Prolonged Release of Bioactive Model Proteins from Anionic Microgels Fabricated with a New Microemulsion Approach.

PURPOSE: Therapeutic proteins have become an integral part of health care. However, their controlled delivery remains a challenge. Protein function depends on a delicate three dimensional structure, which can be damaged during the fabrication of controlled release systems. This study presents a microgel-based controlled release system capable of high loading efficiencies, prolonged release and retention of protein function. METHODS: A new DMSO/Pluronic microemulsion served as a reaction template for the crosslinking of poly(acrylic acid) and oligo (ethylene glycol) to form microgels. Poly(acylic acid) molecular weights and microgel crosslinking densities were altered to make a series of microgels. Microgel capacity to capture and retain proteins of different sizes and isoelectric points, to control their release rate (over ~30 days) and to maintain the biofunctionality of the released proteins were evaluated. RESULTS: Microgels of different sizes and morphologies were synthesized. Loading efficiencies of 100% were achieved with lysozyme in all formulations. The loading efficiency of all other proteins was formulation dependent. Release of lysozyme was achieved for up to 30 days and the released lysozyme retained over 90% of its activity. CONCLUSIONS: High loading efficiencies and prolonged release of different proteins was achieved. Furthermore, lysozyme's functionality remained uncompromised after encapsulation and release. This work begins to lay the foundation for a broad platform for the delivery of therapeutic proteins.

[Psychological factors and erectile function in men with refractory chronic prostatitis].

OBJECTIVE: To study the psychological factors and erectile function in patients with refractory chronic prostatitis. METHODS: We obtained and compared the scores on the NIH scales of chronic prostatitis symptoms, anxiety, depression and erectile function among 232 refractory and medical chronic prostatitis patients who had never received any psychotherapy. RESULTS: No significant differences were observed in the scores on chronic prostatitis symptoms between the refractory and the medical chronic prostatitis groups, while the scores on anxiety and depression were significantly higher and that on erectile function significantly lower in the refractory than in the medical group (P < 0.01), with a negative correlation between the scores on the former two items and that on the latter. CONCLUSION: Obvious psychological factors exist in patients with refractory chronic prostatitis, which may affect their erectile function.

Modification of alternative splicing of Bcl-x pre-mRNA in bladder cancer cells.

To modify the splicing pattern of Bcl-x and compare the effect of this approach with that of the antisense gene therapy in BIU-87 cell line of bladder cancer, by using 5'-Bcl-x AS to target downstream alternative 5'-Bcl-x splice site to shift splicing from Bcl-xL to Bcl-xS and 3'-Bcl-x AS antisense to the 3'-splice site of exon III in Bcl-x pre-mRNA to down regulation of Bcl-xL expression, the inhibitory effects on cancer cells by modification of alternative splicing and antisense gene therapy were observed and compared by microscopy, MTT Assay, RT-PCR, FACS, Western bloting and clone formation. The growth of cells BIU-87 was inhibited in a dose- and time-dependent manner. Its inhibitory effect began 12 h after the exposure, reaching a maximum value after 72h. The number of cells decreased in S phase and the number increased in G1 phase. The ability to form foci was reduced and the antisense gene therapy was approximately half as efficient as modification of alternative splicing in inducing apoptosis. It is concluded that modification of splicing pattern of Bcl-x pre-mRNA in bladder cancer cell BIU-87 is better than antisense gene therapy in terms of tumor inhibition.

[Effects of Omi/HtrA2 on expression of anti-apoptotic protein PED/PEA-15 and apoptosis of prostate cancer cell line PC-3].

BACKGROUND & OBJECTIVE: The interaction between pro-apoptotic factors and anti-apoptotic factors is closely related to the genesis and development of tumors. Omi/HtrA2 is a novel gene involved in the regulation of apoptosis. PED/PEA-15 is a widely expressed anti-apoptotic protein. This study was to explore the effects of Omi/HtrA2 on PED/PEA-15 expression and apoptosis of prostate cancer cell line PC-3. METHODS: Omi/HtrA2 expression and specific siRNA vectors were constructed and transiently transfected into PC-3 cells. The effect of Omi/HtrA2 on PED/PEA-15 expression was assayed by Western blot, and its effect on apoptosis of PC-3 cells was analyzed by ELISA. Caspase-8 activity was assayed using Caspase-8 colorimetric assay kit. The effects of Omi/HtrA2-specific siRNA sequence on its transcription and translation were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot. The sensitivity of PC-3 cells to cisplatin (DDP) after Omi/HtrA2 gene silencing was determined by flow cytometry. RESULTS: Enzyme digestion analysis and DNA sequencing confirmed Omi/HtrA2 expression, and specific siRNA vectors were successfully constructed. After transfection of Omi/HtrA2 expression vector, PED/PEA-15 expression was inhibited, Caspase-8 activity was promoted, and the apoptosis of PC-3 cells was enhanced. The sensitivity of PC-3 cells to DDP was suppressed after Omi/HtrA2 gene silencing. CONCLUSION: Omi/HtrA2 can promote the apoptosis of PC-3 cells through inhibiting PED/PEA-15 expression.

Cooperative therapeutic effects of herpes simplex virus thymidine kinase gene/ganciclovir system and chemotherapeutic agents on prostate cancer in vitro.

The killing effects of herpes simplex virus thymidine kinase gene/ganciclovir (HSV-tk/GCV) approach by the addition of several commonly clinical chemotherapeutic agents on hormone refractory prostate cancer (HRPC) cells PC-3m were investigated. After transferring of the HSV-tk gene into PC-3m cells, mRNA and protein expression of HSV-tk was detected by reverse-transcript polymerase chain reaction (RT-PCR) and strept avidin-biotin complex (SABC) immunohistochemical method. The killing effect of GCV, cisplatin (CDDP), etoposide (VP-16), vincristine (VCR), methotrexate (MTX), 5-fluorouracil (5-Fu), and suramin on PC-3m cells was evaluated by morphological assessment analysis, trypan blue exclusion assay and MTT assay respectively. Additionally, the cooperative effect of HSV-tk/GCV system combined with the above agents on the target cancer cells was determined by MTT. Furthermore, apoptosis and necrosis induced by GCV plus 5-Fu or suramin was analyzed by flow cytometry (FCM). The results showed that that there was HSV-tk mRNA and protein expression in pDR2-tk plasmid transduced PC-3m cell. Combination of GCV with VP-16, VCR, 5-Fu or suramin led to an enhanced cellular killing effect, but with CDDP resulted in a reduced one and with MTX in an approximate one. FCM revealed that synergistic use of GCV and 5-fu or suramin resulted in a rather large proportion of apoptosis and necrosis with the apoptosis index being 36.38% and 35.51%, and the proportion of necrosis being 33.05% and 28.87%, respectively. In conclusion, HSV-tk/CGV approach by addition of certain clinical available chemotherapeutic drugs brings on statistically significant enhanced cell killing over single-agent treatment. Our results highlight the potential for such new combination therapies for future treatments of HRPC.

[The changes of IGF-I in testis and epididymis on a rat model with oligozoospermia/azoospermia induced by cyclophosphamide].

OBJECTIVE: To evaluate the effect of the levels of IGF-I in the epididymis and the expression of IGF-I in the testis of adult male rat after the administration of cyclophosphamide. METHODS: Ninety-six male adult rats (8 weeks age) were divided into 6 groups. The doses given to the rats of the groups 1 to 5 were 10, 20, 40, 80 and 100 mg/(kg x d), respectively. The remaining group was served as control. All those rats were sacrificed and IGF-I were quantitatively determined by ELISA techniques 2 and 4 weeks after the administration of the drug (by gastric fudge). Immunohistochemical SP technique was used to examine expression of IGF-I in rat testis. RESULTS: The levels of cell factors (IGF-I) in the epididymis of the rats were gradually reduced with the increasing time and dose after administration of the drug. In the mean time the expression of IGF-I in the tissues of the testis of those rats were also gradually reduced. CONCLUSION: In the time of oligozoospermia/azoospermia induced by the administration of cyclophosphamide, the expression levels of IGF-I in the genetic system were significantly reduced. The possible mechanism of these changes could be attributed to the lower spermatogenesis function of the testis caused by the administration of cyclophosphamide.

Cloning of human uroplakin II gene from Chinese transitional cell carcinoma of bladder and construction of its eukaryotic expression vector.

To clone Uroplakin Ii gene from Chinese transitional cell carcinoma (TCC) of bladder and construct its eukaryotic expression vector, the molecular cloning method was used to extract total RNA from a GIII / T3N0M0 tissue sample of the bladder TCC patients. The primers were designed by Primer 5.0 software. Full length cDNA of Uroplakin II gene was amplified by reverse transcription polymerase chain reaction (RT-PCR), assayed by nucleic acid sequencing and then inserted between Xba I and Hind III restrictive sites of eukaryotic expression vector pcDNA3. 0. The recombinant was assayed by restricted enzyme digestion. Under the induction of Lipofectamine 2000, the recombinant was transfected into Uroplakin II negative bladder cancer cell line EJ. Cellular expression levels of Uroplakin II were detected by RT-PCR. The nucleic acid sequencing results indicated that Chinese Uroplakin II cDNA (555 bp) was successfully cloned. The BLAST analysis demonstrated that the cloned sequence is 100% homologous with sequences reported overseas. The GenBank accession number AY455312 was also registered. The results of restricted enzyme digestion indicated that eukaryotic vector pcDNA-UP II for Uroplakin II was successfully constructed. After being transferred with pcDNA-UP II for 72 h, cellular Uroplakin II mRNA levels were significantly improved (P < 0.01). It is concluded that human Uroplakin II gene was successfully cloned from Chinese TCC tissues, which provided a basis for further exploration of the roles of Uroplakin II gene in TCC biological behaviors and potential strategies for targeted biological therapy of TCC.

Downregulation of XIAP expression induces apoptosis and enhances chemotherapeutic sensitivity in human gastric cancer cells.

X-linked inhibitor of apoptosis (XIAP) is the most potent member of the inhibitor of apoptosis protein (IAP) gene family in terms of its ability to inhibit caspases and suppress apoptosis. Recent evidence has suggested that XIAP is a key determinant in chemoresistance of cancer cells. To explore a novel approach for ameliorating chemotherapy of gastric cancer, the antisense expression vector for the XIAP gene was constructed and transferred into gastric cancer cell lines, MKN-45 (wild-type p53) and MKN-28 (mutant-type p53). This transfer resulted in significant downregulation of XIAP expression, decreased in vitro cell viabilities, and induced apoptosis. In transferred cells, inactive caspase-3 precursors were cleaved into the active subunits (p20 and p17) during apoptosis induced by downregulation of XIAP. The inhibitory effects of cisplatin and mitomycin C on the growth of XIAP downregulated cancer cells were significantly enhanced. In addition, this process occurred only in wild-type p53 (MKN-45), but not in mutant-type p53 (MKN-28) gastric cancer cells. The data presented suggest that downregulation of XIAP via antisense RNA can lead to apoptosis of gastric cancer cells in vitro, correlating with cellular p53 status and activation of caspase-3. This finding could lead to a potential strategy for improving the efficiency of therapies for gastric cancer.

Selection of optimal antisense accessible sites of survivin and its application in treatment of gastric cancer.

AIM: To select the optimal antisense accessible sites of survivin, a highly expressed gene in tumor tissues, in order to explore a novel approach to improve biological therapy of gastric cancer. METHODS: The 20 mer random oligonucleotide library was synthesized, hybridized with in vitro transcribed total survivin cRNA, then digested by RNase H. After primer extension and autoradiography, the antisense accessible sites (AAS) of survivin were selected. Then RNADraw software was used to analyze and choose the AAS with obvious stem-loop structures, according to which the complementary antisense oligonucleotides (AS-ODNs) were synthesized and transferred into survivin highly- expressing gastric cancer cell line MKN-45. Survivin expression was detected by RT-PCR and Western Blotting. Cellular growth activities were assayed by tetrazolium bromide (MTT) colorimetry. Cellular ultrastructure was observed by electronic microscopy, while apoptosis was detected by annexin V-FITC and propidium iodide staining flow cytometry. RESULTS: Thirteen AAS of survivin were selected in vitro. Four AAS with stem-loop structures were chosen, locating at 207-226 bp, 187-206 bp, 126-145 bp and 44-63 bp of survivin cDNA respectively. When compared with non-tranfection controls, their corresponding AS-ODNs (AS-ODN(1), AS-ODN(2), AS-ODN(3) and AS-ODN(4)) could reduce Survivin mRNA levels in MKN-45 cells by 54.3+/-1.1% (t = 6.12, P<0.01), 86.1+/-1.0% (t = 5.27, P<0.01), 32.2+/-1.3% (t = 7.34, P<0.01) and 56.2+/-0.9% (t = 6.45, P<0.01) respectively, while survivin protein levels were decreased by 42.2+/-2.5% (t = 6.26, P<0.01), 75.4+/-3.1% (t = 7.11, P<0.01), 28.3+/-2.0% (t = 6.04, P<0.01) and 45.8+/-1.2% (t = 6.38, P<0.01) respectively. After transfection with 600 nmol/L AS-ODN1-AS-ODN(4) for 24 h, cell growth was inhibited by 28.12+/-1.54% (t = 7.62, P<0.01), 38.42+/-3.12% (t = 7.75, P<0.01), 21.46+/-2.63% (t = 5.94, P<0.01) and 32.12+/-1.77% (t = 6.17, P<0.01) respectively. Partial cancer cells presented the characteristic morphological changes of apoptosis, with apoptotic rates being 19.31+/-1.16% (t = 7.16, P<0.01), 29.24+/-1.94% (t = 8.15, P<0.01), 11.87+/-0.68% (t = 6.68, P<0.01) and 21.68+/-2.14% (t = 7.53, P<0.01) respectively. CONCLUSION: The AAS of survivin could be effectively selected in vitro by random oligonucleotide library/RNase H cleavage method combined with computer software analysis, this has important reference values for further studying survivin-targeted therapy strategies for gastric cancer.

Immunohistochemical analysis of Omi/HtrA2 expression in prostate cancer and benign prostatic hyperplasia.

To study the expression and significance of the serine protease Omi/HtrA2 in prostate cancer and benign prostatic hyperplasia. The expression of Omi/HtrA2 was assayed by means of immunohistochemical technique in 41 prostate cancer (Cap), 20 benign prostatic hyperplasia (BPH) and 10 normal prostate (NP) specimens. Omi/HtrA2 expression was positive in 30 (73.17%) prostate cancer specimens, and the positive rate of Omi/HtrA2 was lower in well differentiated than in poorly and moderately differentiated groups (P < 0.05). By contrast, the cells in normal prostate and benign prostatic hyperplasia groups showed no or weak expression of Omi/HtrA2. Prostate cancer cells in vivo may need Omi/HtrA2 expression for apoptosis, and that Omi/HtrA2 expression might be involved in prostate cancer development.

The relationship of expression of bcl-2, p53, and proliferating cell nuclear antigen (PCNA) to cell proliferation and apoptosis in renal cell carcinoma.

To investigate the relationship of bcl-2, p53, proliferating cell nuclear antigen (PCNA) to cell proliferation, apoptosis and pathological parameters, the patterns of cell growth and turnover in renal cell carcinoma (RCC), formalin-fixed and paraffin-embedded tissue blocks from 34 patients with RCC were examined. Cell proliferation activity was detected by PCNA immunostaining and the proliferation index (PI) was expressed as a percentage of the PCNA-positive cells in the tumor cells. Apoptosis was detected by terminal deoxy- nucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL), and the apoptotic index (AI) was expressed as a percentage of the TUNEL-positive cells in the tumor cells. Expressions of bcl-2 and p53 were assessed immunohistochemically. Our results showed that the PI ranged from 6.0% to 24.0% (median 12.3%) and the AI from 2.0% to 8.0% (median 5.4%) in RCC. The expression of the bcl-2 protein was demonstrated in 15 cases (44.1%); the expression of the p53 protein, however, was seen in only 3 case. bcl-2 positivity was not associated with PI or AI or any pathological parameters. There were close associations between PI and tumor grade and stage, and a significant relationship between AI and the tumor grade of RCC, Our study suggests that bcl-2 positivity was not associated with PI or AI or any pathological parameters. There are close associations between PI and AI and tumor grade and stage of RCC. Active cell proliferation may be accompanied by frequent apoptosis in RCC.

[Ureteroscopic holmium: YAG laser lithotripsy for managing urinary tract calculi].

OBJECTIVE: To evaluate the effectiveness and safety of ureteroscopic holmium: YAG laser lithotripsy for managing ureteral calculi. METHODS: Ureteroscopic holmium: YAG laser lithotripsy was used in 168 ureteral calculi (proximal 27 cases, middle 33 cases, distal 108 cases). Transurethral cystoscopic holmium: YAG laser lithotripsy in 12 bladder calculi. RESULTS: Four to six weeks after operation, The stone-free rate was 93% (25/27) in the proximal ureteral calculi, 94% (31/33) in the middle ureteral calculi, 94% (102/108) in the distal ureteral calculi, respectively. The complication rate was 5% (8 cases). the stone-free rate of bladder calculi was 100% (12/12), no complication. CONCLUSION: Ureteroscopic holmium: YAG laser lithotripsy is a highly effective and safe treatment modality for managing ureteral calculi.

Expression and implication of hypoxia inducible factor-1alpha in prostate neoplasm.

To study the expression of hypoxia inducible factor-1alpha (HIF-1alpha) protein in prostate cancer (Pca) and its biological significance, the expression of HIF-1alpha was assayed by means of immunohistochemical technique in 42 prostate cancer, 12 prostatic intraepithelial neoplasm (PIN) and 9 normal prostate tissue (NP) specimens. Western blot was used to examine the expression of HIF-1alpha in prostate cancer cell line (PC-3M) induced by different oxygen tension. HIF-1alpha expression was positive in 33 Pca and 9 PIN specimens, and the positive rate of HIF-1alpha was higher in distant metastasis patients than in patients without metastasis of prostate cancer (P<0.05), while there was no expression of HIF-1alpha in NP. The level of HIF-1alpha in PC-3M significantly increased with the decrease of oxygen tension (P<0.01). Overexpression of HIF-1alpha is the preliminary event of the formation of Pca, which may induce carcinoma into malignant phenotype. Thus it may serve as an early diagnosis marker and the novel target for Pca treatment.

Bladder cancer therapy using combined proliferating cell nuclear antigen antisense oligonucleotides and recombinant adenovirus p53.

OBJECTIVE: To evaluate the antitumor efficacy of proliferating cell nuclear antigen antisense oligonucleotide (PCNA-ASO) in combination with recombinant adenovirus p53 (Ad-p53) against bladder cancer EJ and BIU-87 cells in vitro and in vivo. METHODS: Cells were transfected with Ad-p53 (100 MOI), and PCNA-ASO (1.6 micro mol/L) was then introduced into the cells using a cationic lipid (lipofectamine, 20 micro l/ml). In vitro and in vivo antitumor effects of combining PCNA-ASO with Ad-p53 were measured using the MTT assay, flow cytometry, clone formation, and a nude mice model. RESULTS: The combination of PCNA-ASO and Ad-p53 inhibited cell viability in both the EJ (89.3%) and BIU-87 (78.6%) cell lines. The ability of the cells to form foci was also reduced by 74.8% in EJ cells and by 67.5% in BIU-87 cells (P < 0.01). A significant decrease of cells in the S phase (11.4% in EJ cells, 14.6% in BIU-87 cells) and a significant increase of cells in G1 phase (62.2% in EJ, 56.8% in BIU-87) were noted. The mean tumor volume after 7 days of treatment with PCNA-ASO or Ad-p53 in combination decreased to 47.6% or 36.4% of the initial tumor size in the two cell lines respectively. CONCLUSION: These results indicate that combined PCNA-ASO and Ad-p53 in the treatment of bladder cancer with mutant p53 has important therapeutic potential, significantly suppressing the growth of human bladder cancer both in vitro and in vivo.

Expression of mouse telomerase catalytic subunit mTERT gene in testis of SD rats and its significance.

To study the expression of mTERT gene in the testis of SD rats and its significance, in situ hybridization (ISH) techniques were used to detect the expression of telomerase gene mTERT mRNA in the testis of SD rats. The expression of mTERT was detectable in different-age male SD rats testis. There was a positive correlation between the expression of mTERT and the location of germ cells (spermatogonia, spermatocyte, spermatid). In Sertoli cells, leydig cell and spermatozoa, telomerase mTERT was not detected. Type A spermatogonia expressed the highest level of telomerase mTERT mRNA. Our results suggest that the expression of mTERT gene in the testis of SD rats is of lifetime and coincide with the telomerase activity.

Effects of blocking androgen receptor expression with specific hammerhead ribozyme on in vitro growth of prostate cancer cell line.

OBJECTIVE: To study the possibility of gene therapy for prostate cancer by blocking androgen receptor (AR) gene expression using a specific hammerhead ribozyme (RZ). METHODS: The hammerhead ribozyme expression vector pcDNA-hAR-RZ, specific to AR mRNA, was constructed and transfected into the prostate cancer cell line LNCaP by using lipofectamine. Androgen receptor expression was measured by RT-PCR and immunohistochemical methods. Cellular proliferation activities were assayed using the tetrazolium bromide colorimetry method; cell cycle changes were observed by flow cytometry; and cell apoptosis was detected by the TdT-mediated dUTP-biotin nick end labeling method. RESULTS: One to seven days after transfection with the ribozyme expression vector, AR mRNA expression at molecular and protein levels in LNCaP cells decreased by 32.6% - 40.7% (P < 0.05) and 21.0% - 87.64% (P < 0.05) respectively, and cell proliferation was inhibited by 18.28% - 35.34% (P < 0.05). Meanwhile, the cell cycle was arrested at the G2/M stage, and apoptotic morphological changes occurred with an apoptosis rate of 25.17% (P < 0.01). CONCLUSION: Ribozyme specific against AR mRNA is capable of inhibiting the expression AR and inducing the apoptosis in prostate cancer cells.

[Effects of mTR antisense oligodeoxynucleotide on telomerase activity and the expression of telomerase mTR in type A spermatogonia].

OBJECTIVES: To study the inhibitory effects of mouse telomerase RNA (mTR) antisense oligodeoxynucleotide(ASODN) on telomerase activity in rat spermatogonia. METHODS: 9-mer phosphorothioate mTR-ASODN was encapsulated by Lipofect AMINE 2000 (LF 2000) and transfected to type A spermatogonia in Snrague Dawley (SD) rat. Telomerase activity was detected by aid of TRAP-SYBR-Green staining and Bioluminescence technique in type A spermatogonia treated or untreated with ASODN. RESULTS: mTR-ASODN conjugated with LF 2000 could significantly inhibit telomerase activity of spermatogonia(P < 0.01). mTR mRNA level also decreased while the spermatogonia were treated with ASODN for 24 h. No change of telomerase activity and apoptosis were observed when SODN, RODN or single LF 2000 was used. CONCLUSIONS: Antisense oligodeoxynucleotide of mTR conjugated with LF 2000 could significantly inhibit telomerase activity of spermatogonia. mTR-ASODN might inhibit telomerase activity of spermatogonia at transcription level.

[Influence of suramin on the proliferation of prostatic carcinoma cells PC-3M].

OBJECTIVES: To examine the effects of suramin on the growth, cell cycle and apoptosis of a hormone refractory prostate cancer cell line PC-3M, and to explore the possible mechanisms. METHODS: The roles of diverse concentrations (10, 50, 100 and 200 mumol/L) of suramin on PC-3M cell proliferation at different ratios of fetal calf serum (FCS) (2%, 5%, 10%) were assayed respectively by trypan blue exclusion and tetrazolium (MTT) assay. The effect of suramin on cell cycle distribution and apoptosis induction of PC-3M cells was evaluated with flow cytometry (FCM). RESULTS: A higher dosage of suramin (200 mumol/L) had a cytotoxic effect on PC-3M cells, while lower dosages from 10 to 100 mumol/L produced a predominant inhibiting effect. Suramin could also play a growth suppressive role in the culture media containing 10% FCS, but to a much less extent than in the media containing lower concentrations(5%, 2%) of FCS. FCM analysis exhibited that suramin at a high dosage of 200 mumol/L could induce apoptosis, and at the other concentrations, G0/G1 cell cycle arrest. CONCLUSION: Suramin's proliferative suppression on PC-3M cells might result from several mechanisms including antagonistic action on growth stimulation via growth factor, arrest of cell cycle and induction of apoptosis.

Expression of telomerase gene mTR in the testis of SD rats and its significance.

To study the expression of mTR gene in the testis of SD rats with varied ages and its significance, in situ hybridization (ISH) techniques were applied to detect the expression of telomerase gene mTR mRNA in the testis of SD rats. The expression of mTR was found in testes of different-age male SD rats. There was a positive correlation between the expression of mTR and the location of germ cells (spermatogonia, spermatocyte, spermatid). In Setoli cells, leydig cell and spermatozoa, no telomerase mTR was detectable. Type A spermatogonia expressed the highest level of telomerase mTR mRNA. It was suggested that the expression of mTR gene in the testis of SD rats is of lifetime and coincides with the telomerase activity.