PrLZ is expressed in normal prostate development and in human prostate cancer progression.

PURPOSE: We previously reported the isolation and characterization of PrLZ, a novel prostate-specific and androgen-responsive gene of the tumor protein D52 family at chromosome 8q21.1. PrLZ is the only known gene in this locus with prostate specificity. Expression level of PrLZ was elevated specifically in cancer cells, suggesting its association with malignancy. EXPERIMENTAL DESIGN: To define its biological function in the morphogenesis, development, and functional maturation of the prostate gland and to gain further insight into its role in prostate cancer, we examined PrLZ expression in prostate specimens during early embryonic development and in adult tissue. RESULTS: PrLZ first appears in the nuclei of the prostate epithelia at 16 weeks of gestation before its distribution in the cytoplasm at later ages. Its expression peaks at 24 years of age, declines at 31 years of age, and maintains a minimal level in later age. On prostate cancer development, PrLZ expression is reactivated, and its expression increases from primary localized tumor to bone metastasis. Overexpression of PrLZ in prostate cancer cells accelerates their growth in vitro and tumor formation in vivo. CONCLUSION: This work identifies PrLZ as a marker for prostate cancer progression and metastasis, and its pattern of expression is suggestive of a proto-oncogene.     

Endoglin is expressed on a subpopulation of immature erythroid cells of normal human bone marrow

A monoclonal antibody (1G2) was raised by immunization of a Balb/c mouse with the leukemic blasts from a patient suffering from chronic myelogenous leukemia blast crisis (CML-BC). Sequential immunoprecipitation of the protein from human umbilical vein endothelial cells with 1G2 and the endoglin-specific monoclonal antibody 44G4 indicated that both antibodies react with the same molecule, a homodimer of molecular mass 180,000. This protein was first identified on acute lymphoblastic leukemia and was shown to be primarily associated with endothelial cells. In addition, 1G2 and 44G4 identified the same subpopulation of human bone marrow mononuclear cells (BMMNC), as established by two colour immunofluorescence analysis. By cell sorting and colony assays it could be demonstrated that endoglin is not expressed on hemopoietic precursor cells (CFU-G, CFU-GM, CFU-GEMM, BFU-E). May-Grünwald-Giemsa staining of sorted BMMNC revealed that 1G2 recognized immature proerythroblasts and double-fluorescence analysis showed that endoglin is present on a subset of glycophorin A-positive BMMNC. 1G2 was not reactive on bone marrow B-cells (CD19, CD20), T-cells (CD3, CD7), natural killer cells (CD56), myeloid cells (CD13, CD14, CD15, CD33), and on CD34-positive cells. Endoglin contains an arginine-glycine-aspartic acid sequence, a feature generally associated with extracellular matrix proteins which interact with integrins. It is suggested that proerythroblasts may utilize endoglin to interact with integrins in cell-cell adhesion events in the stromal or hemopoietic compartment of the bone marrow.     

MRP is frequently expressed in human lung-cancer cell lines,in non-small-cell lung cancer and in normal lung

The multidrug resistance-associated protein (MRP), a new membrane transporter related to non-Pgp multidrug resistance, is overexpressed in some drug-selected cancer-cell lines. The role of MRP in unselected cell lines and in human cancer is unknown. MRP gene expression, determined by RNase protection assay and chemosensitivity to doxorubicin, etoposide and cisplatin, determined by MTT assay, were assessed in 18 non-drug-selected lung-cancer cell lines (10 small-cell lung cancer, 6 non-small-cell lung cancer, and 1 carcinoid). MRP gene expression was also investigated in normal lung tissue and primary non-small-cell lung cancer. All cell lines except one and all normal lung tissues and primary non-small-cell lung cancers expressed detectable levels of MRP. Expression was significantly lower in cell lines than in normal and neoplastic lung. MRP protein expression was also assessed by immunohistochemistry using the monoclonal antibody MRPrl; comparable levels of expression were observed between mRNA and protein in cell lines; however, in tumor samples intense staining was observed in tumor cells as well as in infiltrating normal cells in tumors, making the results less comparable to those obtained by RNase expression. MRP expression did not directly correlate with function in a calcein accumulation assay in 2 unselected cell lines. No gene amplification was observed by Southern-blot analysis, in the unselected cell lines or in tumor samples. In general, in cell lines, MRP gene expression was correlated with lower chemosensitivity to doxorubicin and etoposide, but not to cisplatin. However, MRP expression did not directly correlate with MRP function as assessed by a calcein accumulation assay in one of 2 unselected cell lines examined. Our results suggest that MRP may be implicated in drug resistance in unselected lung-cancer cell lines and its role in normal lung and primary lung cancer warrants further investigation in patients undergoing chemotherapy. © 1996 Wiley-Liss, Inc.     

Expression of ret proto-oncogene in human neuroblastomas.

We examined the expression of ret proto-oncogene (proto-ret) in surgically resected human neuroblastomas. Slot blot RNA hybridization revealed that all 29 neuroblastomas examined expressed the proto-ret, the relative intensity of the hybridization ranging from 1 to 48. No correlation was found between the level of expression of proto-ret and the clinical stage. The level of expression was also not correlated with N-myc amplification, the patient's age or the histological type of the tumor. Based on the previous finding that proto-ret expression is very rarely detected in tumor cell lines other than those of neuroblastoma, proto-ret expression was suggested to be a characteristic of neuroblastomas, and possibly to be involved in the genesis of neuroblastomas.     

Expression of c-myb protooncogene and other cell cycle-related genes in normal and neoplastic human colonic mucosa

The expression of c-myb, c-myc, histone H3, and ornithine decarboxylase genes was examined by Northern blot analysis in the normal and neoplastic mucosa of ten subjects affected by colon cancer. The mRNA levels of c-myb protooncogene were detected at low levels in all normal samples but were increased in the neoplastic mucosa of six cases in comparison to the normal counterpart. In five of these six cases the mRNA levels of c-myc, histone H3, and ornithine decarboxylase mRNAs were also increased, suggesting that there is a relation between the high expression of c-myb and the fraction of cycling neoplastic cells.     

Nucleostemin mRNA is expressed in both normal and malignant renal tissues

Nucleostemin (NS), a p53-binding protein, has been shown essential for stem and cancer cell proliferation and implicated in oncogenesis. To explore potential contributions of NS to the development of clear cell renal cell carcinomas (ccRCCs), we determined NS expression in ccRCC cell lines, and in paired normal and malignant renal tissues from 31 patients with ccRCC. Nucleostemin mRNA and/or protein expression was observed in all four cell lines and 27 of 31 (87%) tumour specimens. Surprisingly, 16 of 31 (52%) adjacent normal renal samples also expressed NS mRNA and its levels in four of them were comparable with those in paired tumour tissues. Three of the patients had detectable NS mRNA in their normal renal tissues whereas lacked its expression in the matched tumours. Compared to the oncogene c-MYC expression in these same samples, NS expression showed a much less specificity for ccRCC. We further demonstrated that NS mRNA expression was closely associated with cellular proliferation in normal fibroblasts or T lymphocytes and renal cell carcinoma cell lines. Collectively, NS expression widely occurs in normal and malignant renal tissues, and is likely a proliferation marker rather than a unique regulator of cell proliferation and survival in stem and cancer cells.     

ZAP-70 is expressed by a subset of normal human B-lymphocytes displaying an activated phenotype.

The Syk family tyrosine kinase ZAP-70 is essential for normal T-cell development and signaling. Recently, leukemic cells from some patients with B-cell chronic lymphocytic leukemia (B-CLL) were shown to express ZAP-70. Owing to the prognostic value of B-CLL ZAP-70 expression, this phenotype may reflect intrinsic biological differences between the two subsets of disease. However, it remains unclear whether CLL-B cells aberrantly acquire ZAP-70 expression during the transformation process or whether ZAP-70 may be expressed under certain conditions in normal human B-lymphocytes. To discriminate between these two possibilities, we assessed ZAP-70 expression in normal human B-lymphocytes. Our data demonstrate that ZAP-70 is expressed in a subpopulation of tonsillar and splenic normal B-lymphocytes that express an activated phenotype. Furthermore, ZAP-70 expression can be induced in vitro upon stimulation of blood and tonsillar B cells. Finally, we show that phosphorylation of ZAP-70 occurs in tonsillar B cells with stimulation through the B-cell receptor. These results provide new insight into normal human B-cell biology as well as provide clues about the transformed cell in B-CLL.     

ZAP-70 is expressed by normal and malignant human B-cell subsets of different maturational stage.

ZAP-70 tyrosine kinase is involved in signalling pathways following T-cell receptor stimulation and was originally described only in T cells and natural killer cells. ZAP-70 expression has been reported in normal mouse B lineage cells and in human malignant B lymphocytes, mainly in chronic lymphocytic leukemia (CLL) where it correlates with clinical outcome. We analyzed several B-cell lines and ex vivo malignant B cells, ranging from acute lymphoblastic leukemia to multiple myeloma and reflecting different stages of B-cell differentiation, and they showed ZAP-70 expression regardless their maturation stage. We then analyzed by Western blot and flow cytometry different human normal B-lymphocyte subpopulations: na?ve, germinal center and memory B cells from tonsils, CD19+ CD5+ cells from cord blood and CD19+ lymphocytes from peripheral blood. All expressed ZAP-70 protein, though at different levels depending on their differentiation, activation and tissue localization. In addition, ZAP-70 expression levels could be modulated following stimulation via the B-cell receptor. These findings implicate a potential role of ZAP-70 in the signalling pathway of B lymphocytes at different maturational stages, indicate that ZAP-70 expression is not a CLL-specific feature among B-cell malignancies and suggest that the absence of ZAP-70 rather than its presence should be considered abnormal for malignant B lymphocytes.     

Fibroblast growth factor 5 proto-oncogene is expressed in normal human fibroblasts and induced by serum growth factors.

Fibroblast growth factor 5 (FGF-5) is a member of the fibroblast growth factor family with transforming potential. It has been found to be expressed in several human tumor cell lines, but nothing is known about expression of this growth factor in normal cells and its biological functions. Here we show that the FGF-5 gene is expressed in exponentially growing normal human fibroblasts. In quiescent fibroblasts, expression of FGF-5 is strongly induced by serum and several growth factors such as platelet-derived growth factor (PDGF), epidermal growth factor (EGF) and transforming growth factor alpha (TGF-alpha). This induction can be mediated by at least two different pathways involving protein kinase C or cAMP-dependent kinases. Since the effect is independent of de novo protein synthesis, FGF-5 represents the product of a primary response gene. In addition our data suggest that FGF-5 is mitogenic for human fibroblasts, indicating the existence of an FGF-5-mediated positive feedback in these cells which could amplify and prolong the cellular response to the initial stimulus.     

Expression of c-kit protooncogene in human hepatocellular carcinoma

Using comparative genomic hybridisation, DNA copy number changes were investigated in 15 cases of pigmented villonodular synovitis of the knee joint. Additionally DNA content was analysed by flow cytometry. Screening revealed numerical chromosomal imbalances in five of the examined cases. A total number of 18 gains were detected. The most frequent gains involved subregions of chromosomal arms 22q and 16p and 16q. No losses were found. One of the cases showed an aneuploid DNA-pattern, which actually proved to be the case with the most numerical chromosomal changes.