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W D Heston

Publications and source records attributed to W D Heston.

At least 55 records · Page 3Linked to original sources
PubMed1995

Localization and physical mapping of the prostate-specific membrane antigen (PSM) gene to human chromosome 11.

The prostate-specific membrane antigen (PSM) was identified by the monoclonal antibody 7E11-C5.3, which was raised against the human prostatic carcinoma cell line LNCaP (3). The PSM antigen is expressed by normal, neoplastic, and metastatic prostatic tissues. The 2.65-kb cDNA encoding the 100-kDa PSM glycoprotein was cloned from LNCaP cells (4). Studies have shown that the expression of PSM is tissue-specific (5). In the present study monochromosomal somatic cell hybrids were used to localize the PSM gene to human chromosome 11. Using this information, initial mapping studies identified two potential PSM gene loci at 11p11.1-p13 and 11q14. Further high-stringency analysis using cosmid probes identified the 11q14 region as the location of the PSM gene.

Antigens, Neoplasm↗
PubMed1995

Decreased growth of established human prostate LNCaP tumors in nude mice fed a low-fat diet.

BACKGROUND: Geographic variation in the incidence of clinically detected prostate cancer is considerable, with a 120-fold greater incidence in the United States than in China. The incidence of latent prostate cancer, however, shows little variation worldwide, with approximately 30% of men older than age 50 years having microfocal disease (determined by autopsy). Some epidemiologic studies have suggested that a high intake of dietary fat may constitute a risk factor for the development of advanced prostate cancer. PURPOSE: We studied the influence of dietary fat content on the growth of tumors established in athymic nude mice with androgen-sensitive, human prostatic adenocarcinoma cells (LNCaP cells). We also investigated whether manipulation of dietary fat content altered prostate-specific antigen (PSA) production by these tumors. METHODS: Tumors were induced in nude mice by subcutaneous injection of 10(6) LNCaP cells. Both the American Type Culture Collection (ATCC) LNCaP cell line and a more androgen-responsive subline derived from it (i.e., the Harris LNCaP cell line) were used. Mice were fed a 40.5-kcal% fat diet at the time of tumor cell injection. Three weeks later, after measurable tumors were formed, the animals were assigned to receive diets with one of the following fat contents: 40.5, 30.8, 21.2, 11.6, or 2.3 kcal% fat. Food intake, animal weights, and tumor volumes were recorded weekly; serum PSA and testosterone levels were measured at the termination of the study. Post hoc multiple comparisons were made using the Student-Newman-Keuls procedure. Two-sided tests of statistical significance were used to evaluate pairwise comparisons. RESULTS: Tumor growth rates, final tumor weights, and ratios of final tumor weights to animal weights were substantially greater in groups that continued to receive a 40.5-kcal% fat diet than in groups whose diets were changed to 2.3 kcal%, 11.6 kcal%, or 21.2 kcal% fat (all P values < .04). Comparison of these parameters among the 2.3-kcal%, 11.6-kcal%, and 21.2-kcal% dietary fat groups did not reveal any statistically significant differences. No statistically significant differences were noted in total ingested calories, animal weight gain, serum testosterone levels, or histopathologic characteristics of the tumors among the tested dietary groups. Serum PSA levels were highest in the 40.5-kcal% fat group and lowest in the 2.3-kcal% fat group (evaluated only for ATCC LNCaP cells; P < .05). CONCLUSIONS: Reduction of dietary fat substantially slows the growth of tumors established from human prostatic adenocarcinoma cells in a murine xenograft model. A positive association persists between tumor volumes and serum PSA levels even after extreme modification of dietary fat content.

Adenocarcinoma↗
PubMed1995

Alternatively spliced variants of prostate-specific membrane antigen RNA: ratio of expression as a potential measurement of progression.

We examined expression of prostate-specific membrane antigen (PSM) mRNA in normal prostate using reverse transcription-PCR and sequencing. An alternatively spliced variant, PSM', along with the previously described PSM form, was found in normal prostate. PSM' cDNA is shorter (2387 nucleotides) than PSM (2653 nucleotides). The cDNAs are identical except for a 266-nucleotide region near the 5' end of PSM cDNA (nucleotide 114-380) that is absent from PSM'. This deleted region includes the translation initiation codon and codons for the putative transmembrane domain of PSM. Thus, PSM' RNA codes for a protein that has no apparent signal sequence. We verified the existence of spliced mRNA variants in human primary tissue specimens by RNase protection assay. In LNCaP human prostatic cancer cells and in primary prostate tumors, PSM is the dominant form. In contrast, normal human prostate expressed more PSM' than PSM. Benign prostatic hypertrophy samples showed about equal expression of both variants. We quantified the relative expression of each variant by densitometry and compiled a tumor index, which is the ratio of PSM:PSM' level. LNCaP has an index ranging from 9-11, carcinoma of the prostate from 3-6, benign prostatic hypertrophy from 0.75-1.6, and normal prostate from 0.075-0.45. The index reflects the increased expression of PSM over PSM' following the progression from normal to tumor state. This tumor index may be a useful indicator for the measurement of tumor progression. PSM and PSM' may be functionally different proteins as a result of differences in structure or cellular location. We are investigating the prevalence of one form over the other and how it may influence tumor progression.

Alternative Splicing↗
PubMed1995

Reversal by transferrin of growth-inhibitory effect of suramin on hormone-refractory human prostate cancer cells.

BACKGROUND: The second leading cause of cancer-related deaths in American men is metastatic hormone-refractory adenocarcinoma of the prostate, for which there is currently no effective treatment. Transferrin is abundant in bone stroma and has been found to stimulate models of hormone-refractory metastatic prostate cancer. Suramin, a compound that has been used to treat metastatic prostate cancer, has been demonstrated to antagonize the binding of transferrin to the transferrin receptor and to suppress uptake of iron by hematopoietic cells. PURPOSE: The purpose of our study was to determine whether transferrin may reverse the inhibitory action of suramin on metastatic prostate-derived cell lines. METHODS: Five human prostate cell lines (PC-3, PC-3M, DU-145, TSU-Pr1, and LNCaP) derived from metastatic deposits were examined for response to growth stimulation by apotransferrin, for the presence of transferrin receptors by binding of 125I-labeled transferrin, and for relative transferrin receptor messenger RNA (mRNA) content by ribonuclease protection assays. We measured the amount of growth inhibition by suramin in low serum assays to demonstrate maximal inhibition over the apotransferrin to reverse the inhibition of suramin in these tumors. RESULTS: The results clearly demonstrate that the androgen-insensitive metastatic cell lines (PC-3, PC-3M, DU-145, and TSU-Pr1) demonstrate increased cell numbers when exposed to holotransferrin or apotransferrin, while the androgen-sensitive cell line (LNCaP) did not show any increase. All cell lines demonstrated a similar number of transferrin receptors and transferrin receptor mRNA. We used these maximally inhibitory, but clinically relevant, concentrations of suramin to determine whether transferrin could reverse the inhibition, and it did, but only in the androgen-insensitive metastatic lines. Indeed, in the PC-3 cells, inhibition turned to stimulation with the addition of transferrin, and even at the highest concentration of suramin tested, 400 microM, a concentration that would be toxic to patients, the amount of inhibition by suramin was still reduced by more than 50% by transferrin in TSU-Pr1 cells. In the androgen-sensitive LNCaP cells, however, transferrin had limited ability to block the inhibitory activity of suramin. CONCLUSIONS: Concentrations of tumor-stimulating factors, such as transferrin, in the metastatic microenvironment need to be taken into consideration in the use of suramin and suramin-like derivatives. Novel strategies need to be identified that will negate the action of transferrin on androgen-insensitive cells.

Androgens↗
PubMed1995

Sensitive detection of prostatic hematogenous tumor cell dissemination using prostate specific antigen and prostate specific membrane-derived primers in the polymerase chain reaction.

We developed a polymerase chain reaction based assay enabling sensitive detection of hematogenous tumor cell dissemination in patients with prostate cancer. We performed "nested polymerase chain reaction," amplifying messenger ribonucleic acid sequences unique to prostate specific antigen (PSA) and to the prostate specific membrane antigen, and compared the respective results. Prostatic tumor cells were detected in 2 of 30 patients (6.7%) by polymerase chain reaction with PSA derived primers, while prostate specific membrane primers detected tumor cells in 19 (63.3%). All 16 negative controls had negative PSA and prostate specific membrane polymerase chain reaction. Assays were repeated to confirm results, and polymerase chain reaction products were verified by deoxyribonucleic acid sequencing and Southern analysis. Patients harboring circulating prostatic tumor cells as detected by prostate specific membrane and not by PSA polymerase chain reaction included 7 of 13 previously treated by radical prostatectomy who had nonmeasurable serum PSA levels at the time of this assay. The significance of these findings with respect to future disease recurrence and progression will be investigated.

Base Sequence↗
PubMed1995

Characterization of reactive versus tumor-bearing lymph nodes with interstitial magnetic resonance lymphography in an animal model.

RATIONALE AND OBJECTIVES: To determine if magnetic resonance lymphography performed with subcutaneously administered AMI-227, a nanoparticulate iron oxide contrast agent, can distinguish reactive from tumor-bearing lymph nodes. MATERIALS AND METHODS: Mature male Copenhagen rats were inoculated with cell suspensions of R3327-MAT-LyLu rat prostate carcinoma (n = 21) or Freund's complete adjuvant (n = 15) in the left footpad to generate ipsilateral popliteal lymph node metastases or lymphadenitis. At 12 to 14 days after inoculation, T1-and T2-weighted magnetic resonance images of bilateral popliteal areas were obtained before and 24 hours after subcutaneous administration of AMI-227. Contrast-to-noise ratios were calculated in precontrast and postcontrast images. Bilateral popliteal nodes were excised for pathologic assessment. RESULTS: AMI-227 resulted in decreased contrast-to-noise ratios in reactive (T1-W = -7.01 +/- 1.13, T2- W = -31.64 +/- 5.35) and normal (T1 - W = -13.56 +/- 1.97, T2 - W = -21.62 +/- 2.51) nodes. Contrast-to-noise ratios were unchanged (T1 - W = -0.22 +/- 1.71, T2 - W = -2.20 +/- 4.19) in tumor-containing nodes. These differences in contrast-to-noise ratio changes between tumor-bearing versus nontumor-bearing nodes were statistically significant (P < 0.05). Histologic analysis showed similar distribution of AMI-227 within normal and reactive nodes, but not in tumor-bearing nodes. CONCLUSIONS: Differences in AMI-227-uptake between tumor- and nontumor-bearing nodes detected with magnetic resonance imaging are helpful for distinguishing the two entities.

Animals↗
PubMed1994

Immunotherapy of bladder cancer with cytokine gene-modified tumor vaccines.

This study explored the use of cytokine gene-modified tumor cells as cellular vaccines for the treatment of bladder cancer. The mouse MBT-2 tumor is an excellent model for human bladder cancer. This carcinogen-induced tumor of bladder origin resembles human bladder cancer in its etiology and histology and responds to treatment in a manner similar to that of its human counterpart. In a previous study we have shown that interleukin 2 (IL-2)-secreting, irradiated, MBT-2 cell preparations were capable of curing animals from orthotopically established tumors and engendered protective immunological memory in the cured animals. In this study we have compared the effectiveness of several cytokines and found that while IL-1 alpha, IL-1 beta, and gamma-interferon were only weakly effective in the therapeutic vaccination protocol, granulocyte-macrophage colony-stimulating factor was almost as effective as but not superior to IL-2, as reported previously for another tumor model system. Induction of cytotoxic T-lymphocyte correlated only poorly with the therapeutic benefit of the cytokine gene-modified tumor cell preparations, questioning its prognostic value for the development of improved genetically modified tumor vaccines.

Animals↗
PubMed1994

Expression of the prostate-specific membrane antigen.

We have recently cloned a 2.65-kilobase complementary DNA (cDNA) encoding the prostate-specific membrane antigen (PSM) recognized by the 7E11-C5.3 anti-prostate monoclonal antibody. Immunohistochemical analysis of the LNCaP, DU-145, and PC-3 prostate cancer cell lines for PSM expression using the 7E11-C5.3 antibody reveals intense staining in the LNCaP cells with no detectable expression in both the DU-145 and PC-3 cells. Coupled in vitro transcription/translation of the 2.65-kilobase full-length PSM cDNA yields an M(r) 84,000 protein corresponding to the predicted polypeptide molecular weight of PSM. Posttranslational modification of this protein with pancreatic canine microsomes yields the expected M(r) 100,000 PSM antigen. Following transfection of PC-3 cells with the full-length PSM cDNA in a eukaryotic expression vector, we detect expression of the PSM glycoprotein by Western analysis using the 7E11-C5.3 monoclonal antibody. Ribonuclease protection analysis demonstrates that the expression of PSM mRNA is almost entirely prostate specific in human tissues. PSM expression appears to be highest in hormone-deprived states and is hormonally modulated by steroids, with 5-alpha-dihydrotestosterone down-regulating PSM expression in the human prostate cancer cell line LNCaP by 8-10-fold, testosterone down-regulating PSM by 3-4-fold, and corticosteroids showing no significant effect. Normal and malignant prostatic tissues consistently show high PSM expression, whereas we have noted heterogeneous, and at times absent, expression of PSM in benign prostatic hyperplasia. LNCaP tumors implanted and grown both orthotopically and s.c. in nude mice abundantly express PSM, providing an excellent in vivo model system to study the regulation and modulation of PSM expression.

Adrenal Cortex Hormones↗
PubMed1994

Immunotherapy of prostate cancer in the Dunning rat model: use of cytokine gene modified tumor vaccines.

Adenocarcinoma of the prostate is the most common cancer in men. The majority of cancers are discovered once they have already metastasized, and there is no effective therapy for prostatic cancer at this stage. The use of cytokine-secreting tumor cell preparations as therapeutic vaccines for the treatment of advanced prostate cancer was investigated in the Dunning rat R3327-MatLyLu prostatic tumor model. IL-2 secreting, irradiated, tumor cell preparations were capable of curing animals with s.c. established tumors, and induced immunological memory that protected animals from subsequent tumor challenge. Immunotherapy was less effective when tumors were induced orthotopically, but nevertheless led to improved outcome, significantly delaying, and occasionally preventing, recurrence of tumors after resection of the cancerous prostate. Granulocyte-macrophage colony stimulating factor secreting tumor cell preparations were less effective, and interferon-gamma secreting cells had only a marginal effect. Induction of a potent immune response in tumor bearing animals against the nonimmunogenic MatLyLu tumor supports the view that active immunotherapy warrants further investigation as a potential therapeutic approach to prostate cancer.

Adenocarcinoma↗
PubMed1994

TRPM-2 gene expression in normal rat ventral prostate following castration and exposure to diethylstilbestrol, flutamide, MK-906 (finasteride), and coumarin.

TRPM-2, not normally expressed in the rat ventral prostate, has been identified as an important genetic marker of castration-induced apoptotic cell death. It is not known whether other agents capable of causing growth inhibition of the rat ventral prostate also induce TRPM-2 expression. To investigate this further, 270 mature Sprague-Dawley rats were randomized into one of six groups: control, castration, diethylstilbestrol (DES), flutamide, MK-906 (finasteride), or coumarin. Five rats per group were sacrificed on days 1, 3, 5, 7, 10, and 21. Serum testosterone, body weights, and prostate weights were determined at each time point. The ventral prostate was removed and cellular RNA extracted. Northern blot analysis using cDNA probes for TRPM-2 and gamma-actin were performed at each time point. Only DES significantly decreased rat weights. DES and castration reduced serum testosterone to undetectable levels by the next day. Flutamide caused a 3.0- to 4.5-fold increase in serum testosterone above control. Coumarin and MK-906 did not affect serum testosterone levels. DES and castration reduced prostate weights to 20% and 6% of control, respectively, while inducing TRPM-2 expression to a maximum on day 5 of the experiment. DES induced TRPM-2 expression over a longer duration than did castration, suggesting that more than just the decrease of serum testosterone to castrate levels plays a role in the expression of TRPM-2. MK-906, coumarin, and flutamide reduced prostatic weights to a lesser extent (50%, 63%, 71% of control, respectively), but these agents did not induce TRPM-2 expression at any time during the experiment. TRPM-2 expression in the rat ventral prostate does not correlate simply with catabolic effects on the prostate.

Animals↗
PubMed1994

An experimental model simulating local recurrence and pelvic lymph node metastasis following orthotopic induction of prostate cancer.

In order to develop an animal model that more closely simulates the organ environment and metastatic routes of human prostatic cancer, R3327-MatLyLu tumors were induced by orthotopic implantation in the ventral prostatic lobe of Copenhagen rats. This procedure reproducibly resulted in metastatic spread of the intraprostatic tumor to the pelvic and retroperitoneal lymph nodes, and invariably to the lungs. Further, a tumor recurrence model was established using an approach that combined orthotopic tumor implantation and subsequent surgical resection of the primary tumor. When prostatectomy was carried out 4 days or more after induction, tumors recurred locally in all animals. The surgical procedures described may provide an animal model to test the in vivo response to experimental adjuvant treatment protocols for advanced prostate cancer. Immunological studies are now in progress using cytokine gene-modified prostatic tumor cells as cellular antitumor vaccines in orthotopically established R3327-MatLyLu tumors.

Animals↗
PubMed1994

AMI-227-enhanced MR lymphography: usefulness for differentiating reactive from tumor-bearing lymph nodes.

PURPOSE: To determine the value of magnetic resonance (MR) lymphography enhanced with AMI-227, a superparamagnetic reticuloendothelial-system-specific contrast agent, to distinguish normal and reactive from tumor-bearing lymph nodes. MATERIALS AND METHODS: Mature male Copenhagen rats were inoculated with cell suspensions of R3327-MATLyLu rat prostate carcinoma (n = 16) or Complete Freund Adjuvant (n = 15) to generate ipsilateral popliteal lymph node metastases or lymphadenitis. At 12-14 days after inoculation, T1- and T2-weighted MR images of bilateral popliteal areas were obtained before and 24 hours after administration of AMI-227 (dose, 30 mumol Fe/kg). The contralateral popliteal nodes served as controls. Contrast-to-noise ratios (C/Ns) between the nodes and adjacent muscle were calculated in pre- and postcontrast images. Subsequently, bilateral popliteal nodes were excised. RESULTS: AMI-227 resulted in decreased C/N in reactive nodes (T1-weighted, -186% +/- 90% [standard deviation]; T2-weighted, -205% +/- 96%) and normal nodes (n = 7) (T1-weighted, -306% +/- 82; T2-weighted, -350% +/- 96). C/N remained unchanged or increased (T1-weighted, 88% +/- 92; T2-weighted, 306% +/- 256) (P < .05). CONCLUSION: Differences in AMI-227 uptake at MR imaging may help differentiate tumor-bearing from nontumor-bearing nodes.

Animals↗
PubMed1994

Differential expression of protein kinase C isozyme messenger RNAs in dunning R-3327 rat prostatic tumors.

Adenocarcinoma of the prostate is the second leading cause of cancer deaths in men. The protein kinase C (PKC) family of signal transducing kinases has been implicated in neoplastic transformation and progression in other tissues, and some evidence suggests roles for PKC in prostate growth and neoplasia. We have detected expression of eight specific PKC isozyme mRNAs (alpha, beta, gamma, delta, epsilon, eta, theta, and zeta) in normal rat whole prostate and found some of these to be differentially expressed in certain Dunning R-3327 rat prostatic adenocarcinoma sublines. PKC zeta mRNA was detected in normal prostate and Dunning H tumor, whereas an alternatively spliced form of PKC zeta RNA was found in Dunning G tumor and normal brain. Both forms of PKC zeta RNA were markedly reduced in the androgen insensitive, highly metastatic Dunning AT-3, MAT-Lu, and MAT-LyLu tumors. We have cloned and report the sequence of the novel portion of the alternatively spliced form of PKC zeta RNA, which is polyadenylated and present in cytoplasm.

Adenocarcinoma↗
PubMed1993

Tumour necrosis factor-induced cytotoxicity is accompanied by intracellular mitogenic signals in ME-180 human cervical carcinoma cells.

Tumour necrosis factor-alpha (TNF) induced a cytotoxic response in ME-180 human cervical carcinoma cells in vitro. This cytotoxic response was accompanied by a temporal series of intracellular signals that are commonly triggered by a mitogenic stimulus: increased c-fos (20-30 min) and c-myc (40-60 min) expression, increased activity of ornithine decarboxylase (3 h), increased intracellular polyamine content (7 h) and increased thymidine incorporation into DNA (14 h). A cytotoxic response independent of these mitogenic signals could not be explained by an induction of interleukin-6, which is an autocrine cytotoxic agent in some cell types; nor by a biphasic, dose-dependent response in which low concentrations of TNF are mitogenic and higher concentrations are cytotoxic. Conversely, a dependent role of these mitogenic signals was suggested by the absence of a TNF-promoted increase in thymidine incorporation into DNA in an ME-180 clone that is resistant to TNF-induced cytotoxicity. A decrease in the proliferation rate of TNF-sensitive cells induced by either alpha-difluoromethylornithine treatment (resulting in polyamine depletion) or serum starvation rendered the cells insensitive to TNF-induced cytotoxicity, further suggesting a role for mitogenic signals and cell division in TNF-mediated cytotoxicity. However, inhibiting proliferation with cycloheximide resulted in increased sensitivity to TNF, implying that mitogenesis itself was not essential for a cytotoxic response. TNF induced DNA fragmentation in sensitive cells, suggesting that cytotoxicity occurred via apoptosis.

Apoptosis↗
PubMed1993

Molecular cloning of a complementary DNA encoding a prostate-specific membrane antigen.

Recently, a novel M(r) 100,000 prostate-specific membrane glycoprotein (PSM) has been detected by the prostate-specific monoclonal antibody 7E11-C5, raised against the human prostatic carcinoma cell line LNCaP. The PSM antigen is expressed exclusively by normal and neoplastic prostate cells and metastases. We now report the molecular cloning of a full-length 2.65-kilobase complementary DNA encoding the PSM antigen from a human LNCaP complementary DNA library by polymerase chain reaction using degenerate oligonucleotide primers. Analysis of the complementary DNA sequence has revealed that a portion of the coding region, from nucleotide 1250 to 1700, has 54% homology to the human transferrin receptor mRNA. The deduced polypeptide has a putative transmembrane domain enabling the delineation of intra- and extracellular portions of this antigen. In contrast to prostate-specific antigen and prostatic acid phosphatase which are secreted proteins, PSM as an integral membrane protein may prove to be effective as a target for imaging and cytotoxic targeting modalities.

Amino Acid Sequence↗
PubMed1991

Prostatic polyamines and polyamine targeting as a new approach to therapy of prostatic cancer.

The prostate is a rich factory of polyamine production. In spite of this, the prostate is also able to accumulate polyamines from the circulation. Intracellular polyamine depletion has been observed to enhance the accumulation of diamines such as putrescine. This needs to be taken advantage of either as a means for imaging prostatic tumour spread to the lymph nodes or as a means of targeting toxins to the prostatic tumour. Putrescine is a small molecule that may prove difficult for use for synthesizing stable toxin derivatives that can take advantage of the targeting potential of the polyamine transporter. The cloning and sequencing characterization of the transporter is under way. When the prostatic transporter is identified, it will be possible to understand the role of the transporter in normal and cancerous prostatic cell growth and functioning and should serve to aid our understanding of how we can better optimize agents to use the transporter for delivery of antitumour agents.

Aziridines↗