Myosin binding protein C: implications for signal-transduction

Myosin binding protein C (MYBPC) is a crucial component of the sarcomere and an important regulator of muscle function. While mutations in different myosin binding protein C (MYBPC) genes are well known causes of various human diseases, such as hypertrophic (HCM) and dilated (DCM) forms of cardiomyopathy as well as skeletal muscular disorders, the underlying molecular mechanisms remain not well understood. A variety of MYBPC3 (cardiac isoform) mutations have been studied in great detail and several corresponding genetically altered mouse models have been generated. Most MYBPC3 mutations may cause haploinsufficiency and with it they may cause a primary increase in calcium sensitivity which is potentially able to explain major features observed in HCM patients such as the hypercontractile phenotype and the well known secondary effects such as myofibrillar disarray, fibrosis, myocardial hypertrophy and remodelling including arrhythmogenesis. However the presence of poison peptides in some cases cannot be fully excluded and most probably other mechanisms are also at play. Here we shall discuss MYBPC interacting proteins and possible pathways linked to cardiomyopathy and heart failure

Markers of drug resistance in relapsing colon cancer

Purpose: 5-Fluorouracil failure and drug resistance. which often occurs during chemotherapy. is still a great obstacle to the success of human colon cancer treatment. Thus. the comparative study of markers of drug resistance in cancer cells before and after chemotherapy may be extremely helpful in the selection of the appropriate chemotherapeutic drug in colon cancer patients who fail adjuvant treatment with 5-fluorouracil. In the present study we examined the differential expression of three multidrug resistance-related proteins (i.e., P-glycoprotein, MRP, and LRP) and of topoisomerase IIalpha in a series of 20 primary colon carcinomas and their recurrences. Methods: All markers were determined at tissue level by three-step immunohistochemistry using appropriate monoclonal antibodies. and the markers’ immunopositivity was quantified by image analysis. In addition. Feulgen stain was used for the assessment of nuclear DNA content of malignant cells at their primary location. Results: Some degree of aneuploidy was detected in all primary carcinomas. The immunoexpression of the three multidrug resistance-related proteins did not change significantly, either qualitatively (positivity vs negativity) or quantitatively, after chemotherapy. On the contrary, the percentages of topoisomerase IIalpha-positive malignant cells were significantly increased in the tumour recurrences by comparison to their primary locations (P = 0.011). Conclusions: According to our results. increased topoisomerase IIalpha immunohistochemical expression appears to be part of the malignant cells’ phenotype in recurrent colon cancers. Therapeutic options after failure of 5-fluorouracil-based treatment could therefore include appropriate topoisomerase IIalpha-targeted drugs

Cyclin D1 protein tissue detection in laryngeal cancer

Cyclin D1 (CCND1) is a set of periodic regulatory proteins that is believed to govern cell cycle transit from G1 into S phase. Overexpression of CCND1 leads to abnormal cellular proliferation which underlies processes of tumorigenesis; CCND1 can thus function as a cooperative oncogene in cell transformation. In the present study we investigate the immunohistochemical expression of CCND1 in a well-documented series of 58 laryngeal squamous cell carcinomas (LSCC) and search for statistical associations between CCND1 index and various clinicopathological parameters including several immunomarkers’ expression as well as patients’ disease-free survival. Tissue sections from archival paraffin blocks were stained using the avidin-biotin-peroxidase complex method; the H-295 rabbit polyclonal antibody was applied at dilution of 1: 150. The percentage of CCND1 immunoreactive tumor cells for each tumor was counted by an image analysis system. CCND1 staining was confined to cell nuclei and, in the examined samples, ranged from undetectable (i.e. 0% of tumor cells, n = 6) to the majority of tumor cells (i.e. 89% of tumor cells) with mean value: 15.73%. In tumor adjacent, non invasive lesions, strong CCND1 staining was noticed in areas with cellular atypia. In cases with nodal metastases, no change in CCND1 expression in the nodal metastases compared with the primary tumors was observed. p53 protein accumulation in malignant cells was positively linked with CCND1 index (Mann-Whitney U: 205.5, p = 0.034). CCND1 expression appears to be an early event in processes of tumorigenesis and tumor progression in some LSCC. Apart from p53 protein accumulation, CCND1 immunohistochemical expression does not seem to correlate with nodal metastasis, disease recurrence or any other clinicopathological prognostic indicator. Copyright (C) 2005 S. Karger AG, Basel

Multidrug resistance proteins and topoisomerase II alpha expression in colon cancer: association with metastatic potential

Aims: To investigate the role of multidrug resistance proteins and topoisomerase IIalpha in colon cancer. Methods: Tissue sections from 89 Dukes’ stage B-D colon cancer patients were selected. The expression of multidrug resistance proteins and topoisomerase IIalpha in primary tumour cells was assessed by standard immunohistochemistry. The extent of their expression was measured by image analysis and was correlated with clinicopathological features of the patients. Results: P-glycoprotein was associated with the presence of lymph node metastasis (P=0.005), vessel invasion (P=0.0001) and perineural invasion (P=0.020). Conclusions: P-glycoprotein is probably involved in the processes of local invasion and metastatic dissemination