NIH Public Access
`Author Manuscript
`Prostate. Author manuscript; available in PMC 2009 October 1.
`Published in final edited form as:
`Prostate. 2008 October 1; 68(14): 1546–1554. doi:10.1002/pros.20814.
`
`Nonhuman primates as models for studies of prostate specific
`antigen and prostatic diseases
`
`James N. Mubiru1, Gene B. Hubbard1, Edward J. Dick Jr.1, Jaime Furman3, Dean A.
`Troyer3, and Jeffrey Rogers1,2
`1Southwest National Primate Research Center, Southwest Foundation for Biomedical Research,
`San Antonio, Texas
`2Department of Genetics, Southwest Foundation for Biomedical Research, San Antonio, Texas
`3Department of Pathology, University of Texas Health Science Center at San Antonio, Texas
`
`Abstract
`Background—Because prostate specific antigen (PSA) is released at increased levels into the
`blood early in the development of prostate cancer, benign prostatic hyperplasia (BPH) and
`prostatitis, it is widely used as a marker for these diseases. However, PSA has clinical limitations
`as a screen for prostatic diseases due to its low sensitivity and specificity. There is a strong need to
`better understand the biology of PSA and factors affecting its serum levels.
`Methods—We evaluated cynomolgus macaques, rhesus macaques, baboons, and marmosets for
`their suitability as models for the study of PSA biology and prostatic diseases.
`Results—Prostates of several nonhuman primates are anatomically similar to the human
`counterpart. Anti-human PSA antibody detected PSA antigens in all the Old World monkeys
`(cynomolgus macaques, rhesus macaques and baboons) but not in marmosets. Of the Old World
`monkeys, cynomolgus macaques have the highest serum PSA levels; baboons have the lowest.
`Serum PSA levels from macaques includes a number of outlier samples with unusually high
`values. We also report two cases of abnormal pathologies in macaques accompanied by high
`serum PSA levels. One case consisted of prostatic hyperplasia involving both glandular and basal
`cells in a cynomolgus macaque and another of glandular hyperplasia and atrophy in a rhesus
`macaque. The finding that pathological changes in the prostate of macaques may lead to increases
`in serum PSA is worthy of further exploration.
`Conclusion—Cynomolgus macaques and rhesus macaques are promising animal models for
`PSA biology studies.
`
`Keywords
`PSA; nonhuman primates; prostate; macaque; baboon
`
`Introduction
`A major hindrance to the study of the pathogenesis of prostate diseases such as cancer,
`benign prostatic hyperplasia (BPH), and prostatitis is the lack of appropriate animal models.
`
`Corresponding author: James N. Mubiru, Southwest National Primate Research Center, Southwest Foundation for Biomedical
`Research, P.O. Box 760549, San Antonio, TX 78245-0549, Telephone: (210) 258-9744, Fax: (210) 670-3323, E-mail:
`jmubiru@sfbr.org.
`Disclosure Statement: None
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`AVENTIS EXHIBIT 2109
`Mylan v. Aventis, IPR2016-00712
`
`

`
`Mubiru et al.
`
`Page 2
`
`In the case of prostate cancer, animal models for this condition are very limited due to the
`very few species (lions and dogs) that are known to develop prostate cancer spontaneously.
`However, the usefulness of these animal models is questionable due to either availability or
`the differences in anatomy and histology of the prostates of these animals compared to
`humans.
`
`Although nonhuman primates are phylogenetically closer to humans than any other
`laboratory animals and therefore should be considered suitable models for human prostatic
`diseases, they have not been studied systematically as models of prostatic diseases mainly
`because of the widely held view that nonhuman primates do not develop prostatic diseases
`[1].
`
`Presently, a number of proteins are used in the diagnosis, monitoring and management of
`prostatic diseases. In healthy males, prostate specific antigen (PSA) is restricted to the
`prostate gland and very little leaks into the bloodstream. Increased amounts are detected in
`the blood in cases of prostatic diseases and therefore PSA is used for screening, diagnosing
`and monitoring of prostate cancer. Alpha-methyl-acyl-CoA racemase (AMACR) is a
`mitochondrial and peroxisome enzyme that is overexpressed in prostate cancer and is
`presently used as an auxiliary immunohistochemical test for prostate cancer [2].
`
`We evaluated four nonhuman primate species commonly used in research for their
`suitability as models of PSA biology and prostatic diseases. The study also examined
`AMACR, a protein that is clinically important in the diagnosis of prostate cancer. Two cases
`of prostatic lesions which were accompanied by elevated serum PSA are also reported.
`
`Materials and Methods
`Animals and Tissue Collection
`Cynomolgus macaques (Macaca fascicularis), rhesus macaques (Macaca mulatta), baboons
`(Papio hamadryas anubis), and common marmosets (Callithix jacchus) maintained at the
`Southwest National Primate Research Center, Southwest Foundation for Biomedical
`Research (SFBR) in San Antonio, Texas, were used for this study. A total of 114 baboons,
`66 cynomolgus macaques, 12 rhesus macaques and 5 marmosets were examined.
`
`We opportunistically sampled animals that presented for necropsy and an attempt was made
`to use animals across the whole lifespan. Male baboons reach sexual maturity between 6 and
`7 years of age, male cynomolgus macaques and rhesus macaques between 4–5 years of age,
`and male marmosets reach sexual maturity at between 9–13 months.
`
`Body weights were obtained either from SFBR animal records or when animals underwent
`necropsy. All animals were humanely euthanized. Only male animals were used in these
`studies. Complete necropsies were carried out for each animal. Male reproductive organs
`were removed and weighed. Tissue samples were either frozen at −80°C or fixed in neutral
`buffered formalin and processed for routine histological examination. All histopathological
`slides were examined by two board-certified veterinary pathologists (GBH and EJD). Two
`slides with microscopic lesions and elevated serum PSA were also sent to the Armed Forces
`Institute of Pathology (AFIP, Washington, DC) for evaluation.
`
`Serum PSA Assay and Cloning
`Serum was obtained from animals prior to euthanasia or from the archived serum bank
`maintained at SFBR. A radioimmunoassay with the lowest standard curve point of 0.01 ng/
`ml was used to assay PSA in serum (AniLytics, Inc., Gaithersburg, MD).
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 3
`
`For cloning of the baboon PSA cDNA, total RNA was extracted using Trizol reagent
`(Invitrogen, Carlsbad, CA) and reverse-transcribed at 42°C with Moloney murine leukemia
`virus (MMLV) reverse transcriptase and random decamers following the suppliers protocol
`(RETROscript kit, Ambion, Austin, TX). The resulting cDNA was then used as a template
`for PCR reaction using nested primers and touchdown conditions [3]. The primer sequences
`were based on the published rhesus macaque sequence. The primer sequences used were,
`PSA outer forward: 5’CTG GAC AGC TGT GTC ACC AT3’; PSA inner forward: 5’CTG
`TGT CAC CAT GTG GGT TC3’; PSA outer reverse primer: 5’TGA GAT GTC TCC AGG
`CAT GA3’; PSA inner reverse primer: 5’AGG ACA CGG AGA GGA CAA AA3’.The PCR
`products were then cloned into the pCR2.1-TOPO vector (Invitrogen, Carlsbad, CA).
`Positive clones were identified by restriction enzyme analysis and nucleotide sequencing
`was carried out by the Advanced Nucleic Acid Core Facility at University of Texas Health
`Science Center at San Antonio. The PSA cDNA of both the rhesus macaque and the
`cynomolgus macaque were not cloned as they were already reported in the literature [4,5].
`
`PSA Immunoblotting
`Prostate tissue samples were homogenized in sample buffer, separated by 12% SDS-PAGE,
`transferred to nitrocellulose membranes, and probed using standard conditions. Membranes
`were probed at room temperature for 1 hour with either a monoclonal mouse anti-human
`PSA, clone ER-PR8 (Dakocytomation), or a rabbit monoclonal alpha-methyl-acyl-CoA
`racemase (AMACR, P504S Zeta Corporation, Sierra Madre, CA). Goat anti-mouse
`secondary antibody linked to horseradish peroxidase (Pierce) were added to the blots at a
`dilution of 1:5000 and incubated for 1 hour at room temperature. Bound antibodies were
`detected by chemiluminescence (Supersignal West Pico, Pierce Biotechnology, Rockford,
`IL).
`
`Results
`Prostate Anatomy and Body Weight
`The prostate of the adult cynomolgus macaque, rhesus macaque, baboon, and marmoset is
`located at the distal end of the urinary bladder. On gross observation the prostate of
`cynomolgus macaques, rhesus macaques, and baboons is divided into two parts which are
`labeled cranial and caudal according to their proximity to the bladder and seminal vesicles.
`For the marmoset, although the prostate can be seen on gross examination, it cannot be
`divided into two lobes with a naked eye. However, histologically differences in acinar size
`and hematoxylin-eosin staining characteristics can be seen. On the basis of these differences
`the marmoset prostate can also be divided into two lobes which correspond with the other
`three species. In all these monkey species, the glandular prostate does not completely
`surround the urethra (Figure 1) and in this regard differs from what has been reported in
`humans [6,7].
`
`There is a major difference in the size of the two lobes of the prostate between the baboon
`and the two macaque species (rhesus macaque and cynolmolgus macaque). In the macaque
`species the two lobes of the prostate are of almost equal sizes. The cranial lobe constitutes
`59% of weight of the prostate in the cynomologus while it constitutes 47% in the rhesus
`macaque. In the case of the baboon the two lobes are quite different in size; the cranial lobe
`is much smaller, contributing only 36% of the total weight of the prostate (Figure 1). Since
`the marmoset prostate is quite small and the two lobes are not visible on gross examination,
`their relative proportions were not quantified.
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 4
`
`The average adult body weight of the animals studied were 5.82, 10.06, 27.14, and 0.29 kg
`for cynomologus macaques, rhesus macaques, baboons, and marmosets, respectively (Table
`1).
`
`When the weight of the prostate is compared to body weight (g/kg), the macaque species
`have a higher ratio than the baboon. The prostate-to-body-weight ratios are 0.51, 0.68, and
`0.31 for cynomolgus, rhesus, and baboon, respectively (Table 1).
`
`Testis and Epididymis
`The rhesus and cynomolgus macaques had similar testis-to-body-weight ratios, which were
`in turn higher than that of the baboon. The testis-to-body-weight ratios were 2.17 and 2.36
`(g/kg), respectively, in the cynomolgus and rhesus macaque. Baboons, on the other hand,
`had a testis-to-body-weight ratio of only 1.2. Similar trends were observed for the
`epididymis for which the epididymis weight-to-body-weight ratios were 0.33, 0.42, and 0.22
`(g/kg) for cynomolgus, rhesus, and baboons, respectively (Table 1).
`
`Growth and Development of the Prostate and Testis Across the Lifespan
`Changes in body, prostate, and testes weights of the Old World monkeys across the lifespan
`are shown in Figure 2. The weights increased with age up to around 6 years in cynomolgus
`macaque, rhesus macaques, and baboons and thereafter there was minimal change in the
`weights. The changes in growth of the prostate and testis were initially slow or undetectable,
`but at around 5 years in baboons and rhesus macaques, and at around 4 years of age for
`cynomolgus macaques, rapid changes occurred (Figure 2).
`
`Serum Prostate Specific Antigen Assay
`Serum PSA was detected in all the three Catarrhine (Old World) monkeys (cynomolgus
`macaques, rhesus macaques, and baboons) studied but not in marmosets, which are members
`of the Platyrrhine (New World) monkeys. Serum PSA concentration in cynomolgus
`macaques ranged from 0.04 to 6.2 ng/ml, with a median value of 1.2 ng/ml. Serum PSA
`values of the rhesus macaques ranged from 0.07 to 2.35 ng/ml with a median value of 0.31,
`while those of baboons ranged from 0.05 to 0.78 ng/ml with a median value of 0.32 ng/ml.
`Serum PSA could not be detected in marmosets.
`
`Serum levels of PSA correlated positively with age. The coefficient of correlation (R2) was
`0.30 for cynomolgus macaques, 0.183 for rhesus macaques, and 0.059 for baboons. This
`correlation was statistically significant for both cynomolgus macaques and rhesus macaques
`but not for baboons (Figure 3). For both the cynomolgus macaques and rhesus macaques,
`the serum PSA data include a subset of animals whose values are higher than the rest and are
`therefore outliers (See supplementary Table 2). When the serum PSA values for the three
`Old World monkey species are plotted together on the same graph, the cynomolgus
`macaques and rhesus macaques values are higher and follow a different trend from those of
`baboons (Figure 3).
`
`Histopathology Lesions
`The most common pathological change in the animals studied was inflammation. The
`inflammatory response was either lymphocytic, suppurative, or a combination of both. Most
`of the inflammatory changes occurred in the caudal prostate.
`
`A case of prostate hyperplasia in a 17-year-old cynomolgus macaque was studied further
`and it was found that the hyperplasia involved both the glandular and basal cells (Figure 4).
`The prostate in this animal contained a single nodular, minimally expansive area composed
`of closely packed solid nests and glands of cells supported by a thin fibrovascular stroma.
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 5
`
`The cells had indistinct cell borders, clear to slightly basophilic cytoplasm, round to oval
`nuclei with lightly stippled chromatin and prominent nucleoli. The cells lining the glandular
`structures frequently formed papillary structures that extended into the lumen. There was
`occasional eosinophilic fluid within the lumen of these glands. Mitoses were not observed
`(Figure 4). An independent examination of this case by the Armed Forces Institute of
`Pathology (AFIP, Washington, DC) confirmed our earlier diagnosis of hyperplasia involving
`both the glandular and basal cells. Immunohistochemical staining done by the AFIP showed
`basal cells that were immunopositive for p63 but not K903. Immunostaining for prostatic
`acid phosphatase was negative. The serum PSA values at the time of sacrifice for this animal
`that had prostate hyperplasia was 2.07 ng/ml. Serum PSA in this animal rose 1.12 units in a
`period of 10 months. A case of focal glandular atrophy, acute prostatitis with subsequent
`reactive change of mild prostatic hyperplasia in a 20-year-old rhesus macaque was also
`further studied. This case had a serum PSA level of 2.35 ng/ml. Most prostatic glands in this
`animal were distended by clear space and lined by attenuated epithelium. Others contained
`luminal cellular debris and were lined by plump cuboidal cells with increased amounts of
`basophilic cytoplasm and prominent nuclei with lightly stippled chromatin (Figure 4).
`
`Baboon PSA Cloned and Compared with Other Primate PSA Sequences
`Using cloning primers which were based on the published rhesus macaque sequence, the
`baboon PSA cDNA was cloned. The cloned baboon cDNA sequence has been deposited in
`the GenBank under accession number EF676031. This sequence was compared to the
`already published cynomolgus macaque, rhesus macaque, and human PSA sequences. The
`PSA protein sequences of the rhesus, cynomolgus macaque, and baboon were 89.65%,
`89.65%, and 90.42% similar to human PSA, respectively. The rhesus and cynomolgus
`protein sequences were 99.23% similar to each other and 98.45% similar to their baboon
`counterpart (Figure 5).
`
`PSA and AMACR Expression in the Prostate of the Three Species
`Western blots done on prostate tissue showed that PSA and AMACR were both expressed in
`cynomolgus macaques, rhesus macaques, and baboons. The macaque species seemed to
`express more PSA and AMACR per tissue than baboons (Figure 6).
`
`Discussion
`The aims of this project were to study the male reproductive systems of nonhuman primates
`that are commonly used in research in order to evaluate their suitability as models for PSA
`biology studies in particular and for prostatic diseases in general. Preliminary data reported
`in this study suggest the macaque species are more suitable for these studies.
`
`New World monkeys like the marmoset are not useful models for studies of PSA biology
`and prostatic diseases because they do not have the PSA gene. A previous study had
`reported the presence of the PSA gene in a number of nonhuman primates including
`orangutans, chimpanzees, gorillas, and macaques but not in dogs, mice, rats, or cows [8].
`However, the nonhuman primate species examined in these studies did not include New
`World monkeys. More recent studies have reported the absence of the PSA gene in both the
`marmoset and cotton-top tamarin [9–11]. Our failure to detect PSA in marmoset serum in
`this study confirms the absence of the PSA gene. However, the possibility that the human
`antibodies used in our studies cannot detect marmoset PSA cannot be ruled out. Probably the
`PSA gene arose in the Catarrhine primates (Old World monkeys, anthropoid apes and
`humans) after their phylogenetic lineage separated from the Platyrrhines (New World
`primates) approximately 35 to 45 million years ago [12,13].
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 6
`
`Prostate specific antigen, also called human kallikrein 3 (hK3), is one of the 15 members of
`the tissue kallikrein family that are located in a 300-kb region on chromosome 19q13.3–
`19q13.4 in humans. The sequences of two members of this group, KLK1 and KLK2, are
`62% and 80% similar to PSA, respectively [14–16] and it is highly likely that the PSA gene
`could be a result of a duplication and further mutation of one of these two genes.
`
`Serum PSA was detected in all the Old World monkeys we studied (cynomolgus macaques,
`rhesus macaques, and baboons). However, there were significant differences in quantity and
`correlation to age. Both macaque species exhibited greater abundance and stronger
`correlation with age than the baboons. Both macaque species also had more PSA in prostate
`tissue than the baboon. The significance of having higher PSA per unit of tissue is not
`clearly understood, but PSA’s main function is to liquefy coagulated semen. Although this
`study did not investigate the differences in mating behavior of these four species, we
`speculate that the higher concentration of proteins related to reproduction, and larger size of
`the testis, epididymis and prostate in macaques compared to baboons might be related to
`breeding patterns, seasonality of breeding, and dominance structure. We speculate that large
`testis able to produce enough sperm, large seminal vesicles and epididymis able to store and
`nourish the sperm, and large prostate for the production of PSA that maintains semen
`fluidity are advantageous or necessary for reproductive success.
`
`Serum PSA values reported in both rhesus macaques and cynomolgus macaques are similar
`to those reported in a recent study by Williams et al. [17] and are comparable to those in
`humans [18] despite the fact that these animals are smaller in size compared to humans. The
`upper limit of normal for PSA in humans is currently set at 4.0 ng/ml. This is the threshold
`above which a patient is referred for further diagnostic workup. It is interesting to note that
`two cynomolgus macaques in our study had serum PSA values of 5.23 and 6.2 ng/ml, which
`are higher than the human upper limit of normal (see supplementary Table 2). One
`cynomolgus macaque with a PSA value of 2.07 ng/ml was found to have prostatic
`hyperplasia and one rhesus macaque with a PSA value of 2.35 ng/ml had pathological
`lesions in its prostate. The trend of increasing PSA with age is significant in both rhesus
`macaques and cynomolgus macaques studied. In fact the linear regression lines for the two
`species are generally parallel, indicating a similar trend through life. Serum PSA
`distributions from both these two species also includes clear outliers with unusually high
`values.
`
`The finding that pathological changes in the prostate may be accompanied by increases in
`serum PSA is significant, and further lends credence to exploring nonhuman primate
`(especially the macaque species) as models of PSA biology and prostate diseases in humans.
`
`Significant changes in body weight, and the weights of the testis, prostate, and other
`reproductive organs occurred as the animals reached sexual maturity at 4 to 5 years in rhesus
`macaques and cynomolgus macaques and at 6 to 7 years in baboons. These findings are
`similar to those reported previously [19,20].
`
`In light of the data presented here and our previously published research on the baboon [21],
`it is appropriate to revisit the notion that nonhuman primates do not naturally develop
`prostatic diseases, especially prostate cancer. A closer look at the literature shows that
`pathological lesions in the prostate have been reported in nonhuman primates (both Old and
`New World species). Benign prostatic hyperplasia has been reported in tamarins [22],
`baboons [23] and chimpanzees [24]. Prostate cancer and prostatic basal cell hyperplasia has
`also been reported in rhesus macaques [25,26,27].
`
`We are of the view that the macaque species, especially the cynomolgus macaques can be
`used as animal models for studies of PSA biology. Cynomolgus macaques are native to
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 7
`
`Southeast Asia but are now readily available in breeding colonies in the USA. They can also
`be easily imported from their natural habitats and are of reasonably large size.
`
`Further studies are needed to characterize fully the pathology of the male genitourinary
`system of macaque species, especially the cynomolgus macaque. Based on our preliminary
`studies, we envision both cynomolgus macaques and rhesus macaques to be a potential
`models not only for studies of PSA biology, as shown in this paper but also in studies
`concerning the role of diet and individual genetic variation in determining serum PSA
`levels. Another potential area of research in which nonhuman primate can be used involves
`their use in developing PSA based targeted therapies for prostatic diseases. PSA is an
`androgen-regulated serine protease which is secreted by prostate cancer cells and normal
`prostate cells. Intensive efforts are on going to utilize the enzyme activity and specificity of
`PSA production by prostate cancer cells for therapeutic purposes [28–30]. PSA is inactive
`when it is in circulation because it is bound to protease inhibitors. It is only active
`enzymatically when it is in prostate tissue or in tumor microenvironments. One of the many
`approaches for the use of PSA for therapeutic purposes is the construction of PSA cleavable
`prodrugs. The prodrugs circulate in the body but only exhibit their anticancer effects at the
`tumor sites. The tumor cells secrete PSA that cleaves the prodrugs and therefore activates
`them. Nonhuman primates are ideal models in which to develop, test and study these PSA-
`based therapeutic agents.
`
`Supplementary Material
`Refer to Web version on PubMed Central for supplementary material.
`
`Acknowledgments
`We thank Dr. Suzette Tardif for providing the marmoset tissues and Marie Silva, Michealle Hohmann and Denise
`Trejo for technical assistance.
`
`This work was funded in part by the base grant to the Southwest National Primate Research Center (JR) (National
`Institutes of Health/National Center for Research Resources grant P51 RR0139986). A supplement to Promote
`Diversity in Health-related Research (supplement to grant P51 RR0139986) and a grant from Southwest Foundation
`Forum (07-4053) funded JNM’s efforts. Animals were housed in facilities constructed with support from Research
`Facilities Improvement Program Grants C06 RR014578 and C06 RR15456.
`
`References
`1. Waters DJ, Sakr WA, Hayden DW, Lang CM, McKinney L, Murphy GP, Radinsky R, Ramoner R,
`Richardson RC, Tindall DJ. Workgroup 4: spontaneous prostate carcinoma in dogs and nonhuman
`primates. Prostate. 1998; 36:64–67. [PubMed: 9650919]
`2. Rubin MA, Zhou M, Dhanasekaran SM, Varambally S, Barrette TR, Sanda MG, Pienta KJ, Ghosh
`D, Chinnaiyan AM. Alpha-methylacyl coenzyme A racemase as a tissue biomarker for prostate
`cancer. J Am Med Assoc. 2002; 287:1662–1670.
`3. Don RH, Cox PT, Wainwright BJ, Baker K, Mattick JS. 'Touchdown' PCR to circumvent spurious
`priming during gene amplification. Nucleic Acid Res. 1991; 9:4008. [PubMed: 1861999]
`4. Gauthier ER, Chapdelaine P, Tremblay RR, Dube JY. Characterization of rhesus monkey prostate
`specific antigen cDNA. Biochim Biophys Acta. 1993; 1174:207–210. [PubMed: 7689340]
`5. Marshall DJ, Rudnick KA, Lu J, Snyder LA. Cloning and sequencing of the cynomolgus monkey
`prostate specific antigen cDNA. J Med Primatol. 2006; 35:12–17. [PubMed: 16430490]
`6. Ishidoya S, Endoh M, Nakagawa H, Saito S, Arai Y. Novel anatomical findings of the prostatic
`gland and the surrounding capsular structures in the normal prostate. Tohoku J Exp Med. 2007;
`212:55–62. [PubMed: 17464104]
`7. McNeal JE. Normal histology of the prostate. Am J Surg Pathol. 1988; 12:619–633. [PubMed:
`2456702]
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 8
`
`8. Karr JF, Kantor JA, Hand PH, Eggensperger DL, Schlom J. The presence of prostate-specific
`antigen-related genes in primates and the expression of recombinant human prostate-specific
`antigen in a transfected murine cell line. Cancer Res. 1995; 55:2455–2462. [PubMed: 7538903]
`9. Valtonen-André C, Olsson AY, Kullberg M, Nayudu PL, Lundwall A. The common marmoset
`(Callithrix jacchus) has two very similar semenogelin genes as the result of gene conversion. Biol
`Reprod. 2007; 76:604–610. [PubMed: 17192513]
`10. Valtonen-André C, Olsson AY, Nayudu PL, Lundwall A. Ejaculates from the common marmoset
`(Callithrix jacchus) contain semenogelin and beta-microseminoprotein but not prostate-specific
`antigen. Mol Reprod Dev. 2005; 71:247–255. [PubMed: 15791587]
`11. Olsson AY, Valtonen-André C, Lilja H, Lundwall A. The evolution of the glandular kallikrein
`locus: identification of orthologs and pseudogenes in the cotton-top tamarin. Gene. 2004;
`343:347–355. [PubMed: 15588589]
`12. Schrago CG. On the time scale of New World primate diversification. Am J Phys Anthropol. 2007;
`132:344–354. [PubMed: 17133436]
`13. Steiper ME, Young NM. Primate molecular divergence dates. Mol Phylogenet Evol. 2006; 41:384–
`394. [PubMed: 16815047]
`14. Rittenhouse HG, Finlay JA, Mikolajczyk SD, Partin AW. Human Kallikrein 2 (hK2) and prostate-
`specific antigen (PSA): two closely related, but distinct, kallikreins in the prostate. Crit Rev Clin
`Lab Sci. 1998; 35:275–368. [PubMed: 9759557]
`15. Memari N, Grass L, Nakamura T, Karakucuk I, Diamandis EP. Human tissue kallikrein 9:
`production of recombinant proteins and specific antibodies. Biol Chem. 2006; 387:733–740.
`[PubMed: 16800734]
`16. Diamandis EP, Yousef GM, Clements J, Ashworth LK, Yoshida S, Egelrud T, Nelson PS,
`Shiosaka S, Little S, Lilja H, Stenman UH, Rittenhouse HG, Wain H. New nomenclature for the
`human tissue kallikrein gene family. Clin Chem. 2000; 46:1855–1858. [PubMed: 11067830]
`17. Williams SA, Singh P, Isaacs JT, Denmeade SR. Does PSA play a role as a promoting agent
`during the initiation and/or progression of prostate cancer? Prostate. 2007 Feb 15; 67(3):312–329.
`[PubMed: 17143882]
`18. Saraiya M, Kottiri BJ, Leadbetter S, Blackman D, Thompson T, McKenna MT, Stallings FL. Total
`and percent free prostate-specific antigen levels among U.S. men, 2001–2002. Cancer Epidemiol
`Biomarkers Prev. 2005; 14:2178–2182. [PubMed: 16172229]
`19. Dixson, AF. Primate sexuality: comparative studies of the prosimians, monkeys, apes, and human
`beings. New York: Oxford University Press; 1998. p. 41
`20. Alberts SC, Altmann J. Preparation and activation: determinants of age at reproductive maturity in
`male baboons. Behav Ecol Sociobiol. 1995; 36:397–406.
`21. Mubiru JN, Hubbard GB, Dick EJ Jr, Butler SD, Valente AJ, Troyer DA, Rogers J. A preliminary
`study of the baboon prostate pathophysiology. Prostate. 2007; 67:1421–1431. [PubMed:
`17639509]
`22. Ferreira BR, Bechara GH, Pissinatti A, Cruz JB. Benign prostatic hyperplasia in the nonhuman
`primate Leontopithecus. Folia Primatol (Basel). 1995; 65:48–53. [PubMed: 8713543]
`23. Karr JP, Kim U, Resko JA, Schneider S, Chai LS, Murphy GP, Sandberg AA. Induction of benign
`prostatic hypertrophy in baboons. Urology. 1984; 23:276–289. [PubMed: 6199881]
`24. Steiner MS, Couch RC, Raghow S, Stauffer D. The chimpanzee as a model of human benign
`prostatic hyperplasia. J Urol. 1999; 162:1454–1461. [PubMed: 10492237]
`25. Engle ET, Stout AP. Spontaneous primary carcinoma of the prostate in a monkey (Macaca
`mulatta). Am J Cancer. 1940; 39:334–337.
`26. Hubbard GB, Eason RL, Wood DH. Prostatic carcinoma in a rhesus monkey (Macaca mulata). Vet
`Pathol. 1985; 22:88–90. [PubMed: 3976136]
`27. McEntee MF, Epstein JI, Syring R, Tierney LA, Strandberg JD. Characterization of prostatic basal
`cell hyperplasia and neoplasia in aged macaques: comparative pathology in human and nonhuman
`primates. Prostate. 1996; 29:51–59. [PubMed: 8685056]
`28. Denmeade SR, Nagy A, Gao J, Lilja H, Schally AV, Isaacs JT. Enzymatic activation of a
`doxorubicin-peptide prodrug by prostate-specific antigen. Cancer Res. 1998 Jun 15; 58(12):2537–
`2540. [PubMed: 9635575]
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 9
`
`29. Williams SA, Merchant RF, Garrett-Mayer E, Isaacs JT, Buckley JT, Denmeade SR. A prostate-
`specific antigen-activated channel-forming toxin as therapy for prostatic disease. J Natl Cancer
`Inst. 2007; 99(5):376–385. [PubMed: 17341729]
`30. Denmeade SR, Jakobsen CM, Janssen S, Khan SR, Garrett ES, Lilja H, Christensen SB, Isaacs JT.
`Prostate-specific antigen-activated thapsigargin prodrug as targeted therapy for prostate cancer. J
`Natl Cancer Inst. 2003; 95(13):990–1000. [PubMed: 12837835]
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 10
`
`Figure 1.
`Ventral and dorsal views of the prostates of the cynomolgus macaque (top) and baboon
`(bottom) showing the relationship of the prostate to the other urinogenital organs.
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 11
`
`Figure 2.
`A, Body, prostate, and total testis weights across the baboon lifespan; B, body, prostate and
`total testis weight across the rhesus macaque lifespan; C, body, prostate and left testis
`weights across the cynomolgus macaque lifespan.
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 12
`
`Figure 3. Changes of serum PSA values with age of cynomolgus macaques, rhesus macaques and
`baboons
`The coefficient of correlation (R2) was 0.30, 0.183, and 0.059 for cynomolgus macaques,
`rhesus macaques and baboons, respectively. The correlations were statically significant for
`both cynomolgus macaques and rhesus macaques but not for baboons. Outliers are excluded
`in this figure (see supplementary Table 2 for all the data).
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manuscript
`
`

`
`Mubiru et al.
`
`Page 13
`
`Figure 4.
`Top, Prostatic hyperplasia involving both glandular epithelium and several foci comprised
`exclusively of hyperplastic basal cells in the cynomolgus macaque prostate (PSA=2.07 ng/
`ml); Bottom, Glandular atrophy and acute prostatitis with subsequent reactive change of
`mild glandular hyperplasia in the rhesus macaque prostate (PSA=2.25 ng/ml).
`
`Prostate. Author manuscript; available in PMC 2009 October 1.
`
`NIH-PA Author Manuscript
`
`NIH-PA Author Manu