Expression Profiles and Impact of Proton-sensitive G Protein-Coupled Receptors (GPCRs) on Cell Proliferation and Migration in Tumor Growth and Wound Healing

实体肿瘤和伤口是我们医疗保健系统中最重要的成本驱动因素之一。pH失调是肿瘤生长和组织修复的特征。在肿瘤中，微环境变化，如乳酸代谢，导致跨膜pH梯度改变（细胞内pH值降低和增加：pHe <pHi），反之亦然。在伤口中，屏障破坏导致伤口表面上的pH的广泛变化。已知改变的细胞外质子浓度对细胞更新和迁移以及对参与肿瘤扩散和伤口闭合的细胞的代谢活性具有重大影响。质子敏感G蛋白偶联受体（GPCR）GPR4（GPR19）、GPR65（TDAG8，T细胞死亡相关基因8）、GPR68（OGR 1，卵巢癌GPCR 1）和GPR132（G2A，G2积累蛋白）通过pHe的降低被激活，并将该信号传递到分子细胞内途径。基于目前的知识，我们推测质子敏感GPCR在伤口愈合中的作用，以及它们作为肿瘤生长和组织修复的机械接头的潜力，这两个过程高度依赖于细胞增殖和迁移。将首次在细胞培养和组织学中全面研究这些GPCR在正常成人细胞（角质形成细胞、成纤维细胞）和肿瘤细胞（黑色素瘤、鳞状细胞癌）中的表达。此外，我们将研究在选择性敲除不同的质子敏感性GPCR（通过CRISPR/Cas，或者siRNA）后，pHe对细胞增殖和迁移的影响。这些结果将为质子敏感性GPCR在肿瘤生长和伤口愈合中的作用提供新的见解，并且它们对于使用改变肿瘤pH的药物以及直接作用于质子敏感性GPCR的药物也很重要。

Solid tumors and wounds are among the most important cost drivers in our healthcare systems. Dysregulation of pH is a feature of both tumor growth and tissue repair. In tumors,microenvironmental changes, like in lactate metabolism, lead to altered transmembranous pH-gradients (with decreased extra- and increased intracellular pH-values: pHe < pHi) and vice versa. In wounds, barrier disruption results in extensive variations in pHe on the wound surface. It is known that altered extracellular proton concentrations have a major impact on cell turnover and migration as well as on the metabolic activity of cells involved in tumor spread and wound closure. The proton-sensing G protein-coupled receptors (GPCRs) GPR4 (GPR19), GPR65 (TDAG8, T-cell death-associated gene 8), GPR68 (OGR1, ovarian cancer GPCR 1) and GPR132 (G2A, G2 accumulation protein) are activated via a decrease in pHe and transduce this signal to molecular intracellular pathways. Based on the current knowledge, we speculate on the role of proton-sensing GPCRs in wound healing and on their potential as mechanistic linkers of tumor growth and tissue repair, both processes being highly dependent on cell proliferation and migration. The expression of these GPCRs in normal adult cells (keratinocytes, fibroblasts) and tumor cells (melanoma, squamous cell carcinoma) will be studied comprehensively in cell culture and histology for the first time. Additionally, we will study the impact of pHe on cell proliferation and migration after selective knockout of the different proton-sensitive GPCRs (via CRISPR/Cas, alternatively siRNA). The results will provide new insights on the role of proton-sensitive GPCRs in tumor growth and wound healing, and they will be important for the use of drugs modifying tumor pH, potentially also for drugs directly acting on proton-sensitive GPCRs.