NM23 Gene Expression in Human Prostatic Carcinomas and Benign Prostatic Hyperplasias: Altered Expression in Combined Androgen Blockaded Carcinomas

Phase I/II trial of an allogeneic cellular immunotherapy in hormone-naïve prostate cancer

PURPOSE

To determine the toxicity, immunologic, and clinical activity of immunotherapy with irradiated, allogeneic, prostate cancer cells expressing granulocyte macrophage colony-stimulating factor (GM-CSF) in patients with recurrent prostate cancer.

PATIENTS AND METHODS

A single-institution phase I/II trial was done in hormone therapy-naïve patients with prostate-specific antigen (PSA) relapse following radical prostatectomy and absence of radiologic metastases. Treatments were administered weekly via intradermal injections of 1.2 x 10(8) GM-CSF gene-transduced, irradiated, cancer cells (6 x 10(7) LNCaP cells and 6 x 10(7) PC-3 cells) for 8 weeks.

RESULTS

Twenty-one patients were enrolled and treated. Toxicities included local injection-site reactions, pruritus, and flu-like symptoms. One patient had a partial PSA response of 7-month duration. At 20 weeks post first treatment, 16 of 21 (76%) patients showed a statistically significant decrease in PSA velocity (slope) compared with prevaccination (P < 0.001). Injection site biopsies showed intradermal infiltrates consisting of CD1a+ dendritic cells and CD68+ macrophages, similar to previous clinical trials using autologous GM-CSF-transduced cancer cells. Posttreatment, patients developed new oligoclonal antibodies reactive against at least five identified antigens present in LNCaP or PC-3 cells. A high-titer antibody response against a 250-kDa antigen expressed on normal prostate epithelial cells was induced in a patient with partial PSA remission; titers of this antibody decreased when treatment ended, and subsequent PSA relapse occurred.

CONCLUSIONS

This non-patient-specific prostate cancer immunotherapy has a favorable safety profile and is immunologically active. Continued clinical investigation at higher doses and with longer boosting schedules is warranted.

Correlation of protein expression, Gleason score and DNA ploidy in prostate cancer

The prognosis of prostate cancer correlates with tumor differentiation. Gleason score and DNA ploidy are two prognostic factors that correlate with prognosis. We analyzed differences in protein expression in prostate cancer of high and low aggressiveness according to these measures. From 35 prostatectomy specimens, 29 cancer samples and 10 benign samples were harvested by scraping cells from cut surfaces. DNA ploidy was assessed by image cytometry. Protein preparations from cell suspensions were examined by 2-DE. Protein spots that differed quantitatively between sample groups were identified by MS fingerprinting of tryptic fragments and MS/MS sequence analysis. We found 39 protein spots with expression levels that were raised or lowered in correlation with Gleason score and/or DNA ploidy pattern (31 overexpressed in high-malignant cancer, 8 underexpressed). Of these, 30 were identified by MS. Among overexpressed proteins were heat-shock, structural and membrane proteins and enzymes involved in gene silencing, protein synthesis/degradation, mitochondrial protein import (metaxin 2), detoxification (GST-pi) and energy metabolism. Stroma-associated proteins were generally underexpressed. The protein expression of prostate cancer correlates with tumor differentiation. Potential prognostic markers may be found among proteins that are differentially expressed and the clinical value of these should be validated.

Does Finasteride Alter the Pathology of the Prostate and Cancer Grading?

All forms of androgen-deprivation therapy, including finasteride, induce distinctive histologic changes in benign and neoplastic prostatic epithelial cells, including cytoplasmic clearing, nuclear and nucleolar shrinkage, and chromatin condensation. Treated cancer has a significantly higher architectural (Gleason) grade, lower nuclear grade, and smaller nucleolar diameter than untreated controls, creating the potential for grading bias. Recognition of these changes may be difficult in needle biopsies and lymph node metastases with treated cancer because of the subtle infiltrative pattern and inconspicuous nucleoli. The effects of finasteride may be less pronounced than other forms of therapy with variable distribution throughout the prostate; further, there may be greater sensitivity of low and intermediate-grade cancer than high-grade cancer. The Gleason grading system for cancer should not be used after finasteride treatment as it is not validated in this setting and is likely to overestimate the biologic potential of high-grade cancer observed after therapy. Chemoprevention trials with agents such as finasteride that alter morphology should not rely on cancer grading as a secondary endpoint owing to grading bias.

Human prostate cancer risk factors

Prostate cancer has the highest prevalence of any nonskin cancer in the human body, with similar likelihood of neoplastic foci found within the prostates of men around the world regardless of diet, occupation, lifestyle, or other factors. Essentially all men with circulating androgens will develop microscopic prostate cancer if they live long enough. This review is a contemporary and comprehensive, literature-based analysis of the putative risk factors for human prostate cancer, and the results were presented at a multidisciplinary consensus conference held in Crystal City, Virginia, in the fall of 2002. The objectives were to evaluate known environmental factors and mechanisms of prostatic carcinogenesis and to identify existing data gaps and future research needs. The review is divided into four sections, including 1) epidemiology (endogenous factors [family history, hormones, race, aging and oxidative stress] and exogenous factors [diet, environmental agents, occupation and other factors, including lifestyle factors]); 2) animal and cell culture models for prediction of human risk (rodent models, transgenic models, mouse reconstitution models, severe combined immunodeficiency syndrome mouse models, canine models, xenograft models, and cell culture models); 3) biomarkers in prostate cancer, most of which have been tested only as predictive factors for patient outcome after treatment rather than as risk factors; and 4) genotoxic and nongenotoxic mechanisms of carcinogenesis. The authors conclude that most of the data regarding risk relies, of necessity, on epidemiologic studies, but animal and cell culture models offer promise in confirming some important findings. The current understanding of biomarkers of disease and risk factors is limited. An understanding of the risk factors for prostate cancer has practical importance for public health research and policy, genetic and nutritional education and chemoprevention, and prevention strategies.

Metastasis suppression: the evolving role of metastasis suppressor genes for regulating cancer cell growth at the secondary site

PURPOSE

The prevention and treatment of prostate cancer metastasis continue to provide a significant clinical challenge. Identification of the rate limiting steps of metastasis and their underlying molecular mechanisms may lead to new therapeutic targets and also allow more accurate risk stratification for clinical metastases. We review the literature supporting growth of disseminated tumor cells at the secondary site as a key rate limiting step in metastasis. We also reviewed the definition, identification and characterization of metastasis suppressor genes, and discuss their evolving role in regulating this step.

MATERIALS AND METHODS

We performed MEDLINE searches and manual bibliographic reviews on the specific steps of metastasis, including growth at the secondary site. In addition, we performed a comprehensive literature review to identify genes fitting the classic definition of a metastasis suppressor gene. The literature was also searched to assess the status of each gene in clinical cancer and evaluate functional support for the potential involvement of each gene in regulating growth at the secondary site.

RESULTS

Clinical studies in prostate cancer and other cancer types suggest that dissemination to the secondary site is often an early clinical event. However, not all patients with tumor cells at the secondary site have overt metastatic lesions even in the absence of therapy, suggesting that growth at the secondary site may be highly inefficient. Complimentary approaches have allowed researchers to document and quantify the inefficiency of cancer cell growth at the secondary site. Regarding the mechanism of growth control, many studies support a role for the interaction of a cancer cell and the microenvironment at the secondary site influencing whether growth into metastasis may occur. The 7 genes that suppress metastasis without affecting primary tumor growth that have been identified are KAI1, CD44, mitogen activated protein kinase (MAPK) kinase 4, nm23-H1, nm23-H2, KiSS1 and BrMS1. Three of these genes (KAI1, CD44 and MAPK kinase 4) act as metastasis suppressor genes of prostate cancer, while the remainder have yet to be tested in this cancer type. Loss of expression has been demonstrated for most of these genes during the clinical progression of prostate cancer to metastasis. MAPK kinase 4 and KiSS1 appear to suppress metastasis by inhibiting cancer cell growth at the secondary site. Interestingly many metastasis suppressor genes have common roles in growth control, adhesion and cytoskeletal reorganization, suggesting a common mechanism of metastasis suppression. Proposed candidate pathways include signaling through Src kinase and Rac GTPase.

CONCLUSIONS

The findings discussed support growth at the secondary site as a clinical target for metastasis treatment and prevention. Metastasis suppressor genes may offer valuable mechanistic insight for guiding specific therapeutic strategies, which may include drug induced reactivation of metastasis suppressor genes and their signaling pathways. Clinical assessment of metastasis suppressor gene product status in disseminated cancer cells may improve the accuracy of predicting the prognosis in patients with clinically localized disease.

Treatment changes in prostatic hyperplasia and cancer, including androgen deprivation therapy and radiotherapy

Substantial and characteristic changes occur in the microscopic appearance and immunophenotype of the hyperplastic prostate and adenocarcinoma following androgen deprivation therapy and radiotherapy. These changes are rarely seen in untreated cancer, and in the authors' opinion, the combinations of features following therapy are sufficiently distinctive to warrant recognition. Pathologists must be aware of these distinct changes because of the reliance placed on nuclear and nucleolar size in the identification of prostate cancer, particularly in small specimens and lymph node metastases.

Increased RB1 abnormalities in human primary prostate cancer following combined androgen blockade

BACKGROUND

The RB1 proliferation control pathway is a critical determinant of cell cycle progression. Abnormalities of RB1 are found in a variety of cancers, and the association with human prostate cancer (CaP) was examined here.

METHODS

RNA expression levels of RB1 in CaPs were examined by RT-PCR. RNA integrity was assessed by evaluating expression of an endogenous gene standard.

RESULTS

Abnormally low RB1 mRNA expression was found in 12/33 (36%) of CaPs from patients who had received combined androgen blockade (CAB) treatment. In contrast, 6/48 (13%) untreated CaPs showed abnormally low expression. This difference was statistically significant (P = 0.015). In the samples from untreated patients, a higher frequency of abnormal RB1 was found in specimens with a higher Gleason grade (P = 0.038). In addition, one untreated stage C, grade 9 specimen was found to express RB1 transcripts lacking exon 22, as determined by sequencing of DNA from the truncated transcripts.

CONCLUSIONS

These findings suggest that abnormalities of RB1 may contribute to hormone-withdrawal-related survival of CaP cells.

Decreased C-MYC and BCL2 expression correlates with methylprednisolone-mediated inhibition of Raji lymphoma growth

Methylprednisolone (MP) and related corticosteroids are a fundamental part of regimens used to treat lymphoma and leukemia. In many of these malignancies, oncogenic activation of C-MYC and BCL2 is seen. Abnormalities of the tumor suppressor p53, which exerts growth-suppressing and apoptosis-enhancing functions through the transcriptional regulation of downstream genes including CDKN1, GADD45, and BCL2, are also often found. The goal was to determine the modulation of expression of the oncogenes (C-MYC and BCL2), the p53 pathway described above, and the apoptosis marker TGF-beta 1 in the human Raji lymphoma following MP treatment. Raji xenografts were grown in nude mice and growth curves characterized by sequential measurement. Mice were treated daily for 8 days with MP. Tumors were harvested untreated, or at 1 or 8 days after cessation of MP treatment, and the RNA was extracted. RT-PCR was used to determine the level of mRNA expression of the genes. Tumor growth was greatly reduced in the MP-treated mice. Gene expression levels for C-MYC and BCL2 were reduced at 1 day following MP and approached control levels 8 days after MP treatment. Expression levels of p53, CDKN1, and GADD45 were moderately and coordinately decreased at 1 day after cessation of MP treatment and remained repressed a week later. TGF-beta 1 exhibited no change in expression levels. These results suggest that decreased expression of C-MYC and BCL2 may play a role in the molecular events that initiate and are responsible for the growth inhibition of Raji lymphoma xenografts by MP.