Dysferlin is likely required for maintaining the structural integrity of the muscle fiber plasma membrane, and plasma membrane injury is an early event in the pathogenesis of dysferlinopathy. MAC activation can participate in but is not an initial or primary event causing muscle fiber injury.

MicroRNAs are involved in cell proliferation, differentiation, and apoptosis and can function as tumor suppressor genes or oncogenes. The role of microRNAs in neuroendocrine tumors such as ileal carcinoids is largely unknown. We examined the differential expression of 95 microRNAs by RT-PCR using the QuantiMir System in eight matching primary and metastatic carcinoid tumors from the ileum. All microRNAs chosen for the QuantiMir System Array were based on their potential functions related to cancer biology, cell development and apoptosis. The expression of microRNAs for the samples was normalized to microRNA-197, and the matching primary and metastatic tumors were compared. There was down-regulation of microRNA-133a, 145, 146, 222 and 10b in all samples between the primary and matching metastatic tumors and up-regulation of microRNA-183, 488 and 19a + b in six of eight metastatic carcinoids compared to the primary tumors. MicroRNA-133a was further analyzed by TaqMan Real Time RT-PCR and Northern hybridization using six additional matching primary and metastatic samples which supported the PCR Array findings. There were significant differences in microRNA-133a expression with down-regulation in the metastasis compared to the primary in the eight original cases (p<0.009) and in the six additional cases used for validation (p<0.014). Laser capture microdissection and Real Time RT-PCR analysis using normal ileum found microRNA-133a expression in normal enterochromaffin cells. In situ hybridization in normal ileum showed that some of the mucosal endocrine cells expressed microRNA-133a. Both primary and metastatic ileal carcinoid tumors expressed microRNA-133a by in situ hybridization. These results provide information about novel marker microRNAs that may be used as biomarkers and/or therapeutic targets in intestinal carcinoid tumors.

Plectin, an intermediate filament linking protein, is normally associated with the sarcolemma, nuclear membrane, and intermyofibrillar network in muscle, and with hemisdesmosomes in skin. A 20-year-old female with epidermolysis bullosa simplex since birth had progressive ocular, facial, limb, and trunkal weakness and fatigability since age 9, fivefold CK elevation, a 25% decrement with myopathic motor unit potentials and increased electrical irritability on electromyography, and no anti-acetylcholine receptor (AChR) antibodies. Plectin expression was absent in muscle and severe plectin deficiency was noted in skin. Morphologic studies revealed necrotic and regenerating fibers and a wide spectrum of ultrastructural abnormalities: large accumulations of heterochromatic and lobulated nuclei, rare apoptotic nuclei, numerous cytoplasmic and few intranuclear nemaline rods, disarrayed myofibrils, thick-filament loss, vacuolar change, and pathologic alterations in membranous organelles. Many endplates (EPs) had an abnormal configuration with chains of small regions over the fiber surface and a few displayed focal degeneration of the junctional folds. The EP AChR content was normal. In vitro electrophysiologic studies showed normal quantal release by nerve impulse, small miniature EP potentials, and fetal as well as adult AChR channels at the EP. Our findings support the notion that plectin is essential for the structural integrity of muscle and skin, and for normal neuromuscular transmission.

We analyzed promoter methylation of RASSF1A, CTNNB1, CDH1, LAMB3, LAMC2, RUNX3, NORE1A, and CAV1 using methylation-specific PCR in 33 cases of small bowel carcinoid with both matched primary and metastatic tumors. The methylation status of RASSF1A and CTNNB1 were also determined in six primary appendiceal carcinoid tumors. Two neuroendocrine cell lines, NCI-H727 and HTB-119, were analyzed for promoter methylation. Immunohistochemical analyses for RASSF1A and beta-catenin were performed in 28 matched primary and metastatic tumors. Western blot analysis for RASSF1A and beta-catenin was also performed. Normal enterochromaffin cells were unmethylated in all eight genes examined. RASSF1A and CTNNB1 were unmethylated in appendiceal carcinoids. Methylation of RASSF1A and CTNNB1 promoters was more frequent in metastatic compared to primary tumors (p = 0.013 and 0.004, respectively). The NCI-H727 and HTB-119 cells lines were methylated in the RASSF1A promoter region, and after treatment with 5-aza-2'-deoxycytidine (5-AZA), RASSF1A mRNA was expressed in both cell lines. Western blot results for RASSF1A and beta-catenin supported the methylation-specific PCR findings. The other six genes did not show significant differences. These results suggest that increased methylation of RASSF1A and CTNNB1 may play important roles in progression and metastasis of small bowel carcinoid tumors.

MicroRNAs (miRNAs) are involved in cell proliferation, differentiation, and apoptosis, and can function as tumor suppressor genes or oncogenes. The expression of miRNAs in pituitary carcinomas has not been previously examined. We used miRNA profiling with 1,145 probes to study miRNA expression in normal anterior pituitary (6 cases), adrenocorticotropin (ACTH)-producing adenomas (8 cases), and ACTH-producing pituitary carcinomas (two cases). Real-time RT-PCR and in situ hybridization were used to confirm and independently validate miRNAs that were significantly up-regulated or down-regulated between the pituitary tissues. There were more miRNAs up- (188) or down-regulated (160) between adenomas and normal pituitaries compared to carcinomas and normal pituitaries (92 up- and 91 down-regulated) or between carcinomas and adenomas (46 up- and 52 down-regulated). Both real-time RT-PCR and in situ hybridization showed significant up-regulation of miRNA-122 between pituitary carcinomas and adenomas. MiRNA-493 was also up-regulated in carcinomas compared to ACTH adenomas. Analysis of genes that miRNA-493 interacts with included LGALS3 and RUNX2 ( http://microrna.sanger.ac.uk ) both of which have been shown to have roles in pituitary tumor cell growth. These results provide information about marker miRNAs that may lead to further insights into the regulation of pituitary tumor growth and development.