Chemoprevention for prostatic carcinoma: The role of flutamide in patients with prostatic intraepithelial neoplasia

Functional heterogeneity of prostatic intraepithelial neoplasia: the duration of hormonal therapy influences the response

OBJECTIVES

To use a clinical model of androgen-deprivation therapy (ADT) followed by radical prostatectomy (RP) to test the hypothesis that prostatic intraepithelial neoplasia (PIN, a premalignant lesion of the prostate causally linked to prostate cancer) is heterogeneous for hormone responsiveness, which might explain aspects of the heterogeneity of the natural history of prostate cancer, for although ADT has been used to reduce prostate cancer, there are controversial data on the effect of ADT on PIN.

PATIENTS AND METHODS

We assessed retrospectively patients with biopsy-confirmed prostate cancer who had RP; some patients had received >or=3 months of ADT at the discretion of their surgeons, and patients from the same cohort who did not have ADT were used as controls. Patients were sequentially selected from the database and their pathology slides were reviewed by a pathologist unaware of the initial presence of PIN (assessed by an independent observer). Fisher's exact test was used to compare the proportions of patients who had residual PIN in the study and control groups. Exact logistic regression was used to evaluate the duration of ADT on PIN regression.

RESULTS

Eighteen patients initially diagnosed with PIN who had no ADT were identified, and 28 with PIN who had ADT were also assessed. All patients who had had no ADT had residual PIN, whereas seven of 28 receiving ADT had no residual PIN (P=0.043). The evaluation of ADT between responders and nonresponders showed a statistically significant association between PIN regression and the duration of ADT (P<0.001). However, the response of PIN to ADT was not uniform, as 16% of patients on ADT for >6 months had residual PIN, suggesting variable sensitivity of PIN to ADT.

CONCLUSION

These results show that ADT causes PIN to regress, and that there is heterogeneity in this effect with the duration of ADT. We propose future prospective, multicentre, randomized trials in which the effect of ADT on PIN is characterized further.

Morphometric and morphological features of the ventral prostate in rats submitted to chronic nicotine and alcohol treatment

Clinical studies analyzing simultaneous nicotine-alcohol use by patients showed important alterations in various organic systems such as: respiratory, digestory, and genital. Also, the prostatic morphology and physiology have been analyzed, specially due to large occurrence of prostatic diseases. Then, this work aimed at determining the structure and ultrastructure of the prostatic stroma and epithelium, as well as the stroma epithelium interactions from rats submitted to simultaneous long-term alcohol-nicotine treatment. A total of 40 male rats were divided into four groups: control group (10 animals) received tap water; alcoholic group (10 animals) received diluted 10% Gay Lussac ethanol; nicotine group (10 animals) received a 0.125mg/100g of body weight dose of nicotine injected subcutaneosly on a daily basis; nicotine-alcohol group (10 animals) received simultaneous alcohol and nicotine treatment. After 90 days of treatment, the animals were sacrificed and samples from the ventral lobe of the prostate were collected and processed for transmission electron and light microscopies. The results showed atrophied epithelium; prostatic intra-epithelial neoplasia; dilated cisterns of the granular endoplasmic reticulum, large amounts of collagen fibers besides inflammatory cells, specially in the alcoholic and nicotine-alcohol groups. Therefore, it could be concluded that the association between alcohol and nicotine caused the impairment of the prostatic secretory process. Moreover, this association is related to prostatic pathogenesis, which could lead to late glandular malignancy.

Persistence of Prostatic Intraepithelial Neoplasia After Effective Chemoprevention of Microscopic Prostate Cancer With Antiandrogen in a Rat Model

PURPOSE

We determined the chemopreventive effect of the antiandrogen bicalutamide (Zeneca Co., Ltd., Osaka, Japan) on Fisher 344 rat prostate carcinogenesis induced by DMAB (3,2'-dimethyl-4-aminobiphenyl) (Nard Co., Ltd., Osaka, Japan). We have previously reported that rat prostate microscopic carcinogenesis in this model was paradoxically enhanced when continuous treatment with bicalutamide was begun 20 weeks after the initiation of DMAB. In the current study we determined whether antiandrogen would promote or suppress the prostate carcinogenesis when administration was begun at a later period of carcinogenesis.

MATERIALS AND METHODS

DMAB at a dose of 50 mg/kg was injected subcutaneously into all animals 10 times at 2-week intervals. To clarify the target lesions of bicalutamide we used 2 control groups (groups 1 and 2). Animals in groups 1 and 2 were autopsied at 60 and 74 weeks, respectively, after the initiation of DMAB. Treatment with bicalutamide began in the 60th week in group 3 rats and continued for 14 weeks. They were sacrificed in the 74th week.

RESULTS

Microscopic cancer was revealed in 27% of group 1 rats and the incidence was increased to 42% in group 2 (statistically not significant). Delayed bicalutamide treatment significantly suppressed the cancer lesion. No cancerous lesion was detected in the ventral or other lobes of the prostate of the rats in group 3. In contrast, bicalutamide did not affect the incidence of PIN. The difference in the incidence of PIN in groups 2 and 3 (84% and 78%, respectively) was not significant.

CONCLUSIONS

The current investigation indicates that, if bicalutamide is started in the later period, it can efficiently eradicate existing microscopic cancer. Despite this suppressive effect on microscopic cancer bicalutamide permits the persistence of PIN. The latter finding suggests that the sensitivity of PIN to antiandrogen might be more complicated than previously recognized.

Apoptotic regulators in prostatic intraepithelial neoplasia (PIN): value in prostate cancer detection and prevention

Early diagnosis of prostate cancer holds tremendous promise for the effective therapy and impact on survival of prostate cancer patients. High-grade prostatic intraepithelial neoplasia (HGPIN) is generally accepted as a lesion indicative of a late pathological event in the premalignant changes leading to full development of prostate cancer. This review seeks to identify specific molecular events that may be linked directly to the molecular transition from benign prostate epithelial cells to prostate carcinoma. HGPIN is pathologically detected in a limited group of men undergoing prostate cancer screening for an elevated serum prostate-specific antigen (PSA) or abnormal digital rectal examination (DRE). Loss of apoptotic control provides a molecular basis for the contribution of specific defective steps in the pathway towards development and progression of prostate cancer. Comparative dissection of the apoptosis status and expression profile of key apoptotic regulators among foci of highly proliferative benign prostatic epithelium, PIN and prostate adenocarcinoma from adjacent areas of the same gland revealed a novel insight into the dysfunctional apoptosis events contributing to prostate carcinogenesis. The sequential and notable loss of the three critical signaling components of the apoptotic action of transforming growth factor-beta (TGF-beta), in the prostate, that is, the transmembrane receptor II (TbetaRII), the key cell cycle inhibitor p27(Kip1), as well as the protagonist downstream effector of the TGF-beta signaling mechanism, Smad4, points to their potential value to 'faithfully' characterize HGPIN, as a premalignant prostate lesion. Recent evidence on the molecular changes in apoptosis regulators contributing to HGPIN and their role as molecular markers of disease onset, as well as candidates for therapeutic targeting/chemoprevention of prostate cancer in its early stages will be discussed.

Androgen deprivation therapy for prostate cancer: current status and future prospects

Androgens play a major role in promoting the development and progression of prostate cancer. As a result, androgen ablation or blockade of androgen action through the androgen receptor (AR) has been the cornerstone of treatment of advanced prostate cancer. Different strategies involving this hormonal therapy produce a significant clinical response in most of the patients, but most responders eventually lose dependency, resulting in mortality. Thus, whether hormonal therapy contributes to the improvement of overall survival rates, especially in patients with advanced prostate cancer, remains controversial. However, patients with advanced disease clearly have a benefit from androgen deprivation-based treatment for palliating their symptoms and for improving the quality of their lives. In order to improve overall survival, novel treatment strategies that prolong the androgen-dependent state and that are useful for androgen-independent disease based on specific molecular mechanisms need to be identified.

Designing a Randomized Phase I/II Prostate Cancer Chemoprevention Trial Using 1??-Hydroxy-24-Ethyl-Cholecalciferol, an Analogue of Vitamin D3

Prostate cancer continues to be a significant source of morbidity and mortality among older men. One possible means of reducing its impact on overall health and vitality is via cancer chemoprevention, both in the population that is unaffected but at some risk and in those who have undergone some form of curative therapy after the onset of the disease. Chemoprevention holds significant promise, but large phase III clinical trials evaluating chemopreventive agents in prostate cancer can require vast numbers of enrollees and require the commitment of significant financial resources and time before any therapeutic benefit may become apparent. One technique to shorten the time required for chemoprevention clinical trials is to use surrogate endpoint biomarkers in place of the currently used actual endpoints of cancer incidence or survival. The validation of such surrogate endpoint biomarkers will require small, well-designed phase I and/or II trials to accumulate data on the modulation of the surrogate biomarkers and the endpoints of cancer incidence or survival by the chemopreventive agent. Careful statistical correlation and clinical validation of the data will then allow us to justify the use such surrogates in place of the actual endpoint in large, randomized trials, potentially shortening trial duration, improving financial efficiency, and accelerating approval of the chemopreventive agent. To that end, we first review the theoretical construct of cancer chemoprevention trials with particular reference to prostate cancer. We thereafter describe the design of a small, randomized, double-blinded, placebo-controlled phase I/II clinical trial of an analogue of vitamin D, vitamin D5, which we believe could serve as a model for data accumulation on surrogate biomarkers and correlation with other clinical endpoints.

Prostatic Intraepithelial Neoplasia: An Update

High-grade prostatic intraepithelial neoplasia (HGPIN) is commonly encountered on prostate needle biopsies and, based on epidemiologic, molecular, and animal models, has proven to be the most significant risk factor for prostate cancer and likely represents the premalignant phase of prostatic adenocarcinoma. This lesion is characterized by cellular proliferations within pre-existing ducts and glands, with nuclear and nucleolar enlargement similar to prostate cancer. However, unlike cancer, HGPIN retains a basal cell layer identifiable by immunohistochemistry with the basal cell-specific antibody cytokeratin 34bE12. The incidence of HGPIN identified in needle biopsies is as high as 25%, increases with age, and coexists with prostate cancer in approximately 85% of cases. There appears to be no causal relationship between HGPIN and serum prostate-specific antigen (total, percent free, or density) or radiographic characteristics on transrectal ultrasound. In a large series, the identification of HGPIN on initial needle biopsy is associated with about a 35% risk of prostate cancer on subsequent biopsies. Thus, the finding of HGPIN on prostate needle biopsy necessitates a second biopsy in a patient eligible for curative treatment. As a precursor lesion, HGPIN is currently a target for chemopreventive strategies, including antiandrogens and nutritional supplementation.

Interactions of androgens, green tea catechins and the antiandrogen flutamide with the external glucose-binding site of the human erythrocyte glucose transporter GLUT1

This study investigates the effects of androgens, the antiandrogen flutamide and green tea catechins on glucose transport inhibition in human erythrocytes. These effects may relate to the antidiabetogenic effects of green tea. Testosterone, 4-androstene-3,17-dione, dehydroepiandrosterone (DHEA) and DHEA-3-acetate inhibit glucose exit from human erythrocytes with half-maximal inhibitions (Ki) of 39.2+/-8.9, 29.6+/-3.7, 48.1+/-10.2 and 4.8+/-0.98 microM, respectively. The antiandrogen flutamide competitively relieves these inhibitions and of phloretin. Dehydrotestosterone has no effect on glucose transport, indicating the differences between androgen interaction with GLUT1 and human androgen receptor (hAR). Green tea catechins also inhibit glucose exit from erythrocytes. Epicatechin 3-gallate (ECG) has a Ki ECG of 0.14+/-0.01 microM, and epigallocatechin 3-gallate (EGCG) has a Ki EGCG of 0.97+/-0.13 microM. Flutamide reverses these effects. Androgen-screening tests show that the green tea catechins do not act genomically. The high affinities of ECG and EGCG for GLUT1 indicate that this might be their physiological site of action. There are sequence homologies between GLUT1 and the ligand-binding domain (LBD) of hAR containing the amino-acid triads Arg 126, Thr 30 and Asn 288, and Arg 126, Thr 30 and Asn 29, with similar 3D topology to the polar groups binding 3-keto and 17-beta OH steroid groups in hAR LBD. These triads are appropriately sited for competitive inhibition of glucose import at the external opening of the hydrophilic pore traversing GLUT1.

Chemoprevention of carcinoma prostate: a review

PURPOSE

Chemoprevention of prostate cancer is the administration of agents to prevent, inhibit, or delay progression of prostate cancer. Opportunities exist for testing various types of chemopreventive interventsion.

MATERIAL AND METHODS

The authors reviewed the relevant articles published in the last twenty years and studied the biology of the prostate cancer. An attempt is made to identify intermediate markers and surrogate endpoint markers. The various interventions and initial clinical trial results are described. End points for evaluation are mainly based on changes in PSA, changes of histological precursors, or time of onset of clinical disease.

RESULTS

Nutritional factors such as reduced fat intake, vitamin A, vitamin E, vitamin C, vitamin D, Lycopene and selenium may have a protective effect against prostate cancer.

CONCLUSION

Numerous studies implicate dietary and nutritional factors in the onset and progression of prostate cancer. Hence, it is possible that bioactive compounds (anti-oxidants) like vits. A, C, D, E, minerals like selenium and carotenoids like lycopene can be a part of chemopreventive strategies for prostate cancer. Ongoing studies on nutrition and prostate cancer may bring the required evidence to support what is still only a hypothesis at present. However, absolute recommendation will have to await the results of long term prospective clinical trials.

Significance of high-grade prostatic intraepithelial neoplasia on prostate biopsy

The early diagnosis of prostate cancer has been facilitated by the development of serum prostate-specific antigen (PSA) testing and evolution in transrectal ultrasound-guided biopsy of the prostate. Over a decade has passed since the initial recommendations for systematic sextant sampling of the prostate to increase the accuracy of cancer detection. Subsequently, variations in the number and location of biopsies have been proposed to maximize prostate cancer detection and obtain more complete information regarding tumor grade, tumor volume, and local stage. Although current biopsy strategies provide a wide sampling of the prostate gland, biopsy histology may not be conclusive for either the presence or absence of adenocarcinoma. High-grade prostatic intraepithelial neoplasia (HGPIN) is found in a significant fraction of patients undergoing transrectal prostate biopsies. In this article, we discuss the significance of high-grade prostatic intraepithelial neoplasia and other abnormal histology findings and current evidence addressing the presence of cancer and need for additional prostate biopsies.