Faculty Bibliography

Adenosine is a potent modulator of inflammation and tissue repair. We have recently reported that activation of adenosine A(2A) receptors promotes collagen synthesis by human dermal fibroblasts and that blockade or deletion of this receptor in mice protects against bleomycin-induced dermal fibrosis, a murine model of scleroderma. Adenosine deaminase (ADA) is the principal catabolic enzyme for adenosine in vivo, and its deficiency leads to the spontaneous development of pulmonary fibrosis in mice. The aim of this study was to characterize further the contributions of endogenous adenosine and adenosine A(2A) receptors to skin fibrosis. Taking advantage of genetically modified ADA-deficient mice, we herein report a direct fibrogenic effect of adenosine on the skin, in which increased collagen deposition is accompanied by increased levels of key mediators of fibrosis, including transforming growth factor beta1, connective tissue growth factor, and interleukin-13. Pharmacological treatment of ADA-deficient mice with the A(2A) receptor antagonist ZM-241385 prevented the development of dermal fibrosis in this model of elevated tissue adenosine, by reducing dermal collagen content and expression of profibrotic cytokines and growth factors. These data confirm a fibrogenic role for adenosine in the skin and reveal A(2A) receptor antagonists as novel therapeutic agents for the modulation of dermal fibrotic disorders

Thyroid-specific transcription factors, Pax8, TTF-1, and TTF-2, are crucial for thyroid organogenesis and differentiation. Compared with TTF-1, the other two markers have scarcely been investigated in surgical pathology. The goal of this study is to evaluate the expressions of these markers in thyroid tumors of the full spectrum of differentiation, with special emphasis on anaplastic carcinomas. A total of 94 cases of thyroid neoplasms were studied: 17 papillary carcinomas, 18 follicular adenomas, 16 follicular carcinomas, 7 poorly differentiated carcinomas, 28 anaplastic carcinomas, and 8 medullary carcinomas. Immunostains for these three markers were performed. The antibodies to Pax8 and TTF-2 were also applied on 147 lung carcinomas as well as a variety of normal tissues and malignant tumors. All three markers were seen in papillary carcinomas, follicular adenomas and carcinomas, and poorly differentiated carcinomas in a diffuse manner, whereas their expressions in medullary carcinomas were variable. Pax8 was expressed in 79% of anaplastic carcinomas to a variable extent, whereas TTF-1 and TTF-2 were seen only in 18 and 7% of anaplastic carcinomas, respectively. TTF-2 was negative in all other neoplastic and non-neoplastic tissues including those of the lung. Pax8 was expressed in renal tubules, fallopian tubes, ovarian inclusion cysts, and lymphoid follicles as well as renal carcinoma, nephroblastoma, seminoma, and ovarian carcinoma, but not in normal tissue and carcinomas of the lung. Pax8 is a useful marker for the diagnosis of anaplastic carcinomas, particularly when the differential diagnosis includes pulmonary carcinoma. In differentiated thyroid neoplasms, no significant difference in expression was seen in all the three transcription factors.Modern Pathology advance online publication, 14 December 2007; doi:10.1038/modpathol.3801002

ARA70 is a coactivator of androgen receptor (AR), a ligand-dependent transcription factor that plays an important role in prostate cancer. There are 2 variants of ARA70, the full length 70 kd ARA70alpha isoform and the internally spliced 35 kd ARA70beta isoform. Recent studies have suggested different expression and roles of the 2 isoforms in several endocrine malignancies, including prostate, breast, and ovarian cancers. To study the roles of these isoforms in cancers, we produced isoform-specific polyclonal antibodies. The anti-ARA70alpha antibody was raised in rabbits against 326 amino acid peptide corresponding to the internal deletion missing from ARA70beta (ARA70id), whereas the anti-ARA70beta antibody was raised against 18 amino acid polypeptide spanning the splice junction, with Gln-Gln motif unique to ARA70beta. The antisera were affinity purified on CNBr-activated sepharose 4B, and their specificity tested against bacterially expressed, Ni-column-purified ARA70alpha, ARA70beta, and ARA70id. The anti-ARA70alpha antibody recognized ARA70alpha and ARA70id, but not ARA70beta. The anti-ARA70beta antibody was specific to ARA70beta and did not cross-react with ARA70alpha or ARA70id. We then used these antibodies to detect ARA70 isoforms in crude extracts made of prostate cancer cell lines and performed immunohistochemical localization of these proteins in prostate tissues. ARA70beta localized to the cytosol, whereas ARA70alpha was found in the nucleus, supporting the notion of their dissimilar functions

Androgen receptor (AR) mediates transcriptional activation of diverse target genes through interactions with various coactivators that may alter its function and help mediate the switch between prostate cell proliferation and differentiation. We recently identified p44/MEP50 as an AR coactivator and further showed that it is expressed primarily in the nucleus and cytoplasm of benign prostate epithelial and prostate cancer cells, respectively. We also showed that haploinsufficiency in p44(+/-) mice causes prostate epithelial cell proliferation. To establish direct cause-and-effect relationships, we have used p44 fusion proteins that are selectively expressed in the nucleus or cytoplasm of prostate cancer cells (LNCaP), along with RNAi analyses, to examine effects of p44 both in vitro and in vivo (in tumor xenografts). We show that preferential expression of p44 in the nucleus inhibits proliferation of LNCaP cells in an AR-dependent manner, whereas preferential expression of p44 in the cytoplasm enhances cell proliferation. These effects appear to be mediated, at least in part, through the regulation of distinct cell-cycle regulatory genes that include p21 (up-regulated by nuclear p44) and cyclin D2 and CDK6 (up-regulated by cytoplasmic p44). Importantly, we also demonstrate that altered p44 expression is associated with androgen-independent prostate cancer. Our results indicate that nuclear p44 and cytoplasmic p44 have distinct and opposing functions in the regulation of prostate cancer cell proliferation

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

The morphological patterns of glioma cell invasion are known as the secondary structures of Scherer. In this report, we propose a biologically based mechanism for the nonrandom formation of Scherer's secondary structures based on the differential expression of stromal cell-derived factor (SDF)-1alpha and CXCR4 at the invading edge of glioblastomas. The chemokine SDF-1alpha was highly expressed in neurons, blood vessels, subpial regions, and white matter tracts that form the basis of Scherer's secondary structures. In contrast, the SDF-1alpha receptor, CXCR4, was highly expressed in invading glioma cells organized around neurons and blood vessels, in subpial regions, and along white matter tracts. Neuronal and endothelial cells exposed to vascular endothelial growth factor up-regulated the expression of SDF-1alpha. CXCR4-positive tumor cells migrated toward a SDF-1alpha gradient in vitro, whereas inhibition of CXCR4 expression decreased their migration. Similarly, inhibition of CXCR4 decreased levels of SDF-1alpha-induced phosphorylation of FAK, AKT, and ERK1/2, suggesting CXCR4 involvement in glioma invasion signaling. These studies offer one plausible molecular basis and explanation of the formation of Scherer's structures in glioma patients

In previous studies, we have demonstrated that adenosine and its receptors play a role in hepatic fibrosis. Here, we review evidence that toxin-induced increases in hepatic adenosine concentrations are generated from adenine nucleotides by the action of ecto-5'nucleotidase and thus that adenosine-mediated, toxin-induced hepatic fibrosis depends on extracellular conversion of adenine nucleotides to adenosine