SMOKE INDUCED MUCIN TRANSCRIPTION AND MITOGENESIS

烟草烟雾引起慢性支气管炎和肺癌的机制尚不清楚。然而，我们最近的研究结果提供了线索，表明烟雾直接诱导黏液蛋白mRNA和肺上皮细胞的有丝分裂发生，这是在Src激酶激活和EGF受体（EGFr）磷酸化之前发生的。Src激酶抑制剂抑制烟雾诱导的EGFr磷酸化、粘蛋白转录诱导和有丝分裂发生。EGFr激酶抑制剂阻断了烟雾诱导的EGFr磷酸化和有丝分裂，但只能部分阻断粘蛋白转录上调。这使我们假设烟雾激活了Src激酶发出的分支信号通路。该通路的一个分支依赖于egfr，足以解释烟雾诱导的有丝分裂发生；另一个分支与egfr无关，其作用与另一个分支介导粘蛋白转录的作用相同。本提案中描述的实验将提供有关egfr依赖性和非依赖性信号通路的信息。在Specific Aim I中描述的实验中，我们将确定烟雾信号通路中egfr相互作用的元件，导致(a)粘蛋白诱导和(b)有丝分裂发生。在Specific Aim II中描述的实验中，我们将确定烟雾信号通路中src相互作用的元件，导致(a)粘蛋白诱导和(b)有丝分裂发生。在特定目标III中描述的实验中，我们将确定烟雾中负责激活(a)粘蛋白诱导和(b)有丝分裂发生的成分。这些研究的结果应该揭示出可被药物抑制的控制点。

The mechanisms by which tobacco smoke cause chronic bronchitis and lung cancer are unknown. Clues are provided, however, by our recent findings showing that smoke directly induces mucin mRNA and mitogenesis in lung epithelial cells and that this is preceded by activation of Src kinase and phosphorylation of the EGF receptor (EGFr). Src kinase inhibitors abrogate smoke-induced EGFr phosphorylation, mucin transcription induction and mitogenesis. EGFr kinase inhibitors abrogate smoke-induced EGFr phosphorylation and mitogenesis but only partially block mucin transcriptional upregulation. This leads us to hypothesize that smoke activates a branched signaling pathway emanating from Src kinase. One arm of the pathway is EGFr-dependent and is sufficient to account for smoke-induced mitogenesis; the other is EGFr-independent and its effects summate with those of the other branch to mediate mucin transcription. The experiments described in this proposal will provide information regarding both the EGFr-dependent and -independent signaling pathways. In experiments described under Specific Aim I, we will identify EGFr-interacting elements of the smoke-signaling pathway leading to (a) mucin induction and (b) mitogenesis. In experiments described under Specific Aim II, we will identify Src-interacting elements of the smoke signaling pathway leading to (a) mucin induction and (b) mitogenesis. In experiments described under Specific Aim III, we will identify components of smoke responsible for activating (a) mucin induction and (b) mitogenesis. The results of these studies should reveal control points amenable to inhibition by pharmacological agents.