Israel Medical Association Journal

Cancer is a multi-step disease involving a series of genetic alterations that result in the loss of control of cell proliferation and differentiation. Such genetic alterations could emerge from the activation of oncogenes and the loss or malfunctioning of tumor suppressor gene activity. Our understanding of cancer has greatly increased through the use of DNA tumor viruses and their transforming proteins as a biological tool to decipher a cascade of events that lead to deregulation of cell proliferation and subsequent tumor formation. For the past ten years our laboratory has focused on the molecular biology of the human neurotropic papovavirus, JCV. This virus causes progressive multifocal Ieukoencephalopathy, a fatal neuro­degenerative disease of the central nervous system in immunocompromised patients. JCV is a common human virus that infects more than 80% of humans but does not induce any obvious clinical symptoms. The increased incidence of acquired immune deficiency syndrome and the use of immunosuppressive chemotherapy have dramatically raised the incidence of PML. The coincidental occurrence of malignant astrocytes and oligodendrocytes in PML patients, coupled with the induction of glioblastoma in JCV-intected non­human primates, provides intriguing speculation on the association between JCV and CNS malignancies. In this report we discuss clinical data and laboratory observations pointing to the direct involvement of JCV in cancer.

Paraneoplastic syndromes are disorders associated with cancer but without a direct effect of the tumor mass or its metastases on the nervous system. Small cell carcinoma of lung associated with paraneoplastic sensory neuronopathy and/or paraneoplastic encephalomyelitis with the presence of anti-Hu antibodies has been termed “anti-Hu syndrome. Anti-­Hu associated PSN-PEM is an immune disorder in which both cell-mediated and humoral mechanisms are involved. Patients are consiaered affected by Anti-Hu associated PSN-PEM when they develop clinical signs and symptoms of CNS dysfunction and/or sensory neuropathy not caused by metas­tases or other disorders, and serum or cerebrospinal fluid is positive for Hu abs. SCLC is found in more than 90% of patients with cancer and positive Hu abs. Individual patients with Hu abs associated to SCLC may suffer PSN-PEM, Iimbic encephalitis, brainstem encephalopathy, opsoclonus-myoclo­nus, paraneoplastic cerebellar degeneration or myelopathy. Hu abs have a specificity of 99% and sensitivity of 82% in detecting paraneoplastic neurological syndromes. There are two types of treatment: the first is to treat the cancer, the second is to suppress the immune reaction with the use of corticosteroids, cyclophosphamide, azathioprine, plasma ex­change, intravenous immunoglobulin and immunoadsorption however, treatment of paraneoplastic syndromes is generally unsatisfactory.

Knowledge on the pathophysiology of irritable bowel syndrome has evolved, beginning with disturbances in motility to visceral hypersensitivity, and ultimately to alterations in brain-gut bi­directional communication, where neurotransmitters such as serotonin play a key role. Recently, a multicomponent disease model that integrates all these alterations was proposed. This model is divided into physiological, cognitive, emotional and behavioral components that explain the gastrointestinal as well as the constitutional symptoms. In recent years there has been an explosion of research together with new developments in pharmacological treatments for lBS that support each compo­nent of this model. This review presents recent data in favor of these alterations in IBS.

Trophic factors such as nerve and fibroblast growth factors are important modulators of 13 cell physiology. These two factors induce the extension of neurite-Iike processes in primary cultures of adult rat 13 cells. Moreover, both NGF and FGF enhance glucose-induced insulin secretion. Since â cells synthesize NGF and pancreatic islet cells produce FGFs, it is possible that autocrine/paracrine interactions may be major regulators of insulin secretion, and impairment of these interactions could lead to pathological states such as diabetes mellitus.

Background: The transfer of therapeutic genes into malignant brain tumors has been the subject of intense pre­clinical and clinical research in recent years. Most approaches have used direct intratumoral placement of a variety of vectors and genes, such as retroviruses or adenoviruses carrying drug-susceptibility genes, modified replication-competent herpes virus, and several vectors carrying tumor suppressor genes such as the p53 gene. However, clinical results have so far been disappointing, mainly due to the limited ability to effectively distribute the genetic material into the target cell population. Accordingly, alternative delivery approaches into the central nervous system, e.g., intravascular, are under investigation. Genetic vectors administered intravascularly are unlikely to penetrate the blood-brain barrier and transfer a gene into brain or tumor parenchyma. However, intravascular delivery of vectors may target endothelial cells lining the blood vessels of the brain. Since endothetial cells participate in a variety of physiological and pathological processes in the brain, their modulation by gene transfer may be used for a variety of therapeutic purposes. Angiogenically stimulated endothelial cells within tumors replicate rapidly and hence may become targets for retroviral-mediated gene transfer.

Objective: To assess the anti-tumor effect of transferring a drug-susceptibility gene into endothelial cells of the tumor vasculature.

Methods: As a model for this approach we delivered concentrated retroviral vectors carrying a drug-susceptibility gene via the internal carotid artery of rats with malignant brain tumors. The safety and efficacy of this approach, without and with subsequent treatment with a pro-drug (ganciclovir). was evaluated.

Results: No acute or long-term toxicity was observed after intraarterial infusion of the vector. Treatment with ganciclovir resulted in variable hemorrhagic necrosis of tumors, indicating preferential transduction of the angiogenically stimulated tumor vasculature. This was accompanied by severe toxicity caused by subarachnoid hemorrhage and intracerebral hemorrhage in vascular territories shared by the tumor and adjacent brain.

Conclusion: The data indicate that endothelial cells can be targeted by intraarterial delivery of retroviral vectors and can be used for devising new gene therapy strategies for the treatment of brain tumors.

The formerly prevalent concept that intact autoantibodies could not penetrate into viable cells has been defeated by a large amount of experimental findings and clinical observations that indicate otherwise. The penetration of autoantibodies into living cells seems to participate in the pathogenesis of diverse autoimmune diseases, but it may also play a physiological role in healthy individuals. Although the fine mechanisms of the phenomenom remain to be elucidated, the potential use of penetrating autoantibodies as vectors to deliver molecules into cells, with diverse therapeutic purposes, has gained growing interest during the last few years.