Haier J, Nasralla M, Nicolson G L
Institute for Molecular Medicine, Huntington Beach, CA 92649, USA.
Int J Colorectal Dis. 1999 Apr;14(2):119-27. doi: 10.1007/s003840050196.
Organ-specific sites of metastastic lesions are determined in part by integrin-mediated adhesion to extracellular matrix (ECM) components. Using poorly (HT-29P) and highly liver-metastatic (HT-29LMM) colon carcinoma cells we previously found different integrin-mediated adhesion to various ECM components, but similar integrin expression of both cell lines. These HT-29 cell lines were used to study adhesion to collagen I (C I) and possible intracellular signaling mechanisms that could explain different adhesive properties. HT-29LMM cells had significantly poorer rates of adhesion to C I (P < 0.05) than HT-29P cells. For examination of the integrin subunits involved in adhesion to C I, cells were treated with various anti-integrin antibodies. These results demonstrated that adhesion of HT-29 cells to C I is mediated in part by the alpha 2 beta 1 integrin. Using immunoprecipitation and Western blotting, both cell lines expressed similar patterns of integrins (alpha 2, alpha 3, alpha 6, and beta 1). Weaker signals were found for the expression of alpha v and beta 5 integrins. Although poorly and highly metastatic cells possessed different patterns of adhesion to C I, these differences were not caused by different expression of integrin subunits. For investigation of the involvement of phosphotyrosine kinases in adhesion, cells were pretreated with the Erbstatin analog, Genistein, or Herbimycin A. Genistein transiently stimulated the adhesive properties of both cell lines. In contrast, Herbimycin A had biphasic effects. At lower concentrations of Herbimycin A stimulation of adhesion was found after 30 and 90 min. However, higher concentrations inhibited adhesive properties. The stimulatory effect was more pronounced in poorly metastatic HT-29P cells. The Erbstatin analog had no effect, probably because of the lack of epidermal growth factor receptor expression in both cell lines. The results suggest that adhesion of tumor cells to ECM components may be dependent on signal transduction into the cell, and tyrosine phosphorylation appears to be involved.
转移病灶的器官特异性位点部分由整合素介导的与细胞外基质（ECM）成分的黏附所决定。我们先前使用低转移（HT - 29P）和高肝转移（HT - 29LMM）的结肠癌细胞，发现它们对各种ECM成分的整合素介导黏附不同，但两种细胞系的整合素表达相似。这些HT - 29细胞系用于研究对I型胶原（C I）的黏附以及可能解释不同黏附特性的细胞内信号传导机制。HT - 29LMM细胞对C I的黏附率明显低于HT - 29P细胞（P < 0.05）。为了检测参与对C I黏附的整合素亚基，细胞用各种抗整合素抗体处理。这些结果表明，HT - 29细胞对C I的黏附部分由α2β1整合素介导。通过免疫沉淀和蛋白质印迹法，两种细胞系表达相似的整合素模式（α2、α3、α6和β1）。发现αv和β5整合素的表达信号较弱。尽管低转移和高转移细胞对C I具有不同的黏附模式，但这些差异并非由整合素亚基的不同表达引起。为了研究磷酸酪氨酸激酶在黏附中的作用，细胞用厄波他汀类似物、染料木黄酮或赫司特霉素A预处理。染料木黄酮短暂刺激了两种细胞系的黏附特性。相反，赫司特霉素A具有双相作用。在较低浓度的赫司特霉素A下，30分钟和90分钟后发现黏附受到刺激。然而，较高浓度则抑制黏附特性。这种刺激作用在低转移的HT - 29P细胞中更为明显。厄波他汀类似物没有作用，可能是因为两种细胞系中均缺乏表皮生长因子受体表达。结果表明，肿瘤细胞对ECM成分的黏附可能依赖于细胞内的信号转导，并且酪氨酸磷酸化似乎参与其中。
