Immunohistochemical Detection and Molecular Characterization of IDH-mutant Sinonasal Undifferentiated Carcinomas.

Recent studies have identified recurrent isocitrate dehydrogenase 2 (IDH2) mutations in a subset of sinonasal undifferentiated carcinomas (SNUCs); however, the true frequency of IDH mutations in SNUC is unknown. We evaluated the utility of mutation-specific IDH1/2 immunohistochemistry (IHC) in a large multi-institutional cohort of SNUC and morphologic mimics. IHC using a multispecific antibody for IDH1/2 (R132/R172) mutant protein was performed on 193 sinonasal tumors including: 53 SNUCs, 8 poorly differentiated carcinomas (PDCARs) and 132 histologic mimics. Mutant IDH1/2 IHC was positive in 26/53 SNUCs (49%; 20 strongly positive and 6 weak) and 3/8 PDCARs (37.5%; 2 strong; 1 weak) but was absent in all other tumor types (0/132). Targeted next-generation sequencing (NGS) on a subset of SNUC/PDCAR (6 strong and 3 weak positive for IDH1/2 IHC; 7 negative) showed frequent IDH2 R172X mutations (10/16) and a single IDH1 R132C mutation. All 6 cases with strong positive mutant IDH1/2 staining and NGS had IDH2 R172S/G mutations. The 3 IHC-weak cases all had IDH2 R172T mutations. Among the 7 tested cases that were negative for mutant IDH1/2 IHC, NGS detected 1 case each with IDH2 R172T and IDH1 R132C mutation. IDH-mutant carcinomas also had frequent mutations in TP53 (55%) and activating mutations in KIT (45%) or the PI3K pathway (36%). Mutation-specific IDH1/2 IHC identifies IDH mutations in SNUC, however, it lacks sensitivity for the full range of IDH mutations. These findings suggest that IDH-mutant sinonasal carcinoma may represent a distinct pathobiological entity with therapeutic implications that can be identified by a combined approach of multispecific IDH1/2 IHC and sequencing.

Tumour-suppressive microRNA-874 contributes to cell proliferation through targeting of histone deacetylase 1 in head and neck squamous cell carcinoma.

BACKGROUND: Our recent studies of microRNA (miRNA) expression signature demonstrated that microRNA-874 (miR-874) was significantly downregulated in maxillary sinus squamous cell carcinoma (MSSCC), and a putative tumour-suppressive miRNA in human cancers. Our aim of this study was to investigate the functional significance of miR-874 in cancer cells and to identify novel miR-874-mediated cancer pathways and responsible genes in head and neck squamous cell carcinoma (HNSCC). METHODS: Gain-of-function studies using mature miR-874 were performed to investigate cell proliferation and cell cycle distribution in HNSCC cell lines (SAS and FaDu). To identify miR-874-mediated molecular pathways and targets, we utilised gene expression analysis and in silico database analysis. Loss-of-function assays were performed to investigate the functional significance of miR-874 target genes. RESULTS: Expression levels of miR-874 were significantly downregulated in HNSCC tissues (including oral, pharyngeal and laryngeal SCCs) compared with normal counterpart epithelia. Restoration of miR-874 in SAS and FaDu cell lines revealed significant inhibition of cell proliferation and induction of G2/M arrest and cell apoptosis. Our expression data and in silico analysis demonstrated that miR-874 modulated the cell cycle pathway. Moreover, histone deacetylase 1 (HDAC1) was a candidate target of miR-874 regulation. Luciferase reporter assays showed that miR-874 directly regulated HDAC1. Silencing of the HDAC1 gene significantly inhibited cell proliferation and induced G2/M arrest and cell apoptosis in SAS cells. CONCLUSIONS: Downregulation of miR-874 was a frequent event in HNSCC. miR-874 acted as a tumour suppressor and directly targeted HDAC1. Recognition of tumour-suppressive miRNA-mediated cancer pathways provides new insights into the potential mechanisms of HNSCC oncogenesis and suggests novel therapeutic strategies for the disease.

Tumor suppressive microRNA-375 regulates lactate dehydrogenase B in maxillary sinus squamous cell carcinoma.

The expression of microRNA-375 (miR-375) is significantly reduced in cancer tissues of maxillary sinus squamous cell carcinoma (MSSCC). The aim of this study was to investigate the functional significance of miR-375 and a possible regulatory role in the MSSCC networks. Restoration of miR-375 significantly inhibited cancer cell proliferation and invasion in IMC-3 cells, suggesting that miR-375 functions as a tumor suppressor in MSSCC. Genome-wide gene expression data and luciferase reporter assays indicated that lactate dehydro-genase B (LDHB) was directly regulated by miR-375. Cancer cell proliferation and invasion were significantly inhibited by transfection of si-LDHB into IMC-3 cells, suggesting that LDHB may play a role in MSSCC oncogenic function. In clinical MSSCC specimens, LDHB mRNA levels were up-regulated in cancer tissues, which were inversely correlated with the expression of miR-375. In addition, Kaplan-Meier curves and log-rank tests revealed that the high mRNA expression levels of LDHB had a significant adverse effect on survival rate. The identification of a cancer network regulated by the miR-375 tumor suppressor could provide new insights into the molecular mechanisms of MSSCC oncogenesis.

Anaplastic lymphoma kinase expression and prognosis in inflammatory myofibroblastic tumours of the maxillary sinus.

Inflammatory myofibroblastic tumours (IMT) of the nasal cavity and nasal sinus are rare and, although over 50 cases have been reported in the English-language literature, their precise aetiology and biological behaviour have not been elucidated. Recent studies suggest that anaplastic lymphoma kinase (ALK)-positive tumours have a very low risk of metastasis, but ALK reactivity does not appear to correlate with recurrence. Between March 2002 and December 2008, we encountered three cases of maxillary sinus IMT and investigated them to determine the clinicopathological course, prognosis and immunohistochemical expression of ALK. Two of the patients died < 13 months after the initial diagnosis and the third had multiple recurrences. All three cases were immunohisto chemically negative for ALK expression. IMT of the sino-nasal tract is rare and may undergo malignant transformation in a minority of cases. The three cases manifested progressive extension with bone destruction and multiple recurrences, and two cases had a fatal outcome and one case had high recurrence.

Immunoperoxidase investigation of Regan isoenzyme of alkaline phosphatase in maxillary sinus carcinomas.

The Regan isoenzyme of alkaline phosphatase is known to be produced ectopically by various malignant tumors. To assess whether this isoenzyme is expressed in maxillary sinus carcinomas, immunostaining for Regan isoenzyme was carried out on 35 maxillary sinus carcinomas comprising 27 squamous cell carcinomas, 6 adenocarcinomas, and 2 adenoid cystic carcinomas. The enzyme was shown to be present in 11 of 27 cases of squamous cell carcinoma, 2 of 6 cases of adenocarcinoma, and 1 of 2 cases of adenoid cystic carcinoma. Regan isoenzyme was identified in the cytoplasm and/or cell membrane of squamous cell carcinoma cells, whereas it was demonstrated mainly on the luminal membrane and in the secretions of both adenocarcinoma and adenoid cystic carcinoma cells. These findings show that Regan isoenzyme does, indeed, occur in maxillary sinus carcinomas.

Lactate dehydrogenase in human maxillary adenocarcinoma and in experimental adenocarcinoma in mice.

Total lactate dehydrogenase (LDH) activity and isoenzyme pattern were studied in tumour tissue from eight patients with maxillary adenocarcinoma, chronic inflammatory mucosa from 12 patients, normal maxillary mucosa from 12 patients, and an experimental lung adenocarcinoma and normal lung tissue from 12 mice. An increase in the total LDH activity and cathodic shift in LDH isoenzyme pattern was found in human maxillary adenocarcinoma as compared to normal and inflammatory mucosa. The inflammatory mucosa showed an increase in the total LDH activity and a normal isoenzyme pattern. The LDH alterations in the experimental lung adenocarcinoma in mice were similar to those in the human tumours but they were much more marked.

[beta-Glucuronidase in human maxillary sinus and lung cancers: elevation of activity level and appearance of phosphorylated variant forms].

beta-Glucuronidase from human maxillary sinus and lung cancers and from uninvolved tissues was studied. An elevation of beta-glucuronidase activity was observed in cancerous tissues as compared with the corresponding uninvolved tissues, and this increase was significant in adenocarcinoma and squamous cell carcinoma of the lung (p less than 0.01). beta-glucuronidase preparations purified from adenocarcinoma and large cell carcinoma of lung and from normal lung showed similar kinetic properties and antigenicity. beta-Glucuronidase from lung adenocarcinoma showed considerable negative charge heterogeneity in the pI range from 4.2 to 6.2 in an experiment involving isoelectric focusing on polyacrylamide gel. Similar charge heterogeneity was observed in the enzyme from lung large cell carcinoma. Upon treatment of the adenocarcinoma enzyme with exogenous alkaline phosphatase or endoglycosidase H, the heterogeneous variant forms of the tumor enzyme appeared to partly or completely lose their negative charge and to be converted into forms similar to those of the normal lung enzyme. An experiment on the labeling of beta-glucuronidase with [32P]-phosphoric acid provided further evidence that the acidic variants found in lung cancers are extensively phosphorylated forms of the enzyme.