Malignant tenosynovial giant cell tumor with CDKN2A/B genomic alteration: a histological, immunohistochemical, and molecular study.

Diffuse-type tenosynovial giant cell tumor (D-T TSGCT) is regarded as a benign but locally aggressive neoplasm with significant recurrent potential. We report a case of malignant D-T TSGCT with pleural metastases arising in the left knee in a 57-year-old man. The tumor demonstrated atypical features, including a solid infiltrative pattern with spindling of the tumor cells, nuclear pleomorphism with prominent nucleoli, and markedly increased mitotic activity (>20 mitoses/10 high-power fields). The immunoprofile demonstrated clusterin+, D2-40+, CD68+, p63+, MDM2+, and p16+ tumor. The next-generation sequencing-based assay demonstrated loss of the CDKN2A/B gene. Pleural metastases with identical histologic and immunohistochemical features were identified 2 years later after primary tumor resection. To the best of our knowledge, this is the first reported case of D-T TSGCT with CDKN2A/B genomic alteration, MDM2 expression, and p16 loss. Clinicians and pathologists should be aware of the morphologic variability and the metastatic propensity of this entity.

Smad2 overexpression reduces the proliferation of the junctional epithelium.

The overexpression of the intracellular signaling molecule of the transforming growth factor-beta family (TGF-ß) Smad2 was found to induce apoptosis and inhibit the proliferation rate of oral epithelial cells. Therefore, the aim of this study was to investigate in vivo the effect of Smad2 overexpression on the proliferation rate of the junctional epithelium (JE). Smad2 overexpression was driven by the cytokeratin 14 promoter (K14-Smad2) in transgenic mice. The K14-Smad2 mice were compared with wild-type (WT) mice selected as the control group. Samples were stained with hematoxylin and eosin stains and analyzed by image analysis. Immunohistochemistry was conducted for proliferating cell nuclear antigen (PCNA) and c-Myc as markers of cell proliferation. The expression of cyclin-dependent kinase inhibitors (P15, P21, and P27) was determined by real-time polymerase chain-reaction (RT-PCR). The quantity of phosphorylated retinoblastoma (pRB) was determined with Western blots. The overexpression of Smad2 altered the area of the junctional epithelial cells in one-year-old K14-Smad2 mice. The area was 32,768 (± 3,473) µm(2) for the WT and 24,937.25 (± 1,965) µm(2) for the K14-Smad2 mice. There was a significant difference in the proliferation rates of the JE (PCNA-positive cells) between the WT and K14-Smad2 mice, 20.7% (± 1.1) and 2.1% (± 0.5), respectively. A significant difference in c-Myc expression occurred between experimental and control samples. The K14-Smad2 mice had a mean of 2.3% (± 0.6), and the WT mice had a mean of 20.1% (± 3.6). Smad2 overexpression up-regulated the mRNA expression of P15 by 2.3-fold and that of P27 by 5.5-fold in the K14-Smad2 mice. Finally, the pRB protein showed a 2.3 (± 0.5)-fold increase in K14-Smad2 mice when compared with WT mice. Smad2 overexpression inhibits the proliferation of JE cells by down-regulating c-Myc and up-regulating P15 and P27, which resulted in an increase in pRB, leading to cell-cycle arrest.

Overexpression of Smad2 inhibits proliferation of gingival epithelial cells.

BACKGROUND AND OBJECTIVE: Spatiotemporal inhibition of apical migration and proliferation of gingival epithelium are significant factors involved in periodontal regeneration. Transforming growth factor ß (TGF-ß) is important in multiple aspects of wound healing, and Smad2, a downstream transcription factor of TGF-ß, has an inhibitory effect on re-epithelialization during gingival wound healing. Therefore, we investigated the effects on migration and proliferation status, and intra/extracellular signaling regulated by Smad2 overexpression in gingival epithelial cells. MATERIAL AND METHODS: Gingival epithelial cells were isolated from the palatal gingival tissue of transgenic mice overexpressing Smad2 driven by the Keratin14 promoter. Smad2 expression was identified by western blotting and immunofluorescence analysis. Scratch assay and 5-bromo-2'-deoxyuridine staining were performed to assess cell migration and proliferation. To inactivate TGF-ß type I receptor, the cultures were supplemented with SB431542. Secreted TGF-ß was quantified by ELISA. Smad2 target gene expression was examined by real-time RT-PCR and in vivo immunofluorescence analysis of gingival junctional epithelium. RESULTS: Smad2-overexpressing cells were confirmed to have significant phosphorylated Smad2 in the nucleus. Scratch assay and 5-bromo-2'-deoxyuridine staining indicated that Smad2-overexpressing cells showed no significant differences in migration, but had reduced proliferation rates compared to wild-type controls. SB431542 significantly inhibited Smad2 phosphorylation, which coincided with restoration of the proliferation rate in Smad2-overexpressing cells. ELISA of TGF-ß release did not show any differences between genotypes. The cell cycle inhibitors, p15 and p21, showed significant upregulation in Smad2-overexpressing cells compared to wild-type controls. Moreover, junctional epithelium of the transgenic mice showed increased expression of P-Smad2, p15 and p21. CONCLUSION: The signaling activation triggered by overexpression of Smad2 was dependent on TGF-ß type I receptor, and the activated Smad2 increased p15 and p21 expression, responsible for inhibiting cell cycle entry, resulting in antiproliferative effects on gingival epithelial cells. Understanding of Smad2-induced signaling would be useful for possible clinical application to regulate gingival epithelial downgrowth.

Expression of Chr9p21 genes CDKN2B (p15(INK4b)), CDKN2A (p16(INK4a), p14(ARF)) and MTAP in human atherosclerotic plaque.

OBJECTIVE: The pathophysiology underlying the chromosome (Chr) 9p21 locus of atherosclerosis susceptibility is presently unknown. Here, we sought to determine whether protein coding genes in the Chr9p21 region, i.e. cyclin-dependent kinase inhibitors CDKN2B (p15(INK4b)), CDKN2A (p16(INK4a), p14(ARF)) and methylthioadenosine phosphorylase (MTAP) were expressed in human atherosclerotic lesions and whether expression was correlated with lesion composition. METHODS AND RESULTS: Protein expression of p15(INK4b), p16(INK4a), p14(ARF) and MTAP was demonstrated by immunostaining in normal and atherosclerotic coronary arteries and co-localized with CD68 and smooth muscle alpha-actin positive cells. Quantitative RT-PCR in human endarteryectomy specimens (n = 57) revealed increased p16(INK4a) and decreased MTAP expression in macrophage-rich lesions (P<0.001 and P = 0.007, respectively). Functional studies suggest that decreased MTAP expression in macrophage-rich lesions might be mediated through down-regulation by TNF-alpha. No clear association of p15(INK4b), p16(INK4a), p14(ARF), and MTAP expression in plaque tissue with Chr9p21 haplotypes was found. The latter finding was corroborated by the lack of correlation of RNA expression of 9p21-regulated transcripts EU741058 and NR_003529 of antisense non-coding RNA in the INK4 locus (ANRIL) with mRNA expression of these genes. In contrast, ANRIL DQ485454 which is not genetically determined by the 9p21 genotype was significantly correlated with MTAP expression (P = 0.01). CONCLUSION: CDKN2B (p15(INK4b)), CDKN2A (p16(INK4a), p14(ARF)), and MTAP are abundantly expressed in atherosclerotic lesions. While expression levels showed no clear association with Chr9p21 genotype, association of high p16(INK4a) and low MTAP expression with a less stable plaque phenotype suggests a more general role of these proteins in atherogenesis.

p15INK4b methylation correlates with thrombocytopenia, blast percentage, and survival in myelodysplastic syndromes in a dose dependent manner: quantitation using pyrosequencing study.

We investigated how the quantity of p15INK4b methylation related to International Prognosic Scoring System variables and survival in 74 patients with de novo myelodysplastic syndrome (MDS). Pyrosequencing of 11 consecutive CpG sites of the p15INK4b promotor region was performed, with the extent of CpG cytosine methylation assessed in terms of methylation level (MtL). Patients with >5% bone marrow blasts had higher MtL than patients with <5% blasts (10.1% vs. 6.1%, p=0.030, respectively). Methylation was not associated with chromosomal aberrations. The MtL of patients with thrombocytopenia were higher than patients without thrombocytopenia (11.2% vs. 6.2%, p=0.036, respectively); they were higher in patients with cytopenias in > or =2 lineages than in patients with either unilineage or no cytopenia (9.8% vs. 4.1%, p=0.036, respectively). The survival of patients with >7% MtL was worse than patients with <7% MtL (p=0.031). Heavy p15INK4b methylation in MDS is associated with IPSS predictors of poor prognosis and adverse survival.

Aberrant DNA methylation of the transcription factor C/EBPalpha in acute myelogenous leukemia.

We investigated the methylation status of the CCAAT/enhancer binding protein alpha (C/EBPalpha) promoter region near the transcription start site in acute myelogenous leukemia (AML). In hematopoietic tumor cell lines, CpG island hypermethylation of the proximal C/EBPalpha promoter region was associated with transcriptional silencing, and treatment with the demethylating agent 5-aza-2'-deoxycytidine resulted in C/EBPalpha reexpression and promoter demethylation. Aberrant methylation of the C/EBPalpha promoter region occurred in 10/80 diagnostic AML samples, and there was an inverse correlation between aberrant methylation of C/EBPalpha and the negative cell cycle regulator p15. Our results provide further evidence for epigenetic dysregulation of C/EBPalpha in AML.

Senescence and apoptosis in carcinogenesis of cervical squamous carcinoma.

Senescence and apoptosis are two key mechanisms that protect against cancer development. Many cell cycle regulators, such as p14(ARF), p15(INK4b) and p16(INK4a), are important in G1 cell cycle arrest and oncogene-induced senescence. The bcl-2 protein is one of the key components that control apoptosis, while the p53 protein plays key roles in both mechanisms. The genes of these key regulator proteins are often mutated or deleted in various malignancies. It is unknown how senescence and apoptosis are regulated in one of the most common tumors of the female genital tract, cervical squamous cell carcinoma (SCC). In this study the, expression of senescence, apoptosis and proliferation markers in normal cervical epithelium, cervical intraepithelial neoplasia (CIN) and SCC are characterized via immunohistochemical staining for p14(ARF), p15(INK4b), p16(INK4a), bcl-2, p53 and Ki-67 in tissue microarray blocks containing 20 samples each of normal cervix, moderate-to-severe cervical dysplasia (CIN II-III) and invasive SCC. Samples are derived from 60 total cases of cervical biopsies and cervical conizations. Results showed that the proliferation marker, Ki-67, is markedly increased, and the senescence markers, p15(INK4b), p16(INK4a) and p14(ARF) are overexpressed in both dysplasia and carcinoma. P53 immunostain is negative in all normal cervical tissue, and positive in dysplasia and carcinoma. Although the expression of bcl-2 is increased in dysplasia, this marker is negative in approximately half of SCC cases. These results suggest that some senescence pathways are activated and are still maintained in cervical dysplasia and carcinoma. However proliferation is increased and carcinogenesis is not thwarted, leading to eventual development of cervical cancer. Other mechanisms, such as those that account for the apparent overexpression of p53 and paradoxical loss of bcl-2 expression in some SCC cases, as well as additional senescence and apoptotic pathways, may play key roles carcinogenesis of cervical SCC.

Modulation of p53 expression and its role in the conversion to a fully immortalized chicken embryo fibroblast line.

We have established a spontaneously immortalized chicken embryo fibroblast (CEF) cell line (SC-1) that has been in continuous culture for more than three years. This is only the second report of a spontaneously immortalized reverse transcriptase (RT)-negative chicken cell line. The SC-1 cells emerged from crisis (at about passage 29-31) with a slower growth rate than primary cells. Passage 50 SC-1 cells expressed similar levels of p53 mRNA, but slightly lower levels of p53 protein than passage 6 CEF cells. By passage 120, p53 mRNA levels were significantly decreased in the SC-1 cells, while protein levels were slightly increased compared to passage 6 CEF cells. However, functional analysis of p53 revealed reduced activity in later passage SC-1 cells. Other p53-related genes including p21WAF1, p27Kip1, MDM-2, and the p16INK4a alternate reading frame (ARF) sequence showed similar patterns of differential mRNA expression. Levels of p15INK4b mRNA and protein were dramatically decreased in SC-1 cells, suggesting that the Rb pathway also has been compromised. Telomerase expression was undetectable in SC-1 cells. Fluorescence-activated cell sorting analysis showed that SC-1 and primary cells contained a similar proportion of G0/G1 phase cells, unlike the only other spontaneously immortalized chicken cell line (DF-1). The present study suggests that alterations in the p53 and Rb pathways cause fluctuations in expression levels of important cell-cycle regulatory genes during crucial transition periods as the SC-1 spontaneously immortalized chicken fibroblast cells progress toward becoming a fully committed cell line.