Morphological heterogeneity of oral salivary gland carcinomas: a clinicopathologic study of 41 cases with long term follow-up emphasizing the overlapping spectrum of adenoid cystic carcinoma and polymorphous low-grade adenocarcinoma

We analyzed 41 oral salivary gland carcinomas from consecutive 290 salivary gland carcinoma database (14%) with emphasis on the histological spectrum and clinical outcome of adenoid cystic carcinoma (ACC) and polymorphous low-grade adenocarcinoma (PLGA). The cohort included 14 ACCs, 14 mucoepidermoid carcinomas (MECs), 8 PLGAs, 3 adenocarcinomas, not otherwise specified and 2 acinic cell carcinomas. Mean age was 48, 58 and 61 yrs for ACC, MEC and PLGA, respectively. Eight patients (19.5%) died of tumor at a mean interval of 66.5 months. ACC and PLGA showed similar mean age, gender distribution, predominant palatal localization, nodal metastasis, perineural invasion and MIB-1 index. However, ACC tended to show higher tumor stage and residual tumor (R1/R2) more frequently than PLGA, but this was statistically not significant. ACC and PLGA showed overlapping architectural patterns. However, ACCs displayed well organized basal-luminal differentiation, highlighted by CK5/CK7 immunostaining. In contrast, PLGA showed a disorganized histological and immunohistological pattern. C-Kit expression (CD117) was common in ACC, generally mirroring that of CK7 and virtually lacking in PLGA. Kaplan-Meier analysis demonstrated a similar clinical course for ACC and PLGA with 5 years survivals of 87% and 80%, respectively. Fluorescence in situ hybridization (FISH) performed on all 290 salivary carcinomas confirmed the specificity of the translocation t (11; 19) for MEC and its absence in all other carcinomas including ACC and PLGA. Our results emphasize the diversity of oral salivary gland carcinomas and the overlapping clinicopathological features of ACC and PLGA.

Downregulation of runt-related transcription factor 3 associated with poor prognosis of adenoid cystic and mucoepidermoid carcinomas of the salivary gland

Runt-related transcription factor 3 (RUNX3) is a transcription factor of the transforming growth factor (TGF)-β superfamily and acts as a tumor suppressor gene, which is silenced by hypermethylation of the promoter region in various cancers. In this study, we examined the expression and methylation status of RUNX3 in the salivary gland cancers pleomorphic adenoma (PA), adenoid cystic carcinoma (ACC) and mucoepidermoid carcinoma (MEC). The cytoplasmic expression rates of RUNX3 in PA, ACC and MEC were 65% (13/20), 22.2% (8/36) and 20.6% (7/34), respectively. Low expression or deletion of RUNX3 in ACC and MEC was significantly associated with tumor progression and poor prognosis. Using microdissected cDNA, we found that RUNX3 mRNA expression was lower in ACC and MEC than in PA and noncancerous salivary glands; furthermore, hypermethylation of RUNX3 was detected more frequently in PA (2/8, 25%), ACC (6/8, 75%) and MEC (7/8, 87.5%) than in noncancerous salivary glands (0/8, 0%). Our results suggest that low expression or deletion of RUNX3 in salivary gland tumors might play a pivotal role in tumorigenesis and tumor progression and poor prognosis in the case of salivary gland ACC and MEC. Recovery of the tumor suppressive function of RUNX3 might inhibit tumorigenesis and cancer progression in the human salivary gland.

[RUNX3 expression and its methylation of 5'-CpG island in salivary gland adenoid cystic carcinoma cell lines ACC-2, ACC-3 and ACC-M]

OBJECTIVE

To investigate the methylation of 5'-CpG island and expression of RUNX3 in salivary gland adenoid cystic carcinoma cell lines.

METHODS

RT-PCR (reverse transcription-polymerase chain reaction), laser scanning confocal microscope (LSCM) and Western blot were used to detect the expression of RUNX3 gene and protein in salivary gland adenoid cystic carcinoma cell lines, ACC-2, ACC-3, and ACC-M, before/after a treatment of 5-Aza-dc respectively.

RESULTS

A weak expression of RUNX3 was found in ACC-2 and ACC-3. And no expression of RUNX3 was found in ACC-3 cell line. After a treatment of 300 nmol/L 5-Aza-dc for 72 hours, the expression of RUNX3 in ACC-2 and ACC-3 cells was enhanced, and in ACC-M was restored. LSCM results showed that the RUNX3 protein was located mainly in the cytoplasm of ACC cell lines. After a treatment of 300 nmol/L 5-Aza-dc for 72 h, both nuclear and cytoplasmic location of RUNX3 positive signals were found in the ACC-2 and ACC-3 cells. However, a weak positive signal was still only found in the cytoplasm of ACC-M cells. Partial methylation in promoter 5'-CpG island of RUNX3 gene was found in all three cell lines. And the methylation degree of CpG island was 50%, 75% and 33% in ACC-2, ACC-M and ACC-3 respectively. After a treatment of 5-Aza-dc, the RUNX3 gene showed unmethylated status in all three cell lines.

CONCLUSIONS

The methylation of RUNX3 plays an important role in the silencing of RUNX3 expression in ACC cell lines. The cytoplasmic mislocalization of RUNX3 may be correlated with the inhibition of its function in ACC cells.

[Evolution pattern of the Runx3 gene 5'-CpG island methylation in human salivary gland adenoid cystic carcinoma]

OBJECTIVE

To investigate the evolution pattern of the Runx3 gene 5'-CpG island ~3478 bp region methylation in human salivary gland adenoid cystic carcinoma (SGACC).

METHODS

Quantitative MSP method was used to detect the methylation status of CpG island in various regions (No.1-10) of Runx3 promoter region, and Western blot was used for detection of the expression of Runx3 protein in 41 salivary gland SGACC samples and corresponding non-neoplastic salivary gland tissues. A Logistic model was used to analyze the risk ratio between the methylation status of CpG island in Runx3 gene and development of salivary SGACC, meanwhile, the possible association among the methylation of Runx3 gene, the clinicopathological parameters of SGACCs, and Runx3 protein expression was compared.

RESULTS

The results of qMSP showed that the hypermethylation initially occurred at the most 5' region of the Runx3 CpG island and spread to the transcription start site. The methylation rate was highest in region No. 1 and No. 2 among the successive ten regions ranging from the 5' region to the transcription start site within the Runx3 CpG island, and lowest in the transcription start site both in SGACCs and normal salivary glands. Furthermore, there was no methylation in the transcription start site in nomal salivary glands tissues. Together with the results of Logistic model analysis, those results indicate that the transcription start site within the Runx3 promoter CpG island is critical for gene silencing. Western blot results revealed that the Runx3 protein level in SGACC was significantly lower than that in normal salivary glands (P < 0.01). In combination of the results of qMSP, it is presumed that the Runx3 gene methylation is one of the reason inducing the down-regulation of Runx3 in SGACCs.

CONCLUSIONS

Methylation of the Runx3 CpG island spreads from the most 5'-region to the transcription start site in human salivary gland adenoid cystic carcinoma, and the transcription start site may be a critical region for the methylation of Runx3. The evolution pattern of Runx3 gene methylation is related to the tumorigenesis of SGACCs.

erbB2 gene silencing and its effect on PTEN in SACC-83 salivary adenoid cystic carcinoma cells

erbB2 gene plays an important role in carcinoma formation. erbB2 overexpression was observed in many types of tumours, including salivary carcinoma. However, a putative erbB2 and PTEN interaction remains largely unknown in salivary adenoid cystic carcinoma cells. The purpose of this study was to silence erbB2 gene and investigate the functional relationship between erbB2 and PTEN in SACC-83 salivary adenoid cystic carcinoma cells. erbB2-specific siRNAs were transfected into SACC-83 cells using cationic liposome. RT-PCR, immunocytochemistry and Western blotting were employed to detect erbB2 and PTEN expression. Compared with the control groups, erbB2 mRNA expression was decreased in the erbB2-siRNA transfection group, and immunocytochemistry and Western blotting indicated a concordant erbB2 protein reduction. The average optical density values for erbB2 proteins in erbB2-siRNA transfected group were significantly lower than that in the control groups (P<0.05). On the other hand, PTEN expression at both mRNA and protein levels were not significantly affected by erbB2 silencing (P>0.05). In conclusion, the data indicate that siRNA could effectively silence erbB2 gene expression in SACC-83 cells, but PTEN expression appeared unaltered following erbB2 silencing. PTEN expression might not be strictly associated with erbB2 amplification in SACC-83 cells. Future studies will more closely examine the molecular and biological relationships of erbB2 and PTEN in salivary adenoid cystic carcinoma.

Adenoid cystic carcinomas of the breast and salivary glands (or 'The strange case of Dr Jekyll and Mr Hyde' of exocrine gland carcinomas)

Adenoid cystic carcinoma (AdCC) is a tumour with myoepithelial differentiation and characterised by the presence of a dual population of basaloid and luminal cells arranged in specific growth patterns. These tumours, regardless of the anatomical site, are characterised by expression of the proto-oncogene and therapeutic target c-KIT, and seem to harbour a specific chromosomal translocation t(6;9) leading to the fusion gene MYB-NFIB and overexpression of the oncogene MYB. However, the clinical behaviour of salivary gland and breast AdCC differs; while salivary gland lesions have a relatively high proclivity to metastasise, patients with breast AdCCs have an excellent outcome. Here the clinical, morphological and molecular features, and potential therapeutic targets of salivary gland and breast AdCCs are reviewed.

Loss of the tumor suppressor CYLD enhances Wnt/beta-catenin signaling through K63-linked ubiquitination of Dvl

The mechanism by which Wnt receptors transduce signals to activate downstream beta-catenin-mediated target gene transcription remains incompletely understood but involves Frizzled (Fz) receptor-mediated plasma membrane recruitment and activation of the cytoplasmic effector Dishevelled (Dvl). Here, we identify the deubiquitinating enzyme CYLD, the familial cylindromatosis tumor suppressor gene, as a negative regulator of proximal events in Wnt/beta-catenin signaling. Depletion of CYLD from cultured cells markedly enhances Wnt-induced accumulation of beta-catenin and target gene activation. Moreover, we demonstrate hyperactive Wnt signaling in human cylindroma skin tumors that arise from mutations in CYLD. At the molecular level, CYLD interacts with and regulates K63-linked ubiquitination of Dvl. Enhanced ubiquitination of the polymerization-prone DIX domain in CYLD-deficient cells positively links to the signaling activity of Dvl. Together, our results argue that loss of CYLD instigates tumor growth in human cylindromatosis through a mechanism in which hyperubiquitination of polymerized Dvl drives enhancement of Wnt responses.

CYLD negatively regulates cell-cycle progression by inactivating HDAC6 and increasing the levels of acetylated tubulin

CYLD is a tumour-suppressor gene that is mutated in a benign skin tumour syndrome called cylindromatosis. The CYLD gene product is a deubiquitinating enzyme that was shown to regulate cell proliferation, cell survival and inflammatory responses, mainly through inhibiting NF-kappaB signalling. Here we show that CYLD controls cell growth and division at the G(1)/S-phase as well as cytokinesis by associating with alpha-tubulin and microtubules through its CAP-Gly domains. Translocation of activated CYLD to the perinuclear region of the cell is achieved by an inhibitory interaction of CYLD with histone deacetylase-6 (HDAC6) leading to an increase in the levels of acetylated alpha-tubulin around the nucleus. This facilitates the interaction of CYLD with Bcl-3, leading to a significant delay in the G(1)-to-S-phase transition. Finally, CYLD also interacts with HDAC6 in the midbody where it regulates the rate of cytokinesis in a deubiquitinase-independent manner. Altogether these results identify a mechanism by which CYLD regulates cell proliferation at distinct cell-cycle phases.

Genetic profile of adenoid cystic carcinomas (ACC) with high-grade transformation versus solid type

BACKGROUND

ACC can occasionally undergo dedifferentiation also referred to as high-grade transformation (ACC-HGT). However, ACC-HGT can also undergo transformation to adenocarcinomas which are not poorly differentiated. ACC-HGT is generally considered to be an aggressive variant of ACC, even more than solid ACC. This study was aimed to describe the genetic changes of ACC-HGT in relation to clinico-pathological features and to compare results to solid ACC.

METHODS

genome-wide DNA copy number changes were analyzed by microarray CGH in ACC-HGT, 4 with transformation into moderately differentiated adenocarcinoma (MDA) and two into poorly differentiated carcinoma (PDC), 5 solid ACC. In addition, Ki-67 index and p53 immunopositivity was assessed.

RESULTS

ACC-HGT carried fewer copy number changes compared to solid ACC. Two ACC-HGT cases harboured a breakpoint at 6q23, near the cMYB oncogene. The complexity of the genomic profile concurred with the clinical course of the patient. Among the ACC-HGT, p53 positivity significantly increased from the conventional to the transformed (both MDA and PDC) component.

CONCLUSION

ACC-HGT may not necessarily reflect a more advanced stage of tumor progression, but rather a transformation to another histological form in which the poorly differentiated forms (PDC) presents a genetic complexity similar to the solid ACC.

[Relationship between proteoglycans and proliferation of human salivary adencid cystic carcinoma]

OBJECTIVE

To investigate the effect of down-regulated proteoglycans on the proliferation of human salivary adenoid cystic carcinoma (SACC).

METHODS

The short hairpin RNA (shRNA) plasmid silencing human xylosyltransferase-I (XT-I) gene was constructed and named shRNA-WJ3. Adenoid cystic carcinoma cells with high metastatic tendency (ACC-M) were transfected by shRNA-WJ3. The plasmid shRNA-HK not targeting any human gene was transfected into ACC-M cells used as negative control. After 48 h of transfection, the positive cells were screened by G418 to isolate the stable transfected cells. Real-time PCR and Western blotting were used to test the gene silence, and the proteoglycans contents of the cells were detected. The stable cell line silenced XT-I was named ACC-M-WJ3. MTT assay was performed to detect the cell proliferation. The cell cycle was analyzed by flow cytometry.

RESULTS

ShRNA-WJ3 showed powerful RNA interference and gene silence of XT-I. The inhibition rate was 83.70% of mRNA expression and 79.60% of protein expression respectively. The content of proteoglycans in ACC-M-WJ3 was down-regulated by 49.71%-54.59%. The results of MTT assay showed that the cell growth was inhibited significantly. S phrase decreased and G₁-G₀ phrase increased in group ACC-M-WJ3 compared with that of group ACC-M-HK (P < 0.05).

CONCLUSIONS

The down-regulated proteoglycans could inhibit the proliferation of human ACC-M cells.

The effect of proteoglycans inhibited by RNA interference on metastatic characters of human salivary adenoid cystic carcinoma

BACKGROUND

Salivary adenoid cystic carcinoma (SACC) is one of the most common malignancies of salivary gland. Recurrence or/and early metastasis is its biological properties. In SACC, neoplastic myoepithelial cells secrete proteoglycans unconventionally full of the cribriform or tubular and glandular structures of SACC. Literatures have demonstrated that extracellular matrix provided an essential microenvironment for the biological behavior of SACC. However, there is rare study of the effect of proteoglycans on the potential metastasis of SACC.In this study, human xylosyltransferase-I (XTLY-I) gene, which catalyzes the rate-limited step of proteoglycans biosynthesis, was knocked down by RNA interference (RNAi) to inhibit the proteoglycans biosynthesis in SACC cell line with high tendency of lung metastasis (SACC-M). The impact of down-regulated proteoglycans on the metastasis characters of SACC-M cells was analyzed and discussed. This research could provide a new idea for the clinical treatment of SACC.

METHODS

The eukaryotic expression vector of short hairpin RNA (shRNA) targeting XTLY-I gene was constructed and transfected into SACC-M cells. A stably transfectant cell line named SACC-M-WJ4 was isolated. The XTLY-I expression was measured by real-time PCR and Western blot; the reduction of proteoglycans was measured. The invasion and metastasis of SACC-M-WJ4 cells were detected; the effect of down-regulated proteoglycans on the potential lung metastasis of nude mice was observed, respectively.

RESULTS

The shRNA plasmid targeting XTLY-I gene showed powerful efficiency of RNAi. The mRNA level of target gene decreased by 86.81%, the protein level was decreased by 80.10%, respectively. The silence of XTLY-I gene resulted in the reduction of proteoglycans significantly in SACC-M-WJ4 cells. The inhibitory rate of proteoglycans was 58.17% (24 h), 66.06% (48 h), 57.91% (72 h), 59.36% (96 h), and 55.65% (120 h), respectively. The reduction of proteoglycans suppressed the adhesion, invasion and metastasis properties of SACC-M cells, and decreased the lung metastasis of SACC-M cells markedly either.

CONCLUSION

The data suggested that the silence of XTLY-I gene in SACC-M cells could suppress proteoglycans biosynthesis and secretion significantly. The reduction of proteoglycans inhibited cell adhesion, invasion and metastasis of SACC-M cells. There is a close relationship between proteoglycans and the biological behavior of SACC.

Metastasis-associated genes in oral squamous cell carcinoma and salivary adenoid cystic carcinoma: a differential DNA chip analysis between metastatic and nonmetastatic cell systems

Overall modes of differential gene expressions were analyzed between human oral/salivary carcinoma cell systems with (MK-1 and ACCM) and without (ZK-1/ZK-2 and ACC2/ACC3) metastatic potential by using micro-array analysis with cancer-associated DNA chips to determine the kinds of genes associated with metastatic behaviors. MK-1 and/or ACCM showed lower levels of gene expression in extracellular matrix-related molecules, such as collagen type IV, laminin, and adhesion molecules such as cadherin 2, but higher levels of genes which control extracellular matrix degradation, such as MMP 9, as well as cell growth and cycle, such as FGF7 and cyclin D1. Among the differentially expressed genes, similar protein expression tendencies for FGF7, laminin, cyclin D1, and collagen type IV were confirmed by immunofluorescence. Metastatic potentials of oral/salivary carcinoma cells seem to have resulted from certain combinations of over-/underexpression of the genes, which were responsible for extracellular matrix metabolism and cell growth in particular.

[Effects of Ezrin gene on the proliferation and invasion activity of human salivary gland adenoid cystic carcinoma]

OBJECTIVE

To examine the expression of Ezrin in human salivary gland adenoid cystic carcinoma and investigate the effects of Ezrin gene silence on cell proliferation, apoptosis and invasion of adenoid cystic carcinoma (ACC)-M.

METHODS

The expression of Ezrin was detected by immunohistochemistry in normal salivary gland tissue (n=15), pleomorphic adenoma (n=40) and salivary gland adenoid cystic carcinoma (n=43). The Ezrin Stealth RNAi Duplex, containing Stealth RNAi Negative Control Duplex were constructed and transfected into ACC-M cells by Lipofectamine 2000. The expression levels of Ezrin were detected by RT-PCR and immunohistochemistry. The cell cycle and apoptosis rate were analyzed by flow cytometry (FCM). The cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) and cell invasion by Transwell test.

RESULTS

The positive rate of Ezrin expression in ACC was significantly higher than that in normal salivary gland tissue and pleomorphic adenoma (P<0.05). After transfection of Ezrin Stealth RNAi Duplex, the mRNA and protein expression of Ezrin were down-regulated, the cell proliferation activity was inhibited, the G0-G1 Phase cells were increased, and the apoptosis rate of Ezrin Stealth RNAi Duplex group was higher than that in control groups and cell invasion ability was decreased.

CONCLUSIONS

Over expression of Ezrin in human salivary gland adenoid cystic carcinoma may promote genesis, development and metastasis of tumors. Ezrin Stealth RNAi Duplex could efficiently down-regulate the expression of Ezrin gene, and partly inhibited proliferation of ACC-M cells, induce apoptosis and decrease invasion ability of these cells in vitro.

Brooke-Spiegler syndrome with associated pegged teeth

The occurrence of cylindromas, trichoepitheliomas, and spiradenomas completes the triad for Brooke-Spiegler syndrome (BSS). This combination represents a rare genetic syndrome with tumors expressing adnexal differentiation. Malignant transformation is rare but reported, and surgical excision is warranted to prevent turban tumor formation of the scalp. Genetic testing is encouraged, with mutations present on the cylindromatosis gene, CYLD, locus. The occurrence of pegged teeth in our patient was most interesting, as it has not been reported in the literature in patients with BSS.

Trichoepithelioma

A 29-year-old man presented with a long-standing history of asymptomatic, skin-colored, facial papules and nodules. Histopathologic examination of a representative papule demonstrated trichoepithelioma. The patient had a history of a brother with a similar phenotype, which suggests a diagnosis of familial trichoepithelioma. Linkage and mutational analyses support genetic heterogeneity of familial trichoepithelioma, possibly sharing a clinical spectrum with Brooke-Spiegler syndrome and familial cylindromatosis since each entity has been associated with mutations the CYLD gene.

Deletion of 1p32-p36 is the most frequent genetic change and poor prognostic marker in adenoid cystic carcinoma of the salivary glands

PURPOSE

Adenoid cystic carcinoma (ACC) is a relatively uncommon salivary gland malignancy known for its protean phenotypic features and pernicious clinical behavior. Currently, no effective therapy is available for patients with advanced nonresectable, recurrent, and/or metastatic disease. The purpose of this study is to identify prognostic factors other than tumor stage that can be used to predict the outcome of the patients with ACC.

EXPERIMENTAL DESIGN

We used comparative genomic hybridization (CGH) to identify copy number aberrations in 53 primary ACCs. Array CGH and fluorescence in situ hybridization analysis was used to validate CGH results on selected cases. We correlated these copy number aberrations with clinicopathologic factors using Pearson's chi2 or by the two-tailed Fisher exact test. The disease-specific survival and disease-free intervals were generated by the Kaplan-Meier product limit method.

RESULTS

Chromosomal losses (n = 134) were more frequent than gains (n = 74). The most frequent genetic change was the loss of 1p32-p36 in 44% of the cases followed by 6q23-q27, and 12q12-q14. The most frequently gained chromosomal regions were 8 and 18. Of the chromosomal aberrations, loss of 1p32-p36 was the only abnormality significantly associated with patient's outcome.

CONCLUSIONS

This study, for the first time, identifies loss of 1p32-p36 as a significant aberration in ACC. Molecular characterization of 1p32-36 region using the available genomic technologies may lead to the identification of new genes critical to the development of novel therapeutic targets for this disease copy number aberration.

Brooke-Spiegler syndrome: report of a case of multiple cylindromas and trichoepitheliomas

We report a case of Brooke-Spiegler syndrome, a rare autosomal dominant disorder caused by mutations of the cylindromatosis gene (CYLD) tumor suppressor gene resulting in multiple cylindromas and trichoepitheliomas. Treatment of these patients can involve surgical excision, laser therapy, or topical applications of aspirin derivatives.

Gene expression profiling and histopathological characterization of triple-negative/basal-like breast carcinomas

INTRODUCTION

Breast cancer is a heterogeneous group of tumors, and can be subdivided on the basis of histopathological features, genetic alterations and gene-expression profiles. One well-defined subtype of breast cancer is characterized by a lack of HER2 gene amplification and estrogen and progesterone receptor expression ('triple-negative tumors'). We examined the histopathological and gene-expression profile of triple-negative tumors to define subgroups with specific characteristics, including risk of developing distant metastases.

METHODS

97 triple-negative tumors were selected from the fresh-frozen tissue bank of the Netherlands Cancer Institute, and gene-expression profiles were generated using 35K oligonucleotide microarrays. In addition, histopathological and immunohistochemical characterization was performed, and the findings were associated to clinical features.

RESULTS

All triple-negative tumors were classified as basal-like tumors on the basis of their overall gene-expression profile. Hierarchical cluster analysis revealed five distinct subgroups of triple-negative breast cancers. Multivariable analysis showed that a large amount of lymphocytic infiltrate (HR = 0.30, 95% CI 0.09-0.96) and absence of central fibrosis in the tumors (HR = 0.14, 95% CI 0.03-0.62) were associated with distant metastasis-free survival.

CONCLUSION

Triple-negative tumors are synonymous with basal-like tumors, and can be identified by immunohistochemistry. Based on gene-expression profiling, basal-like tumors are still heterogeneous and can be subdivided into at least five distinct subgroups. The development of distant metastasis in basal-like tumors is associated with the presence of central fibrosis and a small amount of lymphocytic infiltrate.

[Effect of shRNA-mediated silence of H-ras gene on proliferation of human SACC-M cells]

OBJECTIVE

To examine the effects of H-ras gene silence on cell cycle, proliferation and apoptosis of salivary adenoid cystic carcinoma -M (SACC-M) cell lines.

METHODS

The plasmid H-ras-shRNA, containing the sequence of shRNA targeting H-ras, and HK-shRNA (without interfering effect) were constructed and transfected into SACC-M cells. The cell line with shRNA plasmid stable expression was isolated by G418. The expression levels of H-ras were detected by RT-PCR and protein immunofluorescent assay; cell cycle and cell apoptosis were analyzed by flow cytometry (FCM). The proliferation of cell was also determined by subcutaneous tumor formation in nude mice.

RESULTS

After transfection of H-ras-shRNA plasmid, the mRNA expression of H-ras in SACC-M cells was down-regulated by 61.80% and protein expression of H-ras was inhibited by 62.76%; the cell proliferation was inhibited obviously; the G0G1 phase cells were increased. The cell apoptosis rate of H-ras-shRNA group was significantly higher than that of HK-shRNA group (P <0.05). The volume of subcutaneous tumor in nude mice was significantly smaller in Hras-shRNA group than in control group.

CONCLUSIONS

The recombinant plasmid HRAS-shRNA could efficiently down-regulate the expression of H-ras gene and protein, induce apoptosis of SACC-M cells and simultaneously inhibit proliferation of these cells in vitro and in vivo.

[Fluorescent imaging of angiogenesis and spontaneous metastasis in transplanted hepatoma: experiment with mice]

OBJECTIVE

To establish stable enhanced green fluorescent protein (GFP) -expressing human adenoid cystic carcinoma (ACC-M-GFP) cell lines with high lung metastatic potential, and to study the value and influential factor of in vivo monitoring of metastasis and angiogenesis by fluorescent imaging.

METHODS

Human adenoid cystic carcinoma cell line ACC-M-GFP labeled with enhanced GFP was established. ACC-M-GFP cells of the dose 10(7)/ml were injected subcutaneously into two nude mice. Once the subcutaneous tumor reached 0.5 cm in diameter, it was removed, cut into 1 mm3 pieces, and implanted into the left hepatic lobe of 8 nude mice. The animals were observed by whole-body optical imaging system and stereofluorescent microscope each two weeks from the fourth week after transplantation. One mouse was killed and autopsied after each examination. The livers, lungs, and adjacent organs, such as diaphragm and lymph nodes were excised, and fluorescent imaging of different organs separately was studied. Hepatoma was cryostat sectioned and angiogenesis was visualized under fluorescence microscope. The findings of fluorescent imaging were compared with those of HE staining on routine paraffin sections.

RESULTS

Liver tumors were transplanted successfully in all 8 nude mice. By whole-body optical system, the fluorescent signal from the liver tumor was detected through a skin-flap window after 6 - 8 weeks. Tumors were visualized directly through skin after 8 - 10 weeks. The hepatoma became enormous after 12 - 14 weeks, when the fluorescent signal of abdominal metastasis was detected. Metastasis of lung and lymph node was found by single organ imaging after 16 -18 weeks. By stereofluorescent microscope, microvessels were detected after 4 weeks, and a large quantity of tumor vessels like black branch stripes were found after 12 - 14 weeks. The tumor vessels appeared as dark tubiform network against the green fluorescence of the implanted tumor in section.

CONCLUSION

Fluorescent imaging provides a method to monitor tumor growing, infiltrating, metastasis and angiogenesis in real time in vivo.

Translocation t(6;14) as the sole chromosomal abnormality in adenoid cystic carcinoma of the base of tongue

We present an adenoid cystic carcinoma of the base of tongue in a 48-year-old male with a restricted chromosomal alteration by cytogenetic and spectral karyotypic analysis (SKY). SKY and G-banding analyses identified the t(6;14)(q25;q13) as the sole structural aberration in all metaphases analyzed. This finding supports a critical role for this event in the development of this tumor. The implications of chromosome 6q translocation in this case and in previously reported adenoid cystic carcinomas are highlighted and discussed.

Mutation of the p16/CDKN2 gene and loss of heterozygosity in malignant mucosal melanoma and adenoid cystic carcinoma of the head and neck

The purpose of this study was to investigate the molecular biological characteristics of malignant mucosal melanoma (MMM) and adenoid cystic carcinoma (ACC) of the head and neck. We analyzed the common genetic abnormalities that may help to identify the loci in the genes involved in the development of MMM and ACC of the head and neck by PCR-LOH on chromosomes 1p, 6q, 9p, 10q, 11q, 12q, 17p, and 19q. LOH was observed in 6 of 12 cases of MMM and in 12 of 15 cases of ACC informative for at least one of the loci analyzed. One distinct deleted region was identified at chromosome 9p21. In addition, to identify a possible involvement of p16/CDKN2 PCR-SSCP and auto-DNA sequence analysis were also performed to detect any mutation of the p16/CDKN2. Particularly, 2 missense mutations were detected in codon 225 and 226, both in MMM and ACC. There were mutational hot spots in the p16/CDKN2 gene. These results suggested that mutation of the p16/CDKN2 gene was a common factor in the development of human MMMs and ACCs, while this gene may be correlated with development and/or progression of a subtype and play a role in the oncogenesis of these cancers.

Prognostic implications of NUMB immunoreactivity in salivary gland carcinomas

The gene numb encodes for a protein (Numb) involved in cell fate decisions in Drosophila, with proposed endocytic and developmental functions in mammalians. The distribution pattern of Numb in human tissues however, has not been fully characterized. We set out to explore the immunohistochemical expression of Numb in normal and neoplastic (28 adenoid cystic and 34 mucoepidermoid carcinomas) salivary glands, and correlated the results with the clinico-pathologic features of the neoplasms. Intense Numb immunoreactivity was detected in normal ductal cells and in a subset of acinar cells. In salivary carcinomas, we detected diffuse and intense Numb immunostaining in 5 adenoid cystic and 8 mucoepidermoid carcinomas. By contrast, the majority of adenoid cystic and mucoepidermoid cancers showed only moderate (14 and 5 cases) or focal staining (9 and 21 cases), respectively. The corresponding expression of Numb mRNA was documented in normal parotid gland and adenoid cystic carcinoma. Numb immunoreactivity was inversely correlated with the histological grade and Ki-67 immunoreactivity of both adenoid cystic and mucoepidermoid carcinomas. In addition, while tumor grade, stage, Ki-67 and Numb immunoreactivity were associated with disease-free survival in univariate analysis, only Numb and Ki-67 immunoreactivities retained independent prognostic significance in multivariate analysis. These data suggest that loss of Numb is implicated in aberrant differentiation programs of salivary gland carcinomas and may serve as a prognostic indicator in patients treated for these neoplasms.

Five new CYLD mutations in skin appendage tumors and evidence that aspartic acid 681 in CYLD is essential for deubiquitinase activity

Brooke-Spiegler syndrome, familial cylindromatosis, and familial trichoepithelioma are autosomal-dominant genetic predispositions for benign tumors of skin appendages caused by mutations in the CYLD gene localized on chromosome 16q12-q13. The encoded protein functions as ubiquitin-specific protease (UBP), which negatively regulates NF-kappaB and c-Jun N-terminal kinase (JNK) signaling. We investigated five families affected with these skin neoplasms and identified four premature stop codons and the novel missense mutation D681G in a family in which 11 of 12 investigated tumors were trichoepitheliomas. CYLD protein harboring this missense mutation had a significant reduced ability to inhibit TNF receptor-associated factor (TRAF)2- and TRAF6-mediated NF-kappaB activation, tumor necrosis factor-alpha (TNFalpha)-induced JNK signaling, and to deubiquitinate TRAF2. CYLD-D681G was coimmunoprecipitated by TRAF2, but was unable to cleave K63-linked polyubiquitin chains. Aspartic acid 681 is highly conserved in CYLD homologues and other members of the UBP family, but does not belong to the Cys and His boxes providing the CYLD catalytic triad (Cys601, His871, and Asp889). As reported previously, the homologous residue D295 of HAUSP/USP-7 forms a hydrogen bond with the C-terminal end of ubiquitin and is important for the enzymatic activity. These results underline that D681 in CYLD is required for cleavage of K63-linked polyubiquitin chains.