Collagenase activity in cultures of rat prostate carcinoma.

A specific collagenase (EC 3.4.24.3) has been found and purified from serum-free culture medium of 11095 epidermoid carcinoma of rat prostate. The molecular weight of this collagenase was estimated at 71 000 and the pH optimum was approx. 7. At 26 degrees C, the collagenase cleaved collagen at a site 3/4 the length from the N-terminus. At 37 degrees C, this collagenase degraded collagen to smaller peptides. The enzyme activity was inhibited by serum, cysteine and EDTA, but not by protease inhibitors. The presence of collagenase in rat tumor tissue suggests that this enzyme might play a significant role in tissue invasion by cancer cells.     

Role of stroma in carcinogenesis of the prostate

Prostatic development is induced by androgens acting via mesenchymal-epithelial interactions. Androgens elicit their morphogenetic effects by acting through androgen receptors (ARs) in urogenital sinus mesenchyme (UGM), which induces prostatic epithelial development. In adulthood reciprocal homeostatic stromal-epithelial interactions maintain functional differentiation and growth-quiescence. Testosterone plus estradiol (T+E2) have been shown to induce prostatic carcinogenesis in animal models. Thus, tissue recombinant studies were undertaken to explore the mechanisms of prostatic carcinogenesis in BPH-1 cells in which ARs and estrogen receptors (ERs) are undetectable. For this purpose, BPH-1 cells were combined with UGM, and the UGM+BPH-1 recombinants were grafted to adult male hosts. Solid branched epithelial cords and ductal structures formed in untreated UGM+BPH-1 recombinants. Growth was modest, and tumors did not develop. UGM+BPH-1 recombinants treated with T+E2 formed invasive carcinomas. BPH-1 cells lack ARs and ERs, whereas rat UGM expresses both of these receptors. These data show that immortalized nontumorigenic human prostatic epithelial cells can undergo hormonal carcinogenesis in response to T+E2 stimulation via paracrine mechanisms and demonstrate that the stromal environment plays an important role in mediating hormonal carcinogenesis. During prostatic carcinogenesis the stroma undergoes progressive loss of smooth muscle with the appearance of carcinoma-associated fibroblasts (CAF). This altered stroma was tested for its ability to promote carcinogenesis of nontumorigenic but immortalized human prostatic epithelial cells (BPH-1). CAF+BPH-1 tissue recombinants formed large carcinomas. In contrast, recombinants composed of normal prostatic stroma+BPH-1 cells exhibited minimal growth. This stroma-induced malignant transformation was associated with additional genetic alterations and changes in gene expression. Thus, alteration in the stromal microenvironment was sufficient to promote malignant transformation of human prostatic epithelial cells.     

Role of the extracellular matrix in prostate carcinogenesis

This review summarizes the current state of knowledge regarding the proteins composing the extracellular matrix in the human prostate. The normal expression as well as the changes which occur in PIN and carcinoma are described for the lamins, collagens, and glycosaminoglycans.     

Epididymal metastasis from carcinoma of the prostate

Epididymal Metastasis from a primary carcinoma of the prostate gland is a rare but recognised phenomena. We describe a case of such metastasis which, unlike previous reports, presents as a painful epididymal mass. Therefore it is important for urologists to consider epididymal metastasis as part of the differential diagnosis in a patient with known carcinoma of the prostate and a tender epididymal mass.     

Hypermethylation of the inhibin alpha-subunit gene in prostate carcinoma

Inhibin is composed of an alpha- and a beta-subunit. Transgenic studies assigned a tumor-suppressive role to the inhibin alpha-subunit, and in human prostate cancer inhibin alpha-subunit gene expression was down-regulated. This study examined the inhibin alpha-subunit gene promoter and gene locus to determine whether promoter hypermethylation or LOH occurred in DNA from prostate cancer. The 5'-untranslated region of the human inhibin alpha-subunit gene was sequenced and shown to be highly homologous to the bovine, rat, and mouse inhibin alpha-subunit promoter sequences. A 135-bp region of the human promoter sequence that continued a cluster of CpG sites was analyzed for hypermethylation. Significant (P < 0.001) hypermethylation of the inhibin alpha-subunit gene promoter occurred in DNA from Gleason pattern 3, 4, and 5 carcinomas compared with nonmalignant tissue samples. A subset of the carcinomas with a cribriform pattern were unmethylated. LOH at 2q32-36, the chromosomal region harboring the inhibin alpha-subunit gene, was observed in 42% of prostate carcinomas. These data provide the first demonstration that promoter hypermethylation and LOH are associated with the inhibin alpha-subunit gene and gene locus in prostate cancer.     

Use of choline tracers in the prostate carcinoma management

Prostate cancer is the second most frequently diagnosed cancer in men. This incidence has increased because of the introduction of screening with prostate-specific antigen (PSA) and the use of improved biopsy techniques. Choline PET/CT cannot be recommended as a first-line screening procedure for primary prostate cancer. PET/CT has a limited sensitivity due to its dependency on tumor configuration and size, and a limited specificity in differentiation between prostate cancer and benign pathologies. PET/CT could be useful in the detection of malignant lymph nodes in case of nodes greater than 5 mm in diameter. An application of choline PET/CT may be to increase the detection rate of clinically suspected prostate cancer with multiple negative prostate biopsies. Choline PET/CT has proved to be useful for restaging patients with prostate cancer with biochemical failure. Studies have shown that the positive detection rate of choline PET/CT increases with increasing PSA values. The definition of a PSA cut-off value to refer prostate carcinoma with biochemical recurrence would be helpful for the clinical management of these patients. Several PSA cut-off values have been proposed by literature. The routine use of choline PET/CT cannot be recommended only in patients with an absolute PSA value of < 1 ng/mL. Moreover, the sensitivity of ¹⁸F-Fluorocholine (FCH) PET/CT is significantly higher in patients with a PSA velocity > 2 ng/mL per year or a PSA-doubling time ≤ 6 months. In case of early bone metastases ¹⁸F-FCH could be superior to ¹⁸F-sodium fluoride due to the absence of bone reaction and remodelling.     

Role of p63 and basal cells in the prostate

The prostate contains two major epithelial cell types - luminal and basal cells - both of which develop from urogenital sinus epithelium. The cell linage relationship between these two epithelial types is not clear. Here we demonstrate that luminal cells can develop independently of basal cells, but that basal cells are essential for maintaining ductal integrity and the proper differentiation of luminal cells. Urogenital sinus (UGS) isolated from p63(+/+) and p63(-/-) embryos developed into prostate when grafted into adult male nude mice. Prostatic tissue that developed in p63(-/-) UGS grafts contained neuroendocrine and luminal cells, but basal cells were absent. Therefore, p63 is essential for differentiation of basal cells, but p63 and thus basal cells are not required for differentiation of prostatic neuroendocrine and luminal epithelial cells. p63(-/-) prostatic grafts also contained atypical mucinous cells, which appeared to differentiate from luminal cells via activation of Src. In the response to castration, regression of p63(-/-) prostate was inordinately severe with almost complete loss of ducts, resulting in the formation of residual cystic structures devoid of epithelium. Therefore, basal cells play critical roles in maintaining ductal integrity and survival of luminal cells. However, regressed p63(-/-) prostate did regenerate in response to androgen administration, indicating that basal cells were not essential for prostatic regeneration.     

Nuclear DNA cytophotometry in prostate carcinoma

Eighty patients with prostate carcinoma underwent fine-needle aspiration biopsy for cytologic grading and DNA-single-cell fluorescence photometry before and at 6-month intervals after endocrine treatment. The histograms of DNA values showed single peaks and bimodal and scattered distributions which correlated to the different tumor grades before therapy. The DNA values were significantly different from the controls with benign prostatic hypertrophy. After start of therapy, regressive changes of the DNA-histograms were increases of diploid and hypodiploid DNA values and disappearance of secondary peaks. Progressive changes were increased scattering of DNA values and appearance of secondary peaks. Progressive changes in the histograms were closely related to clinical remission and stable disease, but related poorly to clinical progression. The survival correlated with the pretherapeutic DNA-histograms and with the DNA-median, third-quartile, and maximum parameters.     

Role of estrogens in development of prostate cancer

Estrogens have previously been extensively used in prostate cancer treatment. Serious side effects, primarily in cardiovascular system have, however, limited their use. The therapeutic effect of estrogen in preventing prostate cancer growth was mainly obtained indirectly by feedback inhibition of the hypothalamic release of LRH leading to lowered serum androgen levels and castration like effects. Prostate tissue is also most probably a target for direct regulation by estrogens. Prostate contains estrogen receptor alpha (ERalpha) and beta (ERbeta), which are localized characteristically in stroma and epithelium, respectively. The physiological function of these receptors is not known but there is evidence of the role of estrogens in prostatic carcinogenesis. Developing prostate seems particularly sensitive to increased level of endogenous and/or exogenous estrogens. Perinatal or neonatal exposure of rats and mice to estrogens leads to "imprinting" of prostate associated with increased proliferation, inflammation and dysplastic epithelial changes later in life. Prolonged treatment of adult rodents with estrogens along with androgens also leads to epithelial metaplasia, PIN-like lesions and even adenocarcinoma of prostate speaking for the role of estrogen in prostate cancer development. Recent results concerning antiestrogen inhibition of prostate cancer development beyond PIN-type lesions in transgenic mouse models further suggests a role for estrogens in prostate cancer progression. These results also suggest that direct inhibition of estrogen action at the level of prostate tissue may provide an important novel principle of development of prostate cancer therapies.     

Role of Wnts in prostate cancer bone metastases

Prostate cancer (CaP) is unique among all cancers in that when it metastasizes to bone, it typically forms osteoblastic lesions (characterized by increased bone production). CaP cells produce many factors, including Wnts that are implicated in tumor-induced osteoblastic activity. In this prospectus, we describe our research on Wnt and the CaP bone phenotype. Wnts are cysteine-rich glycoproteins that mediate bone development in the embryo and promote bone production in the adult. Wnts have been shown to have autocrine tumor effects, such as enhancing proliferation and protecting against apoptosis. In addition, we have recently identified that CaP-produced Wnts act in a paracrine fashion to induce osteoblastic activity in CaP bone metastases. In addition to Wnts, CaP cells express the soluble Wnt inhibitor dickkopf-1 (DKK-1). It appears that DKK-1 production occurs early in the development of skeletal metastases, which results in masking of osteogenic Wnts, thus favoring osteolysis at the metastatic site. As metastases progress, DKK-1 expression decreases allowing for unmasking of Wnt's osteoblastic activity and ultimately resulting in osteosclerosis at the metastatic site. We believe that DKK-1 is one of the switches that transitions the CaP bone metastasis activity from osteolytic to osteoblastic. Wnt/DKK-1 activity fits a model of CaP-induced bone remodeling occurring in a continuum composed of an osteolytic phase, mediated by receptor activator of NFkB ligand (RANKL), parathyroid hormone-related protein (PTHRP) and DKK-1; a transitional phase, where environmental alterations promote expression of osteoblastic factors (Wnts) and decreases osteolytic factors (i.e., DKK-1); and an osteoblastic phase, in which tumor growth-associated hypoxia results in production of vascular endothelial growth factor and endothelin-1, which have osteoblastic activity. This model suggests that targeting both osteolytic activity and osteoblastic activity will provide efficacy for therapy of CaP bone metastases.