Disruption of Abi1/Hssh3bp1 expression induces prostatic intraepithelial neoplasia in the conditional Abi1/Hssh3bp1 KO mice.

Prostate cancer is one of the leading causes of cancer-related deaths in the United States and a leading diagnosed non-skin cancer in American men. Genetic mutations underlying prostate tumorigenesis include alterations of tumor suppressor genes. We tested the tumor suppressor hypothesis for ABI1/hSSH3BP1 by searching for gene mutations in primary prostate tumors from patients, and by analyzing the consequences of prostate-specific disruption of the mouse Abi1/Hssh3bp1 ortholog. We sequenced the ABI1/hSSH3BP1 gene and identified recurring mutations in 6 out of 35 prostate tumors. Moreover, complementation and anchorage-independent growth, proliferation, cellular adhesion and xenograft assays using the LNCaP cell line, which contains a loss-of-function Abi1 mutation, and a stably expressed wild-type or mutated ABI gene, were consistent with the tumor suppressor hypothesis. To test the hypothesis further, we disrupted the gene in the mouse prostate by breeding the Abi1 floxed strain with the probasin promoter-driven Cre recombinase strain. Histopathological evaluation of mice indicated development of prostatic intraepithelial neoplasia (PIN) in Abi1/Hssh3bp1 knockout mouse as early as the eighth month, but no progression beyond PIN was observed in mice as old as 12 months. Observed decreased levels of E-cadherin, ß-catenin and WAVE2 in mouse prostate suggest abnormal cellular adhesion as the mechanism underlying PIN development owing to Abi1 disruption. Analysis of syngeneic cell lines point to the possibility that upregulation of phospho-Akt underlies the enhanced cellular proliferation phenotype of cells lacking Abi1. This study provides proof-of-concept for the hypothesis that Abi1 downregulation has a role in the development of prostate cancer.

Importance of day 21 BM chimerism in sustained neutrophil engraftment following double-unit cord blood transplantation.

Delayed or failed engraftment remains a concern after cord blood transplantation (CBT) even when using double-unit grafts. Therefore, we analyzed the association between BM assessment performed approximately 21 days after transplantation, and the speed and success of sustained donor-derived neutrophil engraftment in 56 myeloablative double-unit CBT (DCBT) recipients. Overall, the cumulative incidence of sustained neutrophil engraftment was 95% (95% confidence intervals (CI): 89-100). Of the percentage of myeloid precursors, the BM cellularity and the total donor chimerism the total donor chimerism percentage had the most critical association with the speed and success of engraftment. DCBT recipients who were 100% donor achieved a 98% engraftment rate at a median of 22 days. This compared with 100% engraftment in patients who were 90-99% donor, but at a delayed median of 29 days and only 68% engraftment in patients <90% donor at a median of 37 days (P=0.001). Multivariate analysis was performed in the subgroup of patients who had not engrafted at the time the BM analysis was performed, the subgroup of most clinical concern. This confirmed donor chimerism was predictive of subsequent neutrophil recovery (P=0.004). These findings demonstrate the importance of the day 21 BM chimerism determinations after DCBT.

PHF6 mutations in adult acute myeloid leukemia.

Loss of function mutations and deletions encompassing the plant homeodomain finger 6 (PHF6) gene are present in about 20% of T-cell acute lymphoblastic leukemias (ALLs). Here, we report the identification of recurrent mutations in PHF6 in 10/353 adult acute myeloid leukemias (AMLs). Genetic lesions in PHF6 found in AMLs are frameshift and nonsense mutations distributed through the gene or point mutations involving the second plant homeodomain (PHD)-like domain of the protein. As in the case of T-ALL, where PHF6 alterations are found almost exclusively in males, mutations in PHF6 were seven times more prevalent in males than in females with AML. Overall, these results identify PHF6 as a tumor suppressor gene mutated in AML and extend the role of this X-linked tumor suppressor gene in the pathogenesis of hematologic tumors.

Prognostic impact of proliferative index determined by quantitative image analysis and the International Prognostic Index in patients with mantle cell lymphoma.

BACKGROUND: The proliferative index (PI) is a powerful prognostic factor in mantle cell lymphoma (MCL); however, its utility is hampered by interobserver variability. The mantle cell international prognostic index (MIPI) has been reported to have prognostic importance. In this study, we determined the prognostic value of the PI as determined by quantitative image analysis in MCL. PATIENTS AND METHODS: Eighty-eight patients with adequate tissue were included in this analysis. Patients were treated with one of two treatment programs: sequential therapy with high-dose therapy consolidation or radioimmunotherapy followed by combination chemotherapy with cyclophosphamide, doxorubicin, vincristine and prednisone. Patients were divided into four groups based on PI (<10%, 10%-29.9%, 30%-49.9%, and >50%), and outcomes were analyzed. RESULTS: Thirty percent was identified as the optimal cut-off for PI. By univariate analysis, intensive treatment and a low PI were associated with a superior progression-free survival (PFS); only PI was associated with overall survival. By multivariate analysis, both intensive treatment and PI correlated with PFS. The MIPI had no prognostic impact. CONCLUSIONS: PI is the most important prognostic factor in MCL. The cut-off of 30% is clinically meaningful and can be used to tailor the intensity of therapy in future clinical trials.

Tumor promoting properties of the ETS protein MEF in ovarian cancer.

We have previously shown that MEF (myeloid ELF1-like factor, also known as ELF4) functions as a transcriptional activator of the interleukin (IL)-8, perforin, granulocyte macrophage-colony stimulating factor (GM-CSF) and IL-3 genes in hematopoietic cells. MEF is also expressed in non-hematopoietic tissues including certain ovarian cancer cells. To define the function of MEF in these cells, we examined primary human ovarian epithelial tumors and found that MEF is expressed in a significant proportion of ovarian carcinomas, and in the CAOV3 and SKOV3 ovarian cancer cell lines, but not in normal ovarian surface epithelium. Manipulating MEF levels in these cell lines altered their behavior; reducing MEF levels, using short hairpin RNA expressing vectors, significantly inhibited the proliferation of SKOV3 and CAOV3 cells in culture, and impaired the anchorage-independent growth of CAOV3 cells. Overexpression of MEF in SKOV3 cells (via retroviral transduction) significantly increased their growth rate, enhanced colony formation in soft agar and promoted tumor formation in nude mice. The oncogenic activity of MEF was further shown by the ability of MEF to transform NIH3T3 cells, and induce their tumor formation in nude mice. MEF is an important regulator of the tumorigenic properties of ovarian cancer cells and could be used a therapeutic target in ovarian cancer.

Macrophage-derived chemokine expression in classical Hodgkin's lymphoma: application of tissue microarrays.

Hodgkin's disease (HD) is a lymphoid malignancy characterized by the presence of Reed-Sternberg (RS) and Hodgkin's cells in a background of mixed inflammatory cells and stromal reaction. Studies have documented that HD is a neoplasm associated with abnormal cytokine and chemokine production. To define the expression of macrophage-derived chemokine (MDC) in HD, 57 cases (18 lymphocyte predominant, 11 mixed cellularity, 28 nodular sclerosis) were stained for MDC by immunohistochemistry and compared with reactive lymph nodes as controls. MDC was expressed by RS cells in classical HD (CHD) and showed a distinct cytoplasmic and Golgi localization. Accumulating evidence suggests that lymphocyte-predominant HD (LPHD) represents an entity distinct from CHD, with different biological properties and clinical course. On the basis of the high level of MDC staining alone, CHD could be distinguished from LPHD (P <.001), which showed only faint staining of scattered histiocytes similar to control tissues. CHD cases with high MDC mRNA levels showed high levels of MDC protein expression by immunohistochemistry (P <.001) and significant eosinophil infiltration, suggesting that MDC may represent another molecule that plays a critical role in eosinophil recruitment. We also analyzed 102 cases of non-Hodgkin's lymphoma and normal spleen, lymph node, and thymic tissue. High levels of MDC expression were specific to CHD cases because only low levels of MDC were observed in a minor subset of LPHD, NHL or normal lymphoid tissues.

The isolation and characterization of MINOR, a novel mitogen-inducible nuclear orphan receptor.

The nuclear (steroid/thyroid/retinoid) receptor superfamily is a set of evolutionarily related ligand-inducible regulators of transcription. One subgroup within this family has been termed the orphan receptors because the potential ligands required for their activity have not been identified. We have cloned a novel orphan receptor, MINOR, which is mitogen inducible in a variety of cell types. Unlike NGFI-B/Nur77, another mitogen-inducible orphan receptor, MINOR gene expression is inhibited in Jurkat cells by the immunosuppressant cyclosporin A, suggesting that it is regulated by distinct second messenger pathways. The conservation of the DNA-binding domain between MINOR and other orphan receptors is reflected in the fact that they are able to bind to the same sequence, AAAG-GTCA [termed the NBRE (NGFI-B response element)]. The marked divergence in other domains, particularly the N-terminal putative transactivation domain, may result in qualitative or quantitative differences in other functions among these proteins. One of these differences may be the apparent squelching of peak levels of MINOR-mediated transcription by supraoptimal levels of MINOR expression, an effect not obtained with NGFI-B/Nur77. When MINOR i coexpressed with submaximal levels of NGFI-B/Nur77, synergistic or additive levels of reporter gene expression are obtained. However, at maximal levels of NGFI-B/Nur77 expression, MINOR antagonizes the level of reporter gene expression in a dose-dependent fashion. These cooperative/competitive interactions, together with the nonidentical expression patterns of MINOR and NGFI-B/Nur77, suggest complexity in the regulation of genes responsive to orphan receptors which bind to the NBRE.