We studied the effects of lysophosphatidylcholine (lysoPC) on the barrier properties and the morphology of the alveolar-capillary membrane in isolated, fluid-filled hamster lungs continuously perfused. When instilled into the airspace at initial concentrations of 8-128 micrograms/ml, lysoPC causes dose-dependent increases in the permeability-surface area product of the alveolar epithelium for small (14C-sucrose, 342) and large (125I-neutral dextran, 70,000) solutes, with maximal values for each solute approximately 15 times control. Rapid whole-lung weight gains are caused by 128 micrograms lysoPC per milliliter, but each of the lower concentrations has no effect on net lung water balance. Electron-microscopic studies demonstrate that type I pneumonocytes are the lung cells most susceptible to lysoPC exposure, with cell swelling being the most prominent feature from low-dose exposure with more severe disruptive changes at the highest concentration tested. The effects of lysoPC are relatively specific, as several structurally related lipids have little or no effect at equivalent concentrations. Instillation of phospholipase A2 causes functional changes similar to those seen with lysoPC, presumably by generation of lysoPC from endogenous phospholipids. Studies employing a 14C-radiolabeled compound show that instilled lysoPC rapidly partitions into the lung lipid fraction where a major portion of the acyl group becomes incorporated into phosphatidylcholine. The amount of instilled lysoPC required to produce functional and morphological effects comprises only a few percent of total lung phospholipids. Since lysoPC is a normal component of lung phospholipids, severe lung dysfunction might result from minor abnormalities in the formation or degradation of this compound.

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Cathepsin B (CB) has been shown to degrade extracellular matrix (ECM) proteins, and has been reported to be involved in invasion and metastasis of several types of solid organ tumors in human and animals, but CB has not been studied in human prostate cancer (CAP). Our objective was to determine the CB protein immunostaining pattern in CAP and to correlate the immunostaining with the degree of malignancy as reflected in the Gleason grading system. We used two types of CB antibodies (namely, monospecific, polyclonal antibodies to human liver CB prepared in rabbits, and polyclonal antibody produced in sheep) to establish CB localization patterns in neoplastic prostate. Our analysis showed a heterogeneous CB immunostaining pattern in the neoplastic human prostate. CB immunostaining occurred in many, but not all, of the neoplastic columnar/cuboidal cells of acini and isolated cells, i.e., in small ragged glands and clusters (groups) of invasive cells in the prostatic stroma. We have shown that, in general, there was a positive correlation of the intensity of CB immunostaining with the Gleason histologic score (or Gleason grade sum) tumors, i.e., from the lowest scores through score 8, but many of the tumors with scores 9 and 10 showed little CB immunostaining. Our study indicated that the increased CB immunostaining in the Gleason grade sum 5-8 tumors may be associated with increased degradation of ECM, but not in 9 and 10 despite the fact that the latter tumors are more malignant clinically. In well-differentiated tumors, fewer CB immunostaining cells were present than the moderately-differentiated tumors. In other words, most of the stromal invasion of the prostatic ECM occurred in tumors of Gleason grade sums 5-8. We suggest that CB immunostaining might be a useful method to assess stromal invasion of prostatic carcinoma, especially in the higher grade tumors.

The levels of several tumor associated proteases, including plasminogen activators (PA), are elevated in many malignant tumors compared to their benign tumor counterparts. Extracellular matrix degradation mediated by PA may facilitate tumor cell invasion and metastasis. To assess whether PA content correlates with the aggressive phenotype in prostate cancer, we studied these activators in the PC-3 human prostate cell line and PC-3CALN, an aggressive in vivo derived variant cell line. Enzymatic assays using H-D-val-leu-lys-pNA (S-2251) as substrate and peroxidase-anti-peroxidase immunohistochemical techniques were used. In an in vitro chemoinvasion assay, the PC-3CALN variant cell line demonstrated significantly greater invasive behavior than the unselected, parental PC-3 line. The activity of PA secreted by PC-3CALN cells was 3.5 times greater than that of PC-3 cells (p less than 0.01). PC-3 metastases obtained following intrasplenic injection of PC-3 cells had greater PA activities than the corresponding primary tumors. Immunohistochemical studies of PC-3 tumors demonstrated preferential localization of urokinase-type PA to areas of apparent tumor cell invasion. These data suggest a correlation between PA and the aggressive phenotype in this model of human prostate cancer. PA, in particular u-PA, may play a role in the migration and invasion of prostate cancer cells and provide a marker of the aggressive phenotype.