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1.
Artículo en Inglés | MEDLINE | ID: mdl-38633403

RESUMEN

Patients with cancer are known to have a poor prognosis when infected with SARS-CoV-2 infection. We aimed in this study to assess health outcomes in COVID-19 patients with different cancers in comparison to non-cancer COVID-19 patients from different centers in the United States (US). We evaluated medical records of 1,943 COVID-19 Cancer patients from 3 hospitals admitted between December 2019 to October 2021 and compared them with non-cancer COVID-19 patients. Among 1,943 hospitalized COVID-19 patients, 18.7% (n=364) have an active or previous history of cancer. Among these 364 cancer patients, 222 were African Americans (61.7%) and 121 were Caucasians (33.2%). Cancer patients had significantly longer hospitalization compared to controls (8.24 vs 6.7 days). Overall, Lung cancer is associated with high mortality. Patients with a previous history of cancer were more prone to death (p=0.04) than active cancer patients. In univariate and multivariate analyses, predictors of death among cancer patients were male sex, older age, presence of dyspnea, elevated troponin, elevated AST (0.001) and ALT (0.05), low albumin (p=0.04) and mechanical ventilation (p=0.001). Patients with a previous history of cancer were more prone to death when compared to active cancer COVID-19 patients. Early recognition of cancer COVID-19 patients' death-associated risk factors can help determine appropriate treatment and management plans for better prognosis and outcome.

2.
J Intern Med ; 289(4): 463-473, 2021 04.
Artículo en Inglés | MEDLINE | ID: mdl-33164230

RESUMEN

The onset of human disease by infection with SARS-CoV-2 causing COVID-19 has revealed risk factors for disease severity. There are four identified factors that put one at high risk for infection and/or mortality creating a disparity: age, co-morbidities, race/ethnicity and gender. Data indicate that the older a person is, and/or the presence of obesity and diabetes, cardiovascular disease and chronic kidney disease place one at higher risk for COVID-19. In the United States, specific race/ethnicities, particularly African Americans and Native Americans, are strong COVID-19 risk components. Male gender has also emerged as a severity risk factor. For age and racial/ethnicities, the accumulation of health co-morbidities is common precipitating mechanisms. In particular, underlying socio-economic structures in the United States likely drive development of co-morbidities, putting affected populations at higher risk for severe COVID-19. Sudden cardiac death triggered by a common sodium channel variant in African Americans with COVID-19 has not been evaluated as a cause for racial disparity. There is no evidence that racial/ethnic differences for COVID-19 are caused by ABO blood groups, use of angiotensin-converting enzyme (ACE) inhibitors or from amino acid substitutions in the SARS-CoV-2 spike protein. There is growing evidence that androgen-enabled expression of ACE2 receptors and the serine protease TMPRSS2, two permissive elements engaging the SARS-CoV-2 spike protein for infection, may contribute to severe COVID-19 in men. Overall, COVID-19 has generated disparities for who is infected and the severity of that infection. Understanding the mechanisms for the disparity will help nullify the differences in risk for COVID-19.


Asunto(s)
COVID-19 , Disparidades en el Estado de Salud , SARS-CoV-2/fisiología , COVID-19/epidemiología , COVID-19/inmunología , COVID-19/fisiopatología , Comorbilidad , Etnicidad , Humanos , Factores de Riesgo , Índice de Severidad de la Enfermedad , Factores Sexuales , Determinantes Sociales de la Salud
4.
Oncogene ; 29(15): 2172-80, 2010 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-20140012

RESUMEN

The activin type II receptor (ACVR2) contains two identical microsatellites in exons 3 and 10, but only the exon 10 microsatellite is frameshifted in mismatch repair (MMR)-defective colonic tumors. The reason for this selectivity is not known. We hypothesized that ACVR2 frameshifts were influenced by DNA sequences surrounding the microsatellite. We constructed plasmids in which exons 3 or 10 of ACVR2 were cloned +1 bp out of frame of enhanced green fluorescent protein (EGFP), allowing -1 bp frameshift to express EGFP. Plasmids were stably transfected into MMR-deficient cells, and subsequent non-fluorescent cells were sorted, cultured and harvested for mutation analysis. We swapped DNA sequences flanking the exon 3 and 10 microsatellites to test our hypothesis. Native ACVR2 exon 3 and 10 microsatellites underwent heteroduplex formation (A(7)/T(8)) in hMLH1(-/-) cells, but only exon 10 microsatellites fully mutated (A(7)/T(7)) in both hMLH1(-/-) and hMSH6(-/-) backgrounds, showing selectivity for exon 10 frameshifts and inability of exon 3 heteroduplexes to fully mutate. Substituting nucleotides flanking the exon 3 microsatellite for nucleotides flanking the exon 10 microsatellite significantly reduced heteroduplex and full mutation in hMLH1(-/-) cells. When the exon 3 microsatellite was flanked by nucleotides normally surrounding the exon 10 microsatellite, fully mutant exon 3 frameshifts appeared. Mutation selectivity for ACVR2 lies partly with flanking nucleotides surrounding each microsatellite.


Asunto(s)
Disparidad de Par Base/genética , Reparación del ADN/genética , ADN Intergénico/genética , Exones/genética , Repeticiones de Microsatélite/genética , Mutagénesis/genética , Receptores de Activinas Tipo II/genética , Proteínas Adaptadoras Transductoras de Señales/deficiencia , Secuencia de Bases , Línea Celular Tumoral , Humanos , Homólogo 1 de la Proteína MutL , Proteínas Nucleares/deficiencia
6.
J Clin Pathol ; 59(10): 1100-1, 2006 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-17021136

RESUMEN

Spirochaetes are organisms that can infect the colon of people with normal or compromised immune systems. Infected patients can present with a variety of gastrointestinal symptoms, including diarrhoea and rectal bleeding. However, some report a lack of association between specific symptoms and the presence of spirochaetes. It is therefore unclear whether the spirochaetes colonising the colon are true pathogens. Diagnosis is typically made by histological examination, with the biopsy specimen showing a band-like growth of spirochaetes adherent to the colonic luminal surface, giving an accentuated brush-border appearance. A course of metronidazole can eliminate the spirochaetes, but treatment might not lead to improvement of symptoms. Owing to the lack of a definite association between symptoms and the presence of spirochaetes, observation without specific antibiotic treatment can be pursued in most patients.


Asunto(s)
Enfermedades del Colon/diagnóstico , Infecciones por Spirochaetales/diagnóstico , Adulto , Enfermedades del Colon/complicaciones , Enfermedades del Colon/inmunología , Diarrea/microbiología , Hemorragia Gastrointestinal/microbiología , Humanos , Inmunocompetencia , Masculino , Infecciones por Spirochaetales/complicaciones , Infecciones por Spirochaetales/inmunología
8.
Dis Colon Rectum ; 44(10): 1503-8, 2001 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11598481

RESUMEN

PURPOSE: This study was designed to determine whether loss of heterozygosity and/or microsatellite instability correlate with HIV infection and tumor recurrence after chemoradiation therapy in patients with squamous-cell carcinoma of the anus. BACKGROUND: The molecular mechanisms leading to the progression of HIV-related squamous-cell carcinoma of the anus are poorly understood. In particular, genetic alterations responsible for resistance to chemoradiation have important clinical and functional implications. METHODS: In a case-control study, we analyzed normal and tumor DNA samples of four patients with squamous-cell carcinoma of the anus who were successfully treated with chemoradiotherapy and four patients with radio-resistant squamous-cell carcinoma of the anus who required abdominoperineal resection for local recurrence. To determine the presence of microsatellite instability, we used the reference panel of five pairs of microsatellite primers recommended for colorectal cancer specimens. These include the microsatellite markers BAT25, BAT26, D5S346 (APC), D2S123 (hMSH2), and D17S250 (P53). In addition, we used microsatellite markers for loss of heterozygosity analyses that were tightly linked to tumor suppressor genes. These included D3S1611 (hMLH1), D17S513 (P53), D18S46 and 18qTA (DCC/SMAD4), D5S107 (APC), and CA5 (hMSH2). RESULTS: There were two HIV-positive and two HIV-negative patients in each group. Three HIV-positive patients (one in the chemoradiotherapy group and two in the nonchemoradiotherapy group) demonstrated loss of heterozygosity. In the chemoradiotherapy group, one HIV-positive patient demonstrated loss of heterozygosity at the hMLH1 locus. In the nonchemoradiotherapy group, two HIV-positive patients exhibited a total of four instances of loss of heterozygosity. One tumor had loss of heterozygosity at hMSH2 and DCC/SMAD4; another tumor demonstrated loss of heterozygosity at hMSH2 and APC. Microsatellite instability-low was found in two HIV-positive patients. No instances of loss of heterozygosity and microsatellite instability were detected in HIV-negative patients. CONCLUSION: Loss of heterozygosity and microsatellite instability, which reflect inactivation of tumor-suppressor genes and genomic instability, occur with increased frequency in HIV-associated squamous-cell carcinoma. These data demonstrate for the first time evidence of loss of heterozygosity at the APC and DCC/SMAD4 gene loci in anal carcinoma. Although the findings presented here need to be expanded in a larger study, the recurrent loss of heterozygosity at D2S123, which was demonstrated in HIV-positive patients with radio-resistant squamous-cell carcinoma of the anus, is notable.


Asunto(s)
Neoplasias del Ano/complicaciones , Neoplasias del Ano/genética , Carcinoma de Células Escamosas/complicaciones , Carcinoma de Células Escamosas/genética , Genes Supresores de Tumor , Infecciones por VIH/complicaciones , Pérdida de Heterocigocidad , Adulto , Neoplasias del Ano/tratamiento farmacológico , Neoplasias del Ano/radioterapia , Carcinoma de Células Escamosas/tratamiento farmacológico , Carcinoma de Células Escamosas/radioterapia , Estudios de Casos y Controles , ADN/análisis , Femenino , Humanos , Masculino , Repeticiones de Microsatélite , Persona de Mediana Edad , Recurrencia Local de Neoplasia/genética , Insuficiencia del Tratamiento
9.
J Clin Gastroenterol ; 33(1): 53-5, 2001 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-11418792

RESUMEN

We report the first case in the English literature of an intramural duodenal hematoma presenting as a complication of Helicobacter pylori-induced peptic ulcer disease. Intramural duodenal hematomas have been previously described in patients-usually in the setting of blunt trauma, postendoscopic biopsy, gastrostomy placement, and hemostatic therapy and in patients with a coagulopathy or bleeding diathesis-but not as a presentation of peptic ulcer disease. It is important to recognize this complication, as surgical management may benefit patients with a duodenal hematoma.


Asunto(s)
Enfermedades Duodenales/etiología , Infecciones por Helicobacter/complicaciones , Helicobacter pylori , Hematoma/etiología , Úlcera Péptica Hemorrágica/etiología , Úlcera Péptica/complicaciones , Biopsia , Diagnóstico Diferencial , Enfermedades Duodenales/patología , Duodeno/patología , Mucosa Gástrica/patología , Obstrucción de la Salida Gástrica/etiología , Obstrucción de la Salida Gástrica/patología , Infecciones por Helicobacter/patología , Hematoma/patología , Humanos , Masculino , Persona de Mediana Edad , Úlcera Péptica/patología , Úlcera Péptica Hemorrágica/patología
10.
J Pediatr ; 138(5): 629-35, 2001 May.
Artículo en Inglés | MEDLINE | ID: mdl-11343035

RESUMEN

OBJECTIVES: Hereditary non-polyposis colorectal cancer (HNPCC) is characterized by the early onset of colorectal cancer (approximately 40 years). Adolescent colorectal cancer is unusual in HNPCC families. We speculated that some DNA mismatch repair germline mutations might be associated with early onset of disease. STUDY DESIGN: Genomic DNA was extracted from members of a kindred with virulent HNPCC fitting the Amsterdam Criteria for HNPCC and sequenced for 2 DNA mismatch repair genes, hMSH2 and hMLH1. A sigmoid adenocarcinoma from the 14-year-old proband was analyzed for highfrequency microsatellite instability and immunostained for DNA mismatch repair gene expression. RESULTS: A germline mutation was identified at nucleotide 676 (codon 226) of the hMLH1 gene. The C to T transition created a nonsense mutation, truncating the hMLH1 protein. This mutation also alters the splice donor sequence, because nucleotide 676 is 2 base pairs from the 3' end of the exon 8. The proband's tumor demonstrated high-frequency microsatellite instability and displayed loss of hMLH1 expression, indicating bi-allelic inactivation of hMLH1. CONCLUSIONS: A complex mutation of hMLH1 at codon 226 is associated with adolescent onset of colorectal cancer in an HNPCC family. Genetic screening of other suspected HNPCC families with unusually young members with cancer might reveal certain genotypes with particularly virulent forms of this disease.


Asunto(s)
Neoplasias Colorrectales/genética , Mutación de Línea Germinal , Proteínas Adaptadoras Transductoras de Señales , Adolescente , Edad de Inicio , Disparidad de Par Base , Biopsia , Proteínas Portadoras , Colon Sigmoide/patología , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Reparación del ADN , Femenino , Pruebas Genéticas , Humanos , Inmunohistoquímica , Homólogo 1 de la Proteína MutL , Proteínas de Neoplasias/metabolismo , Proteínas Nucleares , Linaje , Factores de Riesgo
11.
Cancer Res ; 61(6): 2676-83, 2001 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-11289147

RESUMEN

Colorectal adenomas can be morphologically classified as exophytic or flat. Polypoid cancers and cancers arising de novo (ie., without any adenomatous component) might be the results of genetic progression from exophytic and flat adenomas, respectively. In this study, we examined 94 morphologically distinct neoplastic specimens for mutations in K-RAS and analyzed 10 microsatellite loci tightly linked to the tumor suppressor genes APC, p53, DCC/SMAD4, hMSH2, and hMLH1. K-RAS mutations were significantly associated with exophytic adenomas [11 of 21 (52%)] compared to flat adenomas [2 of 13(15%), P < 0.03] and polypoid cancers [17 of 25 (68%)] compared to cancers arising de novo [7 of 25 (28%), P < 0.01]. Two polypoid cancer cases demonstrated three and four different K-RAS mutations, respectively, suggesting multiple areas of clonal expansion. Cancers arising de novo were significantly associated with loss of heterozygosity (LOH) at chromosome 3p compared to pol ypoid cancers [6 of 18(33%) versus 1 of 20(5%), P < 0.03], whereas the prevalence of LOH at chromosomes 2p, 5q, 17p, and 18q and microsatellite instability were not different between the groups. For all cancers, LOH at chromosomes 17p and 18q occurred in 47 and 51%, respectively. However, LOH at 17p and 18q occurred in 0 and 16% of benign lesions, respectively, suggesting their role in malignant transformation. There was no difference in LOH at chromosomes 17p and 18q between exophytic and flat lesions. These findings suggest that (a) mutant K-RAS is associated with the exophytic growth of colonic neoplasms, and that (b) some colorectal cancers arising de novo lose chromosome 3p during their evolution, which is not seen in polypoid cancers. Half of all cancers lose chromosomes 17p and 18q at or near the malignant transition of benign lesions as reported previously, irrespective of morphology. There may be more than one genetic avenue for colorectal cancer formation, and this correlates with the morphological characteristics.


Asunto(s)
Adenoma/genética , Adenoma/patología , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Genes Supresores de Tumor , Genes ras/genética , Humanos , Pólipos Intestinales/genética , Pólipos Intestinales/patología , Pérdida de Heterocigocidad , Repeticiones de Microsatélite/genética , Mutación , Poliploidía
12.
J Clin Endocrinol Metab ; 86(1): 310-6, 2001 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-11232017

RESUMEN

PTH-related protein (PTHrP) is expressed in many common malignancies such as breast and prostate cancer and can regulate their growth. Little is known, however, about the role of PTHrP in pancreatic adenocarcinoma. To study PTHrP in pancreatic exocrine cancer, we studied its expression in pancreatic cancer cell lines and surgical specimens. Eight human pancreatic adenocarcinoma cell lines were evaluated: AsPC-1, BxPC-3, Capan-1, CFPAC-1, MIA PaCa-2, PANC-1, PANC-28, and PANC-48. Murine monoclonal antibodies to the amino-terminal (1-34), mid-region (38-64), and carboxyl-terminal peptides (109-141) of PTHrP were used to identify cellular PTHrP and secreted PTHrP, including Western blotting and immunocytochemical staining for PTHrP from each cell line. Cellular PTHrP was detected in all cell line extracts by both Western blotting and immunoassay. CFPAC-1, derived from a pancreatic liver metastasis, had the highest concentration of PTHrP, and MIA PaCa-2, derived from primary pancreatic adenocarcinoma, had the lowest. PTHrP was localized by immunocytochemical staining in the cytoplasm in all but one cell line, and both nuclear and cytoplasmic immunostaining were observed in the MIA PaCa-2 and PANC-1 cells. Secretion of PTHrP into cell medium was also observed for each cell line and paralleled intracellular PTHrP levels. Evidence for differential processing of PTHrP expression was provided by studies demonstrating different patterns of PTHrP among the cell lines when assessed by PTHrP immunoassays directed against different PTHrP peptides. In specific, PTHrP secretion measured by a PTHrP-(38-64) assay was highest for BxPC-3, whereas the highest levels of secreted PTHrP-(109-141) occurred in CFPAC-1 and PANC-1. Growth of AsPC-1 cells was stimulated in a dose-dependent manner by PTHrP-(1-34). Immunostaining from archival tissue of patients with pancreatic adenocarcinoma revealed strong PTHrP expression in all 14 specimens. All patients were eucalcemic preoperatively. These results demonstrate that PTHrP is commonly expressed in pancreatic cancer. Our data suggest that PTHrP may have growth-regulating properties in pancreatic adenocarcinoma cells, but further studies are required.


Asunto(s)
Adenocarcinoma/metabolismo , Neoplasias Pancreáticas/metabolismo , Proteínas/metabolismo , Adenocarcinoma/patología , Western Blotting , División Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Humanos , Inmunohistoquímica , Neoplasias Pancreáticas/patología , Proteína Relacionada con la Hormona Paratiroidea , Fragmentos de Péptidos/farmacología , Procesamiento Proteico-Postraduccional , Proteínas/farmacología , Distribución Tisular , Células Tumorales Cultivadas
13.
Clin Cancer Res ; 6(10): 3827-31, 2000 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-11051225

RESUMEN

We have reported that transfer of chromosome 3 (Chr3) containing a single wild-type copy of the hMLH1 gene into HCT116 colon cancer cells, a cell line deficient in DNA mismatch repair (MMR) activity attributable to inactivating hMLH1 mutations, corrects all of the aspects of the MMR repair-deficient phenotype. We inhibited the expression of the wild-type hMLH1 gene using antisense RNA in HCT116+Chr3 cells to determine if this would result in reversion to the MMR-deficient phenotype. Despite profound inhibition of hMLH1 expression, DNA MMR activity and alkylation sensitivity were not impaired in the antisense-transfected HCT116+Chr3 cells. Additionally, arrest of the cell cycle at the G2 phase with alkylation damage occurs in these cells, a phenotype associated with MMR proficiency. These results indicate that even with a reduction in the expression of hMLH1 protein below the limits of detection by Western blotting, DNA MMR activity remained fully functional (by direct DNA MMR activity assay). We would speculate that hMLH1 is expressed in substantially greater abundance than would be minimally necessary for DNA MMR and that minor reductions in the expression of this protein would not be sufficient to permit DNA MMR dysfunction. Alternatively, Chr3 may contain a second hMLH1 homologue that might overlap with the function of hMLH1.


Asunto(s)
Disparidad de Par Base , Cromosomas Humanos Par 3/genética , Reparación del ADN , ADN/metabolismo , Proteínas de Neoplasias/genética , Oligonucleótidos Antisentido/farmacología , Proteínas Adaptadoras Transductoras de Señales , Western Blotting , Proteínas Portadoras , Ciclo Celular/efectos de los fármacos , Clonación Molecular , Neoplasias del Colon/genética , Citoplasma/metabolismo , Relación Dosis-Respuesta a Droga , Fase G2 , Células HeLa , Humanos , Homólogo 1 de la Proteína MutL , Proteínas Nucleares , Fenotipo , Plásmidos/metabolismo , ARN/metabolismo , Factores de Tiempo , Transfección , Células Tumorales Cultivadas
15.
In Vivo ; 14(1): 13-20, 2000.
Artículo en Inglés | MEDLINE | ID: mdl-10757056

RESUMEN

Inactivation of the DNA mismatch repair (MMR) system allows the genome to accumulate mutations because of failure to correct mispairing of nucleotides and slippage mistakes at microsatellite sequences (termed microsatellite instability ¿MSI¿). While most mutations are acquired in noncoding regions by virtue of its larger share of DNA, mutations may occur in exons of genes that contain microsatellite sequences. The type II receptor for TGF beta 1 (TGF beta RII), the insulin-like growth factor II receptor (IGFIIR), and the proapoptotic gene BAX have been shown to contain mononucleotide microsatellites, and in MSI tumors, mutations may occur in these sequences late in the multistep carcinogenesis pathway. Here, we characterize 9 cell lines for MSI and mutations in TGF beta RII, BAX, and IGFIIR by PCR-based assays. The MMR-proficient cell lines SW480 and HT29 demonstrate stability at microsatellite sequences and do not have mutations in TGF beta RII, BAX, or IGFIIR. The MMR-deficient cell lines LoVo, SW48, LS174t, and HCT116 all demonstrate MSI and have only mutant alleles of TGF beta RII. Additionally, SW48 cells were heterozygous for wild-type and mutant IGFIIR. While LoVo and LS174t cells possessed only mutant BAX alleles, HCT116 was heterozygous and SW48 had only the wild-type allele. The MMR-deficient ovarian cell line 2774 demonstrated MSI, but showed only wild-type TGF beta RII, IGFIIR, and BAX alleles. In HCT116+ch2 cells, there was no genotypic change from the hMLH1-mutated HCT116 cells. In HCT116+ch3 cells, MSI was corrected, and this cell line became heterozygous for mutant and wild-type TGF beta RII because wild-type hMLH1 and TGF beta RII are both located on chromosome 3. Thus, the presence of a defective MMR system correlates with MSI, and the wild-type allele of TGF beta RII was absent in all microsatellite unstable colon cell lines, whereas the absence of wild-type BAX occurred in only two colon cell lines. In ovarian cancer cells with MSI, mutations in TGF beta RII, BAX, and IGFIIR may be unimportant in the genesis of this tumor.


Asunto(s)
Repeticiones de Microsatélite/genética , Proteínas Proto-Oncogénicas c-bcl-2 , Proteínas Proto-Oncogénicas/genética , Receptor IGF Tipo 2/genética , Receptores de Factores de Crecimiento Transformadores beta/genética , Disparidad de Par Base , Reparación del ADN/genética , ADN de Neoplasias/genética , Humanos , Mutación , Reacción en Cadena de la Polimerasa , Proteínas Serina-Treonina Quinasas , Receptor Tipo II de Factor de Crecimiento Transformador beta , Células Tumorales Cultivadas , Proteína X Asociada a bcl-2
16.
Cancer Res ; 60(24): 6882-5, 2000 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-11156385

RESUMEN

Juvenile polyposis syndrome (JPS) is an autosomal dominant syndrome characterized by multiple gastrointestinal hamartomatous polyps in the absence of the extraintestinal features that are classic for other hamartomatous polyposis syndromes, such as Bannayan-Riley-Ruvalcaba syndrome (BRRS) and Cowden disease (CD). About 50% of BRRS and >80% of CD demonstrate germ-line mutations in the tumor suppressor and dual phosphatase, PTEN. Germ-line mutation of PTEN as a cause for JPS in a child is controversial because extraintestinal manifestations that would exclude JPS could appear after adolescence, altering the clinical diagnosis. Here, we investigated a family in which the 55-year-old father, who lacks thyroid or skin findings characteristic of CD, demonstrated a germ-line mutation in PTEN that was passed to identical twin daughters, who both manifested JPS. The mutation was a deletion of five bases beginning seven bases from the start of exon 4 of PTEN, which caused aberrant transcripts by reverse transcription-PCR that were absent from a normal individual. Thus, mutations in PTEN are associated with JPS in addition to CD and some BRRS families, although the incidence of PTEN germ-line mutations in JPS might be more rare than that reported for SMAD4, a gene found to be mutated in approximately one-half of the JPS families investigated.


Asunto(s)
Poliposis Adenomatosa del Colon/genética , Mutación de Línea Germinal , Monoéster Fosfórico Hidrolasas/genética , Proteínas Supresoras de Tumor , Secuencia de Bases , Niño , Clonación Molecular , Enfermedades en Gemelos , Electroforesis en Gel de Poliacrilamida , Exones , Salud de la Familia , Femenino , Eliminación de Gen , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Fosfohidrolasa PTEN , Linaje , ARN Mensajero/metabolismo , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Análisis de Secuencia de ADN
17.
Gastroenterology ; 117(1): 123-31, 1999 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-10381918

RESUMEN

BACKGROUND & AIMS: The DNA mismatch repair (MMR) system recognizes certain DNA adducts caused by alkylation damage in addition to its role in recognizing and directing repair of interstrand nucleotide mismatches and slippage mistakes at microsatellite sequences. Because defects in the MMR system can confer tolerance to acquired DNA damage and, by inference, the toxic effects of certain chemotherapeutic agents, we investigated the effect of 5-fluorouracil (5-FU) on colon cancer cell lines. METHODS: We determined growth selection by cell enrichment assay and cloning efficiency after treatment with 5 micromol/L 5-FU, assayed nucleic 3H-5-FU incorporation, and analyzed the cell cycle by flow cytometry. RESULTS: 5-FU treatment provided a growth advantage for MMR-deficient cell lines, indicating a relative degree of tolerance to 5-FU by the MMR-deficient cell lines. Enhanced survival was statistically significant after 5 days of growth, and a 28-fold reduction in survival was noted in the MMR-proficient cells by clonagenic assays after 10 days of growth. Differences in nucleotide uptake of 5-FU did not account for the observed growth differences, and specific cell cycle checkpoint arrest was not detected. CONCLUSIONS: Intact DNA MMR seems to recognize 5-FU incorporated into DNA but may do so in a different manner than other types of alkylation damage. Defective DNA MMR might be one mechanism for tumor resistance to 5-FU.


Asunto(s)
Antimetabolitos Antineoplásicos/farmacología , Disparidad de Par Base/efectos de los fármacos , Disparidad de Par Base/fisiología , Reparación del ADN/efectos de los fármacos , Reparación del ADN/fisiología , Fluorouracilo/farmacología , Animales , Antimetabolitos Antineoplásicos/metabolismo , División Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Fluorouracilo/metabolismo , Fase G2/fisiología , Humanos , Ratones , Ratones Desnudos , Mitosis/fisiología , Ácidos Nucleicos/metabolismo , Células Tumorales Cultivadas/efectos de los fármacos , Células Tumorales Cultivadas/fisiología
18.
J Assoc Acad Minor Phys ; 10(3): 59-67, 1999.
Artículo en Inglés | MEDLINE | ID: mdl-10826011

RESUMEN

Colorectal cancer can develop by two distinct pathogenic mechanisms: one involving chromosomal breakage and aneuploidy (called chromosomal instability) and one involving mutations at DNA micro-satellite sequences (termed micro-satellite instability). Relatively few reports consider these mechanisms of colorectal cancer development across racial or ethnic groups. Available data indicate a moderate increase in colorectal cancer risk among Ashkenazi Jews who have a mutational polymorphism at codon 1307 in the APC gene. In American blacks, there is evidence for a higher prevalence of right-sided colonic tumors and an earlier age of onset of colorectal cancer. In addition, blacks have the highest colon cancer incidence in the United States among ethnic groups and have poorer 5-year survival rates compared with whites. While some differences may be attributed to health care access and socioeconomic differences, these do not completely explain all the variances. In the chromosomal instability pathway, there are polymorphisms within the P53 gene that are more prevalent in blacks, but the significance of these polymorphisms is not fully known. Blacks are more likely to demonstrate micro-satellite instability in their tumors; however, the mechanism for this phenomenon in blacks is unexplored. Differences in diet among racial and ethnic groups and polymorphic variations in drug metabolizing or acetylation genes have not been adequately cataloged. Identification of genetic and environmental factors among racial and ethnic groups should offer some insights into the observed epidemiologic data and advance opportunities to better understand the control and development of colorectal cancer.


Asunto(s)
Neoplasias Colorrectales/etnología , Neoplasias Colorrectales/genética , Adenoma/genética , Neoplasias Colorrectales/mortalidad , Genes p53/genética , Humanos , Pérdida de Heterocigocidad , Repeticiones de Microsatélite , Mutación , Estados Unidos/epidemiología
20.
Cancer Detect Prev ; 22(5): 377-82, 1998.
Artículo en Inglés | MEDLINE | ID: mdl-9727618

RESUMEN

Our understanding of the pathogenesis of cancer has undergone a revolution over the past decade. Tumors develop by the accumulation of damage to genes that regulate cell growth. Many of the genes responsible for disregulation of cell growth have been identified, as have the processes that lead to the genetic damage. One of the most important concepts that has facilitated our understanding of carcinogenesis is that of genetic or "genomic" instability, which is required to permit a sufficient amount of genetic damage to accumulate to permit the neoplastic phenotype to emerge and evolve. Two mechanisms that lead to genomic instability--one of which involves the loss of chromosomal fragments from the nucleus, and a second which is characterized by microsatellite instability--are discussed.


Asunto(s)
Aberraciones Cromosómicas , Neoplasias Colorrectales/genética , Neoplasias Colorrectales/patología , Humanos
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