Growth Factors, Curcumin and Colon Carcinogenesis

描述（由申请人提供）：我们现在知道，原胃泌素（PG）和胰岛素样生长因子（IGFs）对结肠癌（CRC）细胞具有强大的增殖和抗凋亡作用，并可能在结直肠癌发生的所有阶段作为共同致癌物起作用。膳食制剂，如姜黄素，抑制结直肠癌细胞的生长，并在疾病的恶性前期和恶性后阶段抑制结肠癌的发生。然而，目前尚不清楚姜黄素是否可以抑制结肠癌发生过程中自分泌和/或内分泌PG和IGF-II的生长因子作用。我们的初步研究表明，姜黄素的抑制作用在生长因子如IGF-II和PG的存在下减弱；令人惊讶的是，IGF-II存在时的抑制程度明显高于PG存在时的抑制程度。因此，我们的主要假设是，姜黄素的抑制功效将由动物模型的循环生长因子特征或CRC细胞中的自分泌生长因子决定。为了解决这一假设，在第1项研究中，我们将开发表达PG或IGF-II的等基因细胞系，并检测姜黄素对这些细胞的促凋亡和抗增殖能力。姜黄素对完整结肠隐窝细胞的抑制作用也将被检测，这些细胞是由过表达PG或IGFs的转基因小鼠或野生型小鼠制备的。在第2项研究中，我们将研究姜黄素在过表达PG或IGF-II的转基因小鼠中对结肠癌变所有阶段的剂量依赖性作用，无论是在循环中还是在肠粘膜内局部。我们的实验室目前正在研究介导PG和IGFs对结直肠癌和肠上皮（IEC）细胞的抗凋亡和增殖作用的细胞内通路。姜黄素抑制igf和PG的生长因子作用的机制目前尚不清楚。在Aim 3中，我们将研究姜黄素对等基因CRC和IEC细胞中响应PG或IGF-II而激活的几种激酶/磷酸酶的磷酸化/去磷酸化的影响。上述实验将使我们第一次了解姜黄素在与疾病病因相关的生长因子存在的情况下对结肠癌发生的相对有效性。这些研究的结果有望帮助开发基于机制的策略，用于使用姜黄素类药物预防/治疗结直肠癌。

DESCRIPTION (provided by applicant): We now know that progastrins (PG) and insulin-like growth factors (IGFs) exert potent proliferative and anti- apoptotic effects on colon cancer (CRC) cells and can potentially function as co-carcinogens during all phases of colorectal carcinogenesis. Dietary agents, such as curcumin, inhibit the growth of CRC cells and inhibit colon carcinogenesis at both the pre-malignant and post-malignant stages of the disease. It is, however, not known if curcumin can inhibit the growth factor effects of autocrine and/or endocrine PG and IGF-II during colon carcinogenesis. Our preliminary studies suggest that the inhibitory effects of curcumin are attenuated in the presence of growth factors, such as IGF-II and PG; surprisingly the degree of attenuation was significantly higher in the presence of IGF-II than in the presence of PG. Therefore, the major hypothesis of our grant proposal is that the inhibitory efficacy of curcumin will be dictated by either the circulating growth factor profile of animal models or by the autocrine growth factors in CRC cells. To address this hypothesis, in Aim 1, we will develop isogenic cell lines that either express PG or IGF-II, and examine the pro-apoptotic and anti-proliferative potency of curcumin on these cells. Inhibitory effects of curcumin on intact colonic crypt cells, prepared from either transgenic mice over-expressing PG or IGFs or prepared from wild type mice, will also be examined. In Aim 2, we will examine dose-dependent effects of dietary curcumin against all phases of colon carcinogenesis in transgenic mice over-expressing PG or IGF-II, either in the circulation or locally within the intestinal mucosa. The intracellular pathways that mediate anti-apoptotic vs proliferative effects of PG and IGFs, on CRC and intestinal epithelial (IEC) cells, are being currently examined in our laboratory. The mechanisms by which curcumin inhibits the growth factor effects of IGFs and PG are unknown at the present time. In Aim 3 we will examine the effect of curcumin on the phosphorylation/dephosphorylation of several kinases/phosphatases that are activated in response to PG or IGF-II in isogenic CRC and IEC cells. The above experiments will allow us to learn for the first time the relative effectiveness of curcumin on colon carcinogenesis in the presence of growth factors relevant to the etiology of the disease. The results of these studies are expected to help in developing mechanism-based strategies for preventative/treatment protocols for CRC using curcumin like agents.