THE BIOLOGICAL ACTIVITY OF FECAPENTAENE-12 IN HUMAN TISSUES AND CELLS

Fecapentaene-12(FEC-12)，一种潜在的致癌物质 结肠癌的发病机制是细胞毒性、诱变性和诱导性的 DNA单链断裂(SSB)、姐妹染色单体互换(SEC) 和正常人的非程序DNA合成(UDS) 成纤维细胞。DNA修复缺陷的成纤维细胞更敏感 比正常成纤维细胞具有更强的细胞毒性和致突变作用， 它们是剂量依赖的。SSB因以下原因而积累 对切除修复的聚合酶成分的抑制 机制表明，SSB可能部分由DNA介导 修复机制。这些结果表明，FEC-12是 对人类具有遗传毒性、致突变性和直接DNA损伤 细胞。进一步支持FEC-12是一种 结肠癌的启动剂来自于这一发现 化合物诱导小鼠Balb 3T3细胞转化。 用质粒法研究FEC-12-DNA的作用机制 损伤显示有链间DNA交联链和 直接SSB。FEC-12在切除修复中诱导质粒突变- 缺陷性(紫外光)大肠杆菌。限制性内切酶分析与DNA 对从突变体中分离的质粒进行测序表明 大约10%的人有明显的DNA重排。 ~3HFEC-12与小牛胸腺DNA可能的共价结合 氯化铯密度梯度离心法。 DNA酶消化法分离FEC-12-DNA加合物 而高效液相色谱目前正在进行中。初步结果与 ~(32)P-后标记技术表明FEC-12-DNA加合物 可能存在于从接触过的人成纤维细胞中提取的DNA中 体外培养至3HTFEC-12细胞。

Fecapentaene-12 (fec-12), a candidate carcinogen in the pathogenesis of colon cancer, is cytotoxic, mutagenic and induces DNA single strand breaks (SSB), sister chromatid exchanges (SEC) and unscheduled DNA synthesis (UDS) in normal human fibroblasts. DNA repair-deficient fibroblasts are more sensitive than normal fibroblasts to the cytotoxic and mutagenic effects, which are dose dependent. Accumulation of SSB as a result of inhibition of the polymerase component of the excision repair mechanism suggests that SSB may by mediated, in part, by DNA repair mechanisms. These results indicate that fec-12 is genotoxic, mutagenic and causes direct DNA damage in human cells. Further support for the hypothesis that fec-12 is an initiating agent in colon cancer comes from the finding that this compound induces transformation in murine Balb 3T3 cells. Plasmid assays investigating the mechanism of fec-12-DNA damage have shown evidence of interstrand DNA cross-links and direct SSB. Fec-12 induces plasmid mutations in excision repair- deficient (uvra-) E. coli. Restriction digest analysis and DNA sequencing of plasmids isolated from mutants indicated that approximately 10% had marked DNA rearrangements. Possible covalent binding of 3H fec-12 to calf thymus DNA is indicated by cesium chloride density gradient centrifugation. Separation of fec-12-DNA adducts by enzymic digestion of DNA and HPLC is currently in progress. Preliminary results with the 32P-postlabelling technique indicate that fec-12-DNA adducts may be present in DNA extracted from human fibroblasts exposed to 3H fec-12 in vitro.