Regulation of Papillomavirus-Induced Immortalization by EGF-Receptor Inhibition

描述(由申请人提供)：感染人类乳头瘤病毒(HPV)的亚组是宫颈癌的主要危险因素。HPVE6和E7基因在大多数恶性肿瘤中选择性地保留和表达，HPV持续感染和宫颈细胞永生化是宫颈癌发生的重要事件。大多数HPV感染是通过宿主的免疫反应来消除的。然而，患有获得性免疫缺陷综合征(AIDS)的妇女会发展成持续性HPV感染，进而发展为宫颈上皮内瘤变或癌症。艾滋病患者对常规治疗的反应也很差，他们的疾病很可能会复发。因此，艾滋病妇女将受益于针对分子途径的化学预防或治疗，这些途径对宫颈癌的发生具有重要意义。表皮生长因子受体(EGF-R)是相关靶点。EGF-R在宫颈不典型增生和癌组织中过度表达，其肿瘤中EGF-R水平高的患者预后较差。我们的初步结果表明，抑制EGF-R阻断了宫颈癌变的重要一步：HPV-16使宫颈细胞永生化。我们的长期目标是确定EGF-R是否是艾滋病患者宫颈癌化学预防或治疗的有效靶点。这项建议的目的是(1)证实EGF-R抑制阻止HPV-16使宫颈细胞永生化，以及(2)确定抑制永生化的机制。我们将使用来自宫颈转化区的人类上皮细胞培养来研究这些问题，宫颈转化区是大多数宫颈癌的发源地。实验将使用厄洛替尼(Tarceva)，这是一种小分子EGF-R酪氨酸激酶抑制剂，已被批准用于治疗人类癌症。研究将确定厄洛替尼是阻止HPV-16使正常宫颈细胞永生化，还是抑制宫颈癌细胞的生长。实验还将确定Erlotinib是否通过(1)增加E6/E7表达细胞对凋亡的敏感性，(2)刺激过早衰老，或(3)减少HPV-16DNA的表达来防止永生。我们的结果将阐明EGF-R抑制如何针对一种新的途径，该途径对宫颈癌的化学预防和治疗具有潜在的重要意义。患有艾滋病的妇女特别容易患宫颈癌。他们对传统治疗的反应很差，而且他们的癌症很可能会复发。我们的结果为宫颈癌的化学预防或化疗提供了一个新的靶点，它与艾滋病患者或免疫抑制的个体有关。这包括通过抑制表皮生长因子受体来防止乳头瘤病毒永生化。由于抑制这种受体的药物已经被批准用于治疗肺癌和结直肠癌，因此测试它们是否也能抑制宫颈癌的发生是合理的。

DESCRIPTION (provided by applicant): Infection with a subset of human papillomaviruses (HPV) is the major risk factor for cervical cancer. The HPV E6 and E7 genes are selectively retained and expressed in most malignant tumors, and persistent infection with HPV and immortalization of cervical cells are important events in cervical carcinogenesis. The majority of HPV infections are eliminated by the host immune response. However, women with acquired immune deficiency syndrome (AIDS) develop persistent HPV infections that progress to cervical intraepithelial neoplasia or cancer. AIDS patients also respond poorly to conventional therapy and their disease is likely to recur. Thus, women with AIDS would benefit from chemoprevention or therapy targeted to molecular pathways that are important for cervical carcinogenesis. The epidermal growth factor receptor (EGF-R) is a relevant target. The EGF- R is over expressed in cervical dysplasias and carcinomas, and patients with high EGF-R levels in their tumor have a poor prognosis. Our preliminary results indicate that inhibition of the EGF-R blocks an important step in cervical carcinogenesis; immortalization of cervical cells by HPV-16. Our long term goal is to determine whether the EGF-R is an effective target for chemoprevention or therapy of cervical cancer in AIDS patients. The objectives of this proposal are to (1) confirm that EGF-R inhibition prevents immortalization of cervical cells by HPV-16, and (2) identify the mechanism by which immortalization is inhibited. We will examine these questions using cultures of human epithelial cells derived from the cervical transformation zone, the site where most cervical cancers originate. Experiments will use Erlotinib (Tarceva), a small molecule EGF-R tyrosine kinase inhibitor that has been approved for therapy of human cancer. Studies will determine whether Erlotinib prevents immortalization of normal cervical cells by HPV-16 or inhibits growth of cervical cancer cells. Experiments will also determine whether Erlotinib prevents immortalization by (1) increasing susceptibility of E6/E7-expressing cells to apoptosis, (2) stimulating premature senescence, or (3) decreasing expression of HPV-16 DNA. Our results will clarify how EGF-R inhibition targets a novel pathway that is potentially important for chemoprevention and therapy of cervical cancer. Women with AIDS are particularly susceptible to cervical cancer. They respond poorly to conventional therapy and their cancers are likely to recur. Our results describe a novel target for chemoprevention or chemotherapy of cervical cancer that is relevant to AIDS patients or immune suppressed individuals. This involves prevention of immortalization by papillomaviruses by inhibition of the epidermal growth factor receptor. Since drugs that inhibit this receptor have already been approved to treat lung and colorectal cancer, it is reasonable to test whether they also inhibit cervical carcinogenesis.