生物素标记核酸探针检测白血病患者c－myc原癌基因的表达水平

用两种方法制备生物素ｃ－ｍｙｃ癌基因探针，通过ＲＮＡ－ＤＮＡ斑点杂交技术，检测了白血病３０例和２种白血病细胞株中ｃ－ｍｙｃ原癌基因的ＲＮＡ表达水平。结果显示，白血病细胞株、急性白血病和慢性粒细胞性白血病急性变患者的ｃ－ｍｙｃ的ＲＮＡ表达水平明显高于正常人和患其它血液病的患者，提示ｃ－ｍｙｃＲＮＡ水平的判定可提供一些有意义的临床信息；同时探讨了生物素和光敏生物素标记核酸探针的优越性。     

Regulation of C-myc protooncogene expression in osteoblastic cells by arachidonic acid metabolites: Relationship to proliferation

Summary Prostaglandin E₂ and leukotriene B₄ are metabolites of arachidonic acid with well-characterized effects on osteoblastic cells. Prostaglandin E₂ has been shown to be a potent bone-resorbing agent and to stimulate as well as inhibit osteoblastic cell proliferation. Leukotriene B₄ has also been demonstrated to stimulate or inhibit osteoblastic cell proliferation, depending on the cell type tested. In the present study, the potential relationship of the effects of prostaglandin E₂ and leukotriene B₄ on osteoblastic cell proliferation to c-myc protooncogene expression was investigated. Prostaglandin E₂ has been shown previously to inhibit normal rat osteoblastic cell proliferation. The present studies show that prostaglandin E₂ at 10^-6 M decreased c-myc expression in these cells. In the human osteoblastic osteosarcoma cell line, G292, prostaglandin E₂ increased c-myc expression and inhibited proliferation. In contrast, epidermal growth factor increased DNA synthesis as well as c-myc expression. Prostaglandin E₂ also inhibited proliferation of another human osteoblastic osteosarcoma cell line, Saos-2, but it did not produce any changes in c-myc expression. In these cells, epidermal growth factor did not affect either DNA synthesis or c-myc expression. Leukotriene B₄ did not show any effects on c-myc expression in any of the osteoblastic cells tested.     

Cellular localization of PDGF mRNAs in developing human forebrain

Platelet-derived growth factor (PDGF) has been implicated in the processes regulating gliogenesis in the CNS. Conflicting in vivo data in rodents have variously implicated either glia or neurons as being the primary source of PDGF. We have used in situ hybridization and immunocytochemical analysis to study the in vivo expression and cellular localization of PDGF-A, sis/PDGF-B, together with the two PDGF receptors α and β, in developing human forebrain. In this study we demonstrate the strong expression of mRNA and protein of both PDGF chains, A and B, and their receptors, α and β, in human embryonic glial cells. The neurons, in contrast to glial cells, expressed lower levels of PDGF and PDGF-receptor mRNAs and protein. Identification of the cell types expressing the PDGF and PDGF-receptor mRNAs was achieved by counterstaining with antibodies specific for glial cells (GFAP) and neurons (NF). The predominant glial-specific expression of both PDGF-A and PDGF-B, together with the coexpression of their receptors α and β, suggests an important role for the PDGF isoforms in the development of human embryonic glial cells and neurons in vivo .     

IL-6对人系膜细胞c-myc原癌基因表达的影响以及大黄素的拮抗作用

本文应用体外细胞培养和斑点杂交技术,首次对重组人IL-6对人系膜细胞c-myc原癌基因mRNA的表达以及大黄素对IL-6的作用进行了观察。发现IL-6能够促进人系膜细胞c-myc原癌基因mRNA的增殖表达,该作用呈明显的剂量依赖性,而大黄素能够拮抗IL-6的上述作用。本项研究阐明了IL-6促进系膜细胞的可能机理,为进一步论证大黄素对系膜细胞功能的影响,大黄素与细胞因子间的相互作用以及大黄在防治肾小球硬化的作用奠定了基础。     

Somatic Mutations in the RET Protooncogene in Japanese and Chinese Sporadic Medullary Thyroid Carcinomas

Despite advances in the understanding of the genotype-phenotype correlation in multiple endocrine neoplasia type 2A and 2B (multiple endocrine neoplasia (MEN) 2A, MEN 2B), and familial medullary thyroid carcinoma (FMTC), the frequency and prognostic relevance of RET protooncogene mutations in sporadic medullary thyroid carcinomas (MTCs) remain controversial. To study somatic mutations in the RET protooncogene in Japanese and Chinese sporadic MTCs and to analyze comparatively the correlation between RET mutation and tumor differentiation, we investigated somatic mutations in the RET protooncogene in 20 Japanese and 20 Chinese sporadic MTCs by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. Of the 40 sporadic MTCs, 13 had a point mutation in codon 918 of exon 16, a frequency of 32.5%. There was no significant difference in the frequency between Japanese and Chinese sporadic MTCs, as 30% of the Japanese and 35% of the Chinese sporadic MTCs contained this mutation. We did not observe any correlation between the presence or absence of codon 918 mutation and tumor differentiation in either Japanese or Chinese sporadic MTCs. Our findings indicate that the frequency of RET somatic mutations is similar in Japanese and Chinese sporadic MTCs, and the presence or absence of RET mutation does not correlate with the differentiation of sporadic MTCs.