During past decades, knowledge of melanoma biology has increased considerably. Numerous therapeutic modalities based on this knowledge are currently under investigation. Advanced melanoma, nevertheless, remains a prime example of poor treatment response that may, in part, be the consequence of activated N-Ras oncoproteins. Besides oncogenic Ras, wild-type Ras gene products also play a key role in receptor tyrosine kinase growth factor signaling, known to be of importance in oncogenesis and tumor progression of a variety of human neoplasms, including malignant melanoma; therefore, it is reasonable to speculate that a pharmacological approach that curtails Ras activity may represent a sensible approach to inhibit melanoma growth. To test this concept, the antitumor activity of S-trans, trans-farnesylthiosalicylic acid (FTS), a recently discovered Ras antagonist that dislodges Ras from its membrane-anchoring sites, was evaluated. The antitumor activity of FTS was assessed both in vitro and in vivo in two independent SCID mouse xenotransplantation models of human melanoma expressing either wild-type Ras (cell line 518A2) or activated Ras (cell line 607B). We show that FTS (5-50 M) reduces the amounts of activated N-Ras and wild-type Ras isoforms both in human melanoma cells and Rat-1 fibroblasts, interrupts the Rasdependent extracellular signal-regulated kinase in melanoma cells, inhibits the growth of N-Ras-transformed fibroblasts and human melanoma cells in vitro and reverses their transformed phenotype. FTS also causes a profound and statistically significant inhibition of 518A2 (82%) and 607B (90%) human melanoma growth in SCID mice without evidence of drug-related toxicity. Our findings stress the notion that FTS may qualify as a novel and rational treatment approach for human melanoma and possibly other tumors that either carry activated ras genes or rely on Ras signal transduction more heavily than nonmalignant cells.A dvanced human melanoma is the most malignant type of skin cancer and remains a paradigm of poor treatment response intrinsically linked to poor prognosis (1, 2). Although a multitude of factors have been suspected to play a role in melanoma growth and progression (1-4), the most common specific gene defects identified in this tumor are activating mutations in ras genes. The 15% incidence of ras gene mutations in human melanoma represents predominantly alterations in N-ras at codon 61 (3-6), whereas Ha-ras and K-ras mutations are rare (3-6). The high frequency of this particular mutational hotspot (codon 61) in the N-ras gene basically excludes the possibility of its incidental nature and suggests the involvement of the constitutively active N-Ras protein encoded by the mutated gene in the oncogenesis of human melanoma (6). More recent studies have shown that activated N-Ras confers chemoresistance to human melanoma because expression decreases chemotherapy-induced apoptosis in melanoma xenotransplantation models (7). Because Ras proteins are regulators of multiple signaling pathways that contro...
We describe 2 sibs (brother and sister) with myopathy, sideroblastic anemia, lactic acidosis, mental retardation, microcephaly, high palate, high philtrum, distichiasis, and micrognathia. Very low levels of cytochromes a, b, and c were detected in the patients' muscle mitochondria. Deposition of iron within the mitochondria of bone marrow erythroblasts was observed on electron microscopy. Irregular and enlarged mitochondria with paracrystalline inclusions were also seen on electron microscopy of the patients' muscle specimen. Examination of DNA from the affected sibs showed no deletions in the mitochondrial DNA nor the mutations identified in the syndromes of mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes (MELAS) or myoclonus, and epilepsy associated with rugged-red fibers (MERRF). Since the parents were first cousins and 2 of 6 sibs (male and female) were affected, we suggest that the syndrome expressed by our patients represents a previously unknown autosomal recessive disorder that includes mitochondrial myopathy, lactic acidosis, and sideroblastic anemia.
Twenty-two Jewish patients, belonging to 15 families, 11 of them from Iran and three possibly of Iranian stock, suffered from progressive muscle weakness and wasting. The initial symptom was usually distal leg muscle weakness, appearing in the third or fourth decade and insidiously involving the proximal muscles and to a lesser extent the upper limbs. The quadriceps muscle was consistently spared even in advanced cases. Computerized tomography (CT) scans of muscles demonstrated variable wasting and fatty replacement of limb and axial muscles, while the vastus lateralis muscle retained its normal CT appearance. The typical light microscopy features of the affected muscles were: presence of vacuoles within muscle fibres, internal nuclei, longitudinal fibre splitting and, in severely affected muscles, endomysial fibrosis without, inflammation or fibre necrosis. Electron microscopy suggested that the vacuoles were autophagic. Cytoplasmic and intranuclear inclusions were rare. While electromyography (EMG) revealed presence of spontaneous activity, however, analysis of muscle action potentials, turns-amplitude ratio, macro-EMG and single fibre EMG suggested a primary myopathic disorder. Consanguinity in seven families, the parents being first cousins, and the presence of additional affected siblings of both sexes may suggest an autosomal recessive trait. The presence of this disorder in Iranian Jews may indicate that this is a distinct myopathic entity.
Sixteen patients with glycogen storage disease type III (GSD III) aged 3 to 22 years underwent a detailed neuromuscular evaluation. A minimal impairment of skeletal muscle function was presented in eight patients, slight impairment in four and severe impairment in one patient. Serum creatinine phosphokinase (CPK) was elevated in all patients studied. In the nine patients, in whom electromyography (EMG) was performed; six exhibited a myopathic pattern while a "mixed" (neurogenic-myopathic) pattern was present in three. Muscle biopsies performed in 12 patients, revealed in all cases amylo-1,6,-glucosidase deficiency and biochemical as well as morphological evidence of glycogen accumulation. Two brothers suffered from late onset myopathy, which in the older sibling was associated with clinical, EMG and EM findings of a peripheral neuropathy. Fifteen patients had either electrocardiographic and or echographic evidence of cardiomyopathy. Observations based on this patient material suggest a widespread myopathy in GSD III patients with heterogeneous expression, while peripheral nerve involvement is rarely encountered.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.