Biomedical subjects

Jay E Reeder

Publications and source records attributed to Jay E Reeder.

8 recordsLinked to original sources

PubMed2006

Protein tyrosine phosphatase PTP1B is involved in neuroendocrine differentiation of prostate cancer.

BACKGROUND: Prostate cancer (PC) contains a minor component of neuroendocrine (NE) cells that may stimulate androgen-independent growth of the tumor. The mechanism of neuroendocrine differentiation remains unknown. METHODS: The expression of PTP1B, a protein tyrosine phosphatase, was studied in LNCaP cells induced to show neuroendocrine phenotype by androgen withdrawal. Wild-type PTP1B and its dominant-negative mutant were transfected into LNCaP cells to study their effects on neuroendocrine differentiation. In vivo expression of PTP1B in human prostate cancer was studied by immunohistochemistry. RESULTS: Androgen withdrawal of LNCaP cells led to increased expression of PTP1B with a corresponding increase in its tyrosine phosphatase activity. Overexpression of PTP1B in LNCaP cells led to neuroendocrine differentiation while expression of its dominant-negative mutant inhibited neuroendocrine differentiation. Immunohistochemical study showed that PTP1B was exclusively expressed in neuroendocrine cells of human prostate cancer tissue. CONCLUSION: Our findings suggest that PTP1B plays an important role in neuroendocrine differentiation, and therefore, may possibly be involved in the progression of prostate cancer.

Androgens↗

PubMed2006

Early detection and measurement of urothelial tumors in mice.

OBJECTIVES: To establish reliable noninvasive in vivo methods to detect, measure, and monitor experimentally induced urothelial tumors in mice. METHODS: UPII-SV40T transgenic mice reliably develop bladder tumors by expression of simian virus 40 large T antigen specifically in bladder urothelium through the use of the uroplakin II promoter. Two wild-type and 10 UPII-SV40T transgenic mice were monitored for microhematuria two to three times weekly using dipstick analysis. A unique flat panel detector-based cone beam computed tomography (FPD-CBCT) system imaged the urinary tracts of anesthetized mice after tail vein injection of an iodinated contrast agent (Omnipaque) that is excreted in urine. Within 10 seconds, the FPD-CBCT system acquired 290 two-dimensional images, which produced three-dimensional volumes with true isotropic resolution (180 microm)3 using a filtered back projection-based modified Feldkamp reconstruction algorithm. Amira, version 3.1.1-1, for MacOSX was used for data analysis and advanced visualization of the three-dimensional reconstructed FPD-CBCT images. RESULTS: Hematuria was present in UPII-SV40T transgenic mice at 32 days of age; the wild-type animals exhibited no hematuria. Filling defects, associated with histologically confirmed tumors, in the bladders of the UPII-SV40T transgenic mice were visualized in the reconstructed FPD-CBCT images 1 to 45 minutes after contrast agent injection. Longitudinal FPD-CBCT imaging sessions showed the tumor position, volume, and growth. CONCLUSIONS: The combination of early detection of hematuria and high-resolution in vivo FPD-CBCT imaging of murine bladder tumors enabled accurate longitudinal assessment of tumor growth and progression in individual animals. This approach could provide an important alternative to serial sacrifice experimental designs, while refining statistical power and reducing animal use.

Animals↗

PubMed2005

Differential expression of interleukin-8 and its receptors in the neuroendocrine and non-neuroendocrine compartments of prostate cancer.

Hormonal therapy (androgen ablation and/or inhibition of androgen action) is the treatment of choice for advanced prostate cancer. After an initial response in most patients, tumors invariably progress to an androgen-independent state. It is unclear how prostate cancer cells proliferate without androgen. Recent studies suggest that interleukin-8 may promote androgen-independent proliferation, but the source of interleukin-8 in the prostate is unknown. Using immunohistochemistry, we show that interleukin-8 was expressed by the neuroendocrine tumor cells in human prostate cancer tissue. Expression of the interleukin-8 receptor CXCR1 was negative or low in benign prostatic tissue and was frequently increased in malignant cells of high-grade prostatic intraepithelial neoplasia and prostate cancer; however, CXCR1 was not detected in the neuroendocrine tumor cells, suggesting a paracrine mechanism by which interleukin-8 produced by neuroendocrine tumor cells stimulates androgen-independent proliferation of prostate cancer. Neuroendocrine tumor cells expressed another type of interleukin-8 receptor, CXCR2, suggesting an autocrine mechanism by which interleukin-8 regulates the differentiation or function of the neuroendocrine cells. These results, combined with previous reports that neuroendocrine differentiation is induced by hormonal therapy, suggest that neuroendocrine cells play an important role in promoting androgen-independent growth of prostate cancer through interleukin-8 signaling.

Carcinoma, Neuroendocrine↗

PubMed2004

Interstitial cystitis antiproliferative factor (APF) as a cell-cycle modulator.

BACKGROUND: Interstitial cystitis (IC) is a chronic bladder disorder of unknown etiology. Antiproliferative factor (APF), a peptide found in the urine of IC patients, has previously been shown to decrease incorporation of thymidine by normal bladder epithelial cells. This study was performed to determine the effect of APF on the cell cycle of bladder epithelial cells so as to better understand its antiproliferative activity. METHODS: Explant cultures from normal bladder biopsy specimens were exposed to APF or mock control. DNA cytometry was performed using an automated image analysis system. Cell cycle phase fractions were calculated from the DNA frequency distributions and compared by two-way analysis of variance (ANOVA). RESULTS: APF exposure produced statistically significant increases in the proportion of tetraploid and hypertetraploid cells compared to mock control preparations, suggesting a G2 and/or M phase cell cycle block and the production of polyploidy. CONCLUSIONS: APF has a specific effect on cell cycle distributions. The presence of a peptide with this activity may contribute to the pathogenesis of interstitial cystitis through disruption of normal urothelial proliferation and repair processes.

Adult↗

PubMed2004

DBCCR1 mediates death in cultured bladder tumor cells.

Chromosome 9, which is often partially or fully reduced to homozygosity in bladder cancer cells, harbors several tumor suppressor loci including deleted in bladder cancer chromosome region 1 (DBCCR1) at 9q32-33. To study DBCCR1 function, stable cell lines, inducible for DBCCR1 expression by tetracycline, were made, but the DBCCR1 protein was not expressed at detectable levels. To understand the fate of DBCCR1-expressing cells, human bladder tumor cells were transiently transfected with an expression vector containing DBCCR1 fused to enhanced green fluorescent protein (EGFP). Initially, DBCCR1-EGFP-expressing cells demonstrated diffuse cytoplasmic green fluorescence with nuclear exclusion patterns. After time, the intensity level of green fluorescence increased and a granular distribution of protein became visible in the cells. At this point, cells rounded up and detached from the tissue culture dish. Cells transfected with a control vector, containing only EGFP, and partial DBCCR1-EGFP fusion constructs did not demonstrate this behavior. DBCCR1-mediated cell death in cultured tumor cells was independent of caspase-3 activation and did not result in detectable DNA strand breaks by TUNEL staining that are hallmarks of the classical apoptotic pathway.

Animals↗

PubMed2003

Inducible expression of catalytically active type 1 serine/threonine protein phosphatase in a human carcinoma cell line.

BACKGROUND: One of the major cellular serine/threonine protein phosphatases is protein phosphatase type 1 (PP1). Studies employing many eukaryotic systems all point to a crucial role for PP1 activity in controlling cell cycle progression. One physiological substrate for PP1 appears to be the product of the retinoblastoma susceptibility gene (pRB), a demonstrated tumor suppressor. The growth suppressive activity of pRB is regulated by its phosphorylation state. Of critical importance is the question of the in vivo effect of PP1 activity on pRB and growth regulation. As a first step towards addressing this question, we developed an inducible PP1 expression system to investigate the regulation of PP1 activity. RESULTS: We have established a cell line for inducing protein expression of the type 1, alpha-isotype, serine/threonine protein phosphatase (PP1alpha). A plasmid encoding a fusion protein of the catalytic subunit of PP1alpha with a 6-histidine peptide (6His) and a peptide from hemagluttinin (HA) was transfected into the UMUC3 transitional cell carcinoma cell line, previously transfected with the reverse tetracycline transactivator plasmid pUHD172-1neo. A stable cell line designated LLWO2F was established by selection with hygromycin B. 6His-HA-PP1alpha protein appeared in cell lysates within two hours following addition of doxycycline to the culture medium. This protein localizes to the nucleus as does endogenous PP1alpha, and was shown to associate with PNUTS, a PP1-nuclear targeting subunit. Like endogenous PP1alpha, immunocomplexed 6His-HA-PP1alpha is active toward phosphorylase a and the product of the retinoblastoma susceptibility gene, pRB. When forcibly overexpressing 6His-HA-PP1alpha, there is a concomitant decrease in endogenous PP1alpha levels. CONCLUSIONS: These data suggest the existence of an autoregulatory mechanism by which PP1alpha protein levels and activity remain relatively constant. RT-PCR analyses of isolated polysome fractions support the notion that this putative autoregulatory mechanism is exerted, at least in part, at the translational level. Implications of these findings for the study of PP1alpha function in vivo are discussed.

Journal Article↗

PubMed2003

Grade progression and regression in recurrent urothelial cancer.

PURPOSE: Recurrent urothelial cancers are reported to have characteristics similar to those of the primary tumor, with 10% to 25% of low grade tumors recurring as high grade disease. We determined how often grade progression and regression occur and whether abnormalities in p53 protein expression in original tumors are preserved in recurrences. MATERIALS AND METHODS: Two groups of patients treated for recurrent stages Ta/T1 urothelial bladder cancers with at least 1 tumor-free examination between the index and recurrent tumors were reviewed. Group 1 included 115 patients in whom the first available tumor was compared with the last recurrence and group 2 included 42 in whom the initial tumor was compared with the first recurrence. Immunohistochemical analysis of p53 expression was performed on a subset of 34 tumor pairs. RESULTS: In group 1, 33 grade 3 tumors (45%) recurred as grade 1 or 2 tumors, while 9 of 82 grades 1 and 2 tumors (11%) recurred as grade 3 tumors. Five of 7 group 2 grade 3 tumors (71%) recurred as grade 1 or 2 disease, while 1 of 35 grades 1 and 2 tumors (3%) recurred as grade 3 disease. In the 34 pairs studied immunohistochemically 6 of 14 grade 3 tumors recurred at lower grades. Nuclear p53 over expression occurred in 21 index tumors (12 of 14 grade 3, 8 of 17 grade 2 and 1 of 3 grade 1) and in 9 recurrences (6 of 10 grade 3, 2 of 17 grade 2 and 1 of 7 grade 1). Only 7 of 21 p53 positive and 2 of 12 p53 negative index tumors were p53 positive on recurrence. CONCLUSIONS: While progression from low to high grade occurred in less than 15% of patients, grade regression was observed in almost 50%. The loss of p53 positivity in regressing tumors indicates that these recurrences are molecularly distinct from the corresponding initial tumor.

Aged↗

PubMed2002

Increased expression of the acid sphingomyelinase-like protein ASML3a in bladder tumors.

PURPOSE: The function of the tumor suppressor gene DBCCR1 (deleted in bladder cancer chromosome region 1) is unknown despite data supporting an important role for DBCCR1 in bladder tumorigenesis. DBCCR1 has not yet been placed in a protein family or functional pathway. Protein-protein interactions are crucial for almost every aspect of cellular function. We hypothesized that the discovery of DBCCR1 protein binding partners would yield important clues for solving the mystery of DBCCR1 function. MATERIALS AND METHODS: We used the yeast 2-hybrid system to screen an adult human bladder cDNA library for DBCCR1 interacting proteins. RESULTS: In the screen ASML3a (acid sphingomyelinase-like phosphodiesterase 3a) was identified as a novel DBCCR1 binding partner. Transient transfection of bladder tumor cell lines showed that DBCCR1 over expression in human bladder tumor cells results in the up-regulation of ASML3a RNA and protein expression. ASML3a protein was also differentially expressed in 8 of 12 bladder tumors relative to corresponding normal urothelial tissue. CONCLUSIONS: It appears that DBCCR1 and ASML3a are involved in the process of bladder tumorigenesis. Their interaction may provide clues to discern their functions.

3T3 Cells↗