Oxidative Stress, Inflammation, and Cancer: How Are They Linked?

Prostate-specific membrane antigen is a type II membrane protein with folate hydrolase activity produced by prostatic epithelium. The expression of this molecule has also been documented in extraprostatic tissues, including small bowel and brain. In the present study, an extensive immunohistochemical analysis was performed on a panel of well-characterized normal and malignant human tissues to further define the pattern of prostate-specific membrane antigen (PSMA) expression. Detectable PSMA levels were identified in prostatic epithelium, duodenal mucosa, and a subset of proximal renal tubules. A subpopulation of neuroendocrine cells in the colonic crypts also exhibited PSMA immunoreactivity. All other normal tissues, including cerebral cortex and cerebellum, had undetectable levels of PSMA. Thirty-three of 35 primary prostate adenocarcinomas and 7 of 8 lymph node metastases displayed tumor cell PSMA immunostaining. Eight of 18 prostate tumors metastatic to bone expressed PSMA. All of the other nonprostatic primary tumors studied had undetectable PSMA levels. However, intense staining was observed in endothelial cells of capillary vessels in peritumoral and endotumoral areas of certain malignancies, including 8 of 17 renal cell carcinomas, 7 of 13 transitional cell carcinomas, and 3 of 19 colon carcinomas. Extraprostatic PSMA expression appears to be highly restricted. Nevertheless, its diverse anatomical distribution implies a broader functional significance than previously suspected. The decrease in PSMA immunoreactivity noted in advanced prostate cancer suggests that expression of this molecule may be linked to the degree of tumor differentiation. The neoexpression of PSMA in endothelial cells of capillary beds in certain tumors may be related to tumor angiogenesis and suggests a potential mechanism for specific targeting of tumor neovasculature.

https://clincancerres.aacrjournals.org/content/clincanres/3/1/81.full.pdf

Prostate-specific membrane antigen expression in normal and malignant human tissues.

Progress toward understanding the biology of prostate cancer has been slow due to the few animal research models available to study the spectrum of this uniquely human disease. To develop an animal model for prostate cancer, several lines of transgenic mice were generated by using the prostate-specific rat probasin promoter to derive expression of the simian virus 40 large tumor antigen-coding region. Mice expressing high levels of the transgene display progressive forms of prostatic disease that histologically resemble human prostate cancer, ranging from mild intraepithelial hyperplasia to large multinodular malignant neoplasia. Prostate tumors have been detected specifically in the prostate as early as 10 weeks of age. Immunohistochemical analysis of tumor tissue has demonstrated that dorsolateral prostate-specific secretory proteins were confined to well-differentiated ductal epithelial cells adjacent to, or within, the poorly differentiated tumor mass. Prostate tumors in the mice also display elevated levels of nuclear p53 and a decreased heterogeneous pattern of androgen-receptor expression, as observed in advanced human prostate cancer. The establishment of breeding lines of transgenic mice that reproducibly develop prostate cancer provides an animal model system to study the molecular basis of transformation of normal prostatic cells and the factors influencing the progression to metastatic prostate cancer.

https://www.pnas.org/content/pnas/92/8/3439.full.pdf

Prostate cancer in a transgenic mouse.

Prostate cancer afflicts one man in nine over the age of 65 and represents the most frequently diagnosed cancer in American men (Coffey 1993). Early detection through serum testing for prostate specific antigen (PSA) and improved procedures for surgical intervention and radiation therapy have significantly reduced the number of fatalities; however, there is still no effective cure for men with advanced disease. Therefore, much research has been dedicated to identifying prognostic markers that distinguish indolent versus aggressive forms of prostate cancer. In contrast, significantly less research has been devoted to understanding the molecular mechanisms that underlie normal prostate growth and development or cancer initiation and progression. In this review, we address recent progress toward the central objectives of understanding parameters of normal versus abnormal prostatic development and of elucidating a molecular pathway for prostate cancer progression. We focus on key regulatory molecules that have been implicated by analysis of patterns of allelic loss in human prostate cancers and/or by reverse genetic approaches in the mouse.

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Molecular genetics of prostate cancer

Recurrent gene fusions of androgen regulated genes and ETS family member genes in prostate cancer are described. Compositions and methods having utility in prostate cancer diagnosis, research, and therapy are also provided.

Recurrent gene fusions in prostate cancer

Our laboratory has previously reported on the derivation of LNCaP cell sublines from LNCaP tumors maintained in castrated and intact athymic male mice. These LNCaP sublines differ from the parental line in tumorigenicity and androgen dependence. This paper demonstrates that one of these sublines acquired metastatic potential. When inoculated either s.c. or orthotopically, the C4-2 subline metastasized to the lymph node and bone with an incidence of 11-50%. Interestingly, the incidence of osseous metastasis was higher in castrated than in intact male hosts. We evaluated the chromosomal, immunohistochemical, and biochemical characteristics of the LNCaP sublines derived from C4-2 tumors that metastasized to the lymph node and bone. Cytogenetic analysis showed that all sublines were human and shared common marker chromosomes with the parental LNCaP cells. This experimental human prostate cancer model may permit, for the first time, the study of the molecular mechanisms underlying human prostate cancer metastasis.

https://cancerres.aacrjournals.org/content/canres/54/10/2577.full.pdf

Androgen-independent cancer progression and bone metastasis in the LNCaP model of human prostate cancer.

c-erb B2/neu has been demonstrated to be a transforming oncogene in both rodent and human prostatic epithelial cells. To understand the potential role of neu in human prostatic cancer progression, we used a gene transfer procedure to determine whether neu amplification/overexpression leads to increased tumor growth and metastasis. We chose an androgen-independent human prostatic epithelial cell line, PC-3, as the target for gene transfer. PC-3 cells were cotransfected with pSVneu-T (a point-mutated rat neu oncogene construct) and pSV2neo, and single-cell cloned. Fifty cell clones were isolated and characterized, of which two neu-transfected clones (N17 and N35) and a neo control clone (C32) were studied extensively with respect to neu gene integration, levels of neu mRNA and protein expression, anchorage-independent growth, and tumorigenic and metastatic potential. Results showed that: 1) Clone N35 contained 70 copies of the neu oncogene and a high level of neu mRNA transcripts. It acquired increased anchorage-independent growth potential in vitro and increased tumorigenicity in vivo. 2) Clone N17 contained 10 copies of the neu oncogene and a low level of neu mRNA transcripts. It did not acquire additional capability for anchorage-independent growth and tumorigenic potential as compared to the controls. 3) Despite an increased level of neu mRNA transcripts present in clone N35, there was no corresponding increase of the steady-state levels of neu protein in this particular clone. 4) When administered subcutaneously, none of the cell clones tested, including the control neomycin-resistant clone, acquired metastatic potential. However, clone N35 exhibited marked metastatic potential when administered orthotopically; this cell clone was found to disseminate widely to the lymph nodes, kidney, skeletal muscle, lung, liver, and bone. 5) When neu-transfected cell subclones from N35-induced primary and metastatic lymph node, kidney, and bone tumors were analyzed for cytoskeletal, extracellular matrix, and cell adhesion protein expression, the bone metastatic subclone exhibited increased levels of vimentin and collagen IV and decreased levels of cytokeratin and ICAM-1. These results, taken together, suggest that neu transfection induces secondary changes, which, rather than neu protein per se, are responsible for the acquisition of tumorigenic and metastatic potential of prostate cancer cells when an appropriate host microenvironment is present. © 1996 Wiley-Liss, Inc.

Shi Ming Chang

Papers

Androgen-independent cancer progression and bone metastasis in the LNCaP model of human prostate cancer.

Transfected neu oncogene induces human prostate cancer metastasis.