Biomedical subjects

Chinghai Kao

Publications and source records attributed to Chinghai Kao.

31 records · Page 2Linked to original sources

PubMed2003

High-level expression of EphA2 receptor tyrosine kinase in prostatic intraepithelial neoplasia.

EphA2 is a transmembrane receptor tyrosine kinase that is overexpressed in many carcinomas. Specific targeting of EphA2 with monoclonal antibodies is sufficient to inhibit the growth, migration and invasiveness of aggressive cancers in animal models. Using immunohistochemical analyses, we measured the expression of EphA2 in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia, and adjacent benign prostate tissue from ninety-three radical prostatectomy specimens. These results were related to multiple clinical and pathologicalcharacteristics. The fraction of cells staining positively with EphA2 in benign prostatic epithelium (mean, 12%) was significantly lower than that in high-grade prostatic intraepithelial neoplasia (mean, 67%, P < 0.001) and prostatic adenocarcinoma (mean, 85%, P < 0.001). Moreover, the intensity of EphA2 immunoreactivity in prostatic adenocarcinoma was significantly higher than in benign prostatic tissue (P < 0.001) or high-grade prostatic intraepithelial neoplasia (P < 0.001). Benign prostatic epithelium showed weak or no immunoreactivity for EphA2 in all cases examined. Whereas EphA2 immunoreactivity related to neoplastic transformation, it did not correlate with other clinical and pathological parameters examined. Our data suggest that EphA2 levels increase as prostatic epithelial cells progress toward a more aggressive phenotype. Progressively higher levels of EphA2 in high-grade prostatic intraepithelial neoplasia and prostatic carcinoma are consistent with recent evidence that EphA2 functions as a powerful oncogene. Moreover, the presence of high levels of EphA2 in these cells suggests opportunities for prostate cancer prevention and treatment.

Adenocarcinoma↗

PubMed2003

Lovastatin inhibits adipogenic and stimulates osteogenic differentiation by suppressing PPARgamma2 and increasing Cbfa1/Runx2 expression in bone marrow mesenchymal cell cultures.

The mechanism whereby lovastatin can counteract steroid-induced osteonecrosis and osteoporosis is poorly understood. We assessed the effect of lovastatin on a multipotential cell line, D1, which is capable of differentiating into either the osteoblast or the adipocyte lineage. The expression of bone cell and fat cell transcription factors Cbfa1/Runx2 and PPARgamma2, respectively, were determined. 422aP2 gene expression was analyzed. Osteocalcin promoter activity was measured by cotransfecting the cells with the phOC-luc and pSV beta-Gal plasmids. Lovastatin enhanced osteoblast differentiation as assessed by a 1.8x increase in expression of Cbfa1/Runx2 and by a 5x increase in osteocalcin promoter activity. Expression of PPARgamma2 was decreased by 60%. By enhancing osteoblast gene expression and by inhibiting adipogenesis, lovastatin may shunt uncommitted osteoprogenitor cells in marrow from the adipocytic to the osteoblastic differentiation pathway. Future evaluation of lovastatin and other lipid-lowering drugs will help determine their potential as therapeutic agents for osteonecrosis and osteoporosis.

Adipocytes↗

PubMed2002

Fas-Fas ligand signaling pathway mediates an interleukin-12-induced rejection of a murine prostate tumor system.

BACKGROUND: Recent data suggest that anti-tumor activities of interleukin-12 (IL-12) involve the induction of apoptosis. Fas (APO-1/CD95) is a type I membrane protein that is capable of initiating an apoptosis signaling pathway when bound to its ligand (FasL). We undertook this study to test the hypothesis that Fas-FasL-mediated apoptosis plays a role in IL-12-induced tumor regression. METHODS: An mIL-12 expression vector driven by cytomegalovirus promoter was used to express murine IL-12 cDNA in the RM-9 murine prostate carcinoma cell line. Control RM-9 cells and RM-9 cells stably transfected with IL-12 gene (RM-9-IL12) were inoculated subcutaneously in 4- to 6-week-old male C57BL/J6 mice. Tumor size was measured every 3 days. Western blot and immunohistochemical assays were used to evaluate Fas and FasL protein expression. In situ fluorescent end labeling was used to label apoptotic cells. RESULTS: IL-12-expressing RM-9 prostate carcinoma cells transplanted into C57BL/J6 mice grew more slowly than control RM-9 cells and vector control RM-9-Luc cells. The average survival time of the RM-9-IL12 mice was longer than 53 days, whereas the mean survival for mice transplanted with control RM-9 cells was only 16 days. Apoptotic cells were more numerous in RM-9-IL12 tumors: 10.3% vs. 1.5% in control (P = 0.001). Fas and FasL proteins were increased approximately twofold in the RM-9-IL12 tumors compared with the RM-9 control tumors as determined by Western blot and immunohistochemical analyses (P < 0.05). CONCLUSION: The Fas-FasL-mediated apoptosis pathway may contribute to the IL-12-induced rejection of prostate carcinoma.

Animals↗

PubMed2002

Fas and Fas ligand expression is elevated in prostatic intraepithelial neoplasia and prostatic adenocarcinoma.

BACKGROUND: Fas is a Type I membrane receptor of the tumor necrosis factor/nerve growth factor family. On binding to Fas ligand, a Type II transmembrane protein, the Fas/Fas ligand complex, induces apoptosis in target cells. Dysregulation of Fas and Fas ligand expression has been found in some malignant neoplasms. METHODS: Using immunohistochemical analysis, the authors studied the expression of Fas and Fas ligand in prostatic adenocarcinoma, high-grade prostatic intraepithelial neoplasia (PIN), and adjacent benign prostate tissue from 95 radical prostatectomy specimens. RESULTS: The percentage of cells that stained positively with Fas in benign prostate tissue (mean, 2%) was statistically significantly lower compared with that in prostatic intraepithelial neoplasia (mean, 13%; P = 0.0014) and prostatic adenocarcinoma (mean, 31%; P = 0.0001). The staining intensity of Fas was significantly less in benign prostate tissue compared with the staining intensity in PIN and prostatic adenocarcinoma. The percentage of cells that stained positively with Fas ligand in benign prostate tissue (mean, 13%) was statistically significantly lower compared with that in PIN (mean, 47%; P = 0.0001) and in prostatic adenocarcinoma (mean, 53%; P = 0.0001). The staining intensity of Fas ligand was significantly less in benign prostate tissue compared with that in PIN and prostatic adenocarcinoma. CONCLUSIONS: Data from the current study indicate that Fas/Fas ligand is elevated in prostatic malignancy, suggesting that Fas-mediated apoptosis may be a potential target for therapeutic intervention.

Adenocarcinoma↗

PubMed2002

Relative promoter strengths in four human prostate cancer cell lines evaluated by particle bombardment-mediated gene transfer.

BACKGROUND: The particle bombardment (gene gun) method for gene transfer provides a new and efficient means for transfection of various cell types in culture. In this study we evaluate its application to human prostate tumor cells. METHODS: Transient expression of the firefly luciferase gene driven by five viral and five cellular promoters was assessed after in vitro gene transfer using the gene gun method. The relative strengths of these promoters were quantitatively determined in four different human prostate tumor cell lines: DU145, PC-3, LNCaP, and CWR22Rv1 cells. In situ histochemical staining of cells, transfected with bacterial beta-galactosidase cDNA as a reporter gene, was also performed to evaluate the transfection efficiency. Time course of gene expression was determined using the luciferase reporter gene. RESULTS: The peak levels of transient expression of firefly luciferase are observed within 24 hr after gene transfer. Sustained but reduced luciferase levels were also detected as long as 5 days post transfection. Up to 35% of bombarded cells in vitro were found to express transgenic beta-galactosidase activity. Among tested viral promoters, cytomegalovirus early enhancer/promoter activity was observed to confer consistently the highest activity in each test cell line, whereas phosphoglycerate kinase gene promoter possessed the highest activity among the cellular promoters tested. CONCLUSIONS: The particle bombardment gene-transfer technology can be effectively employed as an efficient method for in vitro gene-transfer into prostate tumor cells. The characterization of relative promoter strength and preference may be useful for future studies of cancer gene therapy approaches.

Biolistics↗

PubMed2002

A novel targeting modality to enhance adenoviral replication by vitamin D(3) in androgen-independent human prostate cancer cells and tumors.

We report the development of a novel replication-competent adenoviral vector, Ad-hOC-E1, containing a single bidirectional human osteocalcin (hOC) promoter to drive both the early viral E1A and E1B gene. This vector selectively replicated in OC-expressing but not non-OC-expressing cells, with viral replication enhanced at least 10-fold on vitamin D(3) exposure. Both the artificial TATA-box and hOC promoter element in this bidirectional promoter construct were controlled by a common OC regulatory element which selectively activated OC expression in cells. The expression ofE1A and E1B gene by Ad-hOC-E1 can be markedly induced by vitamin D(3). Unlike Ad-sPSA-E1, an adenoviral vector with viral replication controlled by a strong super prostate-specific antigen (sPSA) promoter which only replicates in PSA-expressing cells with androgen receptor (AR), Ad-hOC-E1 retarded the growth of both androgen-dependent and androgen-independent prostate cancer cells irrespective of their basal level of AR and PSA expression. A single i.v. administration of 2 x 10(9) plaque-forming units of Ad-hOC-E1 inhibited the growth of previously established s.c. DU145 tumors (an AR- and PSA-negative cell line). Viral replication is highly enhanced by i.p. administration of vitamin D(3). Ultimately, enhancing Ad-hOC-E1 viral replication by vitamin D(3) may be used clinically to treat localized and osseous metastatic prostate cancer in men.

Adenoviridae↗

PubMed2002

Novel prostate-specific promoter derived from PSA and PSMA enhancers.

The expression of prostate-specific membrane antigen (PSMA) and prostate-specific antigen (PSA), two well characterized marker proteins, remains highly active in the hormone refractory stage of prostate cancer. In this study, an artificial chimeric enhancer (PSES) composed of two modified regulatory elements controlling the expression of PSA and PSMA genes was tested for its promoter activity and tissue specificity using the reporter system. As a result, this novel PSES promoter remained silent in PSA- and PSMA-negative prostate and non-prostate cancer cell lines, but mediated high levels of luciferase in PSA- and PSMA-expressing prostate cancer cell lines in the presence and absence of androgen. To determine whether PSES could be used for in vivo gene therapy of prostate cancer, a recombinant adenovirus, Ad-PSES-luc, was constructed. Luciferase activity in prostate cancer cell lines mediated by Ad-PSES-luc was 400- to 1000-fold higher than in several other non-prostate cell lines, suggesting the high tissue-specificity of the PSES promoter in an adenoviral vector. Finally, recombinant virus Ad-PSES-luc was injected into mice to evaluate the tissue-discriminatory promoter activity in an experimental animal. Unlike Ad-CMV-luc, the luciferase activity from systemic injection of Ad-PSES-luc was fairly low in all major organs. However, when injected into prostate, Ad-PSES-luc drove high luciferase activity almost exclusively in prostate and not in other tissues. Our results demonstrated the potential use of PSES for the treatment of androgen-independent prostate cancer patients.

Adenoviridae↗

PubMed2002

Prostate cancer gene therapy: past experiences and future promise.

Gene therapy has been used to target prostate cancer with excellent pre-clinical efficacy but limited clinical efficacy. The concept of delivering genetic material to prostate cancer cells to alter their phenotype and ultimately their behavior has been demonstrated in the laboratory over the last decade. Translating those pre-clinical findings into novel therapies for prostate cancer has been difficult. The stigma of gene therapy and the aggressive regulation of clinical trials involving transfer of genetic material to patients are two major impediments to clinical successes in gene therapy. This review hopes to provide a snapshot of prior gene transfer protocol findings and forecast the exciting future directions investigators are heading.

Animals↗

PubMed2002

Adenovirus-mediated suicide-gene therapy in an orthotopic murine bladder tumor model.

BACKGROUND: Patients with high-grade transitional-cell carcinoma (TCC) of the bladder frequently experience recurrence and progress and have a low response rate to chemotherapy in metastatic TCC. In this study, we evaluated the feasibility and long-term efficacy of suicide-gene therapy using adenovirus (Ad)-mediated herpes simplex virus thymidine kinase gene (HSV-TK) and prodrug ganciclovir (GCV) as a potential therapeutic approach in murine-orthotopic models of TCC. METHODS: A replication defective adenoviral vectors containing toxic HSV-TK gene under the transcriptional control of RSV (Rous sarcoma virus) promoter (Ad-RSV-TK) was used. Orthotopic bladder TCC was established with 1 x 106 murine (MBT-2) TCC cells in syngenic C3H/He female mice. Intratumoral injection of Ad-RSV-TK in combination with GCV (20 mg/kg body weight/day i.p. b.i.d. x 7 days) was administered in vivo for the determination of treatment efficacy and long-term host survival in separate controlled experiments. RESULTS: In vivo experiments demonstrated greater than three-fold reductions in MBT-2 tumor growth for the animals treated with Ad-RSV-TK (5 x 108 plaque forming units (pfu)/GCV therapy (P < 0.01)). Central tumor necrosis and apoptosis were revealed by histomorphology and immunohistochemistry compared with other control animals (non-treated, GCV alone, Ad-RSV-TK alone). Direct intratumoral injection with Ad-RSV-TK/GCV also resulted in significantly improved survival over the control groups in separated experiment (log-rank test, P < 0.05). CONCLUSIONS: Suicide-gene therapy using Ad-RSV-TK/GCV provides an effective therapy in an experimental murine orthotopic bladder cancer by significantly inhibiting tumor growth and improving long-term host survival.

Adenoviridae↗

PubMed2001

Regulation of human osteocalcin promoter in hormone-independent human prostate cancer cells.

Osteocalcin (OC) is a small (6 kDa) polypeptide whose expression was thought to be limited to mature osteoblasts. The discovery of OC expression in prostate cancer specimens led us to study the regulation of OC gene in androgen-independent metastatic human prostate PC3 cells. An 800-bp human OC (hOC) promoter-luciferase construct exhibited strong basal and vitamin D-induced activity in OC-positive human prostate and osteosarcoma cell lines. Through deletion analysis of the hOC promoter, the functional hierarchy of the cis-acting elements, OSE1, OSE2, and AP-1/VDRE, was established in PC3 cells (OSE1 > AP-1/VDRE > OSE2). By juxtaposing dimers of these 3 cis-elements, we produced a minimal hOC promoter capable of displaying high tissue specific activity in prostate cancer cells. Our study demonstrated three groups of transcription factors, Runx2, JunD/Fra-2, and Sp1, responsible for the high hOC promoter activity in PC3 cells by binding to the OSE2, AP-1/VDRE, and OSE1 elements, respectively. Among the three groups of transcription factors, the expression levels of Runx2 and Fra-2 are higher in the OC-positive PC3 cells and osteoblasts, compared with the OC-negative LNCaP cells. Interestingly, unlike the mouse OC promoter, the OSE1 site in hOC promoter is regulated by members of Sp1 family instead of the osteoblast-specific factor Osf1. The molecular basis for androgen-independent prostate cancer cells behaving like mature osteoblasts may be explained by the interplay and coordination of these transcription factors under the tight regulation of autocrine and paracrine mediators.

Base Sequence↗

PubMedDate not supplied

Current status of anti-angiogenesis therapy for prostate cancer.

Prostate cancer is the second leading cause of cancer mortality in American men and the single most diagnosed cancer in men. Despite advances in early detection and conventional treatment strategies, prostate cancer progresses and becomes resistant to treatment. Because tumor growth and establishment of metastases are dependent on angiogenesis, interest in the development of anti-angiogenesis therapies has grown. Preclinical studies and early clinical evaluation show promise in the adjunctive use of anti-angiogenesis to overcome the limitations of current therapeutic approaches. In this review, we outline the basic science principles of angiogenesis and their application in the development of anticancer therapies.

Angiogenesis Inhibitors↗

PubMedDate not supplied

Expression of osteocalcin in prostate cancer before and after hormonal therapy.

BACKGROUND: Osteocalcin (OC), a noncollagenous bone matrix protein, is specifically produced by osteoblasts. Previously, we demonstrated that OC immunohistochemical staining was found in primary prostate cancer (PC) and PC metastasis to lymph node and bone. Advanced and metastatic PC is commonly treated by hormonal therapy (H/T). Inevitably, these patients will relapse and develop hormone-refractory (HR) PC. The aim of this study was to realize the OC expression in PC before H/T and after H/T when HRPC developed. MATERIALS AND METHODS: Twenty patients with PC received H/T and later developed HRPC. The interval of androgen-response was classified by good response (Group A, > or = 30 months) and poor response (Group B, < 30 months). The mean interval of androgen-response was 48.8 months in Group A (10 patients) and 17.5 months in Group B (10 patients). Formalin-fixed paraffin-embedded PC before H/T and HRPC for each patient were stained for osteocalcin. RESULTS: Osteocalcin immunohistochemical stain was detected in 18 of 20 PC before H/T and 19 of 20 of HRPC. Compared to PC before H/T, the expression of OC in HRPC increased in 5 cases (4 of Group A, 1 of Group B), did not change in 3 (2 of Group A, 1 of Group B) and decreased in 12 (4 of Group A, 8 of Group B). CONCLUSION: Our data suggest the expression of OC in PC is not correlated to the response of H/T. OC expression was still noted in 95% of HRPC. OC may be a target for treatment of HRPC.

Aged↗

PubMedDate not supplied

Androgen withdrawal inhibits tumor growth and is associated with decrease in angiogenesis and VEGF expression in androgen-independent CWR22Rv1 human prostate cancer model.

Recent evidence suggests that androgens stimulate growth of human prostate cancer partly by regulating expression of growth factors such as vascular endothelial growth factor (VEGF) in vitro and in vivo. In this study, we used CWR22Rv1, a novel androgen-responsive but androgen-independent human prostate cancer model, to evaluate the effect of androgen withdrawal on tumor growth, expression of VEGF and the cell proliferation marker Ki-67, and angiogenesis. A time-release testosterone pellet was implanted three days before inoculation of CWR22Rv1 cells in the mice. The tumor volumes were measured every three days. Serum PSA was measured on days 1, 12, 20, 27 and 34 post inoculation. Castration was performed on the 20th day post inoculation. Immunohistochemical assays were used to evaluate cell proliferation and microvessel density. Enzyme-linked immunosorbent assay (ELISA) was used to quantify VEGF expression. The average tumor volumes in the castration group on the 27th and 34th days were 122 and 168 mm3, respectively, compared to 156 and 210 mm3 in the non-castration group (p<0.01). Serum PSA level in the castration group decreased to about 41% of the level of the non-castration group (p<0.01). The VEGF protein levels in the tumors of castrated and non-castrated mice on day 34 were 0.62 pg and 1.36 pg/100 microg total protein, respectively (p<0.001). The mean percentage of Ki-67-positive tumor cells in the castrated and non-castrated groups were 1.8% and 2.8%, respectively (p=0.015). The mean microvessel densities in the castrated and non-castrated groups were 15 and 22 vessels/field, respectively (p<0.01) We conclude androgen withdrawal reduced both VEGF and microvessel density, and this was associated with decreased cellular proliferation in androgen-independent CWR22Rv1 human prostate cancer tumor in vivo.

Androgens↗