Faculty Bibliography

BACKGROUND: The activation of the zymogen plasminogen to the serine protease plasmin by urokinase-type (uPA) and tissue-type (tPA) plasminogen activators (PA) is an important event in a variety of physiologic and pathophysiologic processes in mammals. Enhanced PA activity occurs during angiogenesis and has been correlated in vitro and in vivo with increased tumor aggressiveness and is an indicator of poor prognosis in a variety of tumors in humans. Preliminary studies suggest that the antiulcer drug irsogladine maleate (IM) diminishes PA activity in vitro and may inhibit angiogenesis in vivo. To define the precise mechanism of angiogenesis inhibition by IM in vivo, we tested the ability of IM to blunt angiogenesis in a mouse cornea neovascularization model performed in wild-type and PA-knockout mice. METHODS: Three days prior to pellet implantation, groups of C57Bl/6 wild-type, uPA-deficient (upA-/-), and tPA-deficient (tPA-/-) mice received IM (300 mg/kg), IM (500 mg/kg), or vehicle (0.5% carboxymethylcellulose) via oral gavage. After 3 days of treatment, hydron polymer-coated pellets of sucrose aluminum sulfate containing 100 ng of basic fibroblast growth factor (bFGF) were inserted into surgically created pockets in the cornea of each mouse. On postoperative day 6, the neovascularization of each cornea was evaluated by a blinded observer using slit lamp microscopy and photographed. Angiogenesis was quantified by calculating vascular area (mm2) +/- SEM using a modified formula for a half ellipse that incorporates calibrated vessel measurements [Vessel length (mm) x Clock hours x pi x 0.2]. RESULTS: IM treatment (300 and 500 mg/kg/day) resulted in a dose-dependent reduction of angiogenesis in wild-type mice by 21 and 45.3% (P < 0.02, P < 0.001), in tPA-deficient mice by 42.6 and 46% (P < 0.001, P < 0.001), and in uPA-deficient mice by 27.2 and 46% (P < 0.05, p < 0.001), respectively. No quantitative differences in neovascularization were observed in either treatment group between transgenic mouse strains. No toxicity was noted in any group. CONCLUSION: IM inhibits bFGF-induced angiogenesis in wild-type, tPA-knockout, and uPA-knockout mice. The observation that IM significantly diminishes angiogenesis in both PA-deficient mice and wild-type mice suggests that the mechanism of action of IM may be independent of plasminogen activation.

Nonrandom numerical chromosomal abnormalities (NCA) are frequent in invasive breast cancer, but little is known about such changes in microscopic precursor lesions. Mammographically detected 'suspicious' breast lesions were localized by specimen radiology of sliced breast tissue. The slices containing the lesion were imprinted onto coated slides by gentle scraping. The corresponding hematoxylin and eosin stained histologic sections and Diff-Quik stained imprints were used for classification as ductal hyperplasia (DH), atypical ductal hyperplasia (ADH), and ductal carcinoma in situ (DCIS). Additional slide imprints were evaluated for copy number of chromosomes 7, 18, and X by using fluorescent in situ hybridization with alpha satellite probes. NCA were detected in 1 of 9 (11%) cases of DH, in 2 of 8 (25%) cases of ADH, and in 14 of 16 (87%) cases of DCIS. There was selective loss (chromosome 18) in one case of DCIS; all other cases with NCA had a gain of at least one chromosome. There is a progressive increase in incidence of NCA in DH, ADH and DCIS. The majority of NCA are chromosomal gains

Urokinase-type plasminogen activator (uPA) is thought to be an important mediator in the proteolytic degradation of extracellular matrix components observed in a wide variety of normal physiological and pathological conditions. However, the phenotype of a recently developed strain of urokinase-deficient (uPA-/-) mice appears to be normal when maintained under ideal nonstressful conditions. We report an outbreak of botryomycosis, an unusual staphylococcal infection, in a colony of uPA-deficient mice. A detailed histological examination of these uPA-deficient animals also revealed a variety of previously unreported phenotypic abnormalities such as pleuritis and the effacement of lymphoid follicles in the regional lymph nodes and spleen. Additional phenotypic abnormalities such as dystrophic calcifications and rectal prolapse were also observed in the uPA-deficient population. These abnormalities were also noted in ostensibly healthy uPA-deficient animals. Botryomycosis did not affect a colony of wild-type (uPA+/+) animals maintained concurrently under identical conditions in the same room. The peculiar predisposition of the uPA-deficient animals to this rare bacterial infection and the development of phenotypic abnormalities associated with the targeted disruption the uPA gene suggests that uPA contributes significantly to the cutaneous microenvironment and is additional evidence of the extensive involvement of the plasminogen activators in mammalian physiology