ANNALS OF CLINICAL AND LABORATORY SCIENCE, Vol. 17, No. 3 Copyright 1987, Institute for Clinical Science, Inc. E levated Prolactin Level in Prostates with Latent Carcinoma RYUICHI YATANI, M.D.,* ITSUO KUSANO, M.D.,* TAIZO SHIRAISHI, M.D.,* SATORU MIURA, M.D.,* H ID E K I TAKANARI, M.D.,* and PAUL I. LIU, M.D., P H.D.tt *Department o f Pathology, Mie University School o f Medicine, Tsu, Mie 514, Japan and fdepartment o f Pathology, University o f South Alabama Medical Center, Mobile, AL 36617 ABSTRACT To evaluate a possible correlation betw een tissue horm one levels and the developm ent of latent prostatic carcinoma, levels of testosterone, estradiol, and prolactin w ere m easured in hom ogenates of prostates by radioim m unoassay. O ne h u n d red and th irte e n prostates obtain ed at autopsy from males over age 50 were morphologically classified into three groups; benign prostates, prostates with latent well differentiated type carcinom a (LWTC), and prostates w ith latent m oderately or poorly differen tiated type carciom a (LMPTC). As detected by double antibody radioimmunoassay, tissue prolactin levels w ere statistically elevated (P < 0.05) in prostates classified as LM PTC com pared to benign prostates only. No statistical differences w ere noted for prostatic tissue levels for testosterone and estradiol in the three groups. Results suggest the possiblity that prolactin may relate to the promotion and/or manifestation of prostatic carcinoma at the tissue level. Introduction In the developm ent of prostate, the concentration of specific horm ones may play a decisive role in determ ining regulation versus prom otion of carcinogenesis. How ever, sifting through the + Address reprint requests to Paul I. Liu, M.D., P h.d., D epartm en t o f Pathology, U niversity o f South Alabama Medical Center, Mobile, AL 36617. 178 array of horm ones, their concentrations in plasm a, prostatic fluid, or prostatic tissue and trying to pinpont a given horm one concentration to a com plex malignant process has rem ained challengingly difficult. Previous studies indicate that plasma levels of estradiol 17(3, follicle stim ulating horm one, luteinizing h o r m one, androstenedione, and testosterone w ere n o t significantly a lte re d in patients w ith prostatic carcinom a.2 In ter 0091-7370/87/0500-0178 $00.90 Institute for Clinical Science, Inc.
LATENT PROSTATIC CARCINOMA 179 estingly, plasma levels of prolactin have been found to be elevated in patients w ith prostatic carcinom a com pared to patients with benign prostatic disease.2,3 F u rth er studies indicate prolactin tends to be higher in serum than in prostatic fluid. In contrast, the horm ones estradiol and estron are elevated in prostatic fluid as com pared to serum.5 Based on the determ ination of horm one levels in prostatic fluid, it has been reported that estrad iol and prolactin concentrations w ere e le v a te d in som e p a tie n ts w ith prostatic carcinom a.5 T he role of testosterone levels in prostatic carcinom a is still unclear. It has been shown that high levels of testosterone exist in serum, but very low levels are found in prostatic fluid.5 To clarify further the role of hormones in the developm ent of prostatic, it is becom ing evident that direct m easurem ent of specific hormones at the tissue level is a b e tte r reflection of the hormonal environm ent and disease process. This study is designed to investigate the relationship betw een levels of hormones in prostatic hom ogenates and latent carcinom a of the prostate. The levels of testosterone, prolactin, and estradiol in the p ro state w ere assayed and the results correlated with the absence or presence of latent carcinom a, and the extent of differentiation of the latent carcinoma as well. M aterials and M ethods Prostates obtained at autopsy for this study w ere selected from m en over age 50 who had no known prostatic surgery or diag n o sis of p ro sta tic carcinom a. Approximately 0.5 to 2 g of prostate tissue was excised from the peripheral portion of the prostate which is known to be rich in glandular structures. Prostate tissue was hom ogenized by poytron* w ith Kinematica, Switzerland. 0.3 M sucrose in phosphate buffered saline (PBS, ph 7.4) to the final concentration of 0.2 g tissue per ml at 4 C for five m inutes and a supernate obtained by centrifugation at 3000 rpm for 15 m inutes. Individual supernates w ere then exam ined in duplicate for levels of testosterone, estradiol, and prolactin using the double antibody radioimmunoassay kit. t 4 The quantity of supernate used in this assay was 50 fxl for testosterone and e s tra d io l a n d 100 (xl for p ro la c tin. Approximately 200,000 cpm of each 125Ilabeled horm one and first antibody was incubated at room tem perature for 24 hours. O ne ml of the second antibody was then added with further incubation at room tem p e ra tu re for 30 m inutes. S upernates w ere centrifuged at 3,000 rpm for 15 m inutes, asp irated by vacuum, and the precipitates washed once w ith two m l of PBS. P recip itates containing bound horm one w ere counted for two m inutes by an autom atic gam m a counter. T he concentration of each horm one was calculated by means of a computerized radioimmunoassay program. R em aining portions of individual prostates w ere sectioned and fixed in Bouins solution, paraffin blocked, step-sectioned at three mm intervals, and m icroscopically exam ined for latent prostate carcinom a. B ased on m o rphological appearance,6 latent prostate carcinomas w ere classified into two types: latent well differentiated type carcinom a (LWTC) and laten t m oderately or poorly differentiated type carcinom a (LM PTC). The LW TC generally consisted of collections of w ell differentiated, clear, or som e tim es dark cells forming small glandular stru c tu re s w hich, individually, w ere occasionally difficult to distinguish from norm al gland b u t w ere associated with invasion and destruction of muscle fibers (figure 1). T he LM PTC w ere characterized by neoplastic glands with a predom - t Midorijuji, Tokyo, Japan.
YATANI, KUSANO, SHIRAISHI, MIURA, TAKANARI, AND LIU m jk: ij S F w m -. : > 180 F i g u r e 1. F i g u r e 2. Latent w ell differentiated type carcinoma (H and E stain, 20 x FK 3.3). Latent moderately and poorly differentiated type carcinoma (H and E stain, 20 x FK 3.3)
inant p a tte rn of invasive grow th into 3 - nerve fibers of th e p erin eu ral space, c o n n e c tiv e tissu e, m uscle b u n d le s, in te rstitial lym phatic space or capsule. The cells w ere usually large, b u t occasionally small cells w ere seen (figure 2). LATENT PROSTATIC CARCINOMA 181 Results Am ong 113 prostates exam ined, 76 w e re b e n ig n, 12 w e re c la ssified as LW TC, and 25 as LM PTC. The m ean ages of the subjects were similar in all three groups. As shown in figure 3, the concentration of tissue prolactin in prostates classified as LM PTC (9.11 ± 1.31 ng p e r w et g tissue ± SD) was significantly higher com pared to the benign prostate group (6.00 ± 0.42, p < 0.05). T issue p rolactin co n centration in p ro s tates classified as LW TC (7.94 ± 1.58) 0 O Nb Oi & 8 0 30 Benign prostates With well differentiated With moderately & poorly differentiated F ig u r e 4. T e s to s te r o n e le v e ls in p r o s ta tic tis - 20 10 0 Benign prostates With well differentiated With moderately & poorly differentiated»significantly different (P<0.05) F ig ur e 3. P rolactin le v e ls in prostatic tissu es. lay in term ed iate betw een the benign and LM PTC groups; how ever, differences w ere not significant. Testosterone levels are shown in figure 4. The concentration of tissue testosterone was 0.44 ± 0.04 ng per w et g tissue, 0.55 ± 0.21, and 0.34 ± 0.64 for benign, LWTC, and LM PTC, respectively. As shown in figure 5, tissue estradiol concentration was 250 ± 24 pg per w et g tissue for benign prostates, 186 ± 44 for LWTC, and 184 ± 38 LM PTC. There were no significant statistical differences in eith er testo sterone or estradiol levels among the three groups. Discussion The relationship betw een levels of testo stero n e, prolactin, and estradiol in
1 82 SATANI, KUSANO, SHIRAISHI, MIURA, TAKANARI, AND LIU o> \ CD Q. 1,000 750 o 500 o < cc t tn LU» > ^» i can be used as a reflection of biological activity of prostastic carcinom a needs further investigation. The action site of p r o la c tin on th e p r o s ta te re m a in s unclear, although it was suggested that prolactin action on th e prostate is indep e n d e n t fro m te s to s te r o n e o r n o t m e d ia te d by a n d ro g e n r e c e p to r s.1 Although testosterone is a major factor in the grow th of th e prostate, it appears that prolactin may play an im portant role in th e prom otion and developm ent of prostatic carcinom a at a laten t stage. D eterm ination of prolactin levels from prostatic tissue may be of value in the diagnosis of som e of th e laten t carcinomas of the prostate. Acknowledgm ents This work was supported in part by Grants-in-Aid for Cancer Research. Benign prostates With well differentiated o With moderately poorly differentiated F ig u r e 5. E stra d io l le v e ls in p r o sta tic tissu e s. h o m o g e n a te s o f p r o s ta te s a n d th e absence or presence of latent prostate carcinom a has b een investigated. Prostates grouped as LM PTC, revealing fullblown prostate carcinom a, show ed elevated levels of prolactin w hen compared to the benign prostate group. However, prostates classified as LWTC showed no clear statistical evidence of increased prolactin at the tissue level. It was noted th o u g h th a t p ro la c tin lev els show a trend toward increasing concentrations as the carcinogenesis process progresses. W hether or not the concentration of prolactin from prostatic tissue and/or fluid References 1. A s s im o s, D., S m it h, C., L e e, C., and G rayh a c k, J. J.: Action o f prolactin in regressing prostate: Independent of action m ediated by androgen receptors. Prostate 5:589-595, 1984 2. H a r p er, M. E., P e e l i n g, W. B., C o w l e y, T., B r o w n s e y, B. G., P h il l ip s, M. E. A., G r o o m, G., F a h m y, D. R., and G r if f it h s, K.: Plasma steroid and protein hormone concentrations in patients with prostate carcinoma, before and d uring e stro g en therapy. Acta E ndocrinol. 52:409-426, 1976. 3. S a r o f f, J., K ir d a n, R. Y., C h u, T. M., W ajsm a n, Z., a n d M u r p h y, G. P.: M ea su r e m e n ts o f prolactin and an d rogens in patien ts w ith prostatic d isea ses. O n co lo g y 37:46-52, 1980. 4. S u z u k i, A., O h a r a, A., Ya s u i, T., M o r i, K., and M o r i, S.: Fundamental and clinical investigaton of the estradiol direct radioimmunoassay kit. Clin. Endocrinol. 33:627-631, 1985. 5. W y n d e r, E. L., L a a k so, K., S o tarauta, M., and R o s e, D. P.: M etabolic epidem iology of prostatic. Prostate 5:47-53, 1984. 6. Yata.n i, R., C h ig u s a, I., A k o z a k i, K.; St e m - m e r m a n n, G. N., W e l s h, R. A., and C o r r ea P.: Geographic pathology of latent prostatic carcinoma. Int. J. Cancer 29:611-616, 1982.