Beatrix Farkas

Induction of Hsp90 protein expression in malignant melanomas and melanoma metastases.

Abstract:  The heat‐shock protein Hsp90 has been shown to be essential for the functional integrity of the telomerase complex. The telomerase activity is enhanced in melanoma and stabilizes the chromosomal integrity in proliferating cells. Furthermore, overexpression of Hsp90 induces silencing of point mutations in transcription factors which, otherwise, would result in a loss‐of‐function phenotype. In melanocytic lesions there is a higher risk of mutations caused by the enhanced proliferation in melanocytic cells. By analyzing microdissected melanocytic tumors by semiquantitative PCR, we demonstrate an overexpression of Hsp90 mRNA in malignant melanomas (10/14) and in melanoma metastases (6/6) as well as in melanoma cell lines (9/9) when compared with melanocytic nevi (2/9). These results could be confirmed on protein level by immunohistochemistry. While melanocytic nevi show discrete Hsp90 expression only in a minor fraction (2/9), malignant melanomas and metastases show a positive Hsp90 immunohistochemistry in the majority of cases; (7/9) and (13/14), respectively. In addition, by analyzing melanoma metastases by flow cytometry we show that Hsp90 is expressed on the surface of tumor cells (7/8). From these data we conclude that Hsp90 is present in advanced malignant melanomas and may have a stabilizing effect on the cellular functions in proliferating cells of melanocytic lesions and could thereby be a prerequisite for the tumor progression. As Hsp90 is expressed on the cell surface, it might also be a potential immunorelevant target structure for immunotherapy of melanoma.

BGP-15, a nicotinic amidoxime derivate protecting heart from ischemia reperfusion injury through modulation of poly(ADP-ribose) polymerase.

The protective effect of O-(3-piperidino-2-hydroxy-1-propyl)nicotinic amidoxime (BGP-15) against ischemia-reperfusion-induced injury was studied in the Langendorff heart perfusion system. To understand the molecular mechanism of the cardioprotection, the effect of BGP-15 on ischemic-reperfusion-induced reactive oxygen species (ROS) formation, lipid peroxidation single-strand DNA break formation, NAD(+) catabolism, and endogenous ADP-ribosylation reactions were investigated. These studies showed that BGP-15 significantly decreased leakage of lactate dehydrogenase, creatine kinase, and aspartate aminotransferase in reperfused hearts, and reduced the rate of NAD(+) catabolism. In addition, BGP-15 dramatically decreased the ischemia-reperfusion-induced self-ADP-ribosylation of nuclear poly(ADP-ribose) polymerase(PARP) and the mono-ADP-ribosylation of an endoplasmic reticulum chaperone GRP78. These data raise the possibility that BGP-15 may have a direct inhibitory effect on PARP. This hypothesis was tested on isolated enzyme, and kinetic analysis showed a mixed-type (noncompetitive) inhibition with a K(i) = 57 +/- 6 microM. Furthermore, BGP-15 decreased levels of ROS, lipid peroxidation, and single-strand DNA breaks in reperfused hearts. These data suggest that PARP may be an important molecular target of BGP-15 and that BGP-15 decreases ROS levels and cell injury during ischemia-reperfusion in the heart by inhibiting PARP activity.

Reduction of acute photodamage in skin by topical application of a novel PARP inhibitor

The ultraviolet (UV) components of sunlight induce damage to the DNA in skin cells, which is considered to be the initiating step in the harmful biological effects of UV radiation. Repair of DNA damage results in the formation of single-strand DNA breaks, which activate the nuclear poly(ADP-ribose) polymerase (PARP). Overactivation of PARP worsens the oxidative cell damage and impairs the energy metabolism, raising the possibility that moderation of PARP activation following DNA damage may protect skin cells from UV radiation. The topical effects of the novel PARP inhibitor O-(3-pyperidino-2-hydroxy-1-propyl) pyridine-3-carboxylic acid amidoxime monohydrochloride (BGP-15M) were investigated on UV-induced skin damage in a hairless mouse model. For evaluation of the UV-induced acute photodamage to the skin and the potential protective effect of BGP-15M, DNA injury was detected by measuring the formation of single-strand DNA breaks and counting the resulting sunburn (apoptotic) cells. The ADP-ribosylation of PARP was assessed by Western blot analysis and then quantified. In addition, the UV-induced immunosuppression was investigated by the immunostaining of tumor necrosis factor alpha and interleukin-10 expressions in epidermal cells. The signs of inflammation were examined clinically and histochemically. Besides its primary effect in decreasing the activity of nuclear PARP, topically applied BGP-15M proved to be protective against solar and artificial UV radiation-induced acute skin damage. The DNA injury was decreased (P<0.01). An inhibition of immunosuppression was observed by down-regulation of the epidermal production of cytokines IL-10 and TNFalpha. In the mouse skin, clinical or histological signs of UV-induced inflammation could not be observed. These data suggest that BGP-15M directly interferes with UV-induced cellular processes and modifies the activity of PARP. The effects provided by topical application of the new PARP-regulator BGP-15M indicate that it may be a novel type of agent in photoprotection of the skin.

BGP-15, a hydroximic acid derivative, protects against cisplatin- or taxol-induced peripheral neuropathy in rats

The neuroprotective effect of BGP-15 against peripheral sensory neuropathy was studied in rats that were exposed to short-term cisplatin or taxol administration. The changes of nerve conduction velocity were determined in situ after treating the Wistar rats with BGP-15 (50, 100, and 200 mg/kg po daily doses throughout the experiment), cisplatin (1.5 mg/kg ip daily dose for 5 days), or taxol (5.0 mg/kg ip daily dose every other day in a 10-day interval) alone or giving the test compound in combination with cisplatin or taxol. Electrophysiological recordings were carried out in vivo by stimulating the sciatic nerve at both sciatic notch and ankle site. Neither motor nor sensory nerve conduction velocity was altered by any dose level of BGP-15 tested. Both anticancer drugs decreased the sensory nerve conduction velocity (SNCV). BGP-15 treatment prevented the impairment of SNCV either in part or totally in the cisplatin- or taxol-treated groups. This neuroprotective potential of BGP-15 could be well correlated with its recently described poly(ADP-ribose) polymerase- inhibitory effect and its ability to protect against the damages induced by the increased level of reactive oxygen species in response to anticancer treatment.

Terbinafine (Lamisil) treatment of toenail onychomycosis in patients with insulin-dependent and non-insulin-dependent diabetes mellitus: a multicentre trial.

Background Diabetes mellitus (DM) affects an estimated 175 million people world‐wide. Approximately one‐third of patients with DM have toenail onychomycosis.

Comparison of tacalcitol ointment with short- contact dithranol therapy in the treatment of psoriasis vulgaris: a randomized multicentre, open prospective study on efficacy and safety

A multicentre, randomized, open, prospective, parallel-group trial was carried out to compare the efficacy, tolerability and safety of topical treatment with tacalcitol ointment (4 μg/g, applied once daily) with that of short-contact dithranol therapy. The tolerability of tacalcitol was significantly (P=0.002) better and its efficacy was slightly better. Tacalcitol proved to be less (P<0.001) irritant than dithranol and did not stain the skin or clothes. The results suggest that tacalcitol is more convenient to use in plaque-type psoriasis than dithranol and does not produce the side-effects of topical corticosteroids and tar, making the drug a first-line treatment for chronic plaque psoriasis.