The a3 isoform of subunit a of the vacuolar ATPase localizes to the plasma membrane of invasive breast tumor cells and is overexpressed in human breast cancer.
The a3 isoform of subunit a of the vacuolar ATPase localizes to the plasma membrane of invasive breast tumor cells and is overexpressed in human breast cancer.
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DOI：
10.18632/oncotarget.10063
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发表时间：
2016-07-19
期刊：
影响因子：
--
通讯作者：
Forgac M
中科院分区：
文献类型：
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作者：
Cotter K;Liberman R;Sun-Wada G;Wada Y;Sgroi D;Naber S;Brown D;Breton S;Forgac M
液泡（H+）-ATP酶（V-ATP酶）是ATP驱动的质子泵家族，其酸化细胞内区室并将质子运输穿过质膜。先前的工作已经证明质膜V-ATP酶对于乳腺癌体外侵袭是重要的，并且V-ATP酶亚基a亚型a3在MDA-MB 231和MCF 10 CA 1a乳腺癌细胞侵袭中上调并且是关键的。已经提出亚基a3存在于侵袭性乳腺癌细胞的质膜上，并且在人乳腺癌中过表达。为了验证这一点，我们使用了α 3特异性抗体来评估乳腺癌细胞的定位。亚基a3定位于迁移性乳腺癌细胞的前缘，而不是正常乳腺上皮细胞的质膜。此外，侵袭性乳腺癌细胞在所有测试的细胞内区室中表达α 3，包括内体、高尔基体和溶酶体。此外，MB 231乳腺癌细胞中的α 3亚基敲低减少了体外迁移。这种减少在添加V-ATP酶抑制剂后没有增强，表明含有α 3的V-ATP酶对于乳腺癌迁移是至关重要的。最后，我们测试了a3在人乳腺癌组织中的表达以及从正常和癌性乳腺组织制备的mRNA。相对于正常组织，在所有测试的乳腺肿瘤cDNA样品中α 3 mRNA上调2.5-47倍，表达通常与癌症阶段相关。此外，相对于非浸润性癌和正常乳腺组织，浸润性乳腺癌组织中a3蛋白表达增加。这些研究表明，亚基a3在浸润性乳腺癌中起着重要作用。
The vacuolar (H+)-ATPases (V-ATPases) are a family of ATP-driven proton pumps that acidify intracellular compartments and transport protons across the plasma membrane. Previous work has demonstrated that plasma membrane V-ATPases are important for breast cancer invasion in vitro and that the V-ATPase subunit a isoform a3 is upregulated in and critical for MDA-MB231 and MCF10CA1a breast cancer cell invasion. It has been proposed that subunit a3 is present on the plasma membrane of invasive breast cancer cells and is overexpressed in human breast cancer. To test this, we used an a3-specific antibody to assess localization in breast cancer cells. Subunit a3 localizes to the leading edge of migrating breast cancer cells, but not the plasma membrane of normal breast epithelial cells. Furthermore, invasive breast cancer cells express a3 throughout all intracellular compartments tested, including endosomes, the Golgi, and lysosomes. Moreover, subunit a3 knockdown in MB231 breast cancer cells reduces in vitro migration. This reduction is not enhanced upon addition of a V-ATPase inhibitor, suggesting that a3-containing V-ATPases are critical for breast cancer migration. Finally, we have tested a3 expression in human breast cancer tissue and mRNA prepared from normal and cancerous breast tissue. a3 mRNA was upregulated 2.5-47 fold in all breast tumor cDNA samples tested relative to normal tissue, with expression generally correlated to cancer stage. Furthermore, a3 protein expression was increased in invasive breast cancer tissue relative to noninvasive cancer and normal breast tissue. These studies suggest that subunit a3 plays an important role in invasive human breast cancer.