RESUMO
PURPOSE: The purpose of this study was to determine whether computed tomography (CT)-based machine learning of radiomics features could help distinguish autoimmune pancreatitis (AIP) from pancreatic ductal adenocarcinoma (PDAC). MATERIALS AND METHODS: Eighty-nine patients with AIP (65 men, 24 women; mean age, 59.7±13.9 [SD] years; range: 21-83 years) and 93 patients with PDAC (68 men, 25 women; mean age, 60.1±12.3 [SD] years; range: 36-86 years) were retrospectively included. All patients had dedicated dual-phase pancreatic protocol CT between 2004 and 2018. Thin-slice images (0.75/0.5mm thickness/increment) were compared with thick-slices images (3 or 5mm thickness/increment). Pancreatic regions involved by PDAC or AIP (areas of enlargement, altered enhancement, effacement of pancreatic duct) as well as uninvolved parenchyma were segmented as three-dimensional volumes. Four hundred and thirty-one radiomics features were extracted and a random forest was used to distinguish AIP from PDAC. CT data of 60 AIP and 60 PDAC patients were used for training and those of 29 AIP and 33 PDAC independent patients were used for testing. RESULTS: The pancreas was diffusely involved in 37 (37/89; 41.6%) patients with AIP and not diffusely in 52 (52/89; 58.4%) patients. Using machine learning, 95.2% (59/62; 95% confidence interval [CI]: 89.8-100%), 83.9% (52:67; 95% CI: 74.7-93.0%) and 77.4% (48/62; 95% CI: 67.0-87.8%) of the 62 test patients were correctly classified as either having PDAC or AIP with thin-slice venous phase, thin-slice arterial phase, and thick-slice venous phase CT, respectively. Three of the 29 patients with AIP (3/29; 10.3%) were incorrectly classified as having PDAC but all 33 patients with PDAC (33/33; 100%) were correctly classified with thin-slice venous phase with 89.7% sensitivity (26/29; 95% CI: 78.6-100%) and 100% specificity (33/33; 95% CI: 93-100%) for the diagnosis of AIP, 95.2% accuracy (59/62; 95% CI: 89.8-100%) and area under the curve of 0.975 (95% CI: 0.936-1.0). CONCLUSIONS: Radiomic features help differentiate AIP from PDAC with an overall accuracy of 95.2%.
Assuntos
Doenças Autoimunes , Pancreatite Autoimune , Neoplasias Pancreáticas , Pancreatite , Idoso , Doenças Autoimunes/diagnóstico por imagem , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Ductos Pancreáticos , Neoplasias Pancreáticas/diagnóstico por imagem , Pancreatite/diagnóstico por imagem , Estudos Retrospectivos , Tomografia Computadorizada por Raios XRESUMO
PURPOSE: The purpose of this study was to report procedures developed to annotate abdominal computed tomography (CT) images from subjects without pancreatic disease that will be used as the input for deep convolutional neural networks (DNN) for development of deep learning algorithms for automatic recognition of a normal pancreas. MATERIALS AND METHODS: Dual-phase contrast-enhanced volumetric CT acquired from 2005 to 2009 from potential kidney donors were retrospectively assessed. Four trained human annotators manually and sequentially annotated 22 structures in each datasets, then expert radiologists confirmed the annotation. For efficient annotation and data management, a commercial software package that supports three-dimensional segmentation was used. RESULTS: A total of 1150 dual-phase CT datasets from 575 subjects were annotated. There were 229 men and 346 women (mean age: 45±12years; range: 18-79years). The mean intra-observer intra-subject dual-phase CT volume difference of all annotated structures was 4.27mL (7.65%). The deep network prediction for multi-organ segmentation showed high fidelity with 89.4% and 1.29mm in terms of mean Dice similarity coefficients and mean surface distances, respectively. CONCLUSIONS: A reliable data collection/annotation process for abdominal structures was developed. This process can be used to generate large datasets appropriate for deep learning.
Assuntos
Abdome/diagnóstico por imagem , Aprendizado Profundo , Tomografia Computadorizada por Raios X/métodos , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Adulto JovemRESUMO
BACKGROUND: In early-stage pancreatic cancer, there are currently no biomarkers to guide selection of therapeutic options. This prospective biomarker trial evaluated the feasibility and potential clinical utility of circulating tumor DNA (ctDNA) analysis to inform adjuvant therapy decision making. MATERIALS AND METHODS: Patients considered by the multidisciplinary team to have resectable pancreatic adenocarcinoma were enrolled. Pre- and post-operative samples for ctDNA analysis were collected. PCR-based-SafeSeqS assays were used to identify mutations at codon 12, 13 and 61 of KRAS in the primary pancreatic tumor and to detect ctDNA. Results of ctDNA analysis were correlated with CA19-9, recurrence-free and overall survival (OS). Patient management was per standard of care, blinded to ctDNA data. RESULTS: Of 112 patients consented pre-operatively, 81 (72%) underwent resection. KRAS mutations were identified in 91% (38/42) of available tumor samples. Of available plasma samples (N = 42), KRAS mutated ctDNA was detected in 62% (23/37) pre-operative and 37% (13/35) post-operative cases. At a median follow-up of 38.4 months, ctDNA detection in the pre-operative setting was associated with inferior recurrence-free survival (RFS) [hazard ratio (HR) 4.1; P = 0.002)] and OS (HR 4.1; P = 0.015). Detectable ctDNA following curative intent resection was associated with inferior RFS (HR 5.4; P < 0.0001) and OS (HR 4.0; P = 0.003). Recurrence occurred in 13/13 (100%) patients with detectable ctDNA post-operatively, including in seven that received gemcitabine-based adjuvant chemotherapy. CONCLUSION: ctDNA studies in localized pancreatic cancer are challenging, with a substantial number of patients not able to undergo resection, not having sufficient tumor tissue for analysis or not completing per protocol sample collection. ctDNA analysis, pre- and/or post-surgery, is a promising prognostic marker. Studies of ctDNA guided therapy are justified, including of treatment intensification strategies for patients with detectable ctDNA post-operatively who appear at very high risk of recurrence despite gemcitabine-based adjuvant therapy.
Assuntos
Biomarcadores Tumorais/sangue , DNA Tumoral Circulante/sangue , Neoplasias Pancreáticas/sangue , Proteínas Proto-Oncogênicas p21(ras)/sangue , Idoso , Idoso de 80 Anos ou mais , Quimioterapia Adjuvante/métodos , Desoxicitidina/administração & dosagem , Desoxicitidina/análogos & derivados , Intervalo Livre de Doença , Feminino , Humanos , Biópsia Líquida , Masculino , Pessoa de Meia-Idade , Mutação , Recidiva Local de Neoplasia/sangue , Recidiva Local de Neoplasia/tratamento farmacológico , Recidiva Local de Neoplasia/patologia , Neoplasias Pancreáticas/tratamento farmacológico , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/cirurgia , Prognóstico , GencitabinaRESUMO
BACKGROUND: Early indicators of treatment response in metastatic colorectal cancer (mCRC) could conceivably be used to optimize treatment. We explored early changes in circulating tumor DNA (ctDNA) levels as a marker of therapeutic efficacy. PATIENTS AND METHODS: This prospective study involved 53 mCRC patients receiving standard first-line chemotherapy. Both ctDNA and CEA were assessed in plasma collected before treatment, 3 days after treatment and before cycle 2. Computed tomography (CT) scans were carried out at baseline and 8-10 weeks and were centrally assessed using RECIST v1.1 criteria. Tumors were sequenced using a panel of 15 genes frequently mutated in mCRC to identify candidate mutations for ctDNA analysis. For each patient, one tumor mutation was selected to assess the presence and the level of ctDNA in plasma samples using a digital genomic assay termed Safe-SeqS. RESULTS: Candidate mutations for ctDNA analysis were identified in 52 (98.1%) of the tumors. These patient-specific candidate tissue mutations were detectable in the cell-free DNA from the plasma of 48 of these 52 patients (concordance 92.3%). Significant reductions in ctDNA (median 5.7-fold; P < 0.001) levels were observed before cycle 2, which correlated with CT responses at 8-10 weeks (odds ratio = 5.25 with a 10-fold ctDNA reduction; P = 0.016). Major reductions (≥10-fold) versus lesser reductions in ctDNA precycle 2 were associated with a trend for increased progression-free survival (median 14.7 versus 8.1 months; HR = 1.87; P = 0.266). CONCLUSIONS: ctDNA is detectable in a high proportion of treatment naïve mCRC patients. Early changes in ctDNA during first-line chemotherapy predict the later radiologic response.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Biomarcadores Tumorais/sangue , Carcinoma/sangue , Neoplasias Colorretais/sangue , DNA/sangue , Idoso , Bevacizumab/administração & dosagem , Biomarcadores Tumorais/genética , Camptotecina/administração & dosagem , Camptotecina/análogos & derivados , Carcinoma/tratamento farmacológico , Carcinoma/genética , Carcinoma/secundário , Neoplasias Colorretais/tratamento farmacológico , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Intervalo Livre de Doença , Feminino , Humanos , Irinotecano , Masculino , Pessoa de Meia-Idade , Mutação , Compostos Organoplatínicos/administração & dosagem , Oxaliplatina , Estudos ProspectivosAssuntos
Biomarcadores Tumorais/genética , Leucemia Linfocítica Crônica de Células B/enzimologia , Leucemia Linfocítica Crônica de Células B/genética , Mutação/genética , Proteínas Quinases/genética , DNA de Neoplasias/genética , Humanos , Leucemia Linfocítica Crônica de Células B/patologia , Reação em Cadeia da Polimerase , Análise de Sequência de DNARESUMO
Bioleaching of metal sulfides is caused by astonishingly diverse groups of bacteria. Today, at least 11 putative prokaryotic divisions can be related to this phenomenon. In contrast, the dissolution (bio)chemistry of metal sulfides follows only two pathways, which are determined by the acid-solubility of the sulfides: the thiosulfate and the polysulfide pathway. The bacterial cell can effect this sulfide dissolution by "contact" and "non-contact" mechanisms. The non-contact mechanism assumes that the bacteria oxidize only dissolved iron(II) ions to iron(III) ions. The latter can then attack metal sulfides and be reduced to iron(II) ions. The contact mechanism requires attachment of bacteria to the sulfide surface. The primary mechanism for attachment to pyrite is electrostatic in nature. In the case of Acidithiobacillus ferrooxidans, bacterial exopolymers contain iron(III) ions, each complexed by two uronic acid residues. The resulting positive charge allows attachment to the negatively charged pyrite. Thus, the first function of complexed iron(III) ions in the contact mechanism is mediation of cell attachment, while their second function is oxidative dissolution of the metal sulfide, similar to the role of free iron(III) ions in the non-contact mechanism. In both cases, the electrons extracted from the metal sulfide reduce molecular oxygen via a complex redox chain located below the outer membrane, the periplasmic space, and the cytoplasmic membrane of leaching bacteria. The dominance of either At. ferrooxidans or Leptospirillum ferrooxidans in mesophilic leaching habitats is highly likely to result from differences in their biochemical iron(II) oxidation pathways, especially the involvement of rusticyanin.
Assuntos
Biopolímeros/fisiologia , Gammaproteobacteria/metabolismo , Ferro/metabolismo , Sulfetos/metabolismo , Biopolímeros/química , OxirreduçãoRESUMO
Hereditary nonpolyposis colorectal cancer (HNPCC) is attributable to a deficiency of mismatch repair. Inactivation of DNA mismatch repair underlies the genesis of microsatellite instability in colorectal cancer. Germline mutations in three DNA mismatch repair genes, hMSH2, hMLH1, and hMSH6, have been found to segregate in HNPCC and HNPCC-like families. The two DNA mismatch repair genes hPMS1 and hPMS2 have also been suggested to predispose to HNPCC. In this study, 84 HNPCC and HNPCC-like kindreds without known mutations in the other three known DNA mismatch repair genes were screened for germline mutations in the hPMS1 or hPMS2 gene. No clear-cut pathogenic mutations were identified. Conversion technology was used to detect a large hMSH2 deletion in two affected members of the kindred in which the hPMS1 mutation was originally reported, whereas the hPMS1 mutation was only present in one of these two individuals. Since the hPMS1 and hPMS2 genes were first reported, germline mutations in hPMS2 have been demonstrated primarily in patients with Turcot's syndrome. However, no mutation in any of the two genes has been found to segregate in HNPCC families. Until there is better evidence for an increased colorectal cancer risk associated with germline mutations in these genes, a conservative interpretation of the role of mutations in these genes is advised.
Assuntos
Adenosina Trifosfatases/genética , Neoplasias Colorretais Hereditárias sem Polipose/genética , Neoplasias Colorretais/genética , Enzimas Reparadoras do DNA , Proteínas de Ligação a DNA/genética , Proteínas de Neoplasias/genética , Adulto , Feminino , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Humanos , Masculino , Pessoa de Meia-Idade , Endonuclease PMS2 de Reparo de Erro de Pareamento , Proteínas MutL , Linhagem , Reação em Cadeia da Polimerase Via Transcriptase ReversaRESUMO
Current chemotherapeutic approaches for cancer are in part limited by the inability of drugs to destroy neoplastic cells within poorly vascularized compartments of tumors. We have here systematically assessed anaerobic bacteria for their capacity to grow expansively within avascular compartments of transplanted tumors. Among 26 different strains tested, one (Clostridium novyi) appeared particularly promising. We created a strain of C. novyi devoid of its lethal toxin (C. novyi-NT) and showed that intravenously injected C. novyi-NT spores germinated within the avascular regions of tumors in mice and destroyed surrounding viable tumor cells. When C. novyi-NT spores were administered together with conventional chemotherapeutic drugs, extensive hemorrhagic necrosis of tumors often developed within 24 h, resulting in significant and prolonged antitumor effects. This strategy, called combination bacteriolytic therapy (COBALT), has the potential to add a new dimension to the treatment of cancer.
Assuntos
Bactérias Anaeróbias/crescimento & desenvolvimento , Neoplasias Experimentais/terapia , Animais , Antineoplásicos/uso terapêutico , Clostridium/genética , Clostridium/fisiologia , Terapia Combinada , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Nus , Neoplasias Experimentais/tratamento farmacológico , Esporos BacterianosRESUMO
To gain insights into the molecular basis for metastasis, we compared the global gene expression profile of metastatic colorectal cancer with that of primary cancers, benign colorectal tumors, and normal colorectal epithelium. Among the genes identified, the PRL-3 protein tyrosine phosphatase gene was of particular interest. It was expressed at high levels in each of 18 cancer metastases studied but at lower levels in nonmetastatic tumors and normal colorectal epithelium. In 3 of 12 metastases examined, multiple copies of the PRL-3 gene were found within a small amplicon located at chromosome 8q24.3. These data suggest that the PRL-3 gene is important for colorectal cancer metastasis and provide a new therapeutic target for these intractable lesions.
Assuntos
Neoplasias Colorretais/enzimologia , Neoplasias Colorretais/genética , Proteínas Imediatamente Precoces/genética , Metástase Neoplásica/genética , Proteínas Tirosina Fosfatases/genética , Adenoma/enzimologia , Adenoma/genética , Adenoma/patologia , Mapeamento Cromossômico , Cromossomos Humanos Par 8 , Colo/enzimologia , Neoplasias Colorretais/patologia , Amplificação de Genes , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Biblioteca Gênica , Humanos , Proteínas Imediatamente Precoces/metabolismo , Mucosa Intestinal/enzimologia , Proteínas de Neoplasias , Estadiamento de Neoplasias , Reação em Cadeia da Polimerase , Proteínas Tirosina Fosfatases/metabolismo , Reto/enzimologiaRESUMO
Loss of p53 gene function, which occurs in most colon cancer cells, has been shown to abolish the apoptotic response to 5-fluorouracil (5-FU). To identify genes downstream of p53 that might mediate these effects, we assessed global patterns of gene expression following 5-FU treatment of isogenic cells differing only in their p53 status. The gene encoding mitochondrial ferredoxin reductase (protein, FR; gene, FDXR) was one of the few genes significantly induced by p53 after 5-FU treatment. The FR protein was localized to mitochondria and suppressed the growth of colon cancer cells when over-expressed. Targeted disruption of the FDXR gene in human colon cancer cells showed that it was essential for viability, and partial disruption of the gene resulted in decreased sensitivity to 5-FU-induced apoptosis. These data, coupled with the effects of pharmacologic inhibitors of reactive oxygen species, indicate that FR contributes to p53-mediated apoptosis through the generation of oxidative stress in mitochondria.
Assuntos
Antimetabólitos Antineoplásicos/farmacologia , Apoptose , Ferredoxina-NADP Redutase/fisiologia , Fluoruracila/farmacologia , Proteína Supressora de Tumor p53/metabolismo , Divisão Celular/efeitos dos fármacos , Neoplasias Colorretais , Ferredoxina-NADP Redutase/genética , Citometria de Fluxo , Expressão Gênica/efeitos dos fármacos , Marcação de Genes/métodos , Humanos , Estresse Oxidativo , Recombinação Genética , Células Tumorais Cultivadas , Proteína Supressora de Tumor p53/genéticaRESUMO
Serial analysis of gene expression was used to identify transcripts encoding secreted or cell surface proteins that were expressed in benign and malignant tumors of the colorectum. A total of 290,394 tags were analyzed from normal, adenomatous, and cancerous colonic epithelium. Of the 21,343 different transcripts observed, 957 were found to be differentially expressed between normal tissue and adenoma or between normal tissue and cancer. Forty-nine transcripts were elevated > or =20-fold in adenomas, 40 transcripts were elevated > or =20-fold in cancers, and 9 transcripts were elevated > or =20-fold in both. Products of six of these nine transcripts (TGFBI, LYS, RDP, MIC-1, REGA, and DEHL) were predicted to be secreted or to reside on the cell surface, and these were analyzed in more detail. The abnormal expression levels predicted by serial analysis of gene expression were confirmed by quantitative PCR analyses of each of these six genes. Moreover, the cell types responsible for the elevated expression were identified by in situ hybridization and by PCR analyses of epithelial cells immunoaffinity purified from primary tumors. This study extends knowledge of the differences in gene expression that underlie various stages of neoplasia and suggests specific diagnostic approaches that may be useful for the early detection of colorectal neoplasia.
Assuntos
Neoplasias Colorretais/genética , Proteínas de Membrana/genética , Polipose Adenomatosa do Colo/genética , Polipose Adenomatosa do Colo/metabolismo , Neoplasias Colorretais/metabolismo , Perfilação da Expressão Gênica/métodos , Regulação Neoplásica da Expressão Gênica , Humanos , Hibridização In Situ , Proteínas de Membrana/biossíntese , Proteínas de Membrana/metabolismo , Reação em Cadeia da Polimerase/métodos , RNA Mensageiro/genéticaRESUMO
Cell-based screening for novel tumor-specific drugs has been compromised by the lack of appropriate control cells. We describe a strategy for drug screening based on isogenic human cancer cell lines in which key tumorigenic genes have been deleted by targeted homologous recombination. As a test case, a yellow fluorescent protein (YFP) expression vector was introduced into the colon cancer cell line DLD-1, and a blue fluorescent protein (BFP) expression vector was introduced into an isogenic derivative in which the mutant K-Ras allele had been deleted. Co-culture of both cell lines allowed facile screening for compounds with selective toxicity toward the mutant Ras genotype. Among 30,000 compounds screened, a novel cytidine nucleoside analog was identified that displayed selective activity in vitro and inhibited tumor xenografts containing mutant Ras. The present data demonstrate a broadly applicable approach for mining therapeutic agents targeted to the specific genetic alterations responsible for cancer development.
Assuntos
Antineoplásicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais/métodos , Androstenos/farmacologia , Animais , Proteínas de Bactérias , Feminino , Deleção de Genes , Genes ras , Proteínas de Fluorescência Verde , Humanos , Proteínas Luminescentes , Camundongos , Camundongos Knockout , Camundongos Nus , Mutagênese , Plicamicina/farmacologia , Recombinação Genética , Compostos de Enxofre/farmacologia , Sais de Tetrazólio/farmacologia , Células Tumorais CultivadasRESUMO
We recently identified genes encoding tumor endothelial markers (TEMs) that displayed elevated expression during tumor angiogenesis. From both biological and clinical points of view, TEMs associated with the cell surface membrane are of particular interest. Accordingly, we have further characterized four such genes, TEM1, TEM5, TEM7, and TEM8, all of which contain putative transmembrane domains. TEM5 appears to be a seven-pass transmembrane receptor, whereas TEM1, TEM7, and TEM8 span the membrane once. We identified mouse counterparts of each of these genes, designated mTEM1, mTEM5, mTEM7, and mTEM8. Examination of these mTEMs in mouse tumors, embryos, and adult tissues demonstrated that three of them (mTEM1, mTEM5, and mTEM8) were abundantly expressed in tumor vessels as well as in the vasculature of the developing embryo. Importantly, expression of these mTEMs in normal adult mouse tissues was either undetectable or detected only in a small fraction of the vessels. These results demonstrate conservation of human and mouse tumor angiogenesis at the molecular level and support the idea that tumor angiogenesis largely reflects normal physiological neovasculaturization. The coordinate expression of TEM1, TEM5, and TEM8 on tumor endothelium in humans and mice makes these genes attractive targets for the development of antiangiogenic therapies.
Assuntos
Biomarcadores Tumorais/genética , Endotélio Vascular/fisiologia , Proteínas de Membrana/genética , Neovascularização Patológica/genética , Animais , Neoplasias Colorretais/irrigação sanguínea , Endotélio Vascular/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Regulação Neoplásica da Expressão Gênica , Humanos , Hibridização In Situ , Melanoma Experimental/irrigação sanguínea , Proteínas de Membrana/metabolismo , Camundongos , Proteínas de Neoplasias , Neovascularização Patológica/metabolismo , Estrutura Terciária de Proteína , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Receptores de Superfície Celular , Regulação para CimaAssuntos
Antineoplásicos/farmacologia , Terapia Genética , Neoplasias/terapia , Proteínas Nucleares , Proteína Supressora de Tumor p53 , Animais , Terapia Biológica , Divisão Celular , Dependovirus/genética , Dependovirus/imunologia , Genes p53 , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-mdm2 , Proteína Supressora de Tumor p53/efeitos dos fármacos , Proteína Supressora de Tumor p53/genética , Proteína Supressora de Tumor p53/fisiologiaRESUMO
Through global profiling of genes that were expressed soon after p53 expression, we identified a novel gene termed PUMA (p53 upregulated modulator of apoptosis). The protein encoded by PUMA was found to be exclusively mitochondrial and to bind to Bcl-2 and Bcl-X(L) through a BH3 domain. Exogenous expression of PUMA resulted in an extremely rapid and profound apoptosis that occurred much earlier than that resulting from exogenous expression of p53. Based on its unique expression patterns, p53 dependence, and biochemical properties, PUMA may be a direct mediator of p53-associated apoptosis.
Assuntos
Apoptose , Proteínas de Ciclo Celular , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Proteínas de Helminto , Proteínas Nucleares/metabolismo , Proteína Supressora de Tumor p53/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Divisão Celular , Linhagem Celular , Clonagem Molecular , Perfilação da Expressão Gênica , Regulação da Expressão Gênica , Genes Letais/genética , Genes Reporter , Humanos , Camundongos , Mitocôndrias/química , Mitocôndrias/metabolismo , Dados de Sequência Molecular , Proteínas Nucleares/química , Proteínas Nucleares/genética , Regiões Promotoras Genéticas/genética , Ligação Proteica , Estrutura Terciária de Proteína , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteína Supressora de Tumor p53/genética , Proteína bcl-XRESUMO
BACKGROUND: Colorectal cancer cells are shed into the stool, providing a potential means for the early detection of the disease using noninvasive approaches. Our goal was to develop reliable, specific molecular genetic tests for the detection of colorectal cancer in stool samples. METHODS: Stool DNA was isolated from paired stools and primary tumor samples from 51 colorectal cancer patients. Three genetic targets-TP53, BAT26, and K-RAS-were used to detect tumor-associated mutations in the stool prior to or without regard to the molecular analyses of the paired tumors. TP53 gene mutations were detected with a mismatch-ligation assay that detects nine common p53 gene mutations. Deletions within the BAT26 locus were detected by a modified solid-phase minisequencing method. Mutations in codons 12 and 13 of K-RAS were detected with a digital polymerase chain reaction-based method. RESULTS: TP53 gene mutations were detected in the tumor DNA of 30 patients, all of whom had the identical TP53 mutation in their stools. Tumors from three patients contained a noninherited deletion at the BAT26 locus, and the same alterations were identified in these patients' stool specimens. Nineteen of 50 tumors tested had a K-RAS mutation; identical mutations were detected in the paired stool DNA samples from eight patients. In no case was a mutation found in stool that was not also present in the primary tumor. Thus, the three genetic markers together detected 36 (71%) of 51 patients (95% confidence interval [CI] = 56% to 83%) with colorectal cancer and 36 (92%) of 39 patients (95% CI = 79% to 98%) whose tumors had an alteration. CONCLUSION: We were able to detect the majority of colorectal cancers by analyzing stool DNA for just three genetic markers. Additional work is needed to determine the specificity of these genetic tests for detecting colorectal neoplasia in asymptomatic patients and to more precisely estimate the prevalence of the mutations and sensitivity of the assay.
Assuntos
Neoplasias do Colo/diagnóstico , Neoplasias do Colo/genética , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/genética , DNA/genética , Fezes/química , Genes p53 , Genes ras , Mutação , Idoso , Neoplasias do Colo/patologia , Neoplasias Colorretais/patologia , DNA/isolamento & purificação , Marcadores Genéticos , Mutação em Linhagem Germinativa , Humanos , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Reação em Cadeia da Polimerase/métodos , Reprodutibilidade dos Testes , Deleção de SequênciaRESUMO
To dissolve pyrite or sulphur, leaching bacteria like Acidithiobacillus ferrooxidans attach to these substrata by extracellular polymeric substances (specifically, lipopolysaccharides). The primary attachment to pyrite at pH 2 is mediated by exopolymer-complexed iron(III) ions in an electrostatic interaction with the negatively charged pyrite surface. Cells grown on sulphur exhibit a different composition of the extracellular lipopolysaccharides, namely with increased hydrophobic properties, and do not attach to pyrite. Thus, the cells adapt the chemical composition of their exopolymers to the substrate/substratum. It is concluded that the mechanism of bacterial pyrite oxidation is basically indirect. The actual corrosive agents are iron(III) ions. Preliminary data indicate that active strains complex more iron(III) ions in their EPS than less active ones. Obviously, the exopolymeric layer comprises a reaction space for the regeneration of these ions by the activity of the iron oxidising bacteria.
Assuntos
Biopolímeros/fisiologia , Matriz Extracelular/fisiologia , Gammaproteobacteria/fisiologia , Modelos Biológicos , Aderência Bacteriana , Biofilmes , Biopolímeros/química , Matriz Extracelular/química , Ferro/química , Lipopolissacarídeos/química , Microscopia de Força Atômica , Eletricidade Estática , Sulfetos , Propriedades de SuperfícieRESUMO
Abnormalities of chromosome number are the most common genetic aberrations in cancer. The mechanisms regulating the fidelity of mitotic chromosome transmission in mammalian cells are therefore of great interest. Here we show that human cells without an hSecurin gene lose chromosomes at a high frequency. This loss was linked to abnormal anaphases during which cells underwent repetitive unsuccessful attempts to segregate their chromosomes. The abnormal mitoses were associated with biochemical defects in the activation of separin, the sister-separating protease, rendering it unable to cleave the cohesin subunit Scc1 efficiently. These results illuminate the function of mammalian securin and show that it is essential for the maintenance of euploidy.