https://scholars.lib.ntu.edu.tw/handle/123456789/521365
標題: | Dephosphorylation of cancer protein by tyrosine phosphatases in response to analogs of luteinizing hormone-releasing hormone and somatostatin | 作者: | Lee L.-T. Schally A.V. Liebow C. Lee P.-P. PO-HUANG LEE Lee M.-T. |
關鍵字: | LHRH; Protein tyrosine kinase; Protein tyrosine phosphatase; Receptor; Somatostatin | 公開日期: | 2008 | 卷: | 28 | 起(迄)頁: | 2599-2605 | 來源出版物: | Anticancer Research | 摘要: | Protein phosphorylation/dephosphorylation of tyrosine residues is an important regulatory mechanism in cell growth and differentiation. Previously it has been reported that RC-160, an octapeptide analog of somatostatin, and [D-Trp6]LHRH, an agonist of luteinizing hormone-releasing hormone (LHRH), stimulate receptor-mediated activity of tyrosine phosphatases (PTP) and reverse growth promotion of the tyrosine kinase (PTK) class of oncogenes in tumor cells. The effect of RC-160 and [D-Trp6]LHRH on protein phosphorylation was further examined in surgical specimens of human carcinomas. Protein extracts of human ovarian, liver, breast and prostate tumor samples were preincubated with epidermal growth factor (EGF) (10-7 M) with or without [D-Trp6]LHRH or RC-160 (10-6 M) at 25°C for 2 h, followed by incubation for 10 min with [γ-32p]ATP. SDS-PAGE, Western blotting, autoradiography and densitometry were then used to quantify the phosphorylation level of individual protein bands. It was found that EGF enhanced, and [D-Trp6]LHRH and RC-160 reduced phosphorylation of a prominent 300-kDa band. Two proteins (65 and 60 kDa), involved in growth control in tumor cell lines, were also identified in this study. The homology of substrate phosphorylation between induced PTK and PTP in the presence of hormones provided evidence that these substrates might be identical or related in tumors. These findings, along with the previous cell culture results, suggest that many solid tumors may respond to treatment with analogues of somatostatin and LHRH. Collectively, the results further support the hypothesis that these 60-, 65- and 300-kDa protein substrates may be involved in growth-message transduction. |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-55749101019&partnerID=40&md5=84294d0f3f6d56380d002be0c3554630 https://scholars.lib.ntu.edu.tw/handle/123456789/521365 |
ISSN: | 0250-7005 | SDG/關鍵字: | adenosine triphosphate; gonadorelin; protein tyrosine phosphatase; somatostatin; vapreotide; article; autoradiography; breast tumor; carcinoma; controlled study; densitometry; human; human tissue; incubation time; liver tumor; ovary tumor; polyacrylamide gel electrophoresis; priority journal; prostate tumor; protein dephosphorylation; Western blotting; Antineoplastic Agents; Antineoplastic Agents, Hormonal; Breast Neoplasms; Epidermal Growth Factor; Female; Humans; Liver Neoplasms; Male; Neoplasm Proteins; Neoplasms; Ovarian Neoplasms; Phosphorylation; Prostatic Neoplasms; Protein Tyrosine Phosphatases; Somatostatin; Triptorelin |
顯示於: | 醫學系 |
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