Carbonic anhydrase and pH control in breast cancer cells

描述（由申请人提供）：肿瘤内的微环境与正常组织显著不同。混乱的脉管系统导致短暂或慢性缺氧，这导致间质空间酸化。这为正常细胞创造了细胞毒性环境，同时通过细胞外基质的降解、血管生成因子的诱导、增强的迁移和免疫逃避而有利于肿瘤生长。我们的应用程序集中在调节酸化的机制。我们已经召集了一批优秀的研究人员，并将使用最先进的方法来提供控制乳腺癌肿瘤微环境的新见解。我们的总体目标是了解膜结合碳酸酐酶的作用，其催化结构域面对细胞外环境，在乳腺癌中控制酸化。具体地说，我们将检验膜 结合的碳酸酐酶在机制上负责调节肿瘤微环境中的pH。原发性乳腺癌中碳酸酐酶IX（CAIX）表达增加是缺氧的标志物，是预后不良的指标，并且与高级别雌激素受体阴性肿瘤相关。由于未知的原因，碳酸酐酶XII（CAXII）在乳腺癌中的表达是预后良好的指标。很少有研究者在天然乳腺癌环境中研究CAIX或CAXII，正如我们所建议的那样，这将提供对它们在pH控制中作用的最准确评估。我们已经开发出的方法来比较这两种蛋白质的动力学，以确定是否在其内在的活性或环境的差异，这一矛盾的基础。我们挑战了目前的范式，即CAIX仅有助于酸性肿瘤微环境的发展。相反，我们的数据表明，CAIX具有通过使用CO2/碳酸氢盐系统改善细胞外缓冲来平衡肿瘤细胞外pH的能力。相比之下，CAXII在较高pH下是更好的酶。我们的建议的目的是：1.比较基底B和管腔乳腺癌细胞中CAIX和CAXII的动力学。2.）分析乳腺癌细胞控制细胞外pH的机制。评估CA对由乳腺癌细胞和人组织移植物组成的异种移植乳腺癌肿瘤中pH控制的作用。这些数据对于那些患有三阴性乳腺癌的女性尤其重要。这些癌症与CAIX表达密切相关，在少数群体中占主导地位，并且没有特定的治疗方式。我们相信，我们的提案具有很高的影响力，因为它使用创新方法，解决了独特的假设，可能揭示乳腺癌治疗干预的新策略，适用于其他癌症类型，并且有很大的成功机会。

DESCRIPTION (provided by applicant): The microenvironment within tumors is significantly different from normal tissue. The chaotic vasculature leads to transient or chronic hypoxia which leads to acidification of the interstitial space. This creates a cytotoxic environment for normal cells while favoring tumor growth through degradation of extracellular matrix, induction of angiogenic factors, enhanced migration, and immunologic evasion. Our application focuses on the mechanisms that regulate acidification. We have assembled a group of outstanding investigators and will use state-of-the-art approaches to provide new insights in control of the tumor microenvironment in breast cancer. Our overall goal is to understand the role of membrane-bound carbonic anhydrases, whose catalytic domains face the extracellular milieu, in controlling acidification in breast cancer. Specifically, we will test the hypothesis that membrane bound carbonic anhydrase is mechanistically responsible for regulating pH in the tumor microenvironment. Increased carbonic anhydrase IX (CAIX) expression in primary breast cancers is a marker for hypoxia, an indicator of poor prognosis, and associated with high-grade estrogen receptor negative tumors. For unknown reasons, carbonic anhydrase XII (CAXII) expression in breast cancer is an indicator of good prognosis. Few investigators have studied CAIX or CAXII in the native breast cancer environment, as we propose, which will provide the most accurate appraisal of their roles in pH control. We have developed the methodology to compare the kinetics of these two proteins to determine if differences in their intrinsic activity r environment underlie this paradox. We challenge the current paradigm that CAIX contributes solely to the development of the acidic tumor microenvironment. Rather, our data suggest that CAIX has the ability to balance tumor extracellular pH by improving extracellular buffering using the CO2/bicarbonate system. In contrast, CAXII is a better enzyme at higher pH. The aims of our proposal are: 1.) To compare the kinetics of CAIX and CAXII in basal B and luminal breast cancer cells. 2.) To analyze the mechanism(s) by which breast cancer cells control extracellular pH. 3.) To assess the role of CA on pH control in xenograft breast cancer tumors comprised of breast cancer cells and human tissue grafts. These data will be particularly important for those women who have triple negative breast cancers. These cancers are strongly associated with CAIX expression, predominate in the minority populations, and have no specific treatment modalities. We believe that our proposal has high impact as it uses innovative approaches, addresses unique hypotheses, may reveal new strategies for therapeutic intervention in breast cancer, has applicability to other cancer types, and has a great chance of success.