Recent studies have shown that the recurrent t(6;9)(q22-23;p23-24) translocation in adenoid cystic carcinoma results in a novel fusion of the MYB proto-oncogene with the transcription factor gene NFIB. To determine the frequency of this finding, we used RT-PCR assays of the MYB and MYB-NFIB fusion transcripts, and immunohistochemistry for the MYB protein, to study adenoid cystic carcinomas and other epithelial tumors of the salivary glands, and head and neck region. MYB-NFIB fusion transcript was detected in 25 of 29 (86%) frozen adenoid cystic carcinoma tumor samples, and in 14 of 32 (44%) formalin-fixed paraffin-embedded adenoid cystic carcinoma tumor specimens. In contrast, the MYB-NFIB fusion was not expressed in non-adenoid cystic carcinoma neoplasms of the head and neck, confirming the high specificity of the MYB-NFIB fusion. Adenoid cystic carcinomas from various anatomic sites, including salivary gland, sinonasal cavity, tracheobronchial tree, larynx, breast, and vulva were repeatedly fusion-positive, indicating that adenoid cystic carcinomas located in different anatomic sites not only have important morphologic features in common, but also probably evolve through activation of the same molecular pathways. Studies of the expression of MYB revealed that 89% of the tumors, including both fusion-positive and fusion-negative cases, overexpressed MYB RNA. Similarly, 82% of adenoid cystic carcinomas stained positive for MYB protein, compared with 14% of non-adenoid cystic carcinoma neoplasms, indicating that MYB immunostaining may be useful for the diagnosis of adenoid cystic carcinoma, but that neoplasms sometimes in the differential diagnosis are also labeled. The latter are, however, fusion-negative. In summary, our studies show that MYB activation through gene fusion or other mechanisms is a major oncogenic event in adenoid cystic carcinoma occurring at various anatomic sites. In addition to being a diagnostically useful biomarker for adenoid cystic carcinoma, MYB and its downstream effectors are also novel potential therapeutic targets.

Polyphosphazene-polyester blends are attractive materials for bone tissue engineering applications due to their controllable degradation pattern with non-toxic and neutral pH degradation products. In our ongoing quest for an ideal completely miscible polyphosphazene-polyester blend system, we report synthesis and characterization of a mixed-substituent biodegradable polyphosphazene poly[(glycine ethyl glycinato)1(phenyl phenoxy)1phosphazene] (PNGEG/PhPh) and its blends with a polyester. Two dipeptide-based blends namely 25:75 (Matrix1) and 50:50 (Matrix2) were produced at two different weight ratios of PNGEG/PhPh to poly(lactic acid-glycolic acid) (PLAGA). Blend miscibility was confirmed by differential scanning calorimetry, Fourier transform infrared spectroscopy, and scanning electron microscopy. Both blends resulted in higher tensile modulus and strength than the polyester. The blends showed a degradation rate in the order of Matrix2 < Matrix1 < PLAGA in phosphate buffered saline at 37°C over 12 weeks. Significantly higher pH values of degradation media were observed for blends compared to PLAGA confirming the neutralization of PLAGA acidic degradation by polyphosphazene hydrolysis products. The blend components PLAGA and polyphosphazene exhibited a similar degradation pattern as characterized by the molecular weight loss. Furthermore, blends demonstrated significantly higher osteoblast growth rates compared to PLAGA while maintaining osteoblast phenotype over a 21-day culture. Both blends demonstrated improved biocompatibility in a rat subcutaneous implantation model compared to PLAGA over 12 weeks.

Hydrogen peroxide mediates vasodilation, but the mechanisms responsible for this process remain undefined. We examined the effect of H 2 O 2 on nitric oxide (NO ⅐ ) production and the signaling events involved. NO ⅐ release from bovine aortic endothelial cells was detected with an NO ⅐ -specific microelectrode. The addition of H 2 O 2 caused a potent dose-dependent increase in NO ⅐ production. This was partially Ca 2ϩ -dependent because BAPTA/AM reduced NO ⅐ production at low (Ͻ50 M) but not high (Ͼ100 M) concentrations of H 2 O 2 . Phosphatidylinositol (PI) 3-kinase inhibition [with wortmannin or 2-(4-morpholinyl)-8-phenyl-1(4H)-benzopyran-4-one hydrochloride], infection with a dominant-negative mutant of Akt, or mitogenactivated protein kinase kinase/extracellular signal-regulated kinase 1 ⁄2 (MEK/ERK1/2) inhibition (with PD98059 or U0126) partially attenuated, whereas inhibition of both PI 3-kinase and MEK1/2 abolished H 2 O 2 -dependent NO ⅐ production. ERK1/2 seemed necessary for NO ⅐ production early (Ͻ5 min) after H 2 O 2 addition, whereas PI 3-kinase/Akt was more important at later time points. Phosphorylation of endothelial nitric-oxide synthase (eNOS) at serine 1179 was observed Ͼ10 min after the addition of H 2 O 2 , and this was prevented by wortmannin but not by PD98059. c-Src family tyrosine kinase(s) was found to be upstream of H 2 O 2 -dependent Akt and eNOS serine 1179 phosphorylation and subsequent NO ⅐ production. In summary, H 2 O 2 causes endothelial NO ⅐ release mediated by cooperative effects between PI 3-kinase/Akt-dependent eNOS serine 1179 phosphorylation and activation of MEK/ERK1/2. This may represent an acute cellular adaptation to an increase in oxidant stress.

CD10 positivity is relatively specific in this context for the diagnosis of AFX. Its utility is enhanced when only strong, diffuse membranocytoplasmic staining is considered as a positive result. In contrast to prior reports, p63 was not found to be highly sensitive for SCC. Similarly, CD99 showed no preferential staining of any single diagnostic group of lesions.

Podoplanin, D2-40, is often used for highlighting lymphatics. However, it has been described in a variety of normal and neoplastic tissues. We evaluated the expression of D2-40 in breast, salivary gland, skin, and mucosa, all organs rich in myoepithelial cells and basal cells. This study assessed the utility of using D2-40 to highlight basal/myoepithelial cells and to identify potential pitfalls in misinterpretation of lymphatic invasion. Our results showed that myoepithelial cells in breast and salivary gland and basal cells in prostate consistently demonstrate D2-40 immunoreactivity, but typically less intensely than lymphatics. Cutaneous and mucosal-based basal cells also have D2-40 expression, but often in a patchy, focal manner. In addition, many salivary gland tumors and squamous cell carcinomas had strong D2-40 expression, sometimes making distinction of lymphatics versus tumor edge staining difficult. D2-40 is excellent for assessing lymphatic invasion in breast, prostate, and cervix as long as the pathologist is aware of the expression in myoepithelial cells/basal cells to avoid misinterpretation of ductal carcinoma in situ or normal prostate glands or tumor stroma retraction as tumor lymphatic invasion. Given the patchy positivity in basal cells of skin and mucosa and the reactivity in squamous cell carcinoma, D2-40 was not helpful in assessing for microinvasion of squamous cell carcinoma.