Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, OX1 3PT, UK.
Institute of Cellular and Organismic Biology, Academia Sinica, Taipei, 115, Taiwan.
J Physiol. 2017 Aug 15;595(16):5525-5544. doi: 10.1113/JP274659. Epub 2017 Jul 20.
The proton sensing ovarian cancer G protein coupled receptor 1 (OGR1, aka GPR68) promotes expression of the canonical transient receptor potential channel subunit TRPC4 in normal and transformed cerebellar granule precursor (DAOY) cells. OGR1 and TRPC4 are prominently expressed in healthy cerebellar tissue throughout postnatal development and in primary cerebellar medulloblastoma tissues. Activation of TRPC4-containing channels in DAOY cells, but not non-transformed granule precursor cells, results in prominent increases in [Ca ] and promotes cell motility in wound healing and transwell migration assays. Medulloblastoma cells not arising from granule precursor cells show neither prominent rises in [Ca ] nor enhanced motility in response to TRPC4 activation unless they overexpressTRPC4. Our results suggest that OGR1 enhances expression of TRPC4-containing channels that contribute to enhanced invasion and metastasis of granule precursor-derived human medulloblastoma.
Aberrant intracellular Ca signalling contributes to the formation and progression of a range of distinct pathologies including cancers. Rises in intracellular Ca concentration occur in response to Ca influx through plasma membrane channels and Ca release from intracellular Ca stores, which can be mobilized in response to activation of cell surface receptors. Ovarian cancer G protein coupled receptor 1 (OGR1, aka GPR68) is a proton-sensing G -coupled receptor that is most highly expressed in cerebellum. Medulloblastoma (MB) is the most common paediatric brain tumour that arises from cerebellar precursor cells. We found that nine distinct human MB samples all expressed OGR1. In both normal granule cells and the transformed human cerebellar granule cell line DAOY, OGR1 promoted expression of the proton-potentiated member of the canonical transient receptor potential (TRPC) channel family, TRPC4. Consistent with a role for TRPC4 in MB, we found that all MB samples also expressed TRPC4. In DAOY cells, activation of TRPC4-containing channels resulted in large Ca influx and enhanced migration, while in normal cerebellar granule (precursor) cells and MB cells not derived from granule precursors, only small levels of Ca influx and no enhanced migration were observed. Our results suggest that OGR1-dependent increases in TRPC4 expression may favour formation of highly Ca -permeable TRPC4-containing channels that promote transformed granule cell migration. Increased motility of cancer cells is a prerequisite for cancer invasion and metastasis, and our findings may point towards a key role for TRPC4 in progression of certain types of MB.
质子感应卵巢癌 G 蛋白偶联受体 1（OGR1，又名 GPR68）促进正常和转化的小脑颗粒前体细胞（DAOY）中经典瞬时受体电位通道亚基 TRPC4 的表达。OGR1 和 TRPC4 在整个出生后发育过程中以及原发性小脑成神经管细胞瘤组织中均在健康的小脑组织中大量表达。在 DAOY 细胞中激活包含 TRPC4 的通道，但在非转化的颗粒前体细胞中则不会，这导致 [Ca]的显著增加，并促进伤口愈合和 Transwell 迁移测定中的细胞迁移。源自颗粒前体细胞的成神经管细胞瘤细胞既不会因 TRPC4 激活而引起 [Ca]的显著升高，也不会增强迁移，除非它们过表达 TRPC4。我们的结果表明，OGR1 增强了包含 TRPC4 的通道的表达，这些通道有助于增强颗粒前体细胞衍生的人类成神经管细胞瘤的侵袭和转移。
异常的细胞内 Ca 信号转导导致多种不同病理的形成和进展，包括癌症。细胞内 Ca 浓度的升高是响应质膜通道的 Ca 内流和细胞内 Ca 储存库的 Ca 释放而发生的，这可以响应细胞表面受体的激活而被动员。卵巢癌 G 蛋白偶联受体 1（OGR1，又名 GPR68）是一种质子感应 G 蛋白偶联受体，在小脑组织中表达水平最高。成神经管细胞瘤（MB）是最常见的起源于小脑前体细胞的小儿脑肿瘤。我们发现，九个不同的人 MB 样本均表达 OGR1。在正常颗粒细胞和转化的人小脑颗粒细胞系 DAOY 中，OGR1 促进了经典瞬时受体电位（TRPC）通道家族中质子敏感受体的表达，即 TRPC4。TRPC4 在 MB 中的作用一致，我们发现所有 MB 样本也表达了 TRPC4。在 DAOY 细胞中，激活包含 TRPC4 的通道导致大量的 Ca 内流和增强的迁移，而在正常的小脑颗粒（前体细胞）细胞和不是来自颗粒前体的 MB 细胞中，只观察到少量的 Ca 内流和没有增强的迁移。我们的结果表明，OGR1 依赖性的 TRPC4 表达增加可能有利于形成高度 Ca 通透性的包含 TRPC4 的通道，从而促进转化的颗粒细胞迁移。癌细胞的迁移能力增加是癌症侵袭和转移的先决条件，我们的发现可能表明 TRPC4 在某些类型的 MB 进展中起着关键作用。
