A distinct pre-existing inflammatory tumour microenvironment is associated with chemotherapy resistance in high-grade serous epithelial ovarian cancer.

BACKGROUND: Chemotherapy resistance is a major determinant of poor overall survival rates in high-grade serous ovarian cancer (HGSC). We have previously shown that gene expression alterations affecting the NF-κB pathway characterise chemotherapy resistance in HGSC, suggesting that the regulation of an immune response may be associated with this phenotype. METHODS: Given that intrinsic drug resistance pre-exists and is governed by both tumour and host factors, the current study was performed to examine the cross-talk between tumour inflammatory microenvironment and cancer cells, and their roles in mediating differential chemotherapy response in HGSC patients. Expression profiling of a panel of 184 inflammation-related genes was performed in 15 chemoresistant and 19 chemosensitive HGSC tumours using the NanoString nCounter platform. RESULTS: A total of 11 significantly differentially expressed genes were found to distinguish the two groups. As STAT1 was the most significantly differentially expressed gene (P=0.003), we validated the expression of STAT1 protein by immunohistochemistry using an independent cohort of 183 (52 resistant and 131 sensitive) HGSC cases on a primary tumour tissue microarray. Relative expression levels were subjected to Kaplan-Meier survival analysis and Cox proportional hazard regression models. CONCLUSIONS: This study confirms that higher STAT1 expression is significantly associated with increased progression-free survival and that this protein together with other mediators of tumour-host microenvironment can be applied as a novel response predictive biomarker in HGSC. Furthermore, an overall underactive immune microenvironment suggests that the pre-existing state of the tumour immune microenvironment could determine response to chemotherapy in HGSC.

Characterization of a novel founder MSH6 mutation causing Lynch syndrome in the French Canadian population.

We identified an MSH6 mutation (c.10C>T, p.Gln4*) causing Lynch syndrome (LS) in 11 French Canadian (FC) families from the Canadian province of Quebec. We aimed to investigate the molecular and clinical implications of this mutation among FC carriers and to assess its putative founder origin. We studied 11 probands and 27 family members. Additionally 6433 newborns, 187 colorectal cancer (CRC) cases, 381 endometrial cancer (EC) cases and 179 additional controls, all of them from Quebec, were used. Found in approximately 1 of 400 newborns, the mutation is one of the most common LS mutations described. We have found that this mutation confers a greater risk for EC than for CRC, both in the 11 studied families and in the unselected cases: EC [odds ratio (OR) = 7.5, p < 0.0001] and CRC (OR = 2.2, p = 0.46). Haplotype analyses showed that the mutation arose in a common ancestor, probably around 430-656 years ago, coinciding with the arrival of the first French settlers. Application of the results of this study could significantly improve the molecular testing and clinical management of LS families in Quebec.

Analysis of active surveillance uptake for localized prostate cancer in Quebec in 2016: A Canadian bicentric study and comparison with 2010 data.

INTRODUCTION: Active surveillance (AS) has emerged as a primary management strategy for low-risk prostate cancer (PC) patients. We aimed to assess AS uptake over a 1-year snapshot throughout Quebec and to compare it to 2010 multicentric Canadian data. METHODS: A retrospective chart review and data collection was performed in 1 academic and 2 non-academic community centres from Quebec, among men identified in 2016 with localized T1c-T2c PC on biopsy, fulfilling NCCN criteria of low-risk (LR)-PC, including very-low-risk (VLR) and non-VLR-PC, and favourable-intermediate risk (FIR)-PC. AS adherence was defined when chosen as initial strategy, without any radical treatment within 6 months. RESULTS: Overall, 259 patients fulfilled the inclusion criteria with 50.2% of VLR-PC patients. At 6 months, 81% patients in the LR group and 65% in the FIR group were considered as adherent to AS, in both centres, but with an increased use of AS in the community centres compared to 2010 data. The rates of AS maintenance decreased at 12 months to respectively 69% and 58%. Among the VLR group, the rate of initiation was 98% and decreased to 85% at 12 months. CONCLUSION: Our data suggest that the majority of low-risk PC patients indeed initiated an AS in 2016, with even a greater proportion of VLR-PC patients compared to 2010. This ideal strategy should be encouraged and improved at 12 months, and assessed with recent data and longer follow-up.

Hierarchical clustering of immunohistochemical analysis of the activated ErbB/PI3K/Akt/NF-kappaB signalling pathway and prognostic significance in prostate cancer.

BACKGROUND: The PI3K/Akt signalling pathway, induced by epidermal growth factor receptor (EGFR) and Her-2, is involved in the constitutive activation of NF-kappaB in prostate cancer cell lines. In this study, we extended the in vitro observation using an ex vivo model of prostate cancer tissues and assessed the prognostic significance of the PI3K/Ak/NF-kappaB signalling determinants. METHODS: We analysed a prostate cancer tissue microarray of 63 patients for the expression of total and activated EGFR, Her-2 receptors and the signalling molecules PTEN, phospho-PTEN, Akt, phospho-Akt and the NF-kappaB subunit p65. Data were analysed using Spearman's rho test, Kaplan-Meier curves and multivariate Cox regression analysis. In addition, a non-supervised hierarchical clustering analysis was applied to stratify patients according to prognostic groups in terms of risk of recurrence. RESULTS: The concomitant overexpression of activated EGFR and Her-2 was correlated with the nuclear expression of NF-kappaB. EGFR, phospho-EGFR, phospho-Her-2, ErbB3 and nuclear NF-kappaB were associated with the overall biochemical recurrence (BCR) of patients. The non-supervised hierarchical clustering analysis resulted in the separation of patients into five groups according to BCR. CONCLUSIONS: These results validate the previous in vitro data on ErbB involvement in NF-kappaB activation and shows evidence for a significant role of ErbB/PI3K/Akt/NF-kappaB signalling in the progression of prostate cancer.

The chronic myelogenous leukemia-specific P210 protein is the product of the bcr/abl hybrid gene.

Chronic myelogenous leukemia (CML) is a human disease associated with a consistent chromosomal translocation that results in sequences from the c-abl locus on chromosome 9 being fused to sequences in a breakpoint cluster region (bcr) on chromosome 22. CML cells have two novel products: an 8.5-kilobase RNA transcript containing both abl and bcr and a 210-kilodalton phosphoprotein (P210) recognized by v-abl-specific antisera. To test whether the P210 is the product of the novel 8.5-kilobase bcr/abl fusion transcript, antibodies were prepared against c-abl and bcr determinants. By using these reagents and v-abl-specific antisera, it was demonstrated that the P210 in CML cells is indeed the protein product of the 8.5-kilobase transcript. By analogy to the gag/abl fusion protein of Abelson murine leukemia virus, the replacement of amino terminal c-abl sequences by bcr sequences in P210 may create a transforming protein involved in CML. A 190-kilodalton phosphoprotein that is a candidate for the normal bcr protein was identified in both HeLa and K562 cells.

Transfer of chromosome 3 fragments suppresses tumorigenicity of an ovarian cancer cell line monoallelic for chromosome 3p.

Multiple chromosome 3p tumor suppressor genes (TSG) have been proposed in the pathogenesis of ovarian cancer based on complex patterns of 3p loss. To attain functional evidence in support of TSGs and identify candidate regions, we applied a chromosome transfer method involving cell fusions of the tumorigenic OV90 human ovarian cancer cell line, monoallelic for 3p and an irradiated mouse cell line containing a human chromosome 3 in order to derive OV90 hybrids containing normal 3p fragments. The resulting hybrids showed complete or incomplete suppression of tumorigenicity in nude mouse xenograft assays, and varied in their ability to form colonies in soft agarose and three-dimensional spheroids in a manner consistent with alteration of their in vivo tumorigenic phenotypes. Expression microarray analysis identified a set of common differentially expressed genes, such as SPARC, DAB2 and VEGF, some of which have been shown implicated in ovarian cancer. Genotyping assays revealed that they harbored normal 3p fragments, some of which overlapped candidate TSG regions (3p25-p26, 3p24 and 3p14-pcen) identified previously in loss of heterozygosity analyses of ovarian cancers. However, only the 3p12-pcen region was acquired in common by all hybrids where expression microarray analysis identified differentially expressed genes. The correlation of 3p12-pcen transfer and tumor suppression with a concerted re-programming of the cellular transcriptome suggest that the putative TSG may have affected key underlying events in ovarian cancer.

Enhanced killing of androgen-independent prostate cancer cells using inositol hexakisphosphate in combination with proteasome inhibitors.

Effective treatments for androgen-independent prostate cancer (AIPCa) are lacking. To address this, emerging therapeutics such as proteasome inhibitors are currently undergoing clinical trials. Inositol hexakisphosphate (IP6) is an orally non-toxic phytochemical that exhibits antitumour activity against several types of cancer including PCa. We have previously shown that treatment of PC3 cells with IP6 induces the transcription of a subset of nuclear factor-kappaB (NF-kappaB)-responsive and pro-apoptotic BCL-2 family genes. In this study, we report that although NF-kappaB subunits p50/p65 translocate to the nucleus of PC3 cells in response to IP6, inhibition of NF-kappaB-mediated transcription using non-degradable inhibitor of kappaB (IkappaB)-alpha does not modulate IP6 sensitivity. Treatment with IP6 also leads to increased protein levels of PUMA, BIK/NBK and NOXA between 4 and 8 h of treatment and decreased levels of MCL-1 and BCL-2 after 24 h. Although blocking transcription using actinomycin D does not modulate PC3 cell sensitivity to IP6, inhibition of protein translation using cycloheximide has a significant protective effect. In contrast, blocking proteasome-mediated protein degradation using MG-132 significantly enhances the ability of IP6 to reduce cellular metabolic activity in both PC3 and DU145 AIPCa cell lines. This effect of combined treatment on mitochondrial depolarisation is particularly striking and is also reproduced by another proteasome inhibitor (ALLN). The enhanced effect of combined MG132/IP6 treatment is almost completely inhibited by cycloheximide and correlates with changes in BCL-2 family protein levels. Altogether these results suggest a role for BCL-2 family proteins in mediating the combined effect of IP6 and proteasome inhibitors and warrant further pre-clinical studies for the treatment of AIPCa.

Construction of a chromosome 17 transcriptome in serous ovarian cancer identifies differentially expressed genes.

Cytogenetic, molecular genetic, and functional analyses have implicated chromosome 17 genes in epithelial ovarian cancer (EOC). To further characterize the contribution of chromosome 17 genes in EOC, the Affymetrix U133A GeneChip was used to perform transcriptome analyses of 15 primary cultures of normal ovarian surface epithelial (NOSE) cells and 17 malignant ovarian tumor (TOV) samples of the serous histopathologic subtype. A two-way comparative analysis of 776 known genes and expressed sequences identified 253 genes that exhibited at least a threefold difference in expression in at least one TOV sample compared to the mean of NOSE samples. Within this data set, 99 of the 253 (39.1%) genes exhibited similar patterns of expression across all tested samples, suggesting a high degree of concordance in the chromosome 17 transcriptome. This observation was supported by hierarchical clustering analysis that segregated the TOV and NOSE samples into two separate groups. There were 77 genes that were differentially expressed in at least 50% of the TOV samples. Five genes (AdoRA(2B)at 17p12, CCL2 at 17q12, ACLY at 17q21.2, WIPI1 at 17q24.2, and SLC16A3 at 17q25.3) were significantly (P < 5.13E-11) differentially expressed at least threefold in all serous TOV samples, and all five genes were underexpressed in these TOV samples as compared to the NOSE samples. Interestingly, several of these differentially expressed genes have been previously associated with response to hypoxia.

Multi-size spheroid formation using microfluidic funnels.

We present a microfluidic platform for automatic multi-size spheroid formation within constant volume hanging droplets (HDs) from a single inlet loading of a constant cell concentration. The platform introduces three technological improvements over the existing spheroid formation platforms: 1) cell seeding control is achieved by enrichment of a cell solution rather than dilution; 2) cell seeding in each HD is fully independent and pre-programmable at the design stage; 3) the fabricated chip operates well using a hydrophobic PDMS surface, ensuring long-term storage possibility for device usage. Pre-programmed cell seeding densities at each HD are achieved using a "microfluidic funnel" layer, which has an array of cone-shaped wells with increasing apex angles acting as a metering unit. The integrated platform is designed to form, treat, stain, and image multi-size spheroids on-chip. Spheroids can be analyzed on-chip or easily transferred to conventional well plates for further processing. Empirically, enrichment factors up to 37× have been demonstrated, resulting in viable spheroids of diameters ranging from 230-420 µm and 280-530 µm for OV90 and TOV112D cell lines, respectively. We envision that microfluidic funnels and single inlet multi-size spheroid (SIMSS) chips will find broad application in 3D biological assays where size-dependent responses are expected, including chemoresponse assays, photodynamic therapy assays, and other assays involving drug transport characterization in drug discovery.

Loss of PRP4K drives anoikis resistance in part by dysregulation of epidermal growth factor receptor endosomal trafficking.

Anoikis acts as a critical barrier to metastasis by inducing cell death upon cancer cell detachment from the extracellular matrix (ECM), thereby preventing tumor cell dissemination to secondary sites. The induction of anoikis requires the lysosomal-mediated downregulation of epidermal growth factor receptors (EGFRs) leading to termination of pro-survival signaling. In this study, we demonstrate that depletion of pre-mRNA splicing factor 4 kinase (PRP4K; also known as PRPF4B) causes dysregulation of EGFR trafficking and anoikis resistance. We also report a novel cytoplasmic localization of PRP4K at the late endosome, and demonstrate both nuclear and cytoplasmic localization in breast, lung and ovarian cancer tissue. Mechanistically, depletion of PRP4K leads to reduced EGFR degradation following cell detachment from the ECM and correlates with increased TrkB, vimentin and Zeb1 expression. As a result, PRP4K loss promotes sustained growth factor signaling and increased cellular resistance to anoikis in vitro and in a novel zebrafish xenotransplantation model of anoikis sensitivity, as well as increased metastasis in a mouse model of ovarian cancer. Thus, PRP4K may serve as a potential biomarker of anoikis sensitivity in ovarian and other epithelial cancers.

Human TDE1, a TDE1/TMS family member, inhibits apoptosis in vitro and stimulates in vivo tumorigenesis.

We have previously described hTDE1, the human homologue of the recently described TDE1/TMS family of proteins whose members have been identified in several species. Although a defined biochemical activity has yet to be assigned to TDE1/TMS family members, previous results point to the overexpression of family members in tumor cell lines or tissues. To define whether hTDE1 may directly impact on neoplastic transformation, we derived and characterized stable Rat-1 transfectants that constitutively express hTDE1 at the plasma membrane. Expression of hTDE1 in Rat-1 transfectants had a significant effect on cell contact inhibition in vitro as judged by a focus formation assay. In addition, by monitoring caspase-3 activity and Hoechst staining, we determined that hTDE1 overexpression partially protects cells from serum starvation- and etoposide-induced apoptosis. Finally, hTDE1 Rat-1-expressing clones accelerated the formation of tumors in a nude mouse assay. Our results suggest that hTDE1 contributes directly to oncogenesis in vivo that may in part be explained by its effect on apoptosis in vitro.

Location of sequences in polyomavirus DNA that are required for early gene expression in vivo and in vitro.

To define the DNA sequences required for the expression of the polyomavirus early transcription unit, we cloned part of the viral genome in a plasmid vector, isolated mutants bearing lesions introduced in vitro within DNA sequences upstream of the transcriptional start site, and measured the capacity of these various mutant genomes to transform cells and to function as templates for transcription in vitro by comparison with wild-type DNA. One set of mutants bore 5' unidirectional deletions beginning at position -810 and extending downstream to position +4. Another set of mutants bore 3' undirectional deletions starting at position +4 and progressing upstream to position -311. The last set of mutants bore internal deletions between positions -810 and +4. Analyses of the properties of these mutant DNAs led us to conclude that the region between positions -403 and -311 includes an enhancer of gene expression. Deletion of this area from the viral genome reduced gene expression in vivo to 1 to 2% of wild-type levels, as measured by transformation assays. Moreover, this region increased the frequency of transformation of thymidine kinase-negative Rat-2 cells by the herpes simplex virus thymidine kinase (tk) gene from 5- to 20-fold. This occurred only if the polyomavirus sequences were covalently linked to the tk gene and then occurred independently of their orientation or position relative to the tk gene. A second transcriptional element is located downstream of the enhancer between positions -311 and -213. This element together with the enhancer was sufficient to bring about transformation of Rat-1 cells at nearly wild-type frequencies, and together these elements constitute the minimal sequences required for gene expression in vivo. The sequences making up the second element may be functionally duplicated downstream of position -165 (between positions -165 and -60). This was revealed by the characterization of mutant genomes with deletions between positions -349 and -60. The role of these redundant elements is not known; however, they may be analogous to the 21-base-pair repeats of simian virus 40. Finally, sequences between positions -57 and -1 were required for accurate and efficient transcription in vitro. However, this DNA stretch, which includes the TATA box and major transcriptional start sites, was not absolutely required for gene expression in vivo. We conclude that the polyomavirus promoter comprises multiple functional elements which are distributed across a DNA stretch of about 400 base pairs.

The Cdc42/Rac1 regulator CdGAP is a novel E-cadherin transcriptional co-repressor with Zeb2 in breast cancer.

The loss of E-cadherin causes dysfunction of the cell-cell junction machinery, which is an initial step in epithelial-to-mesenchymal transition (EMT), facilitating cancer cell invasion and the formation of metastases. A set of transcriptional repressors of E-cadherin (CDH1) gene expression, including Snail1, Snail2 and Zeb2 mediate E-cadherin downregulation in breast cancer. However, the molecular mechanisms underlying the control of E-cadherin expression in breast cancer progression remain largely unknown. Here, by using global gene expression approaches, we uncover a novel function for Cdc42 GTPase-activating protein (CdGAP) in the regulation of expression of genes involved in EMT. We found that CdGAP used its proline-rich domain to form a functional complex with Zeb2 to mediate the repression of E-cadherin expression in ErbB2-transformed breast cancer cells. Conversely, knockdown of CdGAP expression led to a decrease of the transcriptional repressors Snail1 and Zeb2, and this correlated with an increase in E-cadherin levels, restoration of cell-cell junctions, and epithelial-like morphological changes. In vivo, loss of CdGAP in ErbB2-transformed breast cancer cells impaired tumor growth and suppressed metastasis to lungs. Finally, CdGAP was highly expressed in basal-type breast cancer cells, and its strong expression correlated with poor prognosis in breast cancer patients. Together, these data support a previously unknown nuclear function for CdGAP where it cooperates in a GAP-independent manner with transcriptional repressors to function as a critical modulator of breast cancer through repression of E-cadherin transcription. Targeting Zeb2-CdGAP interactions may represent novel therapeutic opportunities for breast cancer treatment.

Micro-dissected tumor tissues on chip: an ex vivo method for drug testing and personalized therapy.

In cancer research and personalized medicine, new tissue culture models are needed to better predict the response of patients to therapies. With a concern for the small volume of tissue typically obtained through a biopsy, we describe a method to reproducibly section live tumor tissue to submillimeter sizes. These micro-dissected tissues (MDTs) share with spheroids the advantages of being easily manipulated on-chip and kept alive for periods extending over one week, while being biologically relevant for numerous assays. At dimensions below ~420 µm in diameter, as suggested by a simple metabolite transport model and confirmed experimentally, continuous perfusion is not required to keep samples alive, considerably simplifying the technical challenges. For the long-term culture of MDTs, we describe a simple microfluidic platform that can reliably trap samples in a low shear stress environment. We report the analysis of MDT viability for eight different types of tissues (four mouse xenografts derived from human cancer cell lines, three from ovarian and prostate cancer patients, and one from a patient with benign prostatic hyperplasia) analyzed by both confocal microscopy and flow cytometry over an 8-day incubation period. Finally, we provide a proof of principle for chemosensitivity testing of human tissue from a cancer patient performed using the described MDT chip method. This technology has the potential to improve treatment success rates by identifying potential responders earlier during the course of treatment and providing opportunities for direct drug testing on patient tissues in early drug development stages.

Decreased Fas antigen receptor expression in testicular tumor cell lines derived from polyomavirus large T-antigen transgenic mice.

MT-PVLT-10 transgenic mice express large T-antigen of polyomavirus under the control of the mouse metallothionein-1 promoter and mates of this transgenic line develop testicular tumors at advanced ages. The differential display technique was employed to compare mRNA expression from immortalized cell lines derived from normal or adenomatous testis from MT-PVLT-10 transgenic males. Using this technique, a complementary DNA fragment corresponding to the mouse Fas antigen receptor was recovered from normal testicular cells but not from tumor cells. RNAse protection assays with the Fas antigen specific fragment confirmed its differential expression. Normal testicular cells from the transgenic animals responded to treatment of interferon-gamma by increasing the expression of Fas antigen specific mRNA and were sensitive to the proliferative inhibitory effect of anti-Fas antibody in vitro. This proliferative inhibition was characterized by an accumulation of cells in S phase of the cell cycle. In contrast, the testicular tumor cells did not respond to either interferon-gamma or to anti-Fas antibody in vitro. These results suggest that the toss of proliferative inhibitory effect mediated by the Fas antigen pathway in tumor cells may be an important step in testicular tumor progression in the MT-PVLT-10 transgenic mice.

Polyomavirus large T-antigen protects mouse cells from Fas-, TNF-alpha- and taxol-induced apoptosis.

Polyomavirus large T-antigen (PyLT-Ag), a nucleophosphoprotein essential for regulating viral gene expression, modulates the cell cycle by binding to the Rb tumor suppressor gene product. PyLT-Ag/Rb binding is essential for in vitro immortalization. However, the effect of PyLT-Ag on apoptosis has not been extensively studied. We have previously reported that FasR agonist antibodies (FasR(Ab)) treatment of Sertoli cells derived from transgenic mice expressing PyLT-Ag induces the growth arrest of these cells without concomitant apoptosis. Here we show that stable expression of PyLT-Ag in murine Sertoli TM4 and hybridoma NSO cell lines confers protection from FasR(Ab)-induced apoptosis. The protection was maintained up to 48 h when cells were grown continuously in the presence of FasR(Ab). Removal of the death stimulus after 24 h exposure was sufficient to allow full recovery of the PyLT-Ag expressing cells. The protective effect conferred by PyLT-Ag was associated with a delay in the sequential activation of caspase-8 and -3 after FasR(Ab) treatment. PyLT-Ag co-precipitated following immunoprecipitation of caspase-8 or FADD, both components of the DISC. Based on these results we suggest that PyLT-Ag directly impedes the recruitment or activation of caspase-8 by the FasR. PyLT-Ag expression in TM4 cells was also associated with protection from TNF-alpha- and taxol-induced apoptosis. In contrast, PyLT-Ag expression was not sufficient to confer protection from captothecin-induced apoptosis. Taken together, these results indicate that PyLT-Ag can be a potent inhibitor of Fas(R)(Ab)-, TNF-alpha- and taxol-induced apoptosis.

Microinjection of metallothionein-oncomodulin DNA into fertilized mouse embryos is correlated with fetal lethality.

Oncomodulin (ONCO) is an oncodevelopmental protein expressed in placental and extraembryonic tissue and re-expressed in a wide variety of tumors. The metallothionein promoter (MT) is active in numerous adult tissues, in parietal and visceral extraembryonic endoderm, and developing liver. To study the function of oncomodulin we microinjected MT-ONCO DNA into one-cell embryos and examined tissues of fetal and adult mice. Analysis of implant sites from embryos, microinjected with MT-ONCO DNA then placed into pseudopregnant females, indicated a greater than three-fold increase in empty and necrotic implant sites relative to SV2NEO-microinjected embryos and a seven-fold rise relative to non-microinjected embryos. The striking feature of the lethality was the presence of a normal placenta but absence of fetal tissue. Few MT-ONCO DNA transgenic mice were isolated (3.5%) and none were able to express oncomodulin protein or RNA in any tissue examined, even after prolonged heavy metal stimulation of the MT promoter. Fetal mortality is best correlated with expression of oncomodulin causing an interruption of either cellular differentiation or organogenesis before day 9 in development.

Allelotyping defines minimal imbalance at chromosomal region 17q25 in non-serous epithelial ovarian cancers.

Allelic deletions of multiple chromosome 17q loci in sporadic ovarian cancer of epithelial origin suggest that inactivation of tumor suppressor gene(s) in these regions may be important for ovarian tumorigenesis. To further define the pattern of allelic imbalance in epithelial ovarian tumors of different histologies, a PCR-based assay was used to assess loss of heterozygosity (LOH) of polymorphic markers representative of TP53, BRCA1, NME1 and GH1, and region 17q23-25. LOH was observed for at least one marker in 68% of malignant tumors (n=60) and in 18% tumors of borderline malignancy (n=11), but not in benign tumors (n=5). The highest frequency of LOH in malignant tumors (64%) was observed with D17S801 on 17q25. Ten of 39 malignant ovarian tumors displaying LOH of at least one 17q marker, displayed a LOH pattern enabling the determination of a minimal region of overlapping deletion defined by D17S795 and D17S801. One borderline tumor also displayed an interstitial LOH pattern that overlapped this 17q25 minimal region of deletion. The histologies of malignant tumors displaying a pattern indicative of interstitial 17q deletions were of the endometrioid, clear cell and mucinous epithelial types. As the minimal region of overlap defined by these tumors overlap regions deleted in malignant tumors of all histologic types, and in a tumor of borderline malignancy, the 17q25-tumor suppressor may be implicated in the development of all types of epithelial ovarian tumors.

Polyomavirus large T-antigen expression in heart of transgenic mice causes cardiomyopathy.

One of the early genes of polyomavirus, large T-antigen (PVLT), has been classified in vitro as an immortalizing gene. In order to determine the ability of PVLT to cause the formation of hyperplasia or tumors in vivo, we generated transgenic mice harboring the cDNA for PVLT linked to the heavy-metal responsive metallothionein-1 promoter (MT). The transgene was primarily expressed in testes and seminal vesicles, but expression was also detected in heart of a single transgenic line. The expression of the transgene in the heart of MT-PVLT line 8 mice was correlated with cardiomyopathy and atrial thrombus formation leading to premature death at approximately 160 days due to cardiac failure. The heart of affected animals was from 1.5 to 5.2 fold greater in weight and 2 fold greater in dimensions than normal nontransgenic mice. Affected hearts fell short of frank tumor phenotype and no macroscopic nor microscopic focal growth was found. Histologically the heart has a heterogenous cardiomyocyte population with markedly enlarged cells mixed with relatively normal cells. Both cell types express PVLT protein. The primary cell type affected is the cardiomyocyte however, as heart proportions are maintained, interstitial and non-myocyte cells must be affected either directly or indirectly. Expression of PVLT has upset normal strict control of cell growth in these hearts to result in a new model of congestive cardiomyopathy.