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Biomedical subjects

Stergios J Moschos

Publications and source records attributed to Stergios J Moschos.

8 recordsLinked to original sources
PubMed2006

Neoadjuvant treatment of regional stage IIIB melanoma with high-dose interferon alfa-2b induces objective tumor regression in association with modulation of tumor infiltrating host cellular immune responses.

PURPOSE: Adjuvant high-dose interferon-alfa-2b (HDI) improves disease-free and overall survival in patients with high-risk melanoma. However, its mechanism of action is largely unknown. Therefore, HDI was investigated in the neoadjuvant setting to assess clinical and pathologic responses after 4 weeks of HDI and to perform immunohistochemical evaluation of immune cell subsets and melanoma-associated antigens. PATIENTS AND METHODS: Patients with palpable regional lymph node metastases from melanoma (American Joint Committee on Cancer stage IIIB-C) underwent surgical biopsy at study entry and then received standard intravenous HDI (20 million units/m2, 5 days per week) for 4 weeks followed by complete lymphadenectomy and standard maintenance subcutaneous HDI (10 million units/m2 3 times per week) for 48 weeks. Biopsy samples were obtained before and after intravenous HDI and subjected to immunohistochemical analysis as well as routine pathologic study. RESULTS: Twenty patients were enrolled, and biopsy samples were informative for 17. Eleven patients (55%) demonstrated objective clinical response, and 3 patients (15%) had complete pathologic response. At a median follow-up of 18.5 months (range, 7 months to 50 months) 10 patients had no evidence of recurrent disease. Clinical responders had significantly greater increases in endotumoral CD11c+ and CD3+ cells and significantly greater decreases in endotumoral CD83+ cells compared with nonresponders. No changes in the expression of melanoma-associated lineage antigens, tumor cell proliferation, angiogenesis, or apoptosis were evident. CONCLUSION: Neoadjuvant HDI is highly effective for the treatment of palpable stage IIIB-C melanoma, and the findings of this study implicate an indirect immunomodulatory mechanism rather than a direct antitumor mechanism.

Adult↗
PubMed2006

Role of SUMO/Ubc9 in DNA damage repair and tumorigenesis.

DNA damage repair is an important cell function for genome integrity and its deregulation can lead to genomic instability and development of malignancies. Sumoylation is an increasingly important ubiquitin-like modification of proteins affecting protein stability, enzymatic activity, nucleocytoplasmic trafficking, and protein-protein interactions. In particular, several important DNA repair enzymes are subject to sumoylation, which appears to play a role in copping with DNA damage insults. Recent reports indicate that Ubc9, the single SUMO E2 enzyme catalyzing the conjugation of SUMO to target proteins, is overexpressed in certain tumors, such as lung adenocarcinoma, ovarian carcinoma and melanoma, suggestive of its clinic significance. This review summarizes the most important DNA damage repair pathways which are potentially affected by Ubc9/SUMO and their role in regulating the function of several proteins involved in the DNA damage repair machinery.

Chromatin↗
PubMed2005

Targeting Ubc9 for cancer therapy.

Ubiquitin-conjugating enzyme (Ubc9) was originally thought to be a conjugating enzyme for ubiquitylation, but was later shown to be responsible for the most recently identified type of post-translational modification, (i.e., SUMO [small ubiquitin-related modifier]) conjugation or sumoylation. Like ubiquitylation, sumoylation modulates protein function through post-translational covalent attachment to lysine residues within targeted proteins. However, although ubiquitylation can lead to protein degradation through the 26S proteasome, sumoylation does not cause protein degradation; instead, it has been implicated in other cellular processes, such as regulating the activity of transcription factors, mediating nuclear translocation of proteins or the formation of subnuclear structures. Interestingly, some proteins can be modified at the same lysine residue by both SUMO and ubiquitin, but with distinct functional consequences. Given that many proteins involved in cell-cycle regulation, proliferation, apoptosis and DNA repair are targets for sumoylation, alterations of sumoylation could ultimately have an impact on cell growth, cancer development and drug responsiveness. As Ubc9 is the sole E2-conjugating enzyme required for sumoylation, and, in particular, Ubc9 is upregulated in an increasing number of human malignancies, such as ovarian carcinoma, melanoma and lung adenocarcinoma, it is a potential target for cancer therapy.

Amino Acid Sequence↗
PubMed2005

Melanoma.

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Humans↗
PubMed2004

Recombinant methionyl human leptin administration activates signal transducer and activator of transcription 3 signaling in peripheral blood mononuclear cells in vivo and regulates soluble tumor necrosis factor-alpha receptor levels in humans with relative leptin deficiency.

Studies of congenital complete leptin deficiency in animals and humans support a role for leptin in regulating immune function. Whether acquired relative leptin deficiency affects immunological parameters in healthy humans remains unknown. We thus used experimental models of relative leptin deficiency and recombinant methionyl human leptin (r-metHuLeptin) administration in humans to investigate whether r-metHuLeptin would activate signaling pathways in peripheral blood mononuclear cells (PBMCs) and whether acquired relative leptin deficiency and/or increasing circulating leptin levels into the physiologic range would change PBMC subpopulations and cytokines important in the T-helper cell and systemic immune responses. We found that r-metHuLeptin administration to healthy humans activates signal transducer and activator of transcription-3 signaling in PBMCs in vivo. Neither short-term leptin deficiency, induced by 3-d complete fasting, nor physiologic r-metHuLeptin replacement for the same period of time had a major effect on PBMC subpopulations or serum cytokines in healthy men. In contrast, normalizing serum leptin levels over 8 wk in lean women with relative leptin deficiency for 5.1 +/- 1.4 yr (mean +/- se) due to chronic energy deficit increased soluble TNFalpha receptor levels, indicating activation of the TNFalpha system. These findings suggest that relative leptin deficiency due to more long-term energy deprivation is associated with defects in immunological parameters that may be corrected with exogenous r-metHuLeptin administration. Further studies are warranted to assess the implications of acquired relative hypoleptinemia and/or r-metHuLeptin administration on the immunosuppression associated with energy- and leptin-deficient states in humans.

Adult↗
PubMed2004

Responsiveness to peripherally administered melanocortins in lean and obese mice.

To elucidate mechanisms of melanocortin action, we investigated the effects of a melanocortin receptor agonist (melanotetan II [MTII]) in lean C57BL/6J and obese (DIO, ob/ob, UCP1-DTA) mice. MTII administration (100 microg q.i.d. i.p.) for 24 h results in similar weight loss but a more pronounced decrease of food intake in DIO mice. After 4 and 8 days of MTII treatment, however, the reduction in both food intake and body weight is more pronounced in DIO mice than in lean mice. MTII administration for 24 h prevents food deprivation-induced alterations in hypothalamic neuropeptide Y (NPY) and liver adiponectin receptor 1 and adiponectin receptor 2 mRNA expression, but does not alter hypothalamic mRNA expression of melanocortin 4 receptor or adiponectin serum and mRNA expression levels. NPY and agouti gene-related protein (AgRP) mRNA expression after 8 days of MTII is increased to levels comparable to pair-fed mice. In summary, 1) MTII is an effective treatment for obesity and related metabolic defects in leptin-resistant (DIO, UCP1-DTA) and leptin-sensitive (ob/ob) mouse models of obesity; 2) the effects of MTII on food intake and body weight are more pronounced in DIO mice than in lean mice; 3) the tachyphylactic effect after prolonged MTII administration appears to be, at least in part, caused by a compensatory upregulation of NPY and AgRP mRNA levels, whereas decreasing leptin levels may play a very minor role in mediating tachyphylaxis; and 4) alterations in adiponectin receptor mRNA expression after fasting or MTII treatment may contribute to altered insulin sensitivity and needs to be studied further.

Animals↗
PubMed2002

The role of the IGF system in cancer: from basic to clinical studies and clinical applications.

Insulin-like growth factors (IGFs) are important mediators of growth, development, and survival, are synthesized by almost any tissue in the body, and their action is modulated by a complex network of molecules, including binding proteins, proteases and receptors, which all comprise the IGF system. Evidence from in vitro and animal studies suggests that overexpression of IGFs by cancer cells and/or the nearby stroma as well as the type IGF-I receptor by the cancer cells may play a significant role in establishing a transformed phenotype in an increasing number of malignancies. More specifically, IGFs may promote cell cycle progression and inhibition of apoptosis either by directly associating with other growth factors or indirectly by interacting with other molecular systems which have an established role in carcinogenesis and cancer promotion, such as the steroid hormones and integrins. In addition, a growing number of epidemiologic studies suggest that increased serum levels of IGFs and/or altered levels of their binding proteins are associated with increased risk for developing several malignancies. These data indicate that IGF dysregulation should now be considered as an important independent factor for cancer risk, and a potential target for novel antineoplastic therapies and/or preventative strategies in high-risk groups.

Animals↗