PIAS4 is an activator of hypoxia signalling via VHL suppression during growth of pancreatic cancer cells.

BACKGROUND: The PIAS4 protein belongs to the family of protein inhibitors of activated STAT, but has since been implicated in various biological activities including the post-translational modification known as sumoylation. In this study, we explored the roles of PIAS4 in pancreatic tumourigenesis. METHODS: The expression levels of PIAS4 in pancreatic cancer cells were examined. Cell proliferation and invasion was studied after overexpression and gene silencing of PIAS4. The effect of PIAS4 on hypoxia signalling was investigated. RESULTS: The protein was overexpressed in pancreatic cancer cells compared with the normal pancreas. Gene silencing by PIAS4 small interfering RNA (siRNA) suppressed pancreatic cancer cell growth and overexpression of PIAS4 induced expression of genes related to cell growth. The overexpression of PIAS4 is essential for the regulation of the hypoxia signalling pathway. PIAS4 interacts with the tumour suppressor von Hippel-Lindau (VHL) and leads to VHL sumoylation, oligomerization, and impaired function. Pancreatic cancer cells (Panc0327, MiaPaCa2) treated with PIAS4 siRNA suppressed expression of the hypoxia-inducible factor hypoxia-inducible factor 1 alpha and its target genes JMJD1A, VEGF, and STAT3. CONCLUSION: Our study elucidates the role of PIAS4 in the regulation of pancreatic cancer cell growth, where the suppression of its activity represents a novel therapeutic target for pancreatic cancers.

Kaposi's sarcoma-associated herpesvirus infection of bone marrow dendritic cells from multiple myeloma patients.

Kaposi's sarcoma-associated herpesvirus (KSHV) was found in the bone marrow dendritic cells of multiple myeloma patients but not in malignant plasma cells or bone marrow dendritic cells from normal individuals or patients with other malignancies. In addition the virus was detected in the bone marrow dendritic cells from two out of eight patients with monoclonal gammopathy of undetermined significance (MGUS), a precursor to myeloma. Viral interleukin-6, the human homolog of which is a growth factor for myeloma, was found to be transcribed in the myeloma bone marrow dendritic cells. KSHV may be required for transformation from MGUS to myeloma and perpetuate the growth of malignant plasma cells.

DLK1: increased expression in gliomas and associated with oncogenic activities.

DLK1 (delta-like) is a transmembrane and secreted protein in the epidermal growth factor-like homeotic family. Although expressed widely during embryonic development, only a few tissues retain the expression in adults. Neuroendocrine tumors often highly express this protein; therefore, we hypothesized that brain tumors might also express it. This study found that the expression of DLK1 in gliomas was higher than that in normal brain (P < 0.05). After stable transfection of a DLK1 cDNA expression vector into GBM cell lines, their proliferation was increased. Furthermore, they lost contact inhibition, had enhanced anchorage-independent growth in soft agar, and had significantly greater capacity to migrate. Western blot studies showed that expression of cyclin D1, CDK2, and E2F4 were increased, and Rb levels were decreased in these cells. DLK1 was found on the cell surface and secreted in the medium from the transfected GBM cells. DLK1-enriched condition medium stimulated the growth of glioblastoma multiforme cell lines and explants. DLK1 antibody blocked cell growth stimulated by DLK1. In summary, these results suggest that DLK1 may play a role in the formation or progression of gliomas.

Synergistic decrease of clonal proliferation, induction of differentiation, and apoptosis of acute promyelocytic leukemia cells after combined treatment with novel 20-epi vitamin D3 analogs and 9-cis retinoic acid.

Patients with acute promyelocytic leukemia (APL) usually relapse after all-trans retinoic acid (RA) treatment because this therapy fails to eradicate the malignant clone. Our data showed that KH 1060 and other 20-epi vitamin D3 analogs alone were potent inhibitors of clonal growth of NB4 cells, an APL cell line (ED50, approximately 5 x 10(-11) M). The combination of KH 1060 and 9-cis-RA synergistically and irreversibly enhanced this effect. Neither KH 1060 nor 9-cis-RA (10(-6) M, 3 d) were strong inducers of differentiation of NB4 cells. However, 98% of the cells underwent differentiation to a mature phenotype with features of both granulocytes and monocytes after exposure to a combination of both compounds. Apoptosis only increased after incubation of NB4 cells with 9-cis-RA alone (28%) or with a combination of 9-cis-RA plus KH1060 (32%). Immunohistochemistry showed that the bcl-2 protein decreased from nearly 100% of the wild-type NB4 cells to 2% after incubation with a combination of KH 1060 and 9-cis-RA, and the bax protein increased from 50% of wild-type NB4 cells to 92% after culture with both analogs (5 x 10(-7) M, 3 d). Western blot analysis paralleled these results. Studies of APL cells from one untreated individual paralleled our results with NB4 cells. Taken together, the data demonstrated that nearly all of the NB4 cells can be irreversibly induced to differentiate terminally when exposed to the combination of KH 1060 and 9-cis-RA.

Ligand for peroxisome proliferator-activated receptor gamma (troglitazone) has potent antitumor effect against human prostate cancer both in vitro and in vivo.

Troglitazone, a thiazolidinedione derivative, is a widely used antidiabetic drug that binds and activates peroxisome proliferator-activated receptor gamma (PPARgamma) and enhances insulin sensitivity. It induces differentiation of adipocytes, which highly express PPARgamma. We report that human prostate cancer cells expressed PPARgamma at prominent levels and normal prostate tissues had very low expression. Dose-response clonogenic assays of the PC-3 prostate cancer cell line with troglitazone showed an antiproliferative effect (ED50, 3 x 10(-7) M) and other PPARgamma ligands (BRL49653: ED50, 8 x 10(-8) M; 15-deoxy-delta12,14-prostaglandin J2: ED50, 2 x 10(-6) M; ciglitizone: ED50, not reached; indomethacin: ED50, not reached) showed similar effects. Combinations of troglitazone and a ligand specific for either retinoid X receptor or retinoic acid receptor did not show a synergistic effect. Pulse-exposure to troglitazone (10(-5) M) for different durations showed that 4 days of pulse-exposure to the agent irreversibly inhibited 50% clonal growth of PC-3 cells. Interestingly, PC-3 cells cultured with troglitazone (10(-5) M) showed dramatic morphological changes both by light and electron microscopy, suggesting that the cells became less malignant. Nevertheless, troglitazone did not affect either the cell cycle or several markers of differentiation. LNCaP cells constitutively produced prostate-specific antigen, and levels were markedly enhanced by all-trans-retinoic acid. Troglitazone (10(-5) M, 4 days) decreased by 50% the levels of prostate-specific antigen produced by these cells. In vivo treatment of PC-3 tumors growing in male BNX triple immunodeficient mice with oral troglitazone (500 mg/kg/day) produced significant inhibition of tumor growth (P = 0.01). The only objective side effect of troglitazone in mice was the elevation of serum transaminases. Short-term culture of four surgically obtained human prostate cancer tumors with troglitazone (10(-5) M, 4 days) produced marked and selective necrosis of the cancer cells (about 60%) but not the adjacent normal prostate cells. Taken together, these results suggest that troglitazone may be a useful therapeutic agent for the treatment of prostate cancer, especially in the setting of low disease burden.

WISH-PC2: a unique xenograft model of human prostatic small cell carcinoma.

Prostatic small cell carcinoma is an aggressive subtype of prostate cancer that usually appears as a progression of the original adenocarcinoma. We describe here the WISH-PC2, a novel neuroendocrine xenograft of small cell carcinoma of the prostate. This xenograft was established from a poorly differentiated prostate adenocarcinoma and is serially transplanted in immune-compromised mice where it grows within the prostate, liver, and bone, inducing osteolytic lesions with foci of osteoblastic activity. It secretes to the mouse Chromogranin A and expresses prostate plasma carcinoma tumor antigen-1, six-transmembrane epithelial antigen of the prostate, and members of the Erb-B receptor family. It does not express prostate-specific antigen, prostate stem cell antigen, prostate-specific membrane antigen, and androgen receptor, and it grows independently of androgen. Altogether, WISH-PC2 provides an unlimited source in which to study the involvement of neuroendocrine cells in the progression of prostatic adenocarcinoma and can serve as a novel model for the testing of new therapeutic strategies for prostatic small cell carcinoma.

Transactivational and DNA binding abilities of endogenous p53 in p53 mutant cell lines.

Cells with divergent mutant alleles of the p53 gene have different biological and biochemical properties in vitro. Increasing evidence indicates that p53 is a transcriptional activator, and recently, high affinity DNA binding sites for p53 have been identified. The purpose of this study was to determine in vivo, the effect that various mutant p53 proteins have on their ability to mediate transactivation and to bind specifically to DNA. Either a p53 responsive or control reporter gene was transfected into 18 human carcinoma cell lines, having various p53 mutations, either with or without a wild-type p53 expression vector. The CAT activity and DNA gel retardation were studied to measure transactivation and DNA binding by these endogenous p53s. As expected, the endogenously produced wild-type p53 binds to DNA binding sequences and can transactivate a reporter construct containing a p53 high affinity DNA binding site. Four of five cell lines with homozygous p53 mutations at codon 273 (273His), contained p53 which had the ability to bind to p53 DNA binding sequences and transactivate. In contrast, all the homozygous, non-codon 273 mutant p53s (156Pro, 175His, 223Leu, 248Gln, 248Trp, 280Lys) present in the other cell lines had no transactivating ability. These findings suggest that the biology of cancers with mutations at codon 273 may be different than those with p53 mutations at other sites. The p53 from WRO, a thyroid carcinoma cell line with p53 mutation at codon 223 (223Leu), was able to bind p53 DNA recognition sequences, but was unable to transactivate. Interestingly, in a vulvar carcinoma cell line (A431) with a p53 mutation at codon 273 (273His), the p53 was unable to transactivate and gave an aberrant band on gel retardation. Both CEM and SK-UT-1, which have compound heterozygous mutations at codons 175/248 (175His/248His), produced p53 which can complex with DNA, as well as transactivate. In contrast, the p53 in cell lines with either homozygous 175His or 248His p53 mutations, were unable either to transactivate or bind to the p53 response element. A cell line (NPA) heterozygous for 266Glu p53 mutation, was able to efficiently transactivate a reporter containing a p53 DNA binding site, therefore showing no evidence of a dominant negative effect of the endogenous p53 mutant allele. In summary, this in vivo study further supports the idea that different p53 mutant alleles have various properties which may affect their function.

Mutations in the mitotic check point gene, MAD1L1, in human cancers.

Aneuploidy is a characteristic of the majority of human cancers, and recent studies suggest that defects of mitotic checkpoints play a role in carcinogenesis. MAD1L1 is a checkpoint gene, and its dysfunction is associated with chromosomal instability. Rare mutations of this gene have been reported in colon and lung cancers. We examined a total of 44 cell lines (hematopoietic, prostate, osteosarcoma, breast, glioblastoma and lung) and 133 fresh cancer cells (hematopoietic, prostate, breast and glioblastoma) for alterations of MAD1L1 by RT-PCR-SSCP and nucleotide sequencing. Eight mutations consisting of missense, nonsense and frameshift mutations were found, together with a number of nucleotide polymorphisms. All the alterations in cell lines were heterozygous. Frequency of mutations was relatively high in prostate cancer (2/7 cell lines and 2/33 tumor specimens). We placed a mutant truncated MAD1L1, found in a lymphoma sample, into HOS, Ht161 and SJSA cell lines and found that it was less inhibitory than wild type MAD1L1 at decreasing cell proliferation. Co-expression experiments showed that the mutant form had a dominant-negative effect. Furthermore, this mutant impaired the mitotic checkpoint as shown by decreased mitotic indices in HOS cells expressing mutant MAD1L1 after culture with the microtubule-disrupting agent, nocodazole. Our results suggest a pathogenic role of MAD1L1 mutations in various types of human cancer.

Prostate stem cell antigen (PSCA) expression increases with high gleason score, advanced stage and bone metastasis in prostate cancer.

Prostate stem cell antigen (PSCA) is a recently defined homologue of the Thy-1/Ly-6 family of glycosylphosphatidylinositol (GPI)-anchored cell surface antigens. PSCA mRNA is expressed in the basal cells of normal prostate and in more than 80% of prostate cancers. The purpose of the present study was to examine PSCA protein expression in clinical specimens of human prostate cancer. Five monoclonal antibodies were raised against a PSCA-GST fusion protein and screened for their ability to recognize PSCA on the cell surface of human prostate cancer cells. Immunohistochemical analysis of PSCA expression was performed on paraffin-embedded sections from 25 normal tissues, 112 primary prostate cancers and nine prostate cancers metastatic to bone. The level of PSCA expression in prostate tumors was quantified and compared with expression in adjacent normal glands. The antibodies detect PSCA expression on the cell surface of normal and malignant prostate cells and distinguish three extracellular epitopes on PSCA. Prostate and transitional epithelium reacted strongly with PSCA. PSCA staining was also seen in placental trophoblasts, renal collecting ducts and neuroendocrine cells in the stomach and colon. All other normal tissues tested were negative. PSCA protein expression was identified in 105/112 (94%) primary prostate tumors and 9/9 (100%) bone metastases. The level of PSCA expression increased with higher Gleason score (P=0.016), higher tumor stage (P=0.010) and progression to androgen-independence (P=0. 021). Intense, homogeneous staining was seen in all nine bone metastases. PSCA is a cell surface protein with limited expression in extraprostatic normal tissues. PSCA expression correlates with tumor stage, grade and androgen independence and may have prognostic utility. Because expression on the surface of prostate cancer cells increases with tumor progression, PSCA may be a useful molecular target in advanced prostate cancer.

Improved prognostication of renal cell carcinoma using an integrated staging system.

PURPOSE: To integrate stage, grade, and Eastern Cooperative Oncology Group (ECOG) performance status (PS) into a clinically useful tool capable of stratifying the survival of renal cell carcinoma (RCC) patients. PATIENTS AND METHODS: The medical records of 661 patients undergoing nephrectomy at University of California Los Angeles between 1989 and 1999 were evaluated. Median age was 61 years, male-to-female ratio was 2.2:1, and median follow-up was 37 months. Survival time was the primary end point assessed. Sixty-four possible combinations of stage, grade, and ECOG PS were analyzed and collapsed into distinct groups. The internal validity of the categorized was challenged by a univariate analysis and a multivariate analysis testing for the accountability of each UCLA Integrated Staging System (UISS) category against independent variables shown to have impact on survival. RESULTS: Combining and stratifying 1997 tumor-node-metastasis stage, Fuhrman's grade and ECOG PS resulted in five survival stratification groups designated UISS, and numbered I to V. The projected 2- and 5-year survival for the UISS groups are as follows for the groups: I, 96% and 94%; II, 89% and 67%; III, 66% and 39%; IV, 42% and 23%; and V, 9% and 0%, respectively. UISS accounted for the significant variables in the variate analysis. CONCLUSION: A novel system for staging and predicting survival for RCC integrating clinical variables is offered. UISS is simple to use and is superior to stage alone in differentiating patients' survival. Our data suggests that UISS is an important prognostic tool for counseling patients with various stages of kidney cancer. Further prospective large-scale validation with external data is awaited.

Immunotherapy against murine leukemia.

The central hypothesis underlying specific anti-leukemia immunotherapy is that leukemic cells express antigenic determinants not expressed on their counterpart normal adult cells. We have developed a murine myeloid leukemia/tumor immunization model using the low-immunogenic WEHI3 leukemia in syngeneic mice. Mice preimmunized with irradiated, transduced IL-7-producing WEHI3 cells showed systemic protection and rejection of a lethal dose of intravenously (i.v.) injected parental WEHI3 cells (5 x 10(4)) with 40% long-term survival. When vaccinated with a mixture of parental WEHI3 cells and IL-2-producing NIH-3T3 fibroblasts (5 x 10(5)), 60% survival was observed. Vaccination with murine granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing WEHI3 cells resulted in only 20% survival of i.v. challenged mice, and the additional combination of IL-2- and IL-7-producing vaccine did not reveal any additive or synergistic effects. Immunizing mice with a pre-established leukemia burden (injected with 5 x 10(4) WEHI3 cells, i.v., 3 days prior to immunization) did not cure or result in a prolongation of survival, indicating that improved methods of immunization are needed. Taken together, we have identified IL-7 and IL-2 as effective cytokines in our leukemia/vaccination model with only marginal activity by GM-CSF.

Alterations of the cyclin-dependent kinase inhibitor p19 (INK4D) is rare in hematopoietic malignancies.

Cyclin-dependent kinase inhibitors (CDKIs) can be classified into two groups based on the structure of the proteins. One group includes the p21 (CIP1, WAF1, CAP20), p27 (Kip1), and p57 (Kip2) CDKIs, which contain a homologous amino-terminal cyclin-dependent kinase (cdk) inhibitory domain. The p16 (INK4A), p15 (INK4B), and p18 (INK4C) CDKIs, which have an ankyrin repeat motifs, belong to the other group. The p16 and p15 CDKI genes are very frequently altered in a variety of cancers including hematopoietic malignancies. The p19 (INK4D) gene is a newly cloned CDKI which belongs to the latter group. To determine if p19 genetic alterations play a role in hematopoietic malignancies, we examined DNA from 45 childhood newly diagnosed acute lymphocytic leukemias (ALLs), 30 acute myeloblastic leukemias (AMLs), 10 chronic myelocytic leukemias (CMLs), 45 adult T cell leukemias (ATLs), 70 non-Hodgkin's lymphomas (NHLs), and 20 multiple myelomas (MM) as well as 14 ALL, 20 AML, two ATL, and five lymphoma cell lines. Using Southern blot analysis, one homozygous deletion of the p19 gene was detected in a human immunodeficiency virus (HIV)-related Burkitt-like lymphoma sample. No point mutations in any of the samples were found by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis. Our investigation suggests that alterations of p19 do not play an important role in the development of most hematopoietic malignancies.

Human herpesvirus 8 open reading frame 26 and open reading frame 65 sequences from multiple myeloma patients: a shared pattern not found in Kaposi's sarcoma or primary effusion lymphoma.

Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma-associated herpesvirus, has been implicated in the pathogenesis of Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), multicentric Castleman's disease, and recently multiple myeloma (MM). DNA sequence analyses of HHV-8 suggest that multiple HHV-8 strains exist. We extracted DNA from 24 patients with MM and 3 patients with monoclonal gammopathy of undetermined significance and compared HHV-8 open reading frames (ORFs) 26 and 65 sequences with those derived from patients with KS, PEL, and two HHV-8-positive PEL cell lines KS-1 and BC-1. ORF26 sequence data suggest that MM patients are consistently carriers of HHV-8 strain subtype C3. All MM patients also consistently revealed either a single bp deletion or substitution at position 112197 in ORF65. This unique alteration is not present in patients with KS or PEL or in PEL cell lines. It occurs in the portion of ORF65 that is known to be responsible for a serological response to HHV-8.

LNK (SH2B3): paradoxical effects in ovarian cancer.

LNK (SH2B3) is an adaptor protein studied extensively in normal and malignant hematopoietic cells. In these cells, it downregulates activated tyrosine kinases at the cell surface resulting in an antiproliferative effect. To date, no studies have examined activities of LNK in solid tumors. In this study, we found by in silico analysis and staining tissue arrays that the levels of LNK expression were elevated in high-grade ovarian cancer. To test the functional importance of this observation, LNK was either overexpressed or silenced in several ovarian cancer cell lines. Remarkably, overexpression of LNK rendered the cells resistant to death induced by either serum starvation or nutrient deprivation, and generated larger tumors using a murine xenograft model. In contrast, silencing of LNK decreased ovarian cancer cell growth in vitro and in vivo. Western blot studies indicated that overexpression of LNK upregulated and extended the transduction of the mitogenic signal, whereas silencing of LNK produced the opposite effects. Furthermore, forced expression of LNK reduced cell size, inhibited cell migration and markedly enhanced cell adhesion. Liquid chromatography-mass spectroscopy identified 14-3-3 as one of the LNK-binding partners. Our results suggest that in contrast to the findings in hematologic malignancies, the adaptor protein LNK acts as a positive signal transduction modulator in ovarian cancers.

Infection of primary dermal microvascular endothelial cells by Kaposi's sarcoma-associated herpesvirus.

OBJECTIVE: To develop an in vitro model for infection of primary human cells with Kaposi's sarcoma (KS) herpesvirus (KSHV). DESIGN: The recent identification of a herpesvirus associated with KS, its successful isolation in vitro, and its complete DNA sequencing facilitates experiments on the pathogenesis of AIDS-related KS. Completed studies demonstrate that the endothelial cells lining the vascular slits in KS lesions are productively infected with KSHV and may be the principal site of virus replication. We have designed a model system to study the infection of primary human cells with KSHV. METHODS: A coculture technique was used with KS cells (KS-1) and primary dermal microvascular endothelial cells. RESULTS: We detected increasing viral DNA concentrations as well as viral mRNA suggesting that a productive virus infection occurs in the target cells. Infection of these cells is dose- and time-dependent and is inhibited by lobucavir, foscarnet and 9-(2-phosphomethoxyethyl) adenine. With a modification of the model, KSHV can be serially passaged in primary cells in excess of 16 passages. CONCLUSIONS: This novel model assay system makes new studies on the role of KSHV and KSHV-induced cellular products on the pathogenesis of KS possible. It also provides a high volume screening method to detect agents that inhibit KSHV infection of primary endothelial cells.

Kaposi's sarcoma-associated herpesvirus/human herpesvirus type 8 encephalitis in HIV-positive and -negative individuals.

OBJECTIVE: Kaposi's sarcoma-associated herpesvirus (KSHV) human herpesvirus type 8 (HHV-8) has been associated with Kaposi's sarcoma and a variety of benign lymphoid proliferations including angioimmunoblastic lymphadenitis with dysproteinemia and Castleman's disease. KSHV/HHV-8 has also been associated with inflammatory conditions including interstitial pneumonitis. Although herpesviruses are commonly associated with encephalitis in immunosuppressed individuals, KSHV/HHV-8 has not previously been associated with central nervous system disease other than lymphoma. The first cases of KSHV/HHV-8 associated encephalitis have been described. METHODS AND DESIGN: KSVH/HHV-8 sequences were evaluated in brain biopsies from three cases of otherwise unexplained encephalitis from three patients, two of whom were positive for HIV. Amplification of the polymerase chain reaction product was confirmed with Southern blot hybridization on three separate occasions, and with appropriate positive and negative controls. RESULTS: All three cases of encephalitis were associated with KSHV/HHV-8 sequences. Characteristic lesions included endothelial cell swelling and perivascular cuffing by lymphocytes. CONCLUSIONS: KSHV/HHV-8 was associated with encephalitis in immunosuppressed individuals, and should have been considered in the differential diagnosis of unexplained viral encephalitis. KSHV/HHV-8 may have tropism for the central nervous system.

Involucrin in squamous and basal cell carcinomas of the skin: an immunohistochemical study.

Involucrin is a precursor of cross-linked protein of human stratum corneum, and its appearance in the upper layers of the epidermis is a function of the normal differentiation of the keratinocyte. Cases of basal cell and squamous cell carcinoma were evaluated for the presence of involucrin using immunoperoxidase techniques on paraffin sections. Basal cell carcinomas were negative for involucrin with staining restricted to squamous horn cysts, while squamous cell carcinomas stained strongly, particularly in large keratinized cells. Cases of squamous cell carcinoma in situ (Bowen's disease) revealed increased staining for involucrin with staining of dyskeratotic cells at all levels in the epithelium. Abnormal patterns of staining were also noted in non-neoplastic epidermis adjacent to carcinomas. Immunohistochemical staining for involucrin identifying abnormal or premature keratinization is a sensitive marker for dyskeratosis in squamous epithelia and may have applications in the histopathologic evaluation of skin specimens.

Remission of acromegaly caused by pituitary carcinoma after surgical excision of growth hormone-secreting metastasis detected by 111-indium pentetreotide scan.

GH-secreting carcinomas of the pituitary are extremely rare. We describe a 37-yr-old woman with refractory acromegaly 15 yr after transphenoidal surgery and radiotherapy, with no evidence of a recurrent pituitary mass. Scanning with 111-indium pentetreotide revealed an area of intense activity in the left neck. A 3.5 x 2.5-cm mass was excised from the neck after demonstrating an arterio-venous GH gradient of 7:1. GH levels (50 ng/mL) dropped to 0.8 ng/mL 3 h after surgery and remained normal. GH gene expression was demonstrated in the metastasis by Northern and Western blot analyses and by positive immunocytochemistry and immunoelectron microscopy. In vitro cultured cells responded to GHRH and TRH by increasing GH levels (P < 0.01). Medium GH was identical to authentic pituitary GH, as demonstrated by high pressure liquid chromatography. RT-PCR of hypothalamic hormone receptor messenger RNA in the mass revealed somatostatin receptor subtypes 2, 3, and 5 and GHRH, TRH, and dopamine receptor expression. No GH gene amplification, rearrangement, or gsp mutation was found. RB gene deletion and H-ras mutations, previously reported in PRL- and ACTH-secreting carcinomas, were not detected. In conclusion, clinical and molecular features of a GH-secreting pituitary carcinoma are presented. This metastatic lesion synthesized GH and expressed functional hypothalamic hormone receptors.

Undifferentiated (embryonal) sarcoma of the liver. A tumor of uncertain histogenesis showing divergent differentiation.

Pathologic features of eight cases of undifferentiated (embryonal) sarcoma of the liver (USL) in childhood were studied. Light microscopic examination showed a diffuse growth of spindle cells with occasional polygonal cells and multinucleated giant cells and also revealed focal areas of storiform pattern in four tumors, cambium layer formation in one tumor, and alveolar arrangement in one tumor. Immunohistochemical study showed positive staining of proliferating cells for suggestive histiocytic markers (A1AT in 6/6, A1ACT in 5/6, lysozyme in 4/6, and KP1 in 4/6) and for muscle markers (desmin in 4/6 and HHF35 in 3/6). Ultrastructural examination demonstrated that the individual tumors were composed of a mixture of cells having fibroblastic, histiocytoid, fibrohistiocytoid, myofibroblastic, and undifferentiated (primitive mesenchymal) morphologies. Also identified were cells with definite myoblastic morphology in three tumors: leiomyoblastic in one and rhabdomyoblastic in two. In conclusion, the tumor cells in USL show phenotypical diversity comparable to those of malignant fibrous histiocytoma with or without additional rhabdomyosarcomatous or leiomyosarcomatous differentiation.

Kaposi's sarcoma-associated herpesvirus and human herpesvirus 8 (KSHV/HHV8)-associated lymphoma of the bowel. Report of two cases in HIV-positive men with secondary effusion lymphomas.

This report describes two cases of Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8 (KSHV/HHV8)-associated lymphomas that primarily involved the large bowel and that secondarily caused malignant effusions. Involvement of the gastrointestinal tract is of interest because epidemiologic evidence suggests that KSHV/HHV-8 may be transmitted via the fecal-oral route, and KSHV/HHV8 DNA has been detected in rectal samples from HIV-positive patients. This report describes two HIV-positive men who developed primary KSHV/ HHV8-associated lymphomas of the bowel. Despite similar morphology and immunophenotype, these cases differ from most KSHV/HHV8-associated primary effusion lymphomas, which present with malignant effusions in the absence of a solid tumor mass. The spectrum of KSHV/HHV8-associated lymphomas is expanded to include a subset of primary bowel lymphomas in individuals infected with human immunodeficiency virus.