P-glycoprotein increases the efflux of the androgen dihydrotestosterone and reduces androgen responsive gene activity in prostate tumor cells

BACKGROUND

P-glycoprotein (P-gp) is commonly associated with multi-drug resistance (MDR) in cancer cells and the efflux of a broad spectrum of chemicals from the cell, including many chemotherapeutics and certain steroid hormones. The impact of P-gp and mechanisms involved in androgen transport and cellular accumulation within normal and malignant prostate cells remains unclear.

METHODS

Following incubation of LNCaP, PC-3, HeLa, and HeLa FLAG-androgen receptor (AR) cells with (3)H-dihydrotestosterone (DHT) alone and in combination with P-gp inhibitors, PSC-833 and verapamil, we examined the cellular accumulation and efflux of androgens, as well as gene transcriptional response.

RESULTS

Our data reveal that the cellular transport and accumulation of DHT is dependent on the expression of functional AR and modulated by P-gp. P-gp over-expression by both transient transfection and aspirin treatment in LNCaP cells showed decreased intracellular DHT accumulation, further suggesting DHT efflux is P-gp regulated.

CONCLUSIONS

Androgen responsiveness may be modulated by P-gp in prostate cancer cells. The biological consequences of increased P-gp expression are decreased androgen accumulation and a corresponding decrease in androgen-regulated transcriptional activity and PSA gene expression.

Inhibition of cell signaling by the combi-nitrosourea FD137 in the androgen independent DU145 prostate cancer cell line

BACKGROUND

FD137, a nitrosourea appended to a quinazoline ring, was designed to simultaneously block epidermal growth factor receptor (EGFR)-mediated signaling and damage genomic DNA in refractory EGF-dependent prostate tumors.

METHODS

The mixed inhibition of cell signaling and DNA damage by FD137 were determined by Western blotting, RT-PCR, flow cytometry, sulforhodamine B (SRB), and comet assay.

RESULTS

FD137 and its metabolite FD110 induced a dose-dependent increase in inhibition of EGF-stimulated EGFR autophosphorylation and this translated into blockade of c-fos gene expression in DU145 cells. FD137 induced significant levels of DNA damage and showed 150-fold greater anti-proliferative activity than BCNU, a classical nitrosourea. In contrast to BCNU, complete inhibition of EGF-induced cell transition to S-phase was observed at concentrations of FD137 as low as 3 microM.

CONCLUSION

FD137 could not only damage DNA, but also significantly block downstream EGFR-mediated signaling. The superior activity of FD137 may be imputable to the combined effect of its mixed EGFR/DNA targeting properties. This novel strategy may well represent a new approach to target nitrosoureas to EGFR-overexpressing carcinomas of the prostate.

Decreased expression of thyrotropin receptor gene suggests a high-risk subgroup for oncocytic adenoma

OBJECTIVE

The malignancy of thyroid oncocytic tumours, or oncocytomas, is higher than that of follicular tumours. The aim of this study was to investigate the role of thyroid-specific genes in oncocytic tumours and papillary carcinomas.

DESIGN AND METHODS

We compared 29 oncocytic tumours with 12 papillary carcinomas. Real-time quantitative PCR was used to measure the expression of thyroid-specific differentiation markers (thyrotrophin-stimulation hormone receptor (TSHR), thyroglobulin (TG) and Na(+)/I(-) symporter (NIS)), transcription factors (thyroid transcription factor-1 (TTF-1) and paired box gene-8 (PAX8)) and nuclear receptors (peroxisome proliferator-activated receptor (PPARgamma1) and thyroid hormone receptor (TRbeta1)) involved in thyroid carcinogenesis.

RESULTS

TSHR, TTF-1 and TRbeta1 levels were significantly lower in oncocytic tumours than in papillary carcinomas, as a result of specific biological changes in oncocytic tumours. However, PAX8 and PPARgamma1 did not seem to be involved in the process. Applying the criterion of the underexpression of the thyroid-specific differentiation markers, TSHR, TG and NIS, we classified the oncocytic tumours and papillary carcinomas into three groups. In the first, all three markers were underexpressed; in the second, TSHR was normal while TG and NIS were underexpressed; and in the third, only NIS was underexpressed. The expression patterns revealed that 13 of the 24 oncocytic adenomas underexpressing TSHR in our study, as did four of the five oncocytic carcinomas.

CONCLUSION

Cases of oncocytic adenoma associated with low levels of TSHR could be putative oncocytic carcinomas and should therefore receive adequate follow-up [corrected].

Expression microarray reproducibility is improved by optimising purification steps in RNA amplification and labelling

Background

Expression microarrays have evolved into a powerful tool with great potential for clinical application and therefore reliability of data is essential. RNA amplification is used when the amount of starting material is scarce, as is frequently the case with clinical samples. Purification steps are critical in RNA amplification and labelling protocols, and there is a lack of sufficient data to validate and optimise the process.

Results

Here the purification steps involved in the protocol for indirect labelling of amplified RNA are evaluated and the experimentally determined best method for each step with respect to yield, purity, size distribution of the transcripts, and dye coupling is used to generate targets tested in replicate hybridisations. DNase treatment of diluted total RNA samples followed by phenol extraction is the optimal way to remove genomic DNA contamination. Purification of double-stranded cDNA is best achieved by phenol extraction followed by isopropanol precipitation at room temperature. Extraction with guanidinium-phenol and Lithium Chloride precipitation are the optimal methods for purification of amplified RNA and labelled aRNA respectively.

Conclusion

This protocol provides targets that generate highly reproducible microarray data with good representation of transcripts across the size spectrum and a coefficient of repeatability significantly better than that reported previously.

Structural organisation of nucleic acids from tumour cells

The DNA from Carcinoma Guerina resistant and sensitive cells of Wistar line rats and their interaction with anti-cancer drugs--cis-platin and doxorubicin (DOX)--have been studied in in vivo experiments. Surface enhanced infrared absorption (SEIRA) in reflectance absorption spectroscopy (RAS) mode was applied for registration of conformational change of the DNA induced by cancer process and anti-cancer drugs. We have registered numerous minor changes in infrared spectra of the DNA from sensitive and resistant cells that could reflect essential changes in molecular structure of DNA from cancer cells. The most significant transformation was undergone by the sugar phosphate backbone of the DNA from cancer cells. The DNA from resistant cancer cells could be characterized as rigid structures and look like the canonical helix form of DNA being practically unchangeable after anti-cancer drug application. The structure of DNA from sensitive cancer cells seems to be flexible and after application of anti-cancer drugs drastically changes and approaches to structure of helix form. It has been shown that doxorubicin strongly influences the DNA structure, leading to DNA stabilization and formation of new H-bonds in DNA doxorubicin complex. We have registered slight cis-platin influence on the DNA structure in in vivo experiment. Principal component analysis of SEIRA spectra can select the DNA from cancer cells.

Fibroblast growth factor-1 transcriptionally induces membrane type-1 matrix metalloproteinase expression in prostate carcinoma cell line

BACKGROUND

We and others have shown that the matrix metalloproteinases, MT1-MMP is overexpressed in human prostate PIN lesions and invasive cancers compared to normal prostate epithelium. However, the mechanism for this overexpression is not understood. Evidence from our laboratory and others has indicated that fibroblast growth factors (FGFs) can regulate the expression of certain matrix metalloproteinase. In addition, human prostate fibroblasts are known to express certain FGFs, including FGF-1. The purpose of the work in this paper was to determine the mechanism involved in FGF-1 induced MT1-MMP expression in prostate carcinoma cells.

METHODS

We tested the ability of recombinant FGF-1 to induce MT1-MMP expression in prostate carcinoma cell line, LNCaP cells. We measured the MT1-MMP message by using Northern analyses and protein levels by Western analysis after FGF-1 treatment. Downstream signaling was investigated using dominant negative constructs for FGFR-1 and signal transducer and activator of transcription-3 (STAT3). Transient transfection was performed using reporter plasmids of the MT1-MMP gene promoter region (7.2 kb) linked to the firefly luciferase gene in the pGL3-Basic vector. For dominant negative studies FGFR-1 dominant negative plasmid in PCEP4 vector or STAT3 dominant negative plasmid in pCMV-1 vector was co-transfected with the MT1-MMP reporter plasmid.

RESULTS

Recombinant FGF-1 significantly induced MT1-MMP expression in LNCaP prostate carcinoma cells. MT1-MMP message increased with FGF-1 treatment compared to that of untreated control LNCaP cells. Quantitation by digital image analysis revealed that this increase was twofold over untreated LNCaP cells. Treatment of pGL3-MT1-MMP-luciferase transfected cells with FGF-1 resulted in a twofold to fourfold increase in luciferase enzyme activity compared with untreated cells. Co-transfection of LNCaP with human MT1-MMP reporter construct and a dominant negative FGFR1 mutant showed that FGF-1-induced MT1-MMP expression in LNCaP cells was completely inhibited by the mutated FGFR-1, indicating that FGF receptor (FGFR) activation is necessary for induction of MT1-MMP. Further, expression of dominant negative STAT3 inhibited the FGF-1-induced transactivation of the human MT1-MMP 7.2-kb promoter.

CONCLUSIONS

From these data, we conclude that FGF-1 induces MT1-MMP expression in prostate carcinoma cells through a transcriptional mechanism mediated through the FGFR and the transcription factor, STAT3. These results confirm earlier data indicating that acidic FGF and STAT3 are involved in the signaling leading to the expression of a MMP. Our findings support the idea that paracrine and autocrine factors play an important role in the regulation of MT1-MMP in human prostate carcinoma cells.

Two somatic TSH receptor mutations in a patient with toxic metastasising follicular thyroid carcinoma and non-functional lung metastases

In a 59-year-old patient, thyroid follicular cancer was diagnosed in two right-sided toxic thyroid nodules, which had presented clinically as unilateral thyroid autonomy. In addition, the patient had histologically proven lung metastases of thyroid cancer; however, these failed to exhibit iodine uptake and were resistant to radioiodine treatment. The functional activity of the thyroid nodules prompted us to screen for TSH receptor (TSHR) mutations, and the histological diagnosis of follicular carcinoma led us to search for the PAX8-PPARgamma1 rearrangement and mutations in the ras genes. Each thyroid nodule harboured a different TSHR mutation (large nodule, Asp633Tyr; small nodule, Phe631Ile). Presence of both mutations in one sample suggestive of local invasion of a thyroid carcinoma could not be demonstrated, although several specimens from different nodule locations were screened. Only the wild-type TSHR sequence was identified in the histologically normal left thyroid lobe, and no genetic alterations were found in the other investigated genes. No TSHR mutations were detected in the pulmonary metastases. This is the first case report of a patient with toxic follicular thyroid carcinoma harbouring two different TSHR mutations and presenting with non-functional lung metastases.

HSP90 is a key for telomerase activation and malignant transition in pheochromocytoma

Recent studies on a limited number of pheochromocytomas (PCs) revealed a potential role of telomerase in the malignant transition of these tumors. Telomerase is a ribonucleoprotein complex that includes the telomerase RNA component (hTR), the telomerase-associated protein (TP1), the telomerase catalytic subunit (hTERT), and the heat-shock protein 90 (HSP90). The interactions between these subunits and the activation machinery of telomerase are still unclear. To test whether the expression and regulation of telomerase subunits are reflected in the malignant transition of PCs, we determined their mRNA and/or protein expression in 28 benign and 9 malignant PCs and compared the results with telomerase activity. Reverse transcriptase polymerase chain reaction analysis revealed that TP1 was ubiquitously expressed. hTR was found in all malignant (100%) and in 13/28 (46%) benign PCs. By contrast, hTERT was clearly associated with aggressive biologic behavior. All the malignant (100%) but only 2/28 benign (7%) PCs expressed hTERT. HSP90 was increased in malignant PCs but was also expressed at a lower level in benign tumors. High telomerase activity was measurable in only hTERT-positive tissues. Our data indicate that hTERT, HSP90, and telomerase activity are upregulated in malignant cells of the adrenal medulla. Overexpression of HSP90 is an important factor in the activation of telomerase via hTERT. The common expression of hTERT and telomerase activity thus represents an additional prognostic marker that may identify more aggressive tumors.

Expression of protein C inhibitor (PCI) in benign and malignant prostatic tissues

BACKGROUND

Protein C inhibitor (PCI) occurs at high concentration in seminal plasma, and inhibits human glandular kallikrein-2 and, less readily, prostate-specific antigen. Previous studies have localized PCI in the male genital tract. Here we have performed a detailed investigation of PCI expression in the prostatic tissues, metastases, and cell lines.

METHODS

Immunohistochemistry, in situ hybridization, and Western blotting were used to study prostatic tissues, metastases, and PC-3, DU-145, and LNCaP cells.

RESULTS

PCI was immunolocalized in tissue microarray spots with BPH epithelium (detection rate 100%), PIN lesions (100%), tumors (96%), metastases (88%), and in all cell lines. ISH and WB supported the findings.

CONCLUSIONS

PCI is widely expressed in benign prostatic epithelium, and may act as a local regulator of enzymatic activity in seminal fluid, of importance for normal sperm function. Lack of PCI expression in a subpopulation of high-grade tumor cells in combination with maintained protease expression may facilitate invasive growth patterns.

Transactivation of epidermal growth factor receptor after heparin-binding epidermal growth factor-like growth factor shedding in the migration of prostate cancer cells promoted by bombesin

BACKGROUND

A pathway consisting of bombesin, G-protein coupling receptors (GPCRs), metalloproteases, pro-heparin-binding epidermal growth factor (proHB-EGF), and epidermal growth factor receptor (EGFR) has been reported in prostate cancer cells. The occurrence of HB-EGF shedding from proHB-EGF in this pathway, however, has not been proven directly. In addition, it is still unclear how much this pathway contributes to the migration of prostate cancer cells. In this study, we tried to directly elucidate HB-EGF shedding in this pathway and to determine its contribution to the migration of prostate cancer cells.

METHODS

RT-PCR and indirect immunofluorescence staining for HB-EGF and its receptors, such as EGFR and HER4/erbB4, were performed on PC-3 cells. The influences of bombesin, anti-EGFR neutralizing monoclonal antibody, HB-EGF, and HB-EGF shedding inhibitor on the migration of PC-3 cells were studied by means of in vitro wound assays. The amount of HB-EGF shed from PC-3 cells with alkaline phosphatase-tagged HB-EGF in the presence of bombesin was determined by measuring AP activity. Immunoprecipitations and phosphotyrosine Western blotting were performed to detect EGFR transactivated by bombesin.

RESULTS

PC-3 expressed HB-EGF and EGFR, but not HER4/erbB4. PC-3 migrated in the presence of bombesin, but its migration was partly inhibited by the neutralizing antibody against EGFR. PC-3 also migrated in the presence of HB-EGF, but HB-EGF shedding inhibitor partly inhibited this phenomenon. HB-EGF was shed from PC-3 cells in the presence of bombesin, and this shedding was inhibited by HB-EGF shedding inhibitor. In addition, the EGFR on PC-3 was activated in the presence of bombesin and inactivated in the presence of HB-EGF shedding inhibitor.

CONCLUSIONS

These results indicated that HB-EGF shedding and the following transactivation of EGFR occurs in this pathway and that this pathway partly contributes to the migration of prostate cancer cells.

Colonic polyps of acromegalic patients are not associated with mutations of the peroxisome proliferator activated receptor gamma gene

Peroxisome proliferator activated receptor (PPAR)gamma plays a pivotal role in regulating adipocyte differentiation and metabolism, but also has an antiproliferative effect in several tissues, including colonic mucosa, where it is highly expressed. Loss-of-function mutations have been reported in about 10% of sporadic primary colon cancer. Acromegalic patients have an increased prevalence of colonic neoplasms and lower PPARgamma levels in the colonic mucosa. Thus, PPARgamma may act as a tumor suppressor gene, and its reduced expression or loss-of-function mutations may contribute to tumorigenesis. In this study the expression and mutations of the PPARgamma gene in the colonic polyps and mucosa outside polyps were investigated in 10 acromegalic and 17 non-acromegalic patients. PPARgamma expression was evaluated by RT-PCR. PPARgamma was expressed in each sample, but expression appeared to be lower in polyps than in mucosa outside polyps from either acromegalic or non-acromegalic patients. All exons of the PPARgamma gene were directly sequenced after PCR amplification: no mutations were found either in acromegalic or in non-acromegalic patients. In conclusion, the results of this preliminary study suggest that the lower expression of PPARgamma rather than somatic mutations of this gene is involved in colonic tumorigenesis.

Human pituitary tumours express the bHLH transcription factors NeuroD1 and ASH1

Among the transcription factors involved in pituitary ontogenesis and physiology, basic helix-loop-helix (bHLH) have been poorly studied. Members of bHLH family include NeuroD1 and ASH1, both involved in neuroendocrine differentiation. We evaluated their mRNA expression patterns, by semi-quantitative RT-PCR analysis (sq-RT-PCR) and/or Northern blot, in a series of 33 pituitary adenomas (PA), anterior pituitaries, and pituitary cell lines. Immunohistochemistry for NeuroD1 was also performed in 25 PA. Low levels of NeuroD1 were observed in normal pituitaries and in the somatomammotroph cell lines GH3/GH4C1, contrasting with high levels in corticotroph AtT20 cells. NeuroD1 mRNA was widely expressed in PA (82%), with measurable levels found especially in those derived from Pit-1 independent lineages, i.e. corticotroph (5/5) and clinically non-secreting (CNS) adenomas (9/11). According to sq-RT-PCR analysis, overexpression of NeuroD1 compared to normal pituitaries was frequent. Variable nuclear NeuroD1 immunopositivity was also present in about 70% of studied cases. ASH1 mRNA was widely detected in normal pituitaries, in all tumour cell lines and in most PA (84%), with measurable levels in corticotroph (5/5) and CNS (9/11) adenomas, and in a significant subset of PA derived from Pit-1 dependent lineages (9/16). We conclude that: a) NeuroD1 is differentially expressed in PA and its possible ontogenetic and/or pathogenetic implications in non-corticotroph PA are discussed; b) ASH1 is a neuroendocrine marker whose expression is largely conserved in normal and neoplastic pituitary cells.

Localization and expression of thyroid hormone receptors normal and neoplastic human thyroid

The aim of this study was to investigate the regional expression of thyroid hormone nuclear receptor forms (TR(alpha) and TR(beta)) and isoform (TR(alpha1) and TR(beta2)) mRNAs in normal and neoplastic (benignant and malignant) human thyroid tissue. Tumor specimens from patients with thyroid carcinomas (papillary: 5 cases; follicular: 5 cases; anaplastic: 2 cases), thyroid follicular adenomas (7 cases) and tissue from normal thyroid glands (12 cases) were analyzed by in situ hybridization and semiquantitative RT-PCR for the expression of TR(alpha1) and beta, as well as for the isoform alpha2 that does not bind the hormone. In normal tissues, TR(alpha2) was expressed at lower levels compared to TR(alpha1) (alpha1/alpha2 = 4.3). In papillary and follicular carcinomas, the expression of TR(alpha1) and TR(beta) did not change as compared with normal thyroid tissue and adenomas (0.87 +/- 0.15 SD vs 0.89 +/- 0.17 densitometric units, DU, and 0.15 +/- 0.02 vs 0.14 +/- 0.03 DU, respectively). However, the expression of TR(alpha2) was significantly higher in differentiated carcinomas compared to normal thyroid tissue and adenomas (0.47 +/- 0.05 vs 0.20 +/- 0.05 DU, p < 0.05) with alpha1/alpha2 = 1.4. In anaplastic carcinoma all TRs were absent. We concluded that both normal and pathological thyroid tissues, with the exception of anaplastic carcinoma, express all TRs in thyreocites and that differentiated thyroid carcinomas are associated in enhancing the expression of TR(alpha2) mRNA.

Heterogeneity of molecular targets on clonal cancer lines derived from a novel hormone-refractory prostate cancer tumor system

OBJECTIVE

We recently described a new hormone refractory prostate cancer cell line, CL1, derived from LNCaP via in vitro androgen deprivation. To study gene expression during prostate cancer progression and to identify molecular targets for therapy, a pure clonal tumor system was generated.

METHODS

Limiting dilution of CL1 stably transfected with a green fluorescent protein, generated 35 single-cell clones, which were expanded into stable cell lines. In vitro responses to various therapeutic modalities were assessed in each clone. Gene expression was determined using reverse transcriptase-polymerase chain reaction and oligonucleotide microarrays. In vivo biology was assessed following orthotopic injection into intact and castrated severe combined immunodeficient mice.

RESULTS

In vitro, all clones demonstrated similar resistance to traditional therapeutic efforts including chemotherapy and radiation therapy, but differential sensitivity to cell-mediated cytotoxicity. The clones demonstrated differential gene expression relative to each other and to the parental CL1 and LNCaP cell lines. Following orthotopic injection into mice, three distinct growth patterns were observed: fast growth with widespread metastasis; slower grower with widespread metastasis; and no tumor formation. Using oligonucleotide microarrays, several genes were identified as differentially expressed between the most aggressive and the nontumorigenic clone.

CONCLUSIONS

We have described a novel fluorescent-labeled clonal hormone refractory prostate cancer tumor system that exhibited marked heterogeneity in its response to various therapeutic modalities, gene expression, and in vivo biology. Our data suggests that given the marked clonal heterogeneity, multi-modality approaches directed against multiple molecular targets rather than single agent therapy will be necessary to adequately eradicate the entire malignant cell population. Clonal tumor lines may allow more accurate examination of molecular pathways involved in tumor progression and resistance to treatment.

Mutation analysis of vinyl carbamate or urethane induced lung tumors in rasH2 transgenic mice

Previous studies showed that significant differences in mutation frequency of the human c-Ha-ras transgene between vinyl carbamate (VC)- and ethyl carbamate (urethane)-induced lung tumors were observed in rasH2 mice. It remains unclear why the point mutation frequency is extremely low in VC-induced lung tumors, although this compound is much more carcinogenic than urethane. In this study, we examined the somatic point mutations of the transgene at the RNA level in VC- and urethane-induced lung tumors of rasH2 mice. We did not find any mutation at codon 12 of the transgene in any of these lung tumors, but codon 61 showed frequent mutations in not only urethane-induced lung tumors (15 out of 16) but also VC-induced lung tumors (11 out of 11) in rasH2 mice. These results suggested that point mutations at codon 61 of the transgene play an important role in the carcinogenesis of VC- and urethane- induced lung tumors in rasH2 mice.

Targeting c-Myb expression in human disease

c-Myb is a transcription factor employed in the haematopoietic system and gastrointestinal tract to regulate the exquisite balance between cell division, differentiation and survival. In its absence, these tissues either fail to form, or show aberrant biology. Mice lacking a functional c-myb gene die in utero by day 15 of development. When inappropriately expressed, as is common in leukaemia and epithelial cancers of the breast, colon and gastro-oesophagus, c-Myb appears to activate gene targets of key importance to cancer progression and metastasis. These genes include cyclooxygenase-2 (COX-2), Bcl-2, BclX(L) and c-Myc, which influence diverse processes such as angiogenesis, proliferation and apoptosis. The clinical potential for blocking c-Myb expression in malignancies is based upon strong preclinical data and some trial-based evidence. The modest clinical experience to date has been with haematopoietic malignancies, but other disease classes may be amenable to similar interventions. The frontline agents to achieve this are nuclease-resistant oligodeoxynucleotides (ODNs), which are proving to be acceptable therapeutic reagents in terms of tolerable toxicities and delivery. Nevertheless, further effort must be focused on improving their efficacy, eliminating non-specific toxicity and optimising delivery. Optimisation issues aside, it would appear that anti-c-Myb therapies will be used with most success when combined with other agents, some of which will be established cytotoxic and differentiation-inducing drugs. This review will explore the future strategic use of ODNs in vivo, focusing on a wide spectrum of diseases, including several beyond the haematopoietic malignancies, in which c-Myb appears to play a role.

Gonadotropin-releasing hormone agonist and danazol normalize aromatase cytochrome P450 expression in eutopic endometrium from women with endometriosis, adenomyosis, or leiomyomas

OBJECTIVE

To investigate whether GnRH agonists or danazol therapy normalizes estrogen metabolism in the eutopic endometrium of women with endometriosis, adenomyosis, or leiomyomas.

DESIGN

Prospective clinical study.

SETTING

University hospital.

PATIENT(S)

Fifty-three women with endometriosis, adenomyosis, or leiomyomas.

INTERVENTION(S)

Patients received GnRH agonist or danazol. Biopsy samples of the endometrium were obtained before and after endocrine therapy. Nontreated endometrial explants were cultured in the presence of either drug.

MAIN OUTCOME MEASURE(S)

Reverse transcription polymerase chain reaction-Southern blot and immunohistochemical analyses of the endometrial expression of aromatase cytochrome P450, estrogen receptor, progesterone receptor, and Ki-67. Nontreated endometrial explants were cultured in the presence of either drug.

RESULT(S)

Messenger RNA and protein of aromatase cytochrome P450 were greatly reduced in the eutopic endometrium of patients treated with GnRH agonist for 2 months or more or with danazol for 1 month or more. Culture of endometrial explants with GnRH agonist (10(-9)-10(-7) M) did not change the amount of aromatase cytochrome P450, whereas danazol (10(-7)-10(-6) M) efficiently reduced aromatase cytochrome P450 expression.

CONCLUSION(S)

Therapy with GnRH agonist or danazol decreases expression of aromatase cytochrome P450 in diseased eutopic endometrium. Endocrine therapy normalized in part the impaired hormonal expression of the eutopic endometrium. GnRH agonist reduced aromatase cytochrome P450 expression mainly by promoting a hypoestrogenic state, whereas danazol reduced aromatase cytochrome P450 in part by direct action on the eutopic endometrium.

mRNA instability in the nucleus due to a novel open reading frame element is a major determinant of the narrow tissue specificity of folate receptor alpha

The folate receptor type alpha (FR-alpha) is a promising tumor marker and target. Here, we investigate the mechanistic basis for the tumor specificity and vast overexpression of FR-alpha. Among representative FR-alpha-positive (HeLa and JAR) and FR-alpha-negative (MG63, Caki1, and HT3) cell lines, the transcription rates of the endogenous FR-alpha gene, as well as the FR-alpha promoter activity, were relatively weak and comparable, but the FR-alpha transcript was abundant only in total RNA and nuclear RNA from the FR-alpha-positive cells. Rous sarcoma virus (RSV) promoter-driven expression of the FR-alpha gene was 7 to 30 times greater in the FR-alpha-positive than in FR-alpha-negative cells, both at the protein and mRNA levels, independently of intron sequences. Through the use of chimeric FR-alpha/FR-beta cDNAs, the above pattern of FR-alpha expression was attributed to a 60-bp sequence in the FR-alpha open reading frame. This sequence element, when placed in the 5' untranslated region of RSV promoter-luciferase, decreased the reporter expression approximately 7- to 20-fold in FR-alpha-negative cells (MG63, Caki1, HT3, BG1, and MCF7) relative to FR-alpha-positive cells (HeLa, JAR, and JEG3). Substitution of this FR-alpha element in FR-beta increased the in vivo degradation rate of the transcript in the nuclei of MG63 cells but not in the nuclei of HeLa cells or in the cytosol of MG63 or HeLa cells. The results reveal an efficient mechanism by which a novel sequence element causes differential transcript degradation in the nucleus to ensure narrow tissue specificity for a gene (e.g., that for FR-alpha) whose transcription is weak and relatively nonselective. FR-alpha exhibited constitutive mRNA and protein synthesis during the cell cycle and a slow protein turnover, presumably ensuring a high steady-state level of the receptor in cells that could override the nuclear mRNA instability determinant.

FTIR microspectroscopy of malignant fibroblasts transformed by mouse sarcoma virus

Fourier transform infrared microspectroscopy (FTIR-MSP), which is based on the characteristic molecular vibrational spectra of cells, was used to investigate spectral differences between normal primary rabbit bone marrow (BM) cells and bone marrow cells transformed (BMT) by murine sarcoma virus (MuSV). Primary cells, rather than cell lines, were used for this research because primary cells are similar to normal tissue cells in most of their characteristics. Our results showed dramatic changes in absorbance between the control cells and MuSV124-transformed cells. Various biological markers, such as the phosphate level and the RNA/DNA obtained, based on the analysis of the FTIR-MSP spectra, also displayed significant differences between the control and transformed cells. Preliminary results suggested that the cluster analysis performed on the FTIR-MSP spectra yielded 100% accuracy in classifying both types of cells.

Intracellular angiotensin II increases the long isoform of PDGF mRNA in rat hepatoma cells

Our recent published studies suggest that angiotensin II (AII), generated and retained intracellularly, enhances growth of H4-II-E-C3 rat hepatoma cells, an average of 33%. Proliferation conferred by introduction of a plasmid [ Ang(-S)Exp/pSVL ] encoding a signal sequence-depleted angiotensinogen [Ang(-S)Exp] into these cells (which we have shown possess ACE and renin mRNAs) is mediated, at least in part, by enhanced PDGF-A chain mRNA production and protein secretion. The mitogenic effect is inhibited by losartan suggesting that it involves AII interaction with an AT(1)-like receptor. Introduction of anti-AII antibodies into the medium of these transfected cells has no effect upon growth of the cells, suggesting that AII is retained by the cells and that intracellular AII is growth stimulatory. In the present study, we sought to further characterize the intracellular localization and mode of action of Ang(-S)Exp. Consistent with our expectations, we now show that a fusion product of Ang(-S)Exp with green fluorescent protein [Ang(-S)Exp/EGFP], generated from an expression plasmid, is abundant and primarily cytoplasmic. Wild-type angiotensinogen/EGFP, in contrast, is only detectable following a cold-block (which acts to enhance folding-kinetics and slow secretion) and is largely restricted to the secretory pathway. We further show, using semi-quantitative RT/PCR that the long isoform of PDGF mRNA is elevated in Ang(-S)Exp transfected cells and in AII-treated naive cells but not in losartan-treated Ang(-S)Exp transfected cells. We identify C-terminal amidation recognition sites within the long-form protein (that are not present in the short-form) and show that these cells possess PAM (amidating enzyme precursor) and carboxypeptidase E mRNAs (the corresponding proteins of which are sufficient for amidation). Inhibitors of amidation inhibit growth of naive and Ang(-S)Cntr/ pSVL -transfected cells (2.6-fold for phenylbutenoic acid and 3.5-fold for disulfiram treatment) but more profoundly inhibit growth of Ang(-S)Exp/pSVL -transfected cells (6.7-fold for phenylbutenoic acid and 13-fold for disulfiram). In conclusion, these data confirm that signal sequence-depleted Ang(-S)Exp is retained within cells and is largely cytoplasmic. Because C-terminal amidation is absolutely required for full biological potency of a number of peptide hormones (including oxytocin, gastrin and calcitonin), we postulate that growth effects of both intracellular AII and exogenous AII can be conferred by PDGF long-form, possibly through an amidation-dependent mechanism.

Surface enhanced IR absorption of nucleic acids from tumor cells: FTIR reflectance study

The data on surface enhanced IR absorption (SEIRA) of nucleic acids deposited on a metal substrate were obtained using FTIR in reflectance mode. A 200-400 A thick gold film on a glass plate was the metal substrate. The approximate enhancement factors of the SEIRA for different vibrations of nucleic acids in our experimental conditions were 3-5. The roughness of the Au surface was about 50 A. Application of this method to nucleic acids isolated from tumor cells revealed some possible peculiarities of their structural organization, namely, the appearance of unusual sugar and base conformations, modification of the phosphate backbone, redistribution of the H-bond net, and so forth. This method enhanced a set of the bands, which is impossible to observe in conventional IR geometry. The SEIRA spectra of the RNA from tumor cells showed more sensitivity to the grade of tumor malignancy than the spectra of the DNA. After application of the anticancer drug doxorubicin to sensitive and resistant strains, the DNA isolated from these strains had different spectral features, especially in the region of the phosphate I and II bands. As induced by anticancer drugs, the conformational changes in the DNA from resistant and sensitive cancer strains could be characterized with different levels of structure disordering.

Differential expression of 17beta-hydroxysteroid dehydrogenase isozyme genes in prostate cancer and noncancer tissues

BACKGROUND

The adrenal steroids dehydroepiandrosterone and androstenediones are converted into active androgen testosterone in prostatic tissues. Different 17beta-hydroxysteroid dehydrogenase (17betaHSD) isozymes are characterized by either oxidation or reduction reactions. These redox reactions represent an important step in both biosynthesis and metabolism of androgens. This study presents the differential expression of 17betaHSD isozyme genes in cancerous and noncancerous prostate tissues of in vivo samples.

METHODS

Thirty-four fresh specimens of transrectal prostatic needle biopsy were obtained; 11 were pathologically diagnosed as adenocarcinoma and 23 as without malignancy. The gene expression levels of five isozymes (type 1-5) of 17betaHSD were evaluated. The quantification of gene expression was assessed by means of the real-time polymerase chain reaction.

RESULTS

The expression levels of the type 3 17betaHSD gene with malignancy were significantly higher than those in prostatic tissues without malignancy, and those of type 2 17betaHSD with malignancy were significantly lower than those in nonmalignant tissues. There were no significant differences in 17betaHSD type 1, type 4, and type 5 gene expression in cancerous and noncancerous tissues.

CONCLUSION

Our results suggest that 17betaHSD type 2 and type 3 play an important role in the conversion of adrenal steroids into potential androgens in prostate cancer tissue.

Evaluation of pyrimidine metabolising enzymes and in vitro uptake of 3'-[(18)F]fluoro-3'-deoxythymidine ([(18)F]FLT) in pancreatic cancer cell lines

Here we report the expression of major pyrimidine metabolising enzymes in pancreatic cancer cell lines, chronic pancreatitis tissue and human pancreatic cancer and the in vitro uptake of 3'-[(18)F]fluoro-3'-deoxythymidine ([(18)F]FLT). The expression of pyrimidine metabolising enzymes was evaluated with real-time PCR, Western blot and immunostaining. Thymidine kinase 1 (TK-1) activity was measured with a fluorocytometric assay. The cellular uptake and intracellular metabolism of [(18)F]FLT were evaluated in pancreatic lobules and in transformed cancer cell lines. TK-1 and thymidine synthetase mRNA were increased in six pancreatic cancer cell lines, while mRNA levels of thymidine kinase 2 and deoxycytidine kinase were down-regulated. High TK-1 activity was confirmed in all cell lines. Furthermore, TK-1 was overexpressed in human pancreatic cancer as compared with normal pancreatic tissue and samples from patients with chronic pancreatitis. The cellular uptake of [(18)F]FLT was 18.4%+/-3.6% and 5.2%+/-1.4% of the applied radioactivity after 240 min in SW-979 and BxPc-3 cells, respectively, while uptake of [(18)F]fluorodeoxyglucose ([(18)F]FDG) was only 0.6%+/-0.04% (SW-979) and 0.3%+/-0.13% (BxPc-3) after 240 min of incubation. In contrast, cellular uptake of [(18)F]FLT in isolated pancreatic lobules and growth-arrested HT1080 cells was lower as compared with the uptake of [(18)F]FDG and with the malignant pancreatic cancer cell lines. HPLC analysis of the perchloric acid-soluble cell fraction demonstrated the phosphorylation of [(18)F]FLT to the respective monophosphate in both cell lines. Furthermore, 0.8%+/-0.12% (BxPc-3) and 1.3%+/-0.38% (SW-979) of the applied radioactivity was detected in the perchloric acid-insoluble cell fraction, indicating the incorporation of [(18)F]FLT into the DNA. Our results demonstrate the cellular uptake, intracellular trapping and incorporation into the DNA of [(18)F]FLT in pancreatic cancer cells in vitro. TK-1, as the rate-limiting enzyme of [(18)F]FLT metabolism, is overexpressed in pancreatic cancer cell lines and in human pancreatic cancer. Thus, we propose [(18)F]FLT as a promising tracer for positron emission tomography that might overcome current limitations in the diagnosis of pancreatic cancer.

Genes that co-cluster with estrogen receptor alpha in microarray analysis of breast biopsies

The estrogen receptor plays a critical role in the pathogenesis and clinical behavior of breast cancer. To better understand the molecular basis of estrogen-dependent forms of this disease we studied gene expression profiles from 53 primary breast cancer biopsies. Gene expression data for more than 7000 genes were generated from each tumor sample with oligo microarrays. A standard correlation-clustering algorithm identified 18 genes that co-clustered with estrogen receptor alpha. Eleven of these genes had previously been associated with estrogen regulation or breast tumorigenesis including trefoil factor 1 and estrogen regulated LIV-1. Additional study of these 18 genes may further delineate the role of estrogen receptor in breast cancer, generate new predictive biomarkers for response to endocrine therapies and identify novel therapeutic targets.

Overexpression of the sis oncogene in a canine osteosarcoma cell line

Specific oncogenes that contribute to the pathogenesis of canine osteosarcoma (OS) have not been identified. In the process of characterizing four OS cell lines, we have found one cell line, CO8, that overexpresses the sis oncogene, which encodes the platelet-derived growth factor (PDGF)-beta. The expression of an important downstream transcriptional target of the PDGF signaling pathway, c-myc, is also elevated fourfold. Conditioned medium from CO8 alone specifically induces tyrosine phosphorylation and therefore the activation of the PDGF-alpha and PDGF-beta receptors on murine 3T3 cells. All of the canine OS lines tested contain PDGF receptors and therefore are capable of responding to PDGE Given the importance of PDGF in promoting cell proliferation, migration, and cell survival, the activation of the sis oncogene and the resultant growth factor autocrine loop potentially contribute to the pathogenesis of a subset of canine osteosarcomas.

Cloning and sequencing of the 3'-region of the canine parathyroid hormone-related protein gene and analysis of alternate mRNA splicing in two canine carcinomas

A canine genomic library in Lambda FIX II vector was screened with a 281-base pair canine PTHrP cDNA to the prepro- and coding regions. Two genomic clones were isolated and mapped to the 3'-end of the PTHrP gene by polymerase chain reaction (PCR) amplification of exons in this region. One clone (3.5 kb) was amplified by PCR, partially sequenced, and compared to the human PTHrP gene. Regions were identified with a high degree of homology to exons 6, 7, and 8 of the human PTHrP gene. A polyadenylation site was present 3' to the exon 8-like region. Reverse transcriptase-polymerase chain reaction (RT-PCR) demonstrated that exon 7 of the PTHrP gene was transcribed in two canine carcinomas (SCC 2/88 cells and CAC-8 tumor line) which produce PTHrP. This confirmed that the 3'-region of the canine PTHrP gene is alternately spliced with splicing of exon 6 to exons 7 or 9. Transcription of exon 8 was not demonstrated by RT-PCR and suggests that the exon 8-like region of the dog PTHrP gene is not utilized. The exon 8-like region contained an early stop codon that was not present in exon 8 of the human PTHrP gene.

Tumor suppressor PTEN is mutated in canine osteosarcoma cell lines and tumors

Canine osteosarcoma (OS) cell lines contain mutations that directly or indirectly inactivate the tumor suppressor genes p53 and retinoblastoma. Another important tumor suppressor, PTEN, is mutated in many human cancers. To determine whether inactivation of PTEN plays a role in the pathogenesis of canine OS, we studied its expression in canine OS cell lines and tumors. Four of five canine OS cell lines (CO2, C03, CO5, and CO7) constitutively express high levels of the phosphorylated form of Akt, an indirect indicator of aberrant PTEN expression. PTEN protein is essentially absent from three of these cell lines (CO2, CO5, and CO7), whereas C03 contains a potentially inactivating amino acid substitution in PTEN at codon 340. Genomic hybridization experiments indicate that CO2, CO5, and CO7 contain large deletions within the PTEN gene. Ten of 15 OS tumors exhibit variable or negative PTEN staining. Evaluation of a PTEN-negative staining tumor by Southern blotting indicates that the PTEN gene is deleted in this tumor. These results indicate that PTEN is mutated or downregulated in a high percentage of canine OS cell lines and tumors and likely plays an important role in the pathogenesis of the disease.

Cancer-specific mRNAs in thyroid carcinomas: detection, use, and their implication in thyroid carcinogenesis

Molecular-based diagnosis ofthyroid carcinomas can be more easily establishedby utilizing specific mRNAs that are expressed in a restricted manner in cancer tissues. Accordingly, several cancer-specific mRNAs in thyroid carcinomas have been identified by means of sequence specific-differential display (SS-DD), serial analysis of gene expression (SAGE) and other new techniques. By using these cancer-specific mRNAs, some new methods of preoperative diagnosis of thyroid carcinomas have been developed. In one such method, Aspiration Biopsy-Reverse Transcription-Polymerase Chain Reaction (ABRP), RNA is extracted from leftover cells within the needle used for fine needle aspiration biopsies (FNABs), thereby allowing cytological and molecular-based diagnoses to be performed simultaneously. ABRP provides both RNA information and a cytological diagnosis without further invasion to the patient. By ABRP detection of cancer-specific mRNAs, papillary, anaplastic and medullary carcinomas and a part of malignant lymphomas can be accurately diagnosed preoperatively. It remains to be clarified why cancer-specific mRNAs, especially those that are overexpressed in fetal tissues, can clearly distinguish benign tissues from carcinomas, while genomic alternations, such as mutations in the RAS or P53 gene cannot. Further, the widely accepted hypothesis of multi-step carcinogenesis cannot explain some of the clinical and experimental findings of thyroid carcinomas. Considering these facts, we propose a novel hypothesis of thyroid carcinogenesis, the "germ-cell carcinogenesis" hypothesis, in which cancer cells derive from the remnants of fetal thyroid germ cells (thyroblasts) instead of normal thyroid follicular cells.

Glucocorticoid inhibition of 235-1 rat pituitary tumor cell cycle progression

Control of the cell cycle is accomplished by sequentially activated cyclin-dependent kinases and the action of inhibitory proteins. We have shown that exposure of 235-1 rat pituitary tumor cells to dexamethasone (DEX) leads to a 50% reduction in growth rate. We examined the mechanism by which DEX affects 235-1 cell proliferation by determining the expression levels of proteins involved in cell-cycle progression. The expression of the G1 markers c-Myc and cyclin D3 were unaffected by DEX treatment. Levels of retinoblastoma family proteins p107 and p116 Rb were not altered. The levels of p1 30/Rb2 were increased by DEX within 36 h of initiating treatment. Additionally, a higher-mobility Rb2-related protein appeared within 24 h and was further increased in DEX-treated cells by 36 h. We also observed reduced levels of M-phase proteins, Cdc2 kinase, and cyclin B in DEX-treated cells. These changes occurred prior to the reduction in cell numbers and thus may represent causative factors. Our data suggest that DEX induces a late G1 block in 235-1 cell-cycle passage, accompanied by a reduction in the levels of the regulatory proteins required for passage through subsequent phases of the cell cycle.

A research-based tumor tissue bank of gynecologic oncology: characteristics of nucleic acids extracted from normal and tumor tissues from different sites

This article describes a gynecology and pathology-oriented tumor tissue bank that is approaching the research requirements of modern molecular oncology and compared characteristics of nucleic acids extracted from preserved tissues. Through August 2000, 8869 specimens, including fresh neoplastic tissues and normal counterparts, body fluids (ascites, tumor content, and blood), and cervical scrapings, were procured from 1853 patients. DNA and RNA were extracted from a random sampling of normal (n = 50) and tumor (n = 53) tissues from the uterine cervix (n = 47), endometrium (n = 24), and ovary (n = 32). As expected, tumor tissues conferred a higher yield of DNA (1.56 +/- 1.24 versus 0.94 +/- 0.72 microg/mg tissue, P = 0.001) and RNA (5.04 +/- 6.21 versus 2.12 +/- 1.76 microg/ml, P < 0.001) than normal tissues. However, the RNA message abundance, as measured by RNA yield/DNA yield, was not different between tumor and normal tissues. With a similar content of DNA in the endometrium, uterine cervix, and ovary, RNA yield was higher in the endometrium than the others (P = 0.013). In tumors from these three sites, similar yields of DNA and RNA were noted. Overall the yield of DNA remained unchanged from specimens preserved for as long as 7 years, although at this length of storage, RNA yield became lower and variable. This study provides the basic characteristics of nucleic acids derived from normal and tumor tissues and ensures future research utility of these frozen specimens.

Novel spectral method for the study of viral carcinogenesis in vitro

Fourier transform infrared (FTIR) spectroscopy is a unique technique for the laboratory diagnosis of cellular variations based on the characteristic molecular vibrational spectra of the cells. Microscopic FTIR was used to investigate spectral differences between normal and malignant fibroblasts transformed by retrovirus infection. A detailed analysis showed significant differences between cancerous and normal cells. The contents of vital cellular metabolites were significantly lower in the transformed cells than in the normal cells. In an attempt to identify the cellular components responsible for the observed spectral differences between normal and cancerous cells, we found significant differences between DNA of normal and cancerous cells.

Endothelin-1 production by prostate cancer cell lines is up-regulated by factors involved in cancer progression and down-regulated by androgens

BACKGROUND

Recent data demonstrate that endothelin-1 (ET-1) concentration increases in plasma of men with advanced, hormone-refractory prostate adenocarcinoma. In addition, ET-1 is involved in osteblastic remodelling and new bone formation, suggesting a role for this vasoactive peptide in the metastatic progression of prostate cancer to the bone.

METHODS

We investigated the regulation of ET-1 expression in androgen-sensitive and insensitive prostate cancer cell lines by androgens and several factors involved in progression of prostate cancer (EGF) and bone remodelling (TGFbeta-1, IL1-alpha and IGF-1).

RESULTS

Northern analysis and radio immunoassay demonstrated that all the ET-1 pathways are tuned off in the androgen-sensitive LNCaP cell line when compared to the androgen-insensitive PC-3 and DU145. In PC-3 cells transfected with a full-length androgen receptor expression vector (PC-3-AR), treatment with androgens reduced gene expression and secretion of ET-1 without affecting the gene expression of ET-3. Collectively, these data support a role for androgens in the regulation of ET-1 production by prostate adenocarcinoma cells. In PC-3 and DU145 cells, ET-1 gene expression and secretion were up-regulated by TGFbeta-1, EGF and IL1-alpha, whereas IGF-1 was ineffective. Conversely, none of the treatments affected ECE-1 or ET-3 gene expression.

CONCLUSIONS

In conclusion, ET-1 production by prostate adenocarcinoma cells is down-regulated by androgens and up-regulated by factors involved in tumour progression indicating a role for this peptide in the biology of prostate cancer. In view of the role exerted by ET-1 in the process of bone metastasis, our data suggest the use of ET-1 receptor antagonists in the treatment of advanced prostate cancer.

Cloning and sequencing full length of canine Brca2 and Rad51 cDNA

Mammary tumors are the most common neoplasm in female dogs, Canis canis, and in women. Mutations in human Brca2 confer an increased risk of female breast cancer. Previous studies have shown that the Brca2 tumor suppressor protein interacts with the recombinational repair protein Rad51. We cloned the full-length cDNA of the canine homologues of Brca2 and Rad51 to obtain a basis for studying their relationship with susceptibility to mammary tumors. The canine Brca2 and Rad51 cDNAs are 11 and 1.5 kb long, encoding 3.471 and 339 amino acids, respectively. The amino acid sequence of canine Brca2 showed 68% homology with the human protein, and 58% homology with a murine protein. There were highly conserved regions in the C-terminus of all three proteins, where the Rad51 interacting domain and putative nuclear localization signals are located. Comparing with the partial genomic sequence previously reported, we found possible nuclear polymorphisms in exon 11, some of which result in amino acid substitutions. On the other hand, canine Rad51 protein had extremely high homology (99%) to the human and murine proteins. Expression of both Brca2 and Rad51 was detected in the mammary gland, suggesting that these two genes interact in the canine mammary gland.

Results of hyperamplification of centrosomes in naturally developing tumors of dogs

OBJECTIVE

To evaluate results of centrosome hyperamplification in naturally developing tumors of dogs.

SAMPLE POPULATION

Tumor specimens from 9 dogs with tumors (rhabdomyosarcoma, osteosarcoma, chondrosarcoma, myxosarcoma, and mammary gland tumor) and 2 canine osteosarcoma cell lines.

PROCEDURE

3 antibodies for centrosome proteins (ie, anti-gamma-tubulin, anti-BRCA1, and anti-pericentrin) were used for immunohistochemical analysis. Double immunostaining for centrosomes was used to confirm the specificity of these antibodies for centrosomes. Mutational analysis of the canine p53 gene was carried out by polymerase chain reaction-single-strand conformation polymorphism analysis, and expression of canine MDM2 protein was evaluated by use of immunohistochemical analysis, using anti-MDM2 antibody.

RESULTS

Immunohistochemical analysis of dog osteosarcoma cell lines with apparent aneuploidy revealed frequent hyperamplification of centrosomes in the osteosarcoma cell lines. Similar hyperamplified centrosomes were detected in the tumor tissues from all of the 9 tumors. The frequency of cells with hyperamplified centrosomes (3 to 20/cell) in each tumor tissue ranged from 9.50 to 48.1%, whereas centrosome hyperamplification was not observed in normal lymph nodes from these dogs. In 8 of the 9 tumors, mutation of p53 gene or overexpression of MDM2, or both, was detected.

CONCLUSIONS AND CLINICAL RELEVANCE

Various types of naturally developing tumors in dogs often have hyperamplification of centrosomes associated with chromosome instability. Hyperamplification of centrosomes is a novel tumor marker for use in cytologic and histologic examinations of clinical specimens obtained from dogs.

Identification of differentially expressed genes in organ-confined prostate cancer by gene expression array

BACKGROUND

To understand the molecular mechanisms underlying prostate cancer, we have utilized the gene expression array to search for genes whose expression is altered in this disease.

METHODS

RNA quality from manual microdissected tissue was compared with that from microselected tissue by electrophoresis. For array analysis, malignant and normal prostate epithelium was enriched using microselection technique from prostate cancer and the peripheral zone of a normal prostate. Identical array membrane was hybridized to labeled cancer and normal cDNA, respectively. The differentially expressed gene was further evaluated by RT-PCR.

RESULTS

Microdissection, but not microselection, causes visible degradation to RNA. Of the 588 genes on the membrane, 87 genes yielded significant signals. Based on a three fold difference relative to normal prostate tissue, 1 gene was overexpressed and 12 genes underexpressed in prostate cancer. Of them, five showed statistically significant reduction in mRNA levels in six prostate cancer specimens compared with seven normal prostate specimens. These five genes are glutathione S-transferase M1 (GSTM1), monocyte chemotactic protein-1 (MCP-1), tumor necrosis factor-alpha receptor-1 (TNFR-1), transforming growth factor beta3 (TGF-beta3), and inhibitor of DNA binding-1 (ID-1).

CONCLUSIONS

GST-based metabolism, cytokine MCP-1 and TNFR-1, and TGF-beta3 signaling pathways, and some helix-loop-helix nuclear proteins could be potentially important in organ-confined prostate cancer and deserve further investigation.

p53 Mutations and microsatellite instability in ovarian cancer: Yin and yang

OBJECTIVE

We tested the hypothesis that p53 frameshift mutations in ovarian cancer occur as a result of genomic instability rather than as a proximal cause of this process.

STUDY DESIGN

Sequencing of the p53 tumor suppressor gene has been carried out on 305 ovarian, fallopian tube, and peritoneal cancers. Two groups of p53 null mutations were identified: (1) those caused by frameshift insertion or deletion mutations (n = 31) and (2) those caused by nonsense mutations (n = 28). As a control group 59 tumors with p53 missense mutations were selected by matching with the p53 null tumors on the basis of patient age at diagnosis, stage and grade of cancer, cancer site, and year of diagnosis. Microsatellite instability was determined from paired normal and tumor tissue deoxyribonucleic acid by means of the following different markers: D2S123, D5S346, D17S250, BAT25, and BAT26. Amplimers from polymerase chain reactions were evaluated on 7% polyacrylamide gels.

RESULTS

The p53 null tumors were more likely to be of higher stage and grade. Fallopian tube cancers were more common (P =.02) in the p53 frameshift group. The overall incidence of microsatellite instability was 39%, 36%, and 25% for tumors with p53 frameshift nonsense and missense mutations (P =.30). Microsatellite instability was seen almost exclusively with ovarian cancer (P =.04).

CONCLUSIONS

Microsatellite instability is a relatively common event in ovarian cancer and is dependent on marker selection. The p53 frameshift mutations do not appear to occur as a consequence of genomic instability.

Diagnostic frozen prostate sextant biopsies: an approach for preserving protein and RNA for additional studies

BACKGROUND

Primary prostate cancer represents 29% of newly diagnosed visceral cancers in men. Despite this common occurrence, relatively little is known about the pathogenesis of this malignancy. High-grade prostatic intraepithelial neoplasia (HGPIN) is generally accepted as a precursor to invasive prostate carcinoma. There is a lack of adequate animal models, and the available cell culture lines are limited. Tissue from prostate needle core biopsies that have been frozen can provide adequate material for both diagnosis and research.

METHODS

Transrectal sextant needle biopsies were snap-frozen, serially sectioned and alternately stained with hematoxylin-eosin or reacted with a basal cell-specific antibody. Two pathologists examined all of the sections, which were scored for the presence or absence of carcinoma and HGPIN. Portions of the remaining tissue were used for studies of protein expression and gene expression.

RESULTS

The incidence of carcinoma was 39%, comparable to the mean percent positive cases reported using conventional fixation and paraffin embedding. The incidence of HGPIN was 33%, higher than previously reported.

CONCLUSIONS

Prostate carcinoma can be accurately diagnosed using frozen material. The observed high frequency of HGPIN is attributed to the instability of nuclear structure in the frozen material of the atypical nuclei, resulting in inflated grading of PIN lesions. Sufficient material remained in the frozen blocks for additional studies of protein and gene expression.

Value of reverse transcription polymerase chain reaction assay in pathological stage T3N0 prostate cancer

BACKGROUND

We tested the ability of the nested reverse transcription polymerase chain reaction (RT-PCR) assay to detect signs of biochemical recurrence of prostate cancer in the lymph nodes and peripheral blood of patients with pT3N0 prostate cancer.

METHODS

Using lymph nodes and pre- and postoperative peripheral blood dissected from 30 patients with pT3N0 prostate cancer treated by radical prostatectomy, we used RT-PCR for prostate-specific membrane antigen (PSM) and serum prostate-specific antigen (PSA) to determine the presence of prostate cancer. Results of the nested RT-PCR assay were compared with pathological stages and biochemical recurrence.

RESULTS

Two of 13 patients with capsular penetration (15%), 6 of 10 patients with invasion of seminal vesicles (60%), and 3 of 7 patients with a positive surgical margin (43%) were RT-PCR-positive for PSM and/or PSA in the lymph nodes. Results of preoperative RT-PCRs of peripheral blood for PSM and for PSA significantly differed between positive and negative results of RT-PCR in lymph nodes (P < 0.001 and P < 0.001, respectively). Results of postoperative RT-PCRs of peripheral blood for PSM and for PSA also significantly different between positive and negative results of RT-PCR in lymph nodes (P = 0.011 and P = 0.001, respectively). Nine of 11 patients with positive nested RT-PCR for PSM and/or PSA in the lymph nodes (82%) experienced biochemical recurrence. Significant difference in Kaplan-Meier recurrence-free actuarial curves was noted between patients who nested positive and negative on RT-PCR in the lymph nodes, pre- and postoperative peripheral blood, biopsy and prostatectomy Gleason score, and preoperative PSA values. In multivariate analysis, biopsy and prostatectomy Gleason score (P = 0.026, P = 0.020, respectively), pre- and postoperative RT-PCR for PSM in peripheral blood (P = 0.030 and P = 0.040, respectively), and RT-PCR for PSM in lymph nodes (P = 0.035) were independent prognostic factors.

CONCLUSIONS

Nested RT-PCR assay of the lymph nodes or peripheral blood significantly predicted biochemical recurrence after surgery. It may help identify patients at risk for recurrence and progression of prostate cancer.

Potentiation of the inhibitory effect of growth hormone-releasing hormone antagonists on PC-3 human prostate cancer by bombesin antagonists indicative of interference with both IGF and EGF pathways

BACKGROUND

In view of the involvement of various neuropeptides and growth factors in the progression of androgen-independent prostate cancer, we investigated the effects of antagonists of growth hormone-releasing hormone (GHRH) alone or in combination with an antagonist of bombesin/gastrin-releasing peptide (BN/GRP) on PC-3 human prostate cancers.

METHODS

Nude mice implanted with PC-3 tumors received GHRH antagonists MZ-5-156 or JV-1-38, each at 20 microgram/day s.c. In experiment 2, treatment consisted of daily injections of JV-1-38 (20 microgram), BN/GRP antagonist RC-3940-II (10 microgram), or a combination of JV-1-38 and RC-3940-II. Serum IGF-I levels, expression of mRNA for IGF-II, and characteristics of BN/GRP and EGF receptors in tumor tissue were investigated.

RESULTS

JV-1-38 induced a greater inhibition of tumor growth and suppression of IGF-II mRNA than MZ-5-156, both compounds causing a similar decrease in serum IGF-I. In experiment 2, JV-1-38 and RC-3940-II produced a comparable reduction in tumor volume (65% and 61%, respectively), but a combination of both antagonists augmented tumor inhibition to 75%. Combined treatment with JV-1-38 and RC-3940-II also led to a greater suppression of IGF-II mRNA (92%), as compared with JV-1-38 (72%) or RC-3940-II (77%). Serum IGF-I concentration was lowered only in mice treated with JV-1-38, while the downregulation of BN/GRP and EGF receptors was specific for groups receiving RC-3940-II.

CONCLUSIONS

The inhibitory effects of GHRH antagonists on PC-3 human androgen-independent prostate cancer can be potentiated by concomitant use of BN/GRP antagonists. The combination of both types of analogs apparently interferes with both IGF and bombesin/EGF pathways, and might be clinically useful for the management of androgen-independent prostate cancer.

Autocrine effect of DHT on FGF signaling and cell proliferation in LNCaP cells: role of heparin/heparan-degrading enzymes

BACKGROUND

LNCaP cells are androgen-sensitive human prostate cancer cells. They are characterized by a bell-shaped growth curve in response to increasing doses of dihydrotestosterone (DHT) in culture. At a low concentration of DHT (0.1 nM), these cells show an increase in proliferation, but their growth is arrested at a high concentration (100 nM) of DHT. Results of our previous study demonstrated that the inhibitory effect of DHT at a high concentration was mediated through the action of TGF-beta1. The objective of the present study was to elucidate the mechanism of the proliferative effect of DHT in LNCaP cells. METHODS AND RESULTS DHT stimulated LNCaP proliferation only when cells were cultured in the presence of serum. In serum-free cultures, the characteristic DHT-induced proliferation was not observed. The addition of neutralizing antibody against FGF-2 (basic fibroblast growth factor) was able to inhibit this DHT-induced proliferation. These results suggest that the proliferative effect of DHT was mediated through the action of FGF-2. However, results of the reverse transcriptase polymerase chain reaction indicated that LNCaP cells did not express FGF-2 message. As a result, the source of FGF-2 in these cultures must be the serum supplemented in the culture media. FGF-2 can bind to heparin sulfate chains within the extracellular matrix (ECM). In cultures treated with exogenous heparin, the proliferative effect of DHT was abolished. These results led to the development of the hypothesis that DHT treatment mediates the release of FGF-2 entrapped in the ECM through increased heparinase activity. The addition of heparinase to cultures of LNCaP cells, in the absence of DHT, was able to stimulate cell proliferation. Moreover, 0.1 nM DHT caused a significant increase in heparinase activity.

CONCLUSIONS

These results provide a possible mechanism for DHT action in LNCaP cells. In the absence of DHT, FGF-2 in culture was trapped in the extracellular matrix and was not available to interact with LNCaP cells. However, in the presence of 0.1 nM DHT, heparinase activity in the culture was elevated and, as a result, it liberated the trapped FGF-2 which, in turn, stimulated proliferation in LNCaP cells.

LNCaP progression model of human prostate cancer: androgen-independence and osseous metastasis

BACKGROUND

Clinically, the lethal phenotypes of human prostate cancer are characterized by their progression to androgen-independence and their propensity to form osseous metastases. We reported previously on the establishment of androgen-independent (AI) human prostate cancer cell lines derived from androgen-dependent (AD) LNCaP cells, with androgen independence defined as the capability of prostate cancer cells to grow in castrated hosts. One of the sublines, C4-2, was found to be AI, highly tumorigenic, and metastatic, having a proclivity for metastasis to the bone.

METHODS

We established the AI and bone metastatic cell sublines B2, B3, B4, and B5 from the parental C4-2 subline, using a previously established coinoculating procedure. We determined the biologic behavior of the parental and derivative LNCaP sublines in vivo and in vitro, as well as their molecular and cytogenetic characteristics.

RESULTS

Unlike other human prostate cancer models, the LNCaP progression model shares remarkable similarities with human prostate cancer. We observed a comparable pattern of metastasis from the primary to the lymph node and to the axial skeleton, with a predominant phenotype of osteoblastic reaction; 25-37.5% of the animals developed paraplegia. Cytogenetic and biochemical characterizations of LNCaP sublines also indicate close similarities between human prostate cancer and the LNCaP progression model. Additional chromosomal changes were detected in B2-B5 sublines derived from C4-2 bone metastases. These LNCaP sublines were found to grow faster under anchorage-dependent but not -independent conditions. The in vitro invasion and in vivo metastatic potential of these LNCaP sublines surprisingly correlated with anchorage-dependent and not -independent growth. The derivative LNCaP sublines when cultured in vitro produced a substantially higher (20-30-fold) amount of basal steady-state concentrations of PSA than that of the parental LNCaP cells. PSA production was high initially, but was markedly reduced when the derivative cell lines were inoculated and allowed to grow long-term in vivo for the establishment of tumors and metastasis, suggesting that unknown host factors derived either from the prostate or the bone can effectively downregulate PSA expression by prostate tumor epithelium.

CONCLUSIONS

The LNCaP model of human prostate cancer progression will help improve our understanding of the mechanisms of androgen-independence and osseous metastasis, and tumor-host determinants of PSA expression.

Cellular retinol-binding protein expression and breast cancer

BACKGROUND

The biologic activity of vitamin A depends, in part, on its metabolism to active nuclear receptor ligands, chiefly retinoic acid. The cellular retinol-binding protein (CRBP) binds vitamin A with high affinity and is postulated to regulate its uptake and metabolism. In this report, we analyze the expression of CRBP in normal and malignant breast tissues.

METHODS

We evaluated CRBP expression by in situ hybridization in six reduction mammoplasty specimens and 49 human breast carcinoma specimens by use of digoxigenin-labeled RNA probes and in nine cultured mammoplasty specimens by northern or western blot analysis. Statistical significance was evaluated with the chi(2) test or Fisher's exact test if the sample sizes were small. All P values are from two-sided tests.

RESULTS

CRBP was expressed in all 15 mammoplasty specimens (normal breast tissue) and in 33 of 35 available specimens of normal tissue adjacent to carcinoma. In contrast, 12 (24%) of 49 carcinoma lesions were uniformly negative for CRBP (P =.023 for comparison with adjacent normal breast tissue). The loss of CRBP expression was as frequent in ductal carcinoma in situ (six [27%] of 22) as in invasive lesions (six [22%] of 27), suggesting that it is a relatively early event in carcinogenesis and not associated with patient age, tumor grade, and expression of steroid receptors or c-Myc. Preliminary experiments did not find an association between CRBP and retinoic acid receptor beta loss, but most (four of five) CRBP-negative tumors were also retinoic acid receptor beta negative.

CONCLUSION

CRBP is underexpressed in 24% (95% confidence interval = 12.5%-36.5%) of human breast carcinomas, implying a link between cellular vitamin A homeostasis and breast cancer. We hypothesize that the loss of CRBP restricts the effects of endogenous vitamin A on breast epithelial cells.

Quantitation of minimal residual disease in acute promyelocytic leukemia patients with t(15;17) translocation using real-time RT-PCR

We took advantage of a recently developed system allowing performance of real-time quantitation of polymerase chain reaction to develop a quantitative method of measurement of PML-RARalpha transcripts which are hallmarks of acute promyelocytic leukemia (APL) with t(15;17) translocation. Indeed, although quantitation of minimal residual disease has proved to be useful in predicting clinical outcome in other leukemias such as chronic myeloid leukemia or acute lymphoblastic leukemia, no quantitative data have been provided in the case of APL. We present here a method for quantitation of the most frequent subtypes of t(15;17) transcripts (namely bcr1 and bcr3). One specific forward primer is used for each subtype in order to keep amplicon length under 200 bp. The expression of PML-RARalpha transcripts is normalized using the housekeeping porphobilinogen deaminase (PBGD) gene. This technique allows detection of 10 copies of PML-RARalpha or PBGD plasmids, and quantitation was efficient up to 100 copies. One t(15;17)-positive NB4 cell could be detected among 106 HL60 cells, although quantitation was efficient up to one cell among 105. Repeatability and reproducibility of the method were satisfying as intra- and inter-assay variation coefficients were not higher than 15%. The efficiency of the method was finally tested in patient samples, showing a decrease of the PML-RARalpha copy number during therapy, and an increase at the time of relapse.

Inactivation of p53 and retinoblastoma family pathways in canine osteosarcoma cell lines

Canine osteosarcoma (OS) has been used as a model system for the study of cancer biology and treatment despite the lack of information regarding its pathogenesis. Expression of tumor suppressor genes known to participate in malignant transformation were studied in five different OS cell lines. Each of the cell lines exhibited properties of transformed cells, and those that were tested grew in soft agarose and formed osteoid-containing tumors when injected subcutaneously into nude mice. p53 function was determined to be defective in each cell line as indicated by the lack of induction of p53-responsive genes, p21 and mdm2, following treatment with 5-fluorouracil. p53 mRNA and protein levels were elevated in three cell lines and were extremely low in two cell lines. p53 protein overexpression correlated with the presence of mutations within the DNA binding domain. Four cell lines appeared to contain normal retinoblastoma (Rb) mRNA and Rb protein and no detectable p16 mRNA or protein. In contrast, the remaining cell line contained high levels of p16 mRNA and protein and significantly reduced levels of Rb, p107, and p130 proteins. These results underscore the importance of inactivating p53 and Rb family pathways in canine OS and suggest that unlike human OS, cells derived from canine OS contain mutations that simultaneously inactivate all three Rb family members.

Delayed cytotoxicity of 6-mercaptopurine is compatible with mitotic death caused by DNA damage due to incorporation of 6-thioguanine into DNA as 6-thioguanine nucleotide

Many protocol studies have shown that low dose 6-mercaptopurine (6MP) in maintenance chemotherapy for childhood acute lymphoblastic leukemia (ALL) can be utilized to cure the disease. Mitotic or reproductive cell death has been recognized after G2 arrest when cells are treated with antitumor agents. The precise mechanism of mode of action of 6MP still remains unclear. We found delayed cytotoxic effect of 6MP in P388 murine leukemic cells. Morphological study showed that 6MP induced delayed death was characterized by an enlargement of cell size and multinucleated nuclei. Agarose gel electrophoresis of fragmented DNA from cells treated with 6MP showed the typical ladder pattern. These findings were compatible with mitotic death. Our results make us hypothesize that the delayed cytotoxicity of 6MP is one of the drug induced mitotic deaths caused by DNA damage due to incorporation of 6-thioguanine (6TG) into DNA as thioguanine nucleotide (TGN). Mitotic death may be a mechanism for killing the cycling cells from residual leukemic cells in G0 or long G1 phases in the treatment of childhood ALL.

Expression and mutational analysis of the MADR2/Smad2 gene in human prostate cancer

BACKGROUND

Loss of heterozygosity (LOH) on chromosome arm 18q is common in sporadic prostate cancer and may be involved in cancer development through inactivation of tumor-suppressor genes (TSG). Recent identification, at 18q21.1, of MADR2/Smad2, a key component in transforming growth factor beta (TGFbeta)-family signaling pathways, led us to investigate the role of this gene in prostate tumorigenesis.

METHODS

Sporadic primary prostate tumors from 25 patients with clinically localized tumors and 7 with metastatic forms were examined for MADR2/Smad2 mutations by using polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) analysis of cDNA, and for gene expression by quantitative reverse transcription-polymerase chain reaction (RT-PCR).

RESULTS

We detected no mutation in MADR2/Smad2 and no abnormal mRNA expression.

CONCLUSIONS

Despite recent evidence indicating that MADR2/Smad2 acts as a tumor-suppressor gene, our findings suggest a limited role of this gene in prostate tumorigenesis, at least in the early stages. Another key tumor-suppressor gene may therefore be the main target of the observed LOH at 18q21.1.

Detection of tumor messenger RNA in the serum of patients with malignant melanoma

Serum RNases are known to be elevated in patients with cancer. Consequently, it is not clear whether human mRNA with sufficient integrity as to permit reverse transcription-PCR (RT-PCR) amplification is detectable in serum. We examined serum from six patients with malignant melanoma for human tyrosinase mRNA using RT-PCR. Serum from 20 normal volunteers served as controls. Tyrosinase mRNA could be demonstrated in serum from four of the six melanoma patients with detection by gel electrophoresis and confirmation by blotting amplified product to a tyrosinase-specific probe. The serum remained tyrosinase mRNA positive, even if passed through a 0.45 microm filter prior to RNA extraction, indicating that the mRNA was extracellular at the time of extraction. Tyrosinase mRNA could not be detected in any control serum (0 of 20 individuals). The presence and integrity of amplifiable RNA was confirmed in all serum specimens (patients and controls) by RT-PCR amplification of c-abl mRNA. Amplifiable RNA could be demonstrated regardless of whether serum was freshly drawn or stored frozen for several years. We conclude that human mRNA can be extracted and amplified from serum. The ability to amplify tumor mRNA from serum may have important utility in cancer diagnostics and monitoring.

[Revisions of the cDNA and primary protein structure of human transcription factor GCF]

GC factor (GCF) was reported as a transcriptional regulator that binds to specific GC-rich sequences in the epidermal growth factor receptor (EGFR) gene promotor, repressing its transcription (Kageyama R. and Pastan I. Cell, 59: 815-825, 1989). In this paper, the author presents revisions of the cDNA and the amino acid sequences of the GCF. 1) 5' rapid amplification of cDNA end (5'RACE) for analysis of RNA of a cancer cell line, A431, was performed, which revealed that the 5' end of GCF cDNA was fused to a 308 bp fragment of other cDNA; simultaneously, the real 5' end cDNA sequence with 31 bp was identified. RNase protection assay presented a main protected band, which was consistent with the result of the RACE analysis. 2) T at the position 787 of the previously reported GCF cDNA was absent from RT-PCR on A431 total RNA. 3) A new sequence with 114 bp was observed on A431 RNA between the positions 851 and 852 of the already reported cDNA by RT-PCR. These observations were confirmed by RT-PCR analyses of RNAs prepared from several other human cell lines, including a non-transformed one (HFL), and white blood cells derived from a normal person. 4) Sequence of genomic GCF DNA was consistent with the new cDNA sequence but not with the previously reported one. 5) The remaining sequence of GCF cDNA was found to be identical to that of the previously reported GCF, based on the results of RT-PCR analyses of RNA prepared from human white blood cells. 6) By the corrections, the GCF cDNA consisted of 2661 bp nucleotides. This revised GCF cDNA (the wild type) encodes a protein of 781 amino acids, including two new sequence regions of 186 amino acids on the N-terminal side of this protein. The revisions eliminated the highly basic region of the amino-terminus of the previously reported GCF, while the other three fourth amino acid sequences of the GCF protein that contained leucine-zipper-like domain had not changed. The revised GCF had no highly homologous protein in the database except the previously reported GCF. 7) The author has developed a specific antibody to human GCF protein. This antibody specifically recognized a protein with a molecular weight of approximately 100 kDa present in the extracts from human cell lines, as confirmed by immunoprecipitation followed by Western blotting. 8) Indirect immunofluorescence of A431 and HeLa cells using the anti-GCF antibody showed that the GCF protein was localized in the nucleus, suggesting that the revised GCF is a nucleoprotein.

Expression of the Ets-1 proto-oncogene correlates with malignant potential in human astrocytic tumors

The protein encoded by the Ets-1 proto-oncogene is a transcription factor that regulates expression of matrix proteases. It has been associated with tumor invasion and angiogenesis. Glioma progression is characterized by increased invasiveness and neovascularization, so we hypothesized that expression of Ets-1 proto-oncogene might play a role in the progression of these tumors. Therefore, we examined the expression of Ets-1 protein by immunohistochemical means and in situ hybridization in tissues obtained from 81 primary and 20 recurrent astrocytic tumors. Twenty-eight (65%) of 43 glioblastomas (Grade IV astrocytomas) stained for Ets-1. The percentage of positive cells in glioblastomas varied from 10 to 90%. Of the 16 anaplastic astrocytomas (Grade III), 4 (25%) were moderately positive (<50% of cells) for Ets-1. None of 22 cases of low-grade astrocytomas (Grade II) expressed endogenous Ets-1. The staining score was significantly associated with tumor grade (P < .0001). Normal brain tissues did not express Ets-1 protein, whereas recurrent astrocytoma cases expressed significantly more positivity for Ets-1 than did primary tumors (P = .03). The Ets-1 protein was observed mainly in the nucleus and corresponded to the cytoplasmic Ets-1 mRNA localization by in situ hybridization. Western and Northern blot analyses confirmed overexpression of Ets-1 protein and mRNA in high-grade tumors. We conclude that Ets-1 protein expression correlates with the malignant potential of tumors of astroglial origin.