Faculty Bibliography

Vestibular schwannomas (VS) arising sporadically or in patients with neurofibromatosis type 2 (NF2) consistently lack expression of Merlin, a tumor suppressor. Conventional treatment options include surgery and radiotherapy but there is no validated medical option. Recent evidence suggests that Merlin deficiency may result in abnormal activation of receptor tyrosine kinases (RTKs) and downstream signaling, promoting tumor growth. Although small-molecule RTK inhibitors are widely available for clinical use, no such therapy has been validated in patients with VS. To screen for RTK activation, surgical VS specimens from patients with and without NF2 were analyzed by phospho-RTK profiling arrays. Downstream signaling pathway activation was analyzed by phospho-MAPK arrays. Activated RTKs and downstream kinases were validated immunohistochemically in corresponding formalin-fixed, paraffin-embedded tissues. Phospho-RTK arrays and immunohistochemistry showed consistent overexpression and activation of EGFR family receptors and evidence of ERK1/2 downstream signaling was observed in all samples analyzed (n = 11). Based on the findings, the small-molecule EGFR/ErbB2 kinase inhibitor lapatinib was selected for evaluation of target inhibition and treatment efficacy in our in vitro human schwannoma model. EGFR/ErbB2 targeted therapy with lapatinib inhibited ErbB2 phosphorylation and survivin upregulation, as well as downstream ERK1/2 and AKT activation, resulting in decreased proliferation. We conclude that EGFR family receptor activation is a consistent feature of both sporadic and NF2-related VS. Molecular targeted therapy with lapatinib downregulates survivin and has antiproliferative activity in a preclinical VS model. Based on these findings, a clinical trial with lapatinib for the treatment of VS is currently underway

AIM: To evaluate circulating endothelial lineage cells (ELCs) as biomarkers of tumor neovascularization in patients with pancreatic ductal adenocarcinoma (PDAC). MATERIALS AND METHODS: ELCs were isolated from the peripheral blood of patients with PDAC (n=14) or controls (n=17) before and after tumor resection/surgery and quantified using flow cytometry. Vascular endothelial growth factor (VEGF) and placental growth factor (PlGF) were detected in tumor using immunohistochemistry and in plasma using an ELISA technique. RESULTS: Circulating ELC levels were increased in patients with PDAC compared to controls. After PDAC resection, ELC levels declined. ELC level increases were associated with cancer recurrence. VEGF and PlGF were identified in cancer cells and exocrine pancreas cells. Only PlGF was detected in tumor-associated inflammatory cells. Plasma levels of PlGF were higher in patients with PDAC compared to controls. CONCLUSION: Circulating ELCs are a potential biomarker of PDAC neovascularization, and PlGF may be an important target in treatment of PDAC

Sinonasal inverted papilloma (IP) is a primary benign lesion with a tendency for local recurrence. Malignant transformation may develop in up to 15% of cases. Fascin (Fascin 1) is an actin cross-link binding protein required for the formation of actin-based cell-surface protrusions and cell motility. Fascin up-regulation in lung, gastric, breast and hepatobiliary carcinomas correlates with aggressiveness and decreased survival. Here we evaluate immunohistochemical expression of fascin in 47 sinonasal IPs from 34 patients. Fascin over-expression is significantly more common in sinonasal IP with high-grade dysplasia than in those with no dysplastic or low-grade dysplastic epithelium (P = 0.0001). No significant change in fascin expression is seen with recurrence. Over expression of fascin in high-grade dysplastic epithelium in IP may be associated with tumor progression and malignant transformation

Fatty liver is commonly associated with alcohol ingestion and abuse. While the molecular pathogenesis of these fatty changes is well understood, the biochemical and pharmacological mechanisms by which ethanol stimulates these molecular changes remain unknown. During ethanol metabolism, adenosine is generated by the enzyme ecto-5'-nucleotidase, and adenosine production and adenosine receptor activation are known to play critical roles in the development of hepatic fibrosis. We therefore investigated whether adenosine and its receptors play a role in the development of alcohol-induced fatty liver. WT mice fed ethanol on the Lieber-DeCarli diet developed hepatic steatosis, including increased hepatic triglyceride content, while mice lacking ecto-5'-nucleotidase or adenosine A1 or A2B receptors were protected from developing fatty liver. Similar protection was also seen in WT mice treated with either an adenosine A1 or A2B receptor antagonist. Steatotic livers demonstrated increased expression of genes involved in fatty acid synthesis, which was prevented by blockade of adenosine A1 receptors, and decreased expression of genes involved in fatty acid metabolism, which was prevented by blockade of adenosine A2B receptors. In vitro studies supported roles for adenosine A1 receptors in promoting fatty acid synthesis and for A2B receptors in decreasing fatty acid metabolism. These results indicate that adenosine generated by ethanol metabolism plays an important role in ethanol-induced hepatic steatosis via both A1 and A2B receptors and suggest that targeting adenosine receptors may be effective in the prevention of alcohol-induced fatty liver.

PURPOSE: The tumor microenvironment significantly influences prostate cancer progression. Androgen receptor exerts its effect through downstream target genes to regulate prostate cancer cell proliferation. The c-FLIP gene was recently shown to be an androgen receptor target gene. c-FLIP is an inactive homologue of caspase-8 and, thus, it inhibits the death receptor mediated apoptosis pathway. c-FLIP over expression was shown to accelerate the progression of prostate cancer cells to androgen independence. We evaluated the role of c-FLIP expression in stromal cells in prostate cancer development. MATERIALS AND METHODS: We examined c-FLIP expression in 53 androgen dependent and 21 androgen independent prostate cancer stromal cells by immunohistochemical analysis. The effects of c-FLIP over expression in stromal cells on the growth and invasion of LNCaP and PC3 prostate cancer cells were determined in indirect coculture systems. RESULTS: At the androgen dependent stage the stromal c-FLIP level was increased in prostate cancer tissue. The expression level of stromal c-FLIP was associated with tumor differentiation. However, stromal c-FLIP expression was not increased in androgen independent human prostate cancer. c-FLIP over expression in stromal cells stimulated the growth and invasion of prostate cancer, including LNCaP and PC3 cells in vitro. CONCLUSIONS: These results indicate the over expression of stromal c-FLIP and its function for promoting prostate cancer growth and invasion

Perisinusoidal hepatic stellate cells (HSC) are the principal fibrogenic cells in the liver. In animal models, HSC apoptosis is the predominant clearance mechanism of activated HSC, although data evaluating whether the same processes occur in humans are limited. We conducted a cross-sectional study to evaluate the association between HSC apoptosis and fibrosis stage in subjects with chronic hepatitis C virus (HCV) infection (n = 44) and HCV-negative controls with normal liver histology (n = 9). We used immunohistochemical techniques to identify activated (alpha-smooth muscle actin+), proliferative (Ki-67+) and apoptotic (terminal deoxynucleotidyl transferase [TdT]-mediated dUTP nick end-labelling+) HSC in liver biopsy specimens from all subjects. The same pathologist enumerated positive cells per high-power field (HPF, x 200) in 20 periportal/lobular areas. HSC apoptosis was decreased in HCV-positive subjects compared with controls (median 0.4, range 0.0-3.1 vs 1.1, 0.2-3.5 cells/HPF, P = 0.02). Among HCV-positive subjects, HSC apoptosis was decreased in those with moderate to advanced fibrosis (P = 0.04) compared with those with mild fibrosis. By multivariate analysis, HSC apoptosis decreased by an average of 0.14 cells/HPF (95% confidence interval 0.01-0.28 cells/HPF) per increase in fibrosis stage (P = 0.04). While the number of activated and proliferative HSC was significantly increased in HCV-infected subjects compared with that in uninfected controls, the numbers of these cells did not differ between HCV-infected subjects with mild vs moderate/advanced fibrosis. In conclusion, the number of apoptotic HSC was significantly decreased in HCV-infected subjects with advanced fibrosis. In chronic HCV infection, inhibition of HSC apoptosis may be one mechanism by which fibrosis progresses

Background: Desmoplastic melanoma (DM) may simulate various benign and malignant lesions, including benign peripheral nerve sheath tumors (BPNSTs) and malignant peripheral nerve sheath tumors (MPNSTs). The latter case is diagnostically challenging because DM generally show only S100 protein expression but no reaction to melanocytic markers. S100 family of proteins consists of over 20 members. We report on S100 subtypes in malignant melanomas (MMs), and BPNSTs and MPNSTs to investigate differential expression. Design: S100A1, S100A2, S100A4, S100A6 and S100B immunostains were performed on 80 MMs including conventional and desmoplastic types, 86 BPNSTs and 77 MPNSTs. Results: S100A1 expression was seen in > 91% of MMs in a diffuse reaction, whereas BPNSTs showed focal or no reaction. Sixteen percent of MPNSTs focally expressed S100A1 except for one case with diffuse reaction. S100A2 staining was negative or focal in all three groups whereas S100A4 reaction was variable in all three. S100A6 was diffusely expressed in MMs, BPNSTs and MPNSTs. S100B was stained diffusely in MMs and BPNSTs, but its reaction was observed in 30% of MPNSTs in a focal fashion. Conclusion: S100A1 expression was diffuse in most of MMs but absent or focal in BPNSTs and MPNSTs. This may be helpful to distinguish between the two entities

Merkel cell carcinoma is the cutaneous counterpart of small cell carcinoma, and the most important differential diagnosis is cutaneous metastasis of small cell carcinoma of the lung. There have been a handful of studies reporting on the utility of a variety of immunohistochemical markers that distinguish between the two entities. Achaete-scute complex-like 1 (MASH1, ASCL1) is important in the development of the brain and the diffuse neuroendocrine system including pulmonary neuroendocrine cells. A recent study, using a cDNA array, identified Mash1 as one of the best classifier genes to differentiate pulmonary small cell carcinoma from Merkel cell carcinoma. We immunohistochemically applied this finding to the diagnostic setting. A total of 30 cases of Merkel cell carcinoma and 59 cases of small cell carcinoma of the lung were immunostained with anti-MASH1 and TTF-1 antibodies. Of 59 small cell carcinomas, 49 (83%) expressed MASH1 in nuclear staining whereas out of 59 small cell carcinomas, 43 (73%) expressed TTF-1 in nuclear staining. MASH1 was completely negative in all 30 Merkel cell carcinomas whereas TTF-1 expression was seen in 1 of the 30 Merkel cell carcinomas (3%). MASH1 is a useful adjunct marker for differentiating small cell carcinoma of the lung from Merkel cell carcinoma.Modern Pathology advance online publication, 27 June 2008; doi:10.1038/modpathol.2008.118