Sphk1 promotes salivary adenoid cystic carcinoma progression via PI3K/Akt signaling.

The progression of salivary adenoid cystic carcinoma (SACC) is closely related to abnormal gene expression. Herein, the role of Sphk1 in SACC was explored. Sphk1 was overexpressed in SACC tissues. In SACC cell lines, Sphk1 induced cell proliferation, inhibited apoptosis, and promoted cell migration. Moreover, Sphk1 overexpression induced up-regulation of the PI3K protein level and AKT phosphorylation level. Rescue assays further showed that activation of the Sphk1 /PI3K/Akt pathway affected various biological functions of SACC cells. Together, these findings suggested that Sphk1 promotes salivary tumorigenesis by activating the PI3K/ Akt pathway, which may provide novel intervention targets for SACC treatment.

Sialadenoma Papilliferum of the Bronchus: An Unrecognized Bronchial Counterpart of the Salivary Gland Tumor With Frequent BRAF V600E Mutations.

Sialadenoma papilliferum (SP) is a rare benign tumor of the salivary glands, and only 3 unequivocal cases of SP arising in the bronchus have been reported. We herein describe the histomorphologic and molecular features of 4 bronchial SP cases and discuss the differential diagnosis of this entity and the relationship with its clinicopathologic mimics, in particular, glandular papilloma and mixed squamous cell and glandular papilloma (GP/MP). We encountered 2 male and 2 female patients with bronchial SP (mean: 66.8 y old). All 4 tumors arose in the central bronchus and were characterized by a combination of surface exophytic endobronchial papillary proliferation and a submucosal multicystic component with complex architecture. The neoplastic epithelium consisted predominantly of nonciliated stratified columnar cells with ciliated, squamous, and mucinous cells present focally. While 2 tumors (50%) harbored a BRAF V600E mutation by molecular and immunohistochemical analysis, similar to GP/MP, no KRAS, HRAS, AKT1, or PIK3CA mutations were detected in any of the cases. Two patients were treated with limited resection, while 2 patients underwent lobectomy based on the diagnosis of adenocarcinoma or possible squamous cell carcinoma in situ in the preoperative biopsy. All survived without recurrence or metastasis for 23 to 122 months after treatment. SP can develop in the central bronchus as the bronchial counterpart of the salivary gland tumor and should be considered in the differential diagnosis of endobronchial tumors. In addition, some histologic resemblance and frequent BRAF V600E mutation raise the possibility of SP and GP/MP being on the same disease spectrum.

Human Tissue Kallikreins in Polymorphous Adenocarcinoma: A Polymerase Chain Reaction and Immunohistochemical Study.

Polymorphous adenocarcinoma (PAC) is the second most common malignant salivary gland tumour of minor salivary glands. Human tissue kallikreins (KLKs) are a family of highly conserved serine proteases expressed by various tissues and organs. The literature demonstrates a link between KLKs and salivary gland neoplasms. The purpose of this study was to determine levels of KLK mRNA in tissue samples of PAC and to determine if KLK expression is limited to tumour cells. Nineteen cases of PAC were reviewed (1987-2013). The diagnosis was confirmed, demographic data was collected, and formalin fixed paraffin-embedded PAC and normal salivary gland tissue samples were obtained. RNA isolation was achieved, followed by conversion to complementary DNA via reverse transcription. Using PCR, the quantitative level of expression of KLKs1-15 was recorded. Samples exhibiting high and low KLK expression were selected for immunohistochemistry staining. Results revealed a statistically significant increase in mean KLK mRNA expression for KLK1, KLK4, KLK10, KLK12 and KLK15 in PAC tissue samples, compared with normal salivary gland tissue (Mann-Whitney U test, p < 0.05). Immunohistochemistry results demonstrated that KLKs were present in tumor cells. Notably, all samples demonstrating relatively higher KLK mRNA expression showed equivalent or increased staining scores relative to the low KLK mRNA expression samples. In conclusion, there appears to be aberrant kallikrein expression in polymorphous adenocarcinoma, suggesting the possibility of a kallikrein cascade influence on tumor development and progression.

ALK alterations in salivary gland carcinomas.

Salivary gland carcinomas represent a heterogeneous group of poorly characterized head and neck tumors. The purpose of this study was to evaluate ALK gene and protein aberrations in a large, well-characterized cohort of these tumors. A total of 182 salivary gland carcinomas were tested for anaplastic lymphoma kinase (ALK) positivity by immunohistochemistry (IHC) using the cut-off of 10% positive cells. ALK positive tumors were subjected to FISH analysis and followed by hybrid capture-based next generation sequencing (NGS). Of the 182 tumors, 8 were ALK positive by IHC. Further analysis using hybrid capture NGS analysis revealed a novel MYO18A (Exon1-40)-ALK (exon 20-29) gene fusion in one case of intraductal carcinoma. Additional genomic analyses resulted in the detection of inactivating mutations in BRAF and TP53, as well as amplifications of ERBB2 and ALK. ALK rearrangements are a rare entity in salivary gland carcinomas. We identified a potentially targetable novel ALK fusion in an intraductal carcinoma of minor salivary glands.

Matrix metalloproteinase-7, -8, -9, -15, and -25 in minor salivary gland adenoid cystic carcinoma.

Knowledge on the role of matrix metalloproteinases (MMPs) in adenoid cystic carcinoma (ACC) is limited. MMPs are capable of degrading almost all extracellular and pericellular components to promote invasion and metastasis. This study aimed to evaluate the immunohistochemical expression of MMP-7, -8, -9, -15, and -25 in ACC and to relate the results with clinicopathological factors and survival. The study included 68 patients with minor salivary gland ACC treated at the Helsinki University Hospital (Helsinki, Finland) in 1974-2012. Samples from 52 patients were available, consisting of 44 primary tumours and eight recurrent tumours. We scored immunostaining of MMP-7, -8, -9, -15, and -25 and analysed the immunoscore against clinical and pathological parameters using statistical correlation test. MMP-9 immunoexpression in pseudocysts of ACC and in peritumoural inflammatory cells associated with better survival and fewer treatment failures. High tumoural MMP-7 and -25 associated with better survival. High tumoural MMP-15 associated with poorer survival and high tumoural MMP-9 with advanced stage and regional recurrences. Tumour cells did not show MMP-8 immunopositivity. These results suggest that MMP-9 may contribute to ACC carcinogenesis in different roles. MMP-7, -8, and -9 can stimulate signalling pathways that may promote tissue modulation and metastatic potential. MMP-15 and -25 may reflect prognosis.

RhoG/Rac1 signaling pathway involved in migration and invasion of salivary adenoid cystic carcinoma cells.

OBJECTIVES: This study aimed to explore whether RhoG/Rac1 was involved in migration and invasion of salivary adenoid cystic carcinoma (SACC). MATERIALS AND METHODS: RhoG and Rac1 were evaluated in two SACC cell lines, namely SACC-83 and SACC-LM, with low and high rates of lung metastasis, respectively. Functional changes were evaluated using cell proliferation, transwell, and wound-healing assays, and molecular events were investigated using real-time PCR and Western blot assays. RESULTS: RhoG and Rac1 were highly expressed and more activated in SACC-LM cells than in SACC-83 cells. RhoG overexpression promoted SACC-83 cell migration and invasion through activating Rac1. The knockdown of RhoG or Rac1 partially blocked epiregulin-induced migration and invasion in SACC-83 cells. Epiregulin-induced activation of RhoG/Rac1 in SACC-83 cells was blocked by a Src inhibitor, or an AKT inhibitor or AKT siRNA, or an ERK1/2 inhibitor. Moreover, the epiregulin-induced phosphorylation of AKT and ERK1/2 in SACC-83 cells was blocked by a Src inhibitor, and the epiregulin-induced phosphorylation of ERK1/2 was blocked by an AKT inhibitor or AKT siRNA. Overexpression of activated AKT induced activation of ERK1/2 and RhoG. CONCLUSIONS: RhoG/Rac1 signaling pathway was involved in SACC cell migration and invasion. RhoG/Rac1 at least partially mediated epiregulin/Src/AKT/ERK1/2 signaling to promote SACC cell migration and invasion.

Adenomyoepitheliomas of the Breast Frequently Harbor Recurrent Hotspot Mutations in PIK3-AKT Pathway-related Genes and a Subset Show Genetic Similarity to Salivary Gland Epithelial-Myoepithelial Carcinoma.

Adenomyoepitheliomas (AME) of the breast and epithelial-myoepithelial carcinomas (EMCs) of salivary gland are morphologically similar tumors defined by the presence of a biphasic population of ductal epithelial elements mixed with myoepithelial cells. We sought to explore the molecular profile of AMEs and determine whether they might also share the PLAG1, HMGA2, and HRAS alterations seen in EMCs. Tumor tissue from 19 AMEs was sequenced and analyzed using Ion AmpliSeq Cancer Hotspot Panel v2 covering ∼2800 COSMIC mutations across 50 cancer-related genes. Cases were additionally screened by FISH for PLAG1 and HMGA2 rearrangements. Of 19 AMEs (12 benign; 7 malignant), 2 cases failed the DNA extraction. Of the remaining 17 cases, 14 had at least one nonsynonymous mutation identified. The most common mutations were in PIK3CA (6/17) and AKT1 (5/17), which were mutually exclusive. Two tumors demonstrated mutations in APC, while 1 demonstrated an STK11 mutation. Mutations in ATM, EGFR, FGFR3 or GNAS were identified in 4 cases with concurrent AKT1 mutations. HRAS mutation co-occurring with PIK3CA mutation was noted in 1 case of ER-negative malignant AME. While 2 cases harbored alterations in HMGA2, none was positive for PLAG1 rearrangement. Our findings confirm that breast AMEs are genetically heterogeneous exhibiting recurrent mutually exclusive mutations of PIK3CA and AKT1 in a majority of cases. HRAS mutations co-occur with PIK3CA mutations in ER-negative AMEs and may possibly be linked to clinically aggressive behavior. We identified hotspot mutations in additional genes (APC, STK11, ATM, EGFR, FGFR3, and GNAS). We report the presence of HMGA2 alterations in 2/16 AMEs, supporting their relationship with EMC of salivary glands in at least a subset of cases. PIK3CA, AKT1 and HRAS may serve as potential actionable therapeutic targets in clinically aggressive AMEs.

Phase II Trial of Trastuzumab and Docetaxel in Patients With Human Epidermal Growth Factor Receptor 2-Positive Salivary Duct Carcinoma.

PURPOSE: Clinical evidence demonstrating the effectiveness of systemic therapy for advanced salivary duct carcinoma (SDC) is lacking because of the disease's rarity. We assessed the efficacy and toxicity of trastuzumab plus docetaxel in patients with locally advanced and/or recurrent or metastatic human epidermal growth factor receptor 2-positive SDC. PATIENTS AND METHODS: This was a single-center, single-arm, open-label, phase II study in Japan. The patients received trastuzumab at a loading dose of 8 mg/kg, followed by 6 mg/kg every 3 weeks. Docetaxel 70 mg/m2 was administrated every 3 weeks. The primary end point was the overall response rate; the secondary end points included the clinical benefit rate, progression-free survival, overall survival, and toxicity. This study is registered with the University Hospital Medical Information Network Clinical Trials Registry (Identification No. UMIN000009437). RESULTS: Fifty-seven eligible patients with SDC were enrolled. The overall response rate was 70.2% (95% CI, 56.6% to 81.6%), and the clinical benefit rate was 84.2% (95% CI, 72.1% to 92.5%). Median progression-free and overall survival times were 8.9 months (95% CI, 7.8 to 9.9 months) and 39.7 months (95% CI, not reached), respectively. The most frequent adverse event was anemia (52 patients [91%]), followed by a decreased WBC count (51 patients [89%]) and neutropenia (50 patients [88%]). The most frequently observed grade 4 adverse event was a decreased neutrophil count (34 patients [60%]). Grade 3 febrile neutropenia was reported in eight patients (14%). No grade 2 or greater adverse events of heart failure or left ventricular ejection fraction decline to less than 50% occurred. CONCLUSION: Our data show encouraging efficacy of trastuzumab plus docetaxel therapy in patients with human epidermal growth factor receptor 2-positive SDC, with a manageable toxicity profile.

Intraductal Papillary Mucinous Neoplasms of Minor Salivary Glands With AKT1 p.Glu17Lys Mutation.

The spectrum of low-grade intraductal papillary proliferations of the salivary glands is heterogenous, and reproducible morphologic diagnostic criteria have not yet been established. Recognized types are sialadenoma papilliferum, inverted ductal papilloma, and intraductal papilloma, but some lesions have been possibly included in the morphologic spectrum of cystadenoma or low-grade intraductal carcinomas. We herein present detailed morphologic, immunophenotypic, and genotypic features of 3 minor salivary gland neoplasms affecting 2 men (aged 65 and 71 y) and 1 woman (aged 78 y). They ranged in size from 1 to 2.5 cm. All tumors showed atypical papillary intraductal growth that presented either as uninodular/unicystic lesions (intraductal papilloma-like; n=2) or as a discontinuous growth along the ductal system in a manner similar to pancreatic intraductal papillary mucinous neoplasm (n=1). Variable cytologic and architectural atypia was observed, ranging from bland intraductal papilloma-like features, to areas mimicking atypical ductal hyperplasia and low-grade ductal carcinoma in situ of the breast. Amplicon-based massive parallel sequencing revealed an identical AKT1 p.Glu17Lys mutation in all 3 cases, but absence of concurring mutations in other genes of the RAS or PI3K pathway. This small series represents the first genetic study on salivary intraductal papillary neoplasms. Our cases showed significant variation in the degree of cytologic and architectural atypia, which overlaps with intraductal papillomas at the one end and with low-grade intraductal carcinoma at the other end of the spectrum, suggesting a disease continuum. As the full biological and morphologic characteristics of these ductal papillary lesions remain to be defined, the noncommitted term "intraductal papillary neoplasms" might be more appropriate. Our novel genetic findings mirror similar activating mutations of AKT1 and other PI3K pathway members in intraductal papillary lesions of the breast and anogenital glands.

AKT3 drives adenoid cystic carcinoma development in salivary glands.

Salivary gland cancer is an aggressive and painful cancer, but a rare tumor type accounting for only ~0.5% of cancer cases. Tumors of the salivary gland exhibit heterogeneous histologic and genetic features and they are subdivided into different subtypes, with adenoid cystic carcinomas (ACC) being one of the most abundant. Treatment of ACC patients is afflicted by high recurrence rates, the high potential of the tumors to metastasize, as well as the poor response of ACC to chemotherapy. A prerequisite for the development of targeted therapies is insightful genetic information for driver core cancer pathways. Here, we developed a transgenic mouse model toward establishment of a preclinical model. There is currently no available mouse model for adenoid cystic carcinomas as a rare disease entity to serve as a test system to block salivary gland tumors with targeted therapy. Based on tumor genomic data of ACC patients, a key role for the activation of the PI3K-AKT-mTOR pathway was suggested in tumors of secretory glands. Therefore, we investigated the role of Akt3 expression in tumorigenesis and report that Akt3 overexpression results in ACC of salivary glands with 100% penetrance, while abrogation of transgenic Akt3 expression could revert the phenotype. In summary, our findings validate a novel mouse model to study ACC and highlight the druggable potential of AKT3 in the treatment of salivary gland patients.

Regulation of ß-Catenin Phosphorylation by PR55ß in Adenoid Cystic Carcinoma.

BACKGROUND/AIM: Adenoid cystic carcinoma (AdCC) is a rare cancer of the salivary gland with high risk of recurrence and metastasis. Wnt signalling is critical for determining tumor grade in AdCC, as it regulates invasion and migration. ß-catenin dephosphorylation plays an important role in the Wnt pathway, but its underlying molecular mechanism remains unclear. MATERIALS AND METHODS: Because the regulatory subunits of protein phosphatase 2A (PP2A) drive Wnt signalling via target molecules, including ß-catenin, we used qRT-PCR and immunoblot analysis to investigate the expression of these subunits in an AdCC cell line (ACCS) and a more aggressive subline (ACCS-M). RESULTS: PR55ß was highly expressed in ACCS-M, suggesting its functional importance. In addition, PR55ß expression was associated with tumor grade, with ACCS-M exhibiting higher PR55ß levels. More importantly, knockdown of PR55ß in ACCS-M cells significantly reduced invasiveness and metastatic ability. Furthermore, dephosphorylation and total levels of ß-catenin were dependent on PR55ß in ACCS-M. Finally, we confirmed a correlation between PR55ß staining intensity and histopathological type in human AdCC tissues. CONCLUSION: Our study provides new insight into the interaction between PR55ß and ß-catenin and suggests that PR55ß may be a target for the clinical treatment of AdCC.

[Expression of midkine and microvessel density in salivary adenoid cystic carcinoma].

OBJECTIVE: This study aimed to investigate the expression of midkine (MK) and microvessel density (MVD) in patients with salivary adenoid cystic carcinoma (SACC) and its clinical significance, as well as detect the correlation between the expression of MK and MVD in SACC. METHODS: Immunohistochemistry analysis (SP method) for MK and MVD were performed on 60 cases of SACC and 26 cases of normal salivary gland tissue. The expression of MK and MVD, as well as the correlation between the expression of MK and MVD in SACC were detected. RESULTS: In SACC, the MK expression rate was 70.0% (42/60), and MK was not expressed in normal tissue. Statistical significance was found between SACC and normal tissue (P<0.05). The MVD values in SACC and normal salivary gland tissues were 38.73 +/- 8.96 and 11.15 +/- 3.33, respectively. These values were statistically significant (P<0.05). The expression levels of MK and MVD were unrelated to age, gender, and type in SACC (P>0.05), but correlated with tumor size, lymph node metastasis, and tumor-node-metastasis in SACC (P<0.05). The expression of MK and MVD was positively correlated with SACC (r=0.560, P<0.05). CONCLUSION: SACC is correlated with the expression of MK protein and the increase in MVD, which may be some of the early diagnostic markers in SACC.

Lysozyme Expression Can be Useful to Distinguish Mammary Analog Secretory Carcinoma from Acinic Cell Carcinoma of Salivary Glands.

Lysozyme is an enzymatic marker of acinar and intercalated duct cells of normal salivary glands. The aim of this study was to verify whether lysozyme expression could be useful to distinguish acinic cell carcinoma (ACC) from its main mimic, mammary analog secretory carcinoma (MASC). For comparison, DOG1 expression was analyzed as well. Seventeen cases of ACC, 15 MASC, and 125 other salivary tumors were studied. Lysozyme expression was found in tumor cells as well as in secreted material of MASC (86.6 % of cases) and in ductal cells of epithelial-myoepithelial carcinoma (EMC-53.8 %), pleomorphic adenoma (PA-29.1 %) and polymorphous low-grade adenocarcinoma (PLGA-23.8 %). However, in ACC, lysozyme was not expressed. Three patterns of DOG1 staining were seen: apical-luminal, cytoplasmic, and mixed cytoplasmic/membranous. The apical-luminal pattern was detected in ductal cells of ACC (58.8 % of cases), EMC (38.4 %), adenoid-cystic carcinoma (AdCC-35.3 %), PA (8.3 %), and PLGA (4.8 %). These tumors also showed mixed membranous/cytoplasmic staining for DOG1. MASC, mucoepidermoid, and salivary duct carcinomas exhibited only DOG1 cytoplasmic staining. In conclusion, lysozyme cannot be used as a marker of acinar differentiation in salivary tumors. However, lysozyme expression can be helpful to distinguish MASC from ACC due to its high frequency in the former and absence in ACC. It is likely that in MASC, lysozyme expression may reflect a lactational-like secretory differentiation since lysozyme belongs to breast milk proteins. Regarding DOG1 expression, the apical-luminal pattern is related to acinar and intercalated duct differentiation whereas the cytoplasmic staining does not seem to be associated with a specific cellular phenotype.

Immunohistochemical expression of caspases 9 and 3 in adenoid cystic carcinoma of salivary glands and association with clinicopathological parameters.

PURPOSE: Adenoid cystic carcinoma (ACC) is one of the most common malignant salivary gland tumors. It is characterized by a high rate of recurrence, perineural invasion and development of distant metastases many years after removal of the primary tumor. Disorders of the induction of apoptosis and its cascade reactions where caspases are involved may be significant in the pathogenesis of this tumor. METHODS: The immunohistochemical expression of caspase 9 and caspase 3 was analyzed by tissue microarray (TMA) in 50 cases of ACC in relation with different clinicopathological parameters (gender, age, localization, histological type and overall survival). RESULTS: Caspase 9 was expressed in the cytoplasm and nuclei of ACC tumor cells with varying degrees of staining intensity (1+, 6%; 2+, 54%, 3+, 40%). Comparison of caspase 9 expression in tumor cells with clinicopathological parameters (gender, age, localization, histological type and overall survival) showed no statistically significant difference except that the expression was more pronounced in females. Caspase 3 was expressed in the cytoplasm of tumor cells with varying degrees of staining intensity (1+, 22%; 2+, 36%; 3+, 42%). No correlation between the expression of caspase 3 and clinicopathological parameters was noticed. CONCLUSIONS: The expression of caspases 9 and 3 in ACC of the salivary glands can contribute in the better characterization of molecules involved in apoptosis of tumor cells.

Carbonic anhydrase VI: a novel marker for salivary serous acinar differentiation and its application to discriminate acinic cell carcinoma from mammary analogue secretory carcinoma of the salivary gland.

AIMS: Carbonic anhydrase VI (CA6) is present in serous acinar cells of human salivary glands. The aim of this study was to investigate the diagnostic utility of CA6 in differentiating acinic cell carcinoma (AciCC) from its morphological mimic mammary analogue secretory carcinoma (MASC) of the salivary gland. METHODS AND RESULTS: CA6 immunostaining was performed in 28 cases of AciCC and 14 cases of MASC. All cases of AciCC showed positive CA6 staining. The staining pattern correlated with the number of serous acinar cells in tumours. All MASCs stained negatively for CA6. The results were compared with those obtained with currently used markers, including DOG1, mammaglobin, S100, and vimentin. CA6 showed sensitivity and specificity as high as those of DOG1 in diagnosing AciCC. CA6 expression was focally observed in basal cell adenoma and in one case of cystadenocarcinoma (1/3), but not in other salivary gland tumours, including mucoepidermoid carcinoma, adenoid cystic carcinoma, salivary duct carcinoma, lymphoepithelial carcinoma, epithelial-myoepithelial carcinoma, and pleomorphic adenoma. CONCLUSIONS: CA6 is a specific marker for serous acinar cells of salivary glands and AciCC. CA6 has sensitivity and specificity equal to those of DOG1 in the differential diagnosis between AciCC and MASC. A combination of CA6 and DOG1 could be an ideal immunohistochemical panel for AciCC.

Potential role for inhibition of protein phosphatase 2A tumor suppressor in salivary gland malignancies.

The aetiology and pathogenesis of salivary gland malignancies remain unknown. To reveal novel molecular factors behind the development of salivary gland cancer, we performed gene expression analyses from Smgb-Tag mouse salivary gland samples. The overall purpose was to apply these results for clinical use to find new approaches for both possible therapeutic targets and more accurate diagnostic tools. Smgb-Tag mouse strain, in which salivary neoplasms arise through a dysplastic phase in submandibular glands, was investigated using genome-wide microarray expression analysis, ingenuity pathway analysis, RT-PCR, and immunohistochemistry. Thirty-eight human salivary gland adenoid cystic carcinoma samples were investigated using immunohistochemistry for validation purposes. Our genome-wide study showed that Ppp2r1b, a PP2A subunit encoding tumor suppressor gene, is underexpressed in submandibular gland tumors of Smgb-Tag mice. mTOR signaling pathway was significantly enriched and mTOR linked PP2A subunit gene B55 gamma was significantly underexpressed in the analyses. Furthermore, parallel immunohistochemical analysis of three PP2A inhibitors demonstrated that two PP2A inhibitors, CIP2A and SET, are highly expressed in both dysplastic and adenocarcinomatous tumors of the Smgb-Tag mice. In addition, all 38 investigated human salivary adenoid cystic carcinoma samples stained positively for CIP2A and most for SET. Finally, p-S6 staining showed activation of mTOR pathway in human adenoid cystic carcinoma samples. Our results suggest that PP2A inhibition either via PP2A subunit underexpression or PP2A inhibitor overexpression play an important role in the formation of salivary gland malignancy, potentially due to mTOR signaling activation.

Lack of PRKD2 and PRKD3 kinase domain somatic mutations in PRKD1 wild-type classic polymorphous low-grade adenocarcinomas of the salivary gland.

AIMS: Polymorphous low-grade adenocarcinoma (PLGA) is the second most common intra-oral salivary gland malignancy. The vast majority of PLGAs harbour a PRKD1 E710D hot-spot somatic mutation or somatic rearrangements of PRKD1, PRKD2 or PRKD3. Given the kinase domain homology among PRKD1, PRKD2 and PRKD3, we sought to define whether PLGAs lacking PRKD1 somatic mutations or PRKD gene family rearrangements would be driven by somatic mutations affecting the kinase domains of PRKD2 or PRKD3. METHODS AND RESULTS: DNA was extracted from eight microdissected PLGAs lacking PRKD1 somatic mutations or PRKD gene family rearrangements. Samples were thoroughly centrally reviewed, microdissected and subjected to Sanger sequencing of the kinase domains of the PRKD2 and PRKD3 genes. None of the PLGAs lacking PRKD1 somatic mutations or PRKD gene family rearrangements harboured somatic mutations in the kinase domains of the PRKD2 or PRKD3 genes. CONCLUSION: PLGAs lacking PRKD1 somatic mutations or PRKD gene family rearrangements are unlikely to harbour somatic mutations in the kinase domains of PRKD2 or PRKD3. Further studies are warranted to define the driver genetic events in this subgroup of PLGAs.

High frequency of loss of PTEN expression in human solid salivary adenoid cystic carcinoma and its implication for targeted therapy.

Salivary gland tumor (SGT) is one of the least studied cancers due to its rarity and heterogeneous histological types. Here, we reported that loss of PTEN expression was most frequently found in the poorly differentiated, high grade solid adenoid cystic carcinomas. Loss of PTEN expression correlated with activation of mTOR by increased phosphorylated S6 ribosome protein. We further functionally studied the role of PTEN in a pair of human SACC cell lines, SACC-83 and SACC-LM. Reduced PTEN level was correlated with the metastasis potential. When we knocked down PTEN in the SACC-83 cell line, we observed increased proliferation and enhanced migration/invasion in vitro, and increased tumor size in vivo. We further tested the therapeutical effect by applying a PI3K/mTOR inhibitor NVP-BEZ235 to both SACC cell lines. Decreased cell proliferation, increased apoptosis, as well as reduced cell migration/invasion were observed in both cell lines upon the NVP-BEZ235 treatment. Moreover, the NVP-BEZ235 treatment in a SGT xenograft mouse model significantly reduced primary tumor size and lung metastasis. Taken together, our results demonstrated that PTEN is a potent tumor suppressor in human SGTs, and targeting PI3K/mTOR pathway may be effective in the targeted therapy for human SGT patients with loss of PTEN expression.

The EGF signaling pathway influences cell migration and the secretion of metalloproteinases by myoepithelial cells in pleomorphic adenoma.

During tumor development, benign neoplastic cells are influenced by the expression of cytokines, growth factors, and proteases present in the tumor microenvironment. Epidermal growth factor (EGF) is the most studied growth factor and is considered important for cell proliferation and migration. Metalloproteinases (MMPs) are also involved in tumor progression. The present study aimed to analyze the proliferation, viability and migration index of pleomorphic adenoma myoepithelial cells, in addition to the secretion of MMPs with EGF supplementation. Benign myoepithelial cells were cultured with two different EGF doses (5 and 10 ng/ml), and the influence of EGF on cell proliferation and viability, using trypan blue and MTT assays, respectively, after 24, 48, and 72 h, was evaluated. To analyze cellular morphology, hematoxylin-eosin staining and indirect immunofluorescence using the anti-vimentin antibody, was performed. In vitro migration assays were performed in Transwell chambers with an 8-µm pore covered with Matrigel and supplemented with 5 or 10 ng/ml of EGF, after 96 h. After 4 days of cell culture, ELISA was performed to determine the MMP-2 and MMP-13 levels. One-way analysis of variance (ANOVA) with post hoc Tukey test was applied, with a significance level of 0.05. The results revealed that EGF influences myoepithelial cell morphology, without alteration of proliferation and viability. The migration assay showed that EGF increased the mean index from 16 % in the control group to 40 and 76 % for 5 and 10 ng/ml of EGF, respectively. ELISA revealed that when the cells were supplemented with either of the EGF doses, an increase in MMP-2 levels was observed when compared with the control group (C). This study concludes that EGF aids in the production of MMP-2, which favors the dissolution of the basement membrane, contributing to cell migration and tumor progression, hence permitting contact between the myoepithelial cells and stroma.