RESUMEN
BACKGROUND: A broad population-based assay to detect individuals with Lynch Syndrome (LS) before they develop cancer would save lives and healthcare dollars via cancer prevention. LS is caused by a germline mutation in a DNA mismatch repair (MMR) gene, especially protein truncation-causing mutations involving MSH2 or MLH1. We showed that immortalized lymphocytes from LS patients have reduced levels of full-length MLH1 or MSH2 proteins. Thus, it may be feasible to identify LS patients in a broad population-based assay by detecting reduced levels of MMR proteins in lymphocytes. METHODS: Accordingly, we determined whether MSH2 and MLH1 proteins can also be detected in fresh lymphocytes. A quantitative western blot assay was developed using two commercially available monoclonal antibodies that we showed are specific for detecting full-length MLH1 or MSH2. To directly determine the ratio of the levels of these MMR proteins, we used both antibodies in a multiplex-type western blot. RESULTS: MLH1 and MSH2 levels were often not detectable in fresh lymphocytes, but were readily detectable if fresh lymphocytes were first stimulated with PHA. In fresh lymphocytes from normal controls, the MMR ratio was ~1.0. In fresh lymphocytes from patients (N > 50) at elevated risk for LS, there was a bimodal distribution of MMR ratios (range: 0.3-1.0). CONCLUSIONS: Finding that MMR protein levels can be measured in fresh lymphocytes, and given that cells with heterozygote MMR mutations have reduced levels of full-length MMR proteins, suggests that our immunoassay could be advanced to a quantitative test for screening populations at high risk for LS.
Asunto(s)
Proteínas Adaptadoras Transductoras de Señales/metabolismo , Neoplasias Colorrectales Hereditarias sin Poliposis/diagnóstico , Reparación de la Incompatibilidad de ADN , Detección Precoz del Cáncer/métodos , Proteína 2 Homóloga a MutS/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Adaptadoras Transductoras de Señales/genética , Línea Celular Tumoral , Células Cultivadas , Neoplasias Colorrectales Hereditarias sin Poliposis/genética , Neoplasias Colorrectales Hereditarias sin Poliposis/metabolismo , Reparación de la Incompatibilidad de ADN/genética , Mutación de Línea Germinal , Células HCT116 , Humanos , Linfocitos/metabolismo , Homólogo 1 de la Proteína MutL , Proteína 2 Homóloga a MutS/genética , Proteínas Nucleares/genéticaRESUMEN
PURPOSE: To evaluate the impact of a CD-ROM intervention in the education of patients with suspected Lynch syndrome (LS) about microsatellite instability (MSI) and immunohisochemistry (IHC) testing. PATIENTS AND METHODS: Two hundred thirteen patients meeting Bethesda criteria were randomly assigned to receive either a brief educational session with a health educator (n = 105) or a brief educational session plus a CD-ROM (n = 108). Assessments were administered at baseline and 2 weeks post-treatment. Primary outcomes included MSI and IHC knowledge and level of satisfaction with and completeness of the preparation to make the decision for MSI testing. Secondary outcomes included decisional conflict, difficulty making the decision, cancer-specific and global anxiety, and level of discussion about MSI testing with family and friends. RESULTS: Participants in the education plus CD-ROM condition reported significant increases in knowledge about the MSI and IHC tests, greater satisfaction with the preparation to make a decision for testing, lower decisional conflict, and greater decisional self-efficacy. The effects of the education plus CD-ROM on most outcomes were not moderated by preintervention levels of exposure to MSI testing, family support for MSI testing, or the family history of cancer. CONCLUSION: Incorporation of new media education strategies for individuals at risk for LS may be a valuable component of the informed consent process. As clinical criteria for MSI and IHC testing continue to expand, the need for alternative educational approaches to meet this increased demand could be met by the self-administered computer-based strategy that we described.