Harald Dinter

The Rho kinase inhibitor fasudil inhibits tumor progression in human and rat tumor models

The ability of cancer cells to undergo invasion and migration is a prerequisite for tumor metastasis. Rho, a Ras-related small GTPase, and the Rho-associated coiled coil–containing protein kinases (Rho kinases, ROCK1 and ROCK2) are key regulators of focal adhesion, actomyosin contraction, and thus cell motility. Inhibitors of this pathway have been shown to inhibit tumor cell motility and metastasis. Here, we show that fasudil [1-(5-isoquinolinesulfonyl)-homopiperazine], an orally available inhibitor of Rho kinases, and its metabolite 1-(hydroxy-5-isoquinoline sulfonyl-homopiperazine) (fasudil-OH) modify tumor cell morphology and inhibit tumor cell migration and anchorage-independent growth. In addition, we show that fasudil inhibited tumor progression in three independent animal models. In the MM1 peritoneal dissemination model, tumor burden and ascites production were reduced by >50% (P < 0.05). In the HT1080 experimental lung metastasis model, fasudil decreased lung nodules by ∼40% (P < 0.05). In the orthotopic breast cancer model with MDA-MB-231, there were 3-fold more tumor-free mice in the fasudil-treated group versus saline control group (P < 0.01). Fasudil has been approved for the treatment of cerebral vasospasm and associated cerebral ischemic symptoms. In patients, fasudil is well tolerated without any serious adverse reactions. Therefore, the concept of Rho kinase inhibition as an antimetastatic therapy for cancer can now be clinically explored. [Mol Cancer Ther 2006;5(9):2158–64]

The type IV phosphodiesterase specific inhibitor mesopram inhibits experimental autoimmune encephalomyelitis in rodents

Experimental autoimmune encephalomyelitis (EAE) is an autoimmune disease with pathological features reminiscent of those seen in multiple sclerosis and thus serves as an animal model for this disease. Inhibition of type IV phosphodiesterase (PDE IV) in animals with this disease has been shown to result in amelioration of disease symptoms. Here we describe the immunomodulatory activity of the novel potent and selective PDE IV inhibitor mesopram. In vitro, mesopram selectively inhibits the activity of type 1 helper T (Th1) cells without affecting cytokine production or proliferation of type 2 helper T (Th2) cells. Administration of mesopram to rodents inhibits EAE in various models. Clinically, EAE is completely suppressed by mesopram in Lewis rats. This is accompanied by a reduction of inflammatory lesions in spinal cord and brain. RT-PCR analysis revealed a marked reduction in the expression of interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha) in the brains of these animals. Furthermore, the ex vivo production of Th1 cytokines by activated spleen cells derived from mesopram-treated animals is significantly reduced compared to vehicle-treated controls. Amelioration of the clinical symptoms is also observed during chronic EAE in mesopram-treated SJL mice as well as in relapsing-remitting EAE in SWXJ mice using a therapeutic treatment regimen. These data demonstrate the anti-inflammatory activity of mesopram and provide a rationale for its clinical development.

Phosphodiesterase type IV inhibitors in the treatment of multiple sclerosis

Abstract Multiple sclerosis is an autoimmune disease with inflammatory lesions localized to the white matter of the central nervous system. Early on, the disease is characterized by episodes of exacerbations and remissions. During exacerbations there is an acute inflammatory infiltrate characterized by the presence of mononuclear cells, monocytes, and T lymphocytes. These cells produce proinflammatory cytokines that have been implicated in the amplification of the inflammatory response as well as in the damage of oligodendrocytes. The inflammation ultimately results in loss of myelin and oligodendrocyte cell death (demyelination). Thus therapies aimed at preventing the inflammatory response may have a beneficial effect on the course of the disease. One such therapy is treatment with inhibitors of phosphodiesterase type IV. These drugs have proven to be extremely effective in the prevention and treatment of experimental allergic encephalomyelitis, the animal model for multiple sclerosis. These experiments, as well as other data discussed here, provide a rationale for the treatment of multiple sclerosis with inhibitors of phosphodiesterase type IV.

Prostaglandins and their receptors

Euler’s description that seminal vesicles contain a prostate-derived hypotonic activity [1] causing various pharmacological effects initiated an intense search for the active entities, the prostaglandins. This marks the beginning of the study of paracrine hormonal regulation in tissues. Research revealed that arachidonic acid, which is cleaved from the cell membrane by phospholipases, is the precursor of the prostaglandins (on which we concentrate in this review) and of the structurally related leukotrienes and lipoxins (Fig. la).

High-level secretion of the four salivary plasminogen activators from the vampire bat Desmodus rotundus by stably transfected baby hamster kidney cells.

The cDNAs coding for the four Desmodus rotundus salivary plasminogen activators (DSPAs) were subcloned into the mammalian expression vector, pMPSV/CMV, which carries the myeloproliferative sarcoma virus promoter and the cytomegalovirus enhancer. These constructs were transfected, together with plasmids harbouring Geneticin (G418)-resistance and puromycin-resistance genes, into baby hamster kidney cells. Through the selective pressure of both antibiotics, cell clones constitutively overexpressing the DSPA alpha 1, DSPA alpha 2, DSPA beta or DSPA gamma cDNAs were obtained. Secretion of active DSPAs was confirmed by zymographic analysis and quantified using a fibrin plate assay and ELISA.

Novel Antibody Therapeutics Targeting Mesothelin In Solid Tumors

Abstract: Background Monoclonal antibodies have become attractive clinical anti-cancer drugs in the last 3 decades due to their targeting specificity and suitable pharmacokinetic properties. Mesothelin is a tumor-associated antigen with limited expression in normal tissues. It is frequently over-expressed on the cell membrane of a number of epithelial malignancies (e.g. mesothelioma, pancreatic, ovarian, lung, triple negative breast and gastric cancers). Methods Mesothelin is validated as a suitable antibody target for cancer therapy. A number of novel antibody therapeutics targeting mesothelin in development are compared and their mechanisms of action are also discussed. Both basic science and clinical data are provided to give a complete veiw of how an agent is developed from bench to bedside. Results Novel antibody therapeutics, including unconjugated monoclonal antibodies, recombinant immunotoxins and antibody-drug conjugates, targeting mesothelin exert anti-tumor activities by different mechanisms of action. Based on the convincing preclinical data generated with these molecules, the antibody therapeutics have been brought into early clinical evaluation where initial promising results were obtained. Conclusion These antibody therapeutics directed against mesothelin are expected to have different safety profiles, based on their different mechanism of action. Further clinical development will reveal which of these molecules shows the best efficacy and widest therapeutic window and thus is best suited to bring benefit to the patients.

Anti-tumor efficacy of the nucleoside analog 1-(2-deoxy-2-fluoro-4-thio-β-D-arabinofuranosyl) cytosine (4′-thio-FAC) in human pancreatic and ovarian tumor xenograft models

1‐(2‐Deoxy‐2‐fluoro‐4‐thio‐β‐D‐arabinofuranosyl) cytosine (4′‐thio‐FAC) is a deoxycytidine analog that has been shown previously to have impressive anti‐proliferative and cytotoxic effects in vitro and in vivo toward colorectal and gastric tumors. In our present studies, the pharmacokinetic behavior in nude mice and the effectiveness of 4′‐thio‐FAC against human pancreatic and ovarian tumor growth were assessed in comparison with standard chemotherapeutic agents. Potent in vitro anti‐proliferative effects were observed against pancreatic (Capan‐1, MIA‐PaCa‐2, BxPC‐3) and ovarian (SK‐OV‐3, OVCAR‐3, ES‐2) cancer cell lines with IC50 of 0.01–0.2 μM. In vivo anti‐tumor activity was evaluated in nude mice bearing subcutaneously (s.c.) implanted human pancreatic tumor xenografts or intraperitoneally (i.p.) disseminated human ovarian xenografted tumors. Oral daily administration of 4′‐thio‐FAC for 8–10 days significantly inhibited the growth of gemcitabine‐resistant BxPC‐3 pancreatic tumors and induced regression of gemcitabine‐refractory Capan‐1 tumors. 4′‐Thio‐FAC was also a highly effective inhibitor of ovarian peritoneal carcinomatosis. In the SK‐OV‐3 and ES‐2 ovarian cancer models, 4′‐thio‐FAC prolonged survival to a greater extent than that observed with gemcitabine. Furthermore, the superiority of 4′‐thio‐FAC to carboplatin and paclitaxel was demonstrated in the ES‐2 clear cell ovarian carcinoma model. Studies provide evidence that 4′‐thio‐FAC is a promising new alternative to gemcitabine and other chemotherapeutic drugs in the treatment of a variety of tumor indications, including pancreatic and ovarian carcinoma.

Molekulare Aspekte der Behandlung der Multiplen Sklerose

Die Multiple Sklerose (MS) ist die haufigste Autoimmunerkrankung des Nervensystems und mit die Hauptursache einer neurologischen Behinderung junger Erwachsener. Pathologie, Pathophysiologie und Pathogenese der MS, die als Prototyp einer Entmarkungskrankheit angesehen wird, werden zunehmend besser verstanden.