analyzed with whole-exome sequencing (WES) with mutation calling using a custom pipeline optimized for shallow whole-exome sequencing with low tumor purity (TP). Tumor mutation changes over the course of treatment were profiled. RESULTS: 216 samples were collected and successfully sequenced for 70 patients (94% of total number of tumor samples collected). A total of 33 patients had a complete set of samples at all four time points. The mean mapping rate was 98% for all samples, and the mean target coverage was 180. Estimated TP was greater than 5% for all samples. Overall mutation frequency decreased during CRT but mapping rate and mean target coverage remained at >98% and >180 reads at week 5. CONCLUSION: This study demonstrates the feasibility and application of a noninvasive swab-based technique for WES analysis which may be applied to investigate dynamic tumor mutational changes during treatment to identify novel genes which confer radiation resistance.

Exome↗

PubMed2004

Clinical features of hypertrophic cardiomyopathy caused by an Arg278Cys missense mutation in the cardiac troponin T gene.

To further examine the genetic and clinical features of hypertrophic cardiomyopathy caused by mutations in the cardiac troponin T (cTnT) gene, we screened 143 probands from our hypertrophic cardiomyopathy population for mutations in this gene. We report that the Arg278Cys missense mutation in the cTnT gene had a different clinical presentation in 2 different families and was associated with a clinical profile that deviates from what is currently expected for cTnT gene mutations.

Adolescent↗

PubMed2006

Origins of proton transport behavior from selectivity domain mutations of the aquaporin-1 channel.

The permeation free-energy profile and maximum ion conductance of proton transport along the channel of three aquaporin-1 (AQP1) mutants (H180A/R195V, H180A, and R195V) are calculated via molecular dynamics simulations and Poisson-Nernst-Planck theory. The proton dynamics was described by the multistate empirical valence bond (MS-EVB) model. The results reveal three major contributions to the overall free-energy barrier for proton transport in AQP1: 1), the bipolar field, 2), the electrostatic repulsion due to the Arg-195 residue, and 3), the dehydration penalty due to the narrow channel pore. The double mutation (H180A/R195V) drastically drops the overall free-energy barrier by roughly 20 kcal/mol via simultaneously relaxing the direct electrostatic interaction (by R195V) and dehydration effect (by H180A).

Amino Acid Substitution↗

PubMed2004

Genes causing inherited cancer as beacons to identify the mechanisms of chemoresistance.

Mechanisms of resistance to cancer chemotherapy are poorly understood. Molecular pathways involving genes associated with inherited cancer syndromes could represent mechanisms of chemoresistance. Microarray techniques can identify simultaneous alterations in the mRNA expression of multiple genes, but identification of the exact mechanism responsible for a particular phenotype, including resistance to a specific drug, remains problematic. Genes in which mutations cause inherited cancers play vital roles in apoptosis, growth arrest and/or DNA repair, and are inactivated by somatic mutations, deletions or hypermethylation in most cancer tissues. Similarities between carcinogenic injury and cell damage created by chemotherapeutics suggests that somatic inactivation of such genes is crucially important to drug sensitivity.

Antineoplastic Agents↗

PubMed1995

Genetic and comparative analyses reveal an alternative secondary structure in the region of nt 912 of Escherichia coli 16S rRNA.

Mutations at position 912 of Escherichia coli 16S rRNA result in two notable phenotypes. The C-->U transition confers resistance to streptomycin, a translational-error-inducing antibiotic, while a C-->G transversion causes marked retardation of cell growth rate. Starting with the slow-growing G912 mutant, random mutagenesis was used to isolate a second site mutation that restored growth nearly to the wild-type rate. The second site mutation was identified as a G-->C transversion at position 885 in 16S rRNA. Cells containing the G912 mutation had an increased doubling time, abnormal sucrose gradient ribosome/subunit profile, increased sensitivity to spectinomycin, dependence upon streptomycin for growth in the presence of spectinomycin, and slower translation rate, whereas cells with the G912/C885 double mutation were similar to wild type in these assays. Comparative analysis showed there was significant covariation between positions 912 and 885. Thus the second-site suppressor analysis, the functional assays, and the comparative data suggest that the interaction between nt 912 and nt 885 is conserved and necessary for normal ribosome function. Furthermore, the comparative data suggest that the interaction extends to include G885-G886-G887 pairing with C912-U911-C910. An alternative secondary structure element for the central domain of 16S rRNA is proposed.

Drug Resistance, Microbial↗