Biomedical subjects

Franky L Chan

Publications and source records attributed to Franky L Chan.

At least 19 recordsLinked to original sources

PubMed2007

Epigenetic inactivation of the deleted in lung and esophageal cancer 1 gene in nasopharyngeal carcinoma.

Deletion of the short arm of chromosome 3 is a common event in nasopharyngeal carcinoma (NPC), suggesting that one or more tumor suppressor genes at 3p are involved in this cancer. DLEC1, Deleted in Lung and Esophageal Cancer 1, located at 3p22.2, was recently identified as a candidate tumor suppressor gene in lung, esophageal, and renal cancers. In this study, we investigated the involvement of DLEC1 in the development of NPC. Down-regulation of DLEC1 and promoter hypermethylation were observed in all NPC cell lines and xenografts but not in normal nasopharyngeal epithelial cells. Promoter hypermethylation of DLEC1 was also detected in 30 of 42 (71%) NPC primary tumors. Treatment of NPC cell lines with demethylating agent or histone deacetylase inhibitor resulted in restoration of DLEC1 expression. Overexpression of DLEC suppressed growth and reduced invasiveness of NPC cells. Furthermore, the tumorigenic potential of DLEC1 expressing NPC cells was highly reduced in nude mice. Taken together, our results strongly suggest that silencing of DLEC1 expression by promoter hypermethylation and histone deacetylation may be important in NPC tumorigenesis.

Adult↗

PubMed2006

Molecular cloning and functional study of rat estrogen receptor-related receptor gamma in rat prostatic cells.

BACKGROUND: Based on high homology of ERRs with ERs, we hypothesize that ERRs might functionally cross talk with ERs or independently in prostatic cells. METHODS: We examined the ERRgamma expressions in rat prostates and Nb rat prostate cancer model, and its growth regulation in stable transfectants of prostatic cells. RESULTS: We cloned the ERRgamma cDNA from rat prostate by RACE-PCR. Its expression was confirmed by Northern and immunoblottings. Real-time RT-PCR showed that its expression in castrated prostates was androgen-dependent. ERRgamma was expressed in prostatic epithelial cells, but showed reduced expressions in neoplastic prostates. Transfections confirmed that ERRgamma was expressed in prostatic cells as nuclear protein and transcriptionally active without estradiol. Its overexpression in ERRgamma-stable transfectants of NbE-1 and MAT-Lu cells inhibited their in vitro proliferation, anchorage-independent growth in soft-agar and tumorigenicity in nude mice. CONCLUSIONS: Our studies show that ERRgamma is functionally expressed in rat prostate and may play anti-proliferative actions in prostatic cells. Its co-expression with ERs suggests that besides ERs, ligand-independent ERRgamma is also involved in prostatic growth and functions.

Adenocarcinoma↗

PubMed2006

The red wine polyphenol resveratrol displays bilevel inhibition on aromatase in breast cancer cells.

Estrogen plays a crucial role in the development of breast cancer, and the inhibition of estrogen synthesis has been an important target for the prevention and treatment of this disease. The rate-limiting reaction of the hormone biosynthesis is catalyzed by cytochrome P450 (CYP) 19 enzyme or aromatase. It has been of genuine interest to uncover an aromatase-inhibitory compound from a dietary source. Resveratrol is a polyphenolic compound that can be isolated from grape peel. Because of its structural resemblance to estrogen, resveratrol's agonistic and antagonistic properties on estrogen receptor have been examined and demonstrated. In the present study, the effect of resveratrol on the expression and enzyme activity of aromatase was investigated. By assaying on MCF-7 cells stably transfected with CYP19 (MCF-7aro cells), resveratrol inhibited the aromatase activity with an IC(50) value of 25 microM. Kinetic analysis indicated that both competitive and noncompetitive inhibition might be involved. The administration of 10 nmol/l testosterone-a substrate of aromatase-produced a 50% increase in the MCF-7aro cell number. This cell proliferation specifically induced by testosterone was significantly reduced by 10 microM resveratrol. In addition, 50 microM resveratrol significantly reduced the CYP19-encoding mRNA abundance in SK-BR-3 cells. The transcriptional control of CYP19 gene is tissue specific, and promoter regions I.3 and II have previously been shown to be responsible for CYP19 expression in breast cancer cells. Luciferase reporter gene assays revealed that resveratrol could repress the transcriptional control dictated by the promoter regulation. The present study illustrated that pharmacological dosage of resveratrol inhibited aromatase at both the enzyme and mRNA levels.

Aromatase↗

PubMed2005

FTY720, a fungus metabolite, inhibits in vivo growth of androgen-independent prostate cancer.

FTY720, a derivative of fungus, has demonstrated dramatic anticancer effect in several malignancies recently. Our study evaluates the therapeutic potential of FTY720 in the treatment of androgen-independent prostate cancer using a human prostate cancer xenograft in nude mice. CWR22R, an androgen-independent human prostate tumor xenograft was inoculated into castrated nude mice and the animals were administrated with either normal saline or FTY720 (10 mg/kg) through intraperitoneal (i.p.) injection for 20 days. Body weight and tumor volume were recorded every 2 days, and serum prostate specific antigen (PSA) levels were also measured before and after the treatment. The effect of FTY720 on tumor cell proliferation was examined using antibodies against PCNA and Ki-67 by immunohistochemical staining, MTT assay and colony forming assay, whereas apoptotic effect of FTY720 was evaluated by TUNEL assay and immunostaining using antibodies against cleaved caspase 3 and Bcl-2. In addition, the potential inhibitory effect of FTY720 on prostate cancer angiogenesis and metastasis was investigated by immunostaining of CD31, VEGF, E-cadherin and beta-catenin. Our results showed that FTY720 treatment led to suppression of CWR22R tumor growth without causing any detectable side effects in nude mice. The FTY720-induced tumor suppression was correlated with decreased serum PSA level as well as reduced proliferation rate, suppression of angiogenic factors, and restoration of E-cadherin and beta-catenin expression. In addition, the FTY720-treated tumors showed increased apoptosis rate demonstrated by increased TUNEL- and cleaved caspase 3-positive cells, and decreased Bcl-2 expression. Our results suggest a potential novel agent in the suppression of androgen-independent prostate cancer.

Androgens↗

PubMed2005

Up-regulation of TWIST in prostate cancer and its implication as a therapeutic target.

Androgen-independent metastatic prostate cancer is the main obstacle in the treatment of this cancer. Unlike a majority of solid cancers, prostate cancer usually shows poor response to chemotherapeutic drugs. In this study, we have shown a potential novel target, TWIST, a highly conserved bHLH transcription factor, in the treatment of prostate cancer. Using malignant and nonmalignant prostate tissues, we found that TWIST expression was highly expressed in the majority (90%) of prostate cancer tissues but only in a small percentage (6.7%) of benign prostate hyperplasia. In addition, the TWIST expression levels were positively correlated with Gleason grading and metastasis, indicating its role in the development and progression of prostate cancer. Furthermore, down-regulation of TWIST through small interfering RNA in androgen-independent prostate cancer cell lines, DU145 and PC3, resulted in increased sensitivity to the anticancer drug taxol-induced cell death which was associated with decreased Bcl/Bax ratio, leading to activation of the apoptosis pathway. More importantly, inactivation of TWIST suppressed migration and invasion abilities of androgen-independent prostate cancer cells, which was correlated with induction of E-cadherin expression as well as morphologic and molecular changes associated with mesenchymal to epithelial transition. These results were further confirmed on the androgen-dependent LNCaP cells ectopically expressing the TWIST protein. Our results have identified TWIST as a critical regulator of prostate cancer cell growth and suggest a potential therapeutic approach to inhibit the growth and metastasis of androgen-independent prostate cancer through inactivation of the TWIST gene.

Adenocarcinoma↗

PubMed2005

The plant polyphenol butein inhibits testosterone-induced proliferation in breast cancer cells expressing aromatase.

Chalcones are precursor compounds for flavonoid synthesis in plants, and they can also be synthesized in laboratory. Previous study has documented some of the pharmacological applications of these compounds. Estrogen has long been associated with the initiation and promotion of breast cancer. Inhibiting estrogen synthesis can be effective in the prevention and treatment of the disease. Since most breast cancers received estrogen supplied from local tissues, we employed a breast cancer cell line expressing aromatase to screen for the inhibitory potentials of five hydroxychalcones, i.e. 2-hydroxychalcone, 2'-hydroxychalcone, 4-hydroxychalcone, 4,2',4'-trihydroxy-chalcone (isoquiritigenin), 3,4,2',4'-tetrahydroxychalcone (butein). In the preliminary results, butein was found to be the strongest inhibitor among the tested compounds, and its IC(50) value was 3.75 microM. Subsequent enzyme kinetic study revealed that butein acted on aromatase with a mixed type of inhibition and the K(i) value was determined to be 0.32 microM. Cell proliferation assay indicated that the cell number increased by 10 nM-testosterone treatment was significantly reduced by 5 microM butein, and the administration of flutamide could not reverse the effect. The present study illustrated that butein was an aromatase inhibitor and a potential natural alternative for the chemoprevention or therapy of breast cancer.

Aromatase↗

PubMed2005

Knockin of SV40 Tag oncogene in a mouse adenocarcinoma of the prostate model demonstrates advantageous features over the transgenic model.

Prostate cancer (CaP) is the most common cancer in adult men in North America. Since there is no naturally occurring prostate cancer in the mouse, preclinical studies stipulate for the establishment of a genetically manipulated mouse CaP model with features close to the human situation. In view of the limitations of transgenic technique-derived CaP models, herein we report the first application of knockin technology to establish a new mouse adenocarcinoma prostate model (PSP-KIMAP) by targeting of SV40 Tag to a prostate tissue-specific gene, PSP94 (prostate secretory protein of 94 amino acids). In order to demonstrate its novelty, we compared KIMAP to a PSP94 gene-directed transgenic mouse adenocarcinoma of the prostate (PSP-TGMAP) model. The CaP development of the PSP-KIMAP mice started almost immediately after puberty at 10 weeks of age from mouse prostatic intraepithelial neoplasia (mPIN) with microinvasion to well-differentiated CaP, and demonstrated a close-to-human kinetics of prolonged tumor growth and a predominance of well and moderately differentiated tumors. The invasive nature of KIMAP model was demonstrated by multitissue metastases (lymph node, lung and liver etc) and also by immunohistochemical study of multiple invasive prostate tumor markers. PSP-KIMAP model is responsive to androgen deprivation (castration). The knockin technology in our KIMAP model demonstrates highly predictive CaP development procedures and many advantageous features, which the traditional transgenic technique-derived CaP models could not reach for both basic and clinical studies. These features include the high stability of both phenotype and genotype, highly synchronous prostate cancer development, high and precise prostate tissue targeting and with no founder line variation. The differences between the two CaP models were attributed to the introduction of a single endogenous knockin mutation, resulting in a CaP model self-regulated and controlled by a prostate gene promoter/enhancer of PSP94.

Adenocarcinoma↗

PubMed2005

Hydroxychalcones exhibit differential effects on XRE transactivation.

Chalcones are phenolic compounds that can be isolated from plants. Previous studies have described some pharmacological applications for these compounds. Making use of our established reporter gene system, we determined the effect of five hydroxychalcones--2-hydroxychalcone, 2'-hydroxychalcone, 4-hydroxychalcone, 4,2',4'-trihydroxychalcone, and 3,4,2',4'-tetrahydroxychalcone--on the cellular xenobiotic responsive element (XRE)-transactivation. The interference of chalcones acting against polycyclic aromatic hydrocarbon (PAH)-DNA binding was also examined. Enzyme inhibition assays of cytochrome P450 (CYP) 1A1 and CYP1B1 were initially performed on recombinant protein expressed in insect microsomes. 2'-Hydroxychalcone and 2-hydroxychalcone were the most effective among the tested hydroxychalcones. The two hydroxychalcones had comparable IC50 values for CYP1A1 and CYP1B1, which were determined to be at the micromolar and submicromolar range, respectively. However, reporter gene assays indicated that 2'-hydroxychalcone suppressed XRE-transactivation, whereas 2-hydroxychalcone induced it when 7,12-dimethylbenz[a]anthracene (DMBA) was co-administered. In the absence of DMBA, 10 microM 2-hydroxychalcone and 2'-hydroxychalcone increased XRE-transactivation by 18- and 2.5-fold, respectively, while other chalcones did not significantly alter the response. Cultures treated with the two hydroxychalcones also displayed separate trends in ethoxyresorufin-O-deethylase (EROD) activity and DMBA-DNA covalent binding. In summary, the present study illustrated that the inhibition of hydroxychalcone on CYP1 enzymes and XRE-transactivation was affected by the position and number of hydroxyl groups in its structure.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2005

Enhanced induction of prostatic dysplasia and carcinoma in Noble rat model by combination of neonatal estrogen exposure and hormonal treatments at adulthood.

Estrogens have been implicated to play certain but yet undefined roles in the normal and neoplastic growth of prostate gland. Studies of perinatal exposure in rodents demonstrate that effects of perinatal estrogenization are permanent and carcinogenic in prostate gland. In the Noble (Nb) rat model, prostatic dysplasia and neoplastic lesions can be induced by a chronic treatment with both testosterone and estrogen at adulthood. However, by this conventional protocol, neoplastic lesions are mostly confined to the lateral (LP) and ventral (VP) prostates, while gross prostatic tumors are rarely induced. Based on these two experimental models, we developed a modified treatment protocol for the enhancement of prostate cancer induction in Nb rat model by combining neonatal estrogen exposure of male offspring followed by the hormonal treatment at adulthood (NeoE + T-E2). Using this modified protocol, we were able to induce more extensive development of neoplastic lesions in all three prostatic lobes and also gross tumors at relatively high incidence within 6-9 months. Western blottings and immunohistochemistry showed that ERalpha expression was increased in the hypertrophic peri-acinar and -ductal smooth muscle cells while ERbeta and AR expressions are markedly decreased in dysplastic and neoplastic lesions in NeoE + T-E2-treated prostates. Immunohistochemistry showed that expression of three tumor suppressors (BRCA2, PTEN, and Rap1) and tubulin-alpha are markedly decreased in dysplastic and neoplastic lesions. In addition, loss of expression of smooth muscle differentiation markers (desmin, alpha-actin, and vinculin) and defects of basement membranes were also seen in the reactive stroma. These results suggest that exposure to high levels of estrogens, either endogenous or exogenous, in early life could play a role in the development of prostate cancer in later life.

Actins↗

PubMed2004

Expression and functional study of estrogen receptor-related receptors in human prostatic cells and tissues.

Estrogen receptor-related receptors (ERRs; alpha, beta, gamma) are orphan nuclear receptors and constitutively active without binding to estrogen. Like estrogen receptors (ERs), ERRs bind to estrogen receptor elements and estrogen receptor element-related repeats. Growing evidence suggests that ERRs can cross-talk with ERs in different cell types via competition for DNA sites and coactivators. We hypothesize that ERRs might play regulatory roles in normal and neoplastic prostatic cells by sharing similar ER-mediated pathways or acting independently. In this study, we investigated mRNA and protein expression patterns of three ERR members in normal human prostate epithelial cells, established cell lines, cancer xenografts, and prostatic tissues. Additionally, effects of transient transfection of ERRs on prostatic cell proliferation and ER expression were also examined. RT-PCR showed that ERRalpha and ERRgamma transcripts were detected in most cell lines and xenografts, whereas ERRbeta was detected in normal epithelial cells and few immortalized cell lines but not in most cancer lines. Similar results were demonstrated in clinical prostatic specimens. Western blottings and immunohistochemistry confirmed similar expression patterns that ERR proteins were detected as nuclear proteins in epithelial cells, whereas their expressions became reduced or undetected in neoplastic prostatic cells. Transient transfection confirmed that ERRs were expressed in prostatic cells as nuclear proteins and transcriptionally active in the absence of estradiol. Transfection results showed that overexpression of ERRs inhibited cell proliferation and repressed ERalpha transcription in PC-3 cells. Our study shows that ERRs, which are coexpressed with ERs in prostatic cells, could regulate cell growth and modulate ER-mediated pathways via interference on ERalpha transcription in prostatic cells.

Adolescent↗

PubMed2004

Estrogen and tamoxifen modulate cerebrovascular tone in ovariectomized female rats.

Postmenopausal estrogen deficiency increases the incidence of cerebrovascular disease. However, hormone replacement therapy is associated with an increased cardiovascular risk. Tamoxifen is a selective estrogen receptor modulator with estrogenic effects on cardiovascular risk factors, but its long-term impacts on cerebral vasculature are unknown. We hypothesized that chronic 17beta-estradiol or tamoxifen treatment exerted similar effects in reducing cerebrovascular tension in ovariectomized rats. We therefore determine whether (1) chronic 17beta-estradiol treatment could influence vasomotor activities, (2) chronic tamoxifen therapy could exert an estrogen-like or estrogen-antagonistic effect, and (3) acute exposure to estrogen could mimic the effect of 17beta-estradiol. Isometric tension was measured in cerebral arteries from female rat groups: control, ovariectomy, ovariectomy plus 17beta-estradiol treatment, ovariectomy plus tamoxifen treatment, and ovariectomized rats treated with tamoxifen and 17beta-estradiol. Ovariectomy enhanced cerebrovascular contractions to endothelin-1 or CaCl2, but not to U46619 or phenylephrine. 17beta-Estradiol therapy reversed these effects. Chronic tamoxifen treatment exerted estrogen-like actions by reversing ovariectomy-induced enhancement of vessel tone without antagonizing the effect of chronic 17beta-estradiol treatment. Ovariectomy enhanced the relaxing potency of nicardipine, and 17beta-estradiol treatment prevented this effect. Acute exposure to 10(-9) mol/L 17beta-estradiol or 10(-8) mol/L tamoxifen did not modulate contractions in rings from nonoperated female rats. In conclusion, ovariectomy differentially enhances agonist-induced cerebrovascular tone, an effect that was reversed by estrogen therapy. Tamoxifen does not act as an estrogen antagonist; instead, it functions as an estrogen agonist during estrogen deficiency. Thus, tamoxifen may confer beneficial effects similar to estrogen in cerebrovascular vessels.

Animals↗

PubMed2004

Raloxifene relaxes rat cerebral arteries in vitro and inhibits L-type voltage-sensitive Ca2+ channels.

BACKGROUND AND PURPOSE: Because of their mixed estrogen-agonist and estrogen-antagonist properties, selective estrogen receptor modulators (SERMs) are considered promising substitutes for hormone replacement therapy. Raloxifene and other SERMs confer estrogen-like cardiovascular protective effects but lack the carcinogenic activity of exogenous estrogen. However, little is known about the cerebrovascular action of raloxifene. Therefore, we studied the effects of raloxifene on the mechanisms regulating rat cerebral artery tone. METHODS: Ring segments of the isolated rat posterior communicating cerebral arteries were mounted in a microvessel myograph for measurement of isometric tension. Whole-cell L-type voltage-sensitive Ca2+ currents were recorded using the perforated patch-clamp technique. Raloxifene (0.1 to 10 micromol/L) reduced the contractile responses to U46619, phenylephrine, and endothelin-1 in normal Krebs solution or to CaCl2 in Ca2+-free, high K+-containing solution. Raloxifene-induced relaxation was identical in endothelium-intact and endothelium-denuded rings. ICI 182780 had no effect on raloxifene-induced relaxation. Raloxifene reduced L-type Ca2+ currents with a pD2 of 5.98+/-0.06, close to that (6.44+/-0.09) for raloxifene-induced relaxation of 60 mmol/L K+-contracted rings. CONCLUSIONS: This study demonstrates that raloxifene acutely relaxes rat cerebral arteries largely via an endothelium-independent mechanism, involving inhibition of Ca2+ influx through L-type Ca2+ channels.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗

PubMed2004

Mitochondrial DNA mutations in chemical carcinogen-induced rat bladder and human bladder cancer.

Mitochondrial (mt) DNA mutations have been described recently in different tumors, whereas similar studies focusing on bladder cancer are scarce. In an effort to understand the significance of mtDNA mutations in bladder cancer, we investigated the mtDNA alterations in both clinical human bladder cancer and in a carcinogen-induced rat bladder cancer model. Human bladder cancer tissues were obtained by radical cystectomy and transurethral resection of bladder tumors. Rat bladder tumors were induced in SD rats by treatment with N-butyl-N-(4-hydroxybutyl) nitrosamine in drinking water for 24-28 weeks. Genomic DNA was extracted from tumor specimens and microdissected normal bladder mucosae. Mitochondrial genes and D-loop region were amplified by PCR. The amplified PCR fragments were either cloned into plasmid vector or used for direct DNA sequencing. The results of DNA sequence revealed numerous point mutations in the non-coding D-loop region and different mtDNA genes in both human and rat bladder cancers. In addition, we also detected deletions of variable lengths in mononucleotide repeats in the D-loop region, ND2, ATPase 8 and COIII genes in human bladder cancer samples. Our results show that mtDNA exhibits a high rate of mutations in both human and rat bladder cancers. We also demonstrate that the repetitive sequences of mononucleotides within the mt genome are unstable and subjected to deletions. The high incidence of mtDNA mutations in bladder cancer suggests that mtDNA and mitochondria could play an important role in the process of carcinogenesis and also mtDNA could be valuable as a marker for early bladder cancer diagnosis.

Animals↗

PubMed2003

The nucleus of HeLa cells contains tubular structures for Ca2+ signaling with the involvement of mitochondria.

Calcium is an important messenger that controls many nuclear functions such as gene expression in mammalian cells but the regulation of nuclear Ca(2+) remains unclear. It has long been thought that Ca(2+) is translocated from the cytosol by a long distance to the nucleus through the nuclear pore complexes to activate or suppress gene transcription. However, this model is at best an incomplete one. With an aid of confocal and transmission electron microscopy, we demonstrated here that tubules, in a vertical or horizontal orientation, extended deep inside the nucleus of HeLa cells. These nuclear tubules (NTs) are double-membraned invaginations of the nuclear envelope and are usually associated with nucleolus. Also, membrane bound vesicles are found inside and inositol 1,4,5 trisphosphate (IP(3)) receptors are enriched in some but not all of these tubular structures. Interestingly, shuttling of mitochondria was observed in the NT and cytoplasm of the HeLa cells loaded with dihydro-rhod-2/AM. After stimulation with histamine that increases cytosolic [Ca(2+)] through IP(3) production, a slow rise of dihydro-rhod-2 fluorescence for the measurement of intra-mitochondrial Ca(2+) was observed in the area of NT indicating that Ca(2+) was sequestered by mitochondria inside the tubular invagination. Our work therefore suggests that the NTs and mitochondrial activities represent a specialized compartment and dynamic process involved in the regulation of Ca(2+) inside the cell nucleus.

Biological Transport↗

PubMed2003

Soy leaf lowers the ratio of non-HDL to HDL cholesterol in hamsters.

The present study was to examine effect of soy leaf powder (SLP) and soy leaf ethanol extract (SLEE) on serum lipoproteins in hamsters. The control group was fed a semisynthetic diet containing 0.1% cholesterol, while the tested groups were maintained on the same diet but supplemented with 3% SLP or the equivalent amount of SLEE derived from 3% SLP for 4 weeks. SLP supplementation led to a trend of lowering serum total cholesterol (TC) and nonhigh density lipoprotein cholesterol (non-HDL-C), with HDL-C being unaffected, whereas incorporation of SLEE into the diet led to an elevated level of HDL-C and a lower level of non-HDL-C with TC being unchanged. Both SLP and SLEE supplementation caused favorably a decrease in the ratio of non-HDL-C to HDL-C. The present results demonstrate that not only soybean seeds but also soy leaves are cardioprotective, by favorably modulating serum lipid profile.

Animals↗

PubMed2003

Expression study of three secretory proteins (prostatic secretory protein of 94 amino acids, probasin, and seminal vesicle secretion II) in dysplastic and neoplastic rat prostates.

BACKGROUND: Prostatic secretory protein of 94 amino acids (PSP94), probasin, and seminal vesicle secretion II (SVSII) are the three major proteins secreted by the lateral lobe of the rat prostate gland. Among these proteins, rodent PSP94 but not probasin and SVSII has a human homologue and it is also a major secretory protein of the human prostate, in addition to prostatic acid phosphatase and prostate-specific antigen. METHODS: In this study, we examined and compared the mRNA expression of these three secretory markers in three rat models of prostate cancer including the sex steroid-induced dysplasia (prostatic intraepithelial neoplasia or PIN) in Noble (Nb) rat model, an androgen-independent Nb rat prostatic tumor (AIT) and Dunning rat prostatic adenocarcinomas (both androgen-dependent and -independent) by in situ hybridization (ISH), reverse transcriptase-polymerase chain reaction (RT-PCR), and immunohistochemistry. RESULTS: The transcripts for the three markers were highly expressed in the secretory epithelium of normal lateral prostate (LP). Their hybridization signals became reduced in the epithelial cells in the low-grade PINs and significantly weakened or lost in the high-grade PINs induced in the LP. Interestingly, we observed that some dysplastic cells located at the basal compartment of the PIN lesions, and nests of outpouching epithelial cells in the vicinity of PINs, expressed positive hybridization signals of three markers. In the adenocarcinoma, signals of probasin but not PSP94 and SVSII were detected. No hybridization signals were detected in both Dunning and AIT tumors. By RT-PCR, transcripts for these proteins were still detected but significantly reduced in the Dunning tumors, whereas in the AIT tumor, only SVSII transcripts were detected. Immunohistochemistry of PSP94 also showed a reduced staining in the PIN lesions, but no immunoreactivity was seen in the rat prostatic tumors. CONCLUSIONS: The mRNA expression of the three prostatic secretory markers were decreased in the hormone-induced PINs and in two rat prostatic tumors, indicating that the androgen-regulated secretory differentiation was impaired during the development of the premalignant lesion and further reduced in advanced tumors. The abnormal expression pattern of these secretory markers and androgen receptor (AR) in the basal compartment of the PIN lesions suggests that there is a population of cell types with secretory phenotype appearing in the basal cell layer during the early malignant transformation of the prostatic epithelium.

Adenocarcinoma↗

PubMed2003

Mouse PSP94 expression is prostate tissue-specific as demonstrated by a comparison of multiple antibodies against recombinant proteins.

Prostate tissue-specific gene expression is crucial for driving potentially therapeutic genes to target specifically to the prostate. Prostate secretory protein of 94 amino acids (PSP94), also known as beta-MSP (microseminoprotein), is one of the three most abundant secretory proteins of the prostate gland, and is generally considered to be prostate tissue-specific. We have previously demonstrated that the expression of the rat PSP94 gene is strictly prostate tissue-specific by an antibody against a recombinant rat PSP94. In order to study prostate targeting utilizing the PSP94 gene in a mouse pre-clinical experimental model, we need to establish antibodies against mouse PSP94 to confirm if it is prostate tissue-specific as well. In this study, firstly we raised a polyclonal antibody against a recombinant glutathione-S-transferase- (GST-) mouse mature form of PSP94. However, it showed very poor immunoreactivity against prostate tissue PSP94 as tested in Western blotting experiments. Neither antibodies against rat PSP94 nor mouse PSP94 showed significant cross-reactivity. Thus a second antibody was established against a recombinant mouse mature PSP94 containing N-terminal polyhistidines, and stronger immunoreactivity against mouse prostate tissue PSP94 was identified in Western blotting experiments. Both of these antibodies showed immunohistochemical reactivity, while the latter showed stronger reactivity in IHC when tested with different fixatives. By studying tissue distribution, we demonstrated that, as with rat PSP94, mouse PSP94 is strictly prostate tissue-specific in experiments of both Western blotting and immunohistochemistry (IHC). This conclusion was also derived from a comparison among antibodies against human, rat, and mouse PSP94, showing very different immunoreactivities in Western blotting and IHC. Finally, a competitive assay between different species was performed. We demonstrated that antibodies against PSP94 from different species (human, primate, rodents) have poor cross-reactivities. These observations also indicate that the PSP94 gene is a rapidly evolving gene in all species. Results from this study have led to the possibility of utilizing PSP94 as a targeting agent specifically to the prostate in a mouse experimental model.

Animals↗

PubMed2003

Identification of a specifically expressed modified form of novel PSP-94 protein in the secretion of benign prostatic hyperplasia.

Using two-dimensional gel electrophoresis, we investigated the profile of prostatic secretory proteins in human expressed prostatic secretion (EPS) from benign prostate hyperplasia (BPH) patients and compared the patterns with normal controls. We identified three specifically expressed proteins, including prostate secretory protein 61 (PSP61), in EPS from benign BPH patients but absent in normal controls. In addition, we found that PSP61 was a modified isoform of the well-documented PSP-94, which had a perfect matching (100% homology) to the first 61 amino acids of the PSP-94 protein but with a deleted C-terminus. This shortened PSP61 was not due to alternative splicing of the PSP-94 gene at transcription level. Our results provide first evidence on the possibility of using PSP61 as a specific biological marker for diagnosis of BPH.

Aged↗