CTGF in Pancreatic Tumor Growth

描述(申请人提供)：在上一次资助期间，我们获得了结缔组织生长因子(CTGF)在人胰腺肿瘤中表达升高的证据，但在正常胰腺或胰腺炎中没有表达。由于胰腺肿瘤是高度低氧的，而CTGF是已知的低氧诱导性的，我们将这项研究的重点放在了解低氧和CTGF在胰腺肿瘤进展中的作用。这些研究的基础是研究CTGF在胰腺肿瘤进展中的重要性，因为我们的研究表明，用单抗靶向抑制CTGF可以显著抑制作为皮下肿瘤移植的两种不同的胰腺癌细胞系的生长。在这项资助中，我们将重点研究在常氧和低氧条件下CTGF及其各个结构域在胰腺肿瘤进展中的机制作用。我们的初步数据表明，CTGF能够促进胰腺肿瘤细胞的生长。CTGF的诱导对塑料上的细胞生长没有影响，但显著促进了软琼脂中的球状生长。最显著的是CTGF表达诱导的细胞黏附增加。这些细胞黏附的变化是3D生长所必需的，这让我们检验了一种假设，即CTGF在恶性进展中的主要作用之一是调节细胞与细胞的黏附，而抑制这一活性将影响肿瘤的生长和转移。因此，本提案的目的是1)通过操纵表达不同水平的HIF-1的细胞中的结构域特异性缺失突变体，确定CTGF在常氧和低氧条件下如何影响胰腺癌细胞的细胞黏附，2)确定CTGF在常氧和低氧条件下对三维生长和侵袭的重要性，3)确定抑制CTGF介导的黏附如何影响转移生长，4)确定CTGF抑制细胞黏附如何影响胰腺癌细胞的皮下和原位肿瘤生长，5)确定间质和肿瘤细胞CTGF在肿瘤生长中的作用，6)确定与单纯电离辐射或吉西他滨相比，CTGF-Ab联合电离辐射或吉西他滨对控制胰腺肿瘤生长的效果如何。总之，建议的研究旨在解决CTGF影响胰腺癌肿瘤进展的一个重要机制，并确定将其引入临床的联合治疗的有效性。

DESCRIPTION (provided by applicant): During the last grant period, we have obtained evidence that the expression of connective tissue growth factor (CTGF) is elevated in human pancreatic tumors, but not in normal pancreas or pancreatitis. Since pancreatic tumors are highly hypoxia and CTGF is known to be hypoxia inducible, we have focused this grant to understand the role of hypoxia and CTGF in pancreatic tumor progression. The basis for these studies to investigate the importance of CTGF in pancreatic tumor progression derive from our demonstration that targeted inhibition of CTGF with a monoclonal specific antibody results in significant growth inhibition of two different pancreatic cancer cell lines implanted as subcutaneous tumors. In this grant, we will focus on determining the mechanistic role of CTGF and its individual domains on pancreatic tumor progression under normoxic and hypoxic conditions. Our preliminary data suggests that CTGF is able to enhance the growth of pancreatic tumor cells. Induction of CTGF had no effect on cell growth on plastic, but significantly enhanced spheroid growth in soft agar. Most striking was the increase in cell adhesion induced by CTGF expression. These changes in cell adhesion that are necessary for 3-D growth lead us to test the hypothesis that one of the major roles of CTGF in malignant progression is to regulate cell-cell adhesion, and that inhibiting this activity will impact tumor growth and metastases. Thus, the aims of this proposal are to 1) determine how CTGF affects cell adhesion of pancreatic tumor cells under normoxic and hypoxic conditions using domain specific deletion mutants in cells that are manipulated to express different levels of HIF-1, 2) determine how important CTGF is for 3-D growth and invasion under normoxic and hypoxic conditions, 3) determine how inhibition of CTGF mediated adhesion affects metastatic growth, 4) determine how inhibition of cell adhesion by CTGF affects subcutaneous and orthotopic tumor growth of pancreatic tumor cells, 5) determine the role of stromal and tumor cell CTGF on tumor growth, 6) determine how effective the combination of CTGF Ab and ionizing radiation or gemcitabine are in controlling pancreatic tumor growth compared to ionizing radiation or gemcitabine alone. In summary, the proposed studies are intended to address an important mechanism by which CTGF affects tumor progression in pancreatic cancers and to determine how effective it is in combination therapy to bring it to the clinic.