Peripheral benzodiazepine receptor antisense knockout increases tumorigenicity

ABSTRACT: Peripheral benzodiazepine receptors (PBR), first described more than 20 years ago, have been attributed with many putative functions including ones in cellular proliferation and cellular respiration. Hence, it is quite conceivable that deregulation of this receptor could lead to pathology. We and others have reported the existence of PBR overexpression in different human and nonhuman malignancies, but it has never been made clear whether this aberrant malignant PBR expression is a cause or consequence of the cancer. In the current study we induced PBR underexpression by downregulating one critical subunit of the PBR complex, the isoquinoline-binding protein (IBP), using the stable antisense knockout approach, in the MA-10 Leydig cell line. Resultant clones, showing PBR deregulation, also demonstrated increased tumorigenicity, using both in vitro (loss of contact inhibition and growth in soft agar) and in vivo (increased mortality on grafting back into isogenic mice) assays. We suggest that this type of deregulation could be a later event in natural tumor progression. Consequently, PBR deregulation should be more closely studied in human malignancy. Peripheral benzodiazepine receptors (PBR), 1 while widely expressed throughout the body, exhibit different patterns of tissue-specific expression (1-5). Although the PBR were first described more than 20 years ago (6) and a broad spectrum of putative functions has been suggested for them The PBR is an intracellular multisubunit protein receptor, located mainly on the outer mitochondrial membrane (26) and composed of three subunits: the isoquinoline-binding protein (IBP), 1 which is 18 kDa in mass, the voltagedependent anion channel (32 kDa), and the adenine nucleotide transporter (30 kDa) MATERIALS AND METHODS Cells. The MA-10 cell line, originally cloned from the solid M5480P mouse tumor Leydig cell, was a kind gift of Dr. Mario Ascoli (Department of Pharmacology, University of Iowa College of Medicine, Iowa City, IA). MA-10 cell cultures were grown as previously described (30). Briefly, cells were maintained in RPMI 1640 medium with Lglutamine, containing 20 mM HEPES buffer, 15% horse serum, 300 mg/L glutamine, and 50 µg/mL gentamicin sulfate (all purchased from Biological Industries, Beit HaEmek, Israel). MA-10 transfected cells were grown in similar medium, except for the use of 7.5% horse serum and 7.5% fetal calf serum in place of 15% horse serum

Angiotensin converting enzyme inhibition from birth reduces body weight and body fat in Sprague-Dawley rats

In vitro studies have demonstrated that angiotensin II (ANG II) induces adipocyte hyperplasia and hypertrophy. The aim of the present study was to determine the effect of angiotensin-converting enzyme inhibition on body weight, adiposity and blood pressure in Sprague&ndash;Dawley rats. From birth half of the animals (n = 15) were given water to drink, while the remainder were administered perindopril in their drinking water (2 mg/kg/day). Food intake, water intake and body weight were measured weekly. Blood pressure was measured by tail cuff plethysmography at 11-weeks. Body fat content and distribution were assessed using dual energy X-ray absorptiometry and Magnetic Resonance Imaging at 12 weeks. Animals administered with perindopril had a body fat proportion that was half that of controls. This was consistent with, but disproportionately greater than the observed differences in food intake and body weight. Perindopril treatment completely removed hypertension. We conclude that the chronic inhibition of ANG II synthesis from birth specifically reduces the development of adiposity in the rat.<br /