Tumor Risks and Genotype-Phenotype-Proteotype Analysis in 358 Patients With Germline Mutations in SDHB and SDHD

Succinate dehydrogenase B (SDHB) and D (SDHD) subunit gene mutations predispose to adrenal and extraadrenal pheochromocytomas, head and neck paragangliomas (HNPGL), and other tumor types. We report tumor risks in 358 patients with SDHB (n = 295) and SDHD (n = 63) mutations. Risks of HNPGL and pheochromocytoma in SDHB mutation carriers were 29% and 52%, respectively, at age 60 years and 71% and 29%, respectively, in SDHD mutation carriers. Risks of malignant pheochromocytoma and renal tumors (14% at age 70 years) were higher in SDHB mutation carriers; 55 different mutations (including a novel recurrent exon 1 deletion) were identified. No clear genotype-phenotype correlations were detected for SDHB mutations. However, SDHD mutations predicted to result in loss of expression or a truncated or unstable protein were associated with a significantly increased risk of pheochromocytoma compared to missense mutations that were not predicted to impair protein stability (most such cases had the common p.Pro81Leu mutation). Analysis of the largest cohort of SDHB/D mutation carriers has enhanced estimates of penetrance and tumor risk and supports in silicon protein structure prediction analysis for functional assessment of mutations. The differing effect of the SDHD p.Pro81Leu on HNPGL and pheochromocytoma, risks suggests differing mechanisms of tumorigenesis in SDH-associated HNPGL and pheochromocytoma. Hum Mutat 31:41-51, 2010. (C) 2009 Wiley-Liss, Inc.

Cancer-related ectopic expression of the bone-related transcription factor RUNX2 in non-osseous metastatic tumor cells is linked to cell proliferation and motility

Introduction: Metastatic breast cancer cells frequently and ectopically express the transcription factor RUNX2, which normally attenuates proliferation and promotes maturation of osteoblasts. RUNX2 expression is inversely regulated with respect to cell growth in osteoblasts and deregulated in osteosarcoma cells.

Desmoplastic Small Round Cell Tumor of Major Salivary Glands: Report of 1 Case and a Review of the Literature

Desmoplastic small round cell tumor is a rare malignant neoplasm mostly occurring in the vicinity of or within the peritoneal cavity, and is uncommon in the head and neck region. Tumor location within a major salivary gland is exceptional. We report a case of a 41-year-old Chinese man with a history of diabetes mellitus and end-stage renal failure on peritoneal dialysis with a desmoplastic small round cell tumor occurring in the left submandibular gland. Fine-needle aspiration cytology showed variably cohesive clusters of small cells with hyperchromatic nuclei and fine granular chromatin. On histology the neoplasm displayed classic features of a desmoplastic small round cell tumor with angulated nests of small round blue cells in a fibromyxoid/desmoplastic stroma. Neoplastic cells were immunoreactive for cytokeratins (AE1/3), desmin (paranuclear dot-like), WT-1 (nuclear), epithelial membrane antigen, and CD56. EWS gene translocation and EWS-WT1 gene fusion were detected by fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction, respectively. The case presented is the sixth case of and the oldest reported patient with a desmoplastic small round cell tumor occurring in a major salivary gland to date. Desmoplastic small round cell tumor should be considered in the differential diagnosis of a salivary gland neoplasm with a basaloid or small cell pattern on fine-needle aspiration cytology.

Claudin-1 Has Tumor Suppressive Activity and Is a Direct Target of RUNX3 in Gastric Epithelial Cells

BACKGROUND & AIMS: The transcription Factor RUNX3 is a gastric tumor suppressor. Tumorigenic Runx3(-/-) gastric epithelial cells attach weakly to each other, compared with nontumorigenic Runx3(+/+) cells. We alined to identify RUNX3 target genes that promote cell-cell contact to Improve our understanding of RUNX3's role in Suppressing gastric carcinogenesis. METHODS: We compared gene expression profiles of Runx3(+/+) and Runx3(-/-) cells and observed down-regulation of genes associated with cell-cell adhesion in Runx3(-/-) cells. Reporter, mobility shift, and chromatin immunoprecipitation assays were used to examine the regulation of these genes by RUNX3. Tumorigenesis assays and immunohistologic, analyses of human gastric tumors were performed to confirm the role of the candidate genes ill gastric tumor development. RESULTS: Mobility shift and chromatin immunoprecipitation assays revealed that the promoter activity of the gene that encodes the tight Junction protein claudin-1 was up-regulated via the binding of RUNX3 to the RUNX consensus sites. The tumorigenicity of gastric epithelial cells From Runx3(-/-) mice was significantly reduced by restoration of claudin-1 expression, whereas knockdown of claudin-1. increased the tumorigenicity of human gastric cancer cells. Concomitant expression of RUNX3 and claudin-1 was observed in human normal gastric epithelium and cancers. CONCLUSIONS: The tight junction protein claudin-1 has gastric tumor suppressive activity and is a direct transcriptional target of RUNX3. Claudin-1 is down-regulated during the epithelial-mesenchymal transition; RUNX3 might therefore act as a tumor suppressor to antagonize the epithelial-mesenchymal transition.

Repression of NHE1 Expression by PPAR gamma Activation Is a Potential New Approach for Specific Inhibition of the Growth of Tumor Cells In vitro and In vivo

Ligand-induced activation of peroxisome proliferator-activated receptor gamma (PPAIR gamma) inhibits proliferation in cancer cells in vitro and in vivo; however, the downstream targets remain undefined. We report the identification of a peroxisome proliferator response element in the promoter region of the Na+/ H transporter gene NHE1, the overexpression of which has been associated with carcinogenesis. Exposure of breast cancer cells expressing high levels of PPAR gamma to its natural and synthetic agonists resulted in downregulation of NHE1 transcription as well as protein expression. Furthermore, the inhibitory effect of activated PPAR gamma on tumor colony-forming ability was abrogated on overexpression of NHE1, whereas small interfering RNA-mediated gene silencing of NHE1 significantly increased the sensitivity of cancer cells to growth-inhibitory stimuli. Finally, histopathologic analysis of breast cancer biopsies obtained from patients with type II diabetes treated with the synthetic agonist rosiglitazone showed significant repression of NHE1 in the tumor tissue. These data provide evidence for tumor-selective downregulation of NHE1 by activated PPAR gamma in vitro and in pathologic specimens from breast cancer patients and could have potential implications for the judicious use of low doses of PPAR gamma ligands in combination chemotherapy regimens for an effective therapeutic response. [Cancer Res 2009;69(22):8636-44]

Overexpression of endoplasmic reticulum protein 29 regulates mesenchymal-epithelial transition and suppresses xenograft tumor growth of invasive breast cancer cells

Endoplasmic reticulum protein 29 (ERp29) is a novel endoplasmic reticulum ( ER) secretion factor that facilitates the transport of secretory proteins in the early secretory pathway. Recently, it was found to be overexpressed in several cancers; however, little is known regarding its function in breast cancer progression. In this study, we show that the expression of ERp29 was reduced with tumor progression in clinical specimens of breast cancer, and that overexpression of ERp29 resulted in G(0)/G(1) arrest and inhibited cell proliferation in MDA-MB-231 cells. Importantly, overexpression of ERp29 in MDA-MB-231 cells led to a phenotypic change and mesenchymal-epithelial transition (MET) characterized by cytoskeletal reorganization with loss of stress fibers, reduction of fibronectin (FN), reactivation of epithelial cell marker E-cadherin and loss of mesenchymal cell marker vimentin. Knockdown of ERp29 by shRNA in MCF-7 cells reduced E-cadherin, but increased vimentin expression. Furthermore, ERp29 overexpression in MDA-MB-231 and SKBr3 cells decreased cell migration/invasion and reduced cell transformation, whereas silencing of ERp29 in MCF-7 cells enhanced cell aggressive behavior. Significantly, expression of ERp29 in MDA-MB-231 cells suppressed tumor formation in nude mice by repressing the cell proliferative index (Ki-67 positivity). Transcriptional profiling analysis showed that ERp29 acts as a central regulator by upregulating a group of genes with tumor suppressive function, for example, E-cadherin (CDH1), cyclin-dependent kinase inhibitor (CDKN2B) and spleen tyrosine kinase (SYK), and by downregulating a group of genes that regulate cell proliferation (eg, FN, epidermal growth factor receptor ( EGFR) and plasminogen activator receptor ( uPAR)). It is noteworthy that ERp29 significantly attenuated the overall ERK cascade, whereas the ratio of p-ERK1 to p-ERK2 was highly increased. Taken together, our results showed that ERp29 is a novel regulator leading to cell growth arrest and cell transition from a proliferative to a quiescent state, and reprogramming molecular portraits to suppress the tumor growth of MDA-MB-231 breast cancer cells. Laboratory Investigation (2009) 89, 1229-1242; doi: 10.1038/labinvest.2009.87; published online 21 September 2009

The tumor suppressor gene DLEC1 is frequently silenced by DNA methylation in hepatocellular carcinoma and induces G1 arrest in cell cycle

Background/Aims: The chromosome locus 3p21.3 is a

RUNX3, a novel tumor suppressor, is frequently inactivated in gastric cancer by protein mislocalization

Loss of RUNX3 expression is suggested to be causally related to gastric cancer as 45% to 60% of gastric cancers do not express RUNX3 mainly due to hypermethylation of the RUNX3 promoter. Here, we examined for other defects in the properties of RUNX3 in gastric cancers that express RUNX3. Ninety-seven gastric cancer tumor specimens and 21 gastric cancer cell lines were examined by immunohistochemistry using novel anti-RUNX3 monoclonal antibodies. In normal gastric mucosa, RUNX3 was expressed most strongly in the nuclei of chief cells as well as in surface epithelial cells. In chief cells, a significant portion of the protein was also found in the cytoplasm. RUNX3 was not detectable in 43 of 97 (44%) cases of gastric cancers tested and a further 38% showed exclusive cytoplasmic localization, whereas only 18% showed nuclear localization. Evidence is presented suggesting that transforming growth factor-beta is an inducer of nuclear translocation of RUNX3, and RUNX3 in the cytoplasm of cancer cells is inactive as a tumor suppressor. RUNX3 was found to be inactive in 82% of gastric cancers through either gene silencing or protein mislocalization to the cytoplasm. In addition to the deregulation of mechanisms controlling gene expression, there would also seem to be at least one other mechanism controlling nuclear translocation of RUNX3 that is impaired frequently in gastric cancer.