TRPC6 forms non-selective cation channels activated by a variety of stimuli that are involved in a wide number of cellular functions. In estrogen receptor-positive (ER+) breast cancer cells, the store-operated Ca2+ entry has been reported to be dependent on STIM1, STIM2 and Orai3, with TRPC6 playing a key role in the activation of store-operated Ca2+ entry as well as in proliferation, migration and viability of breast cancer cells. We have used a combination of biotinylation, Ca2+ imaging as well as protein knockdown and overexpression of a dominant-negative TRPC6 mutant (TRPC6dn) to show that TRPC6 and STIM2 are required for the maintenance of cytosolic and endoplasmic reticulum Ca2+ content under resting conditions in ER+ breast cancer MCF7 cells. These cells exhibit a greater plasma membrane expression of TRPC6 under resting conditions than non-tumoral breast epithelial cells. Attenuation of STIM2, TRPC6 and Orai3, alone or in combination, results in impairment of resting cytosolic and endoplasmic reticulum Ca2+ homeostasis. Similar results were observed when cells were transfected with expression plasmid for TRPC6dn. TRPC6 co-immunoprecipitates with STIM2 in resting MCF7 cells, a process that is impaired by rises in cytosolic Ca2+ concentration. Impairment of TRPC6 function leads to abnormal Ca2+ homeostasis and endoplasmic reticulum stress, thus, suggesting that TRPC6 might be a potential target for the development of anti-tumoral therapies.

中文翻译：

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TRPC6和STIM2在静止的雌激素受体阳性乳腺癌细胞的胞质和内质网Ca2 +含量中的功能作用。

TRPC6形成由多种细胞功能涉及的多种刺激激活的非选择性阳离子通道。在雌激素受体阳性（ER +）乳腺癌细胞中，据报道储库操纵的Ca2 +进入依赖于STIM1，STIM2和Orai3，而TRPC6在激活储库操纵的Ca2 +进入中起关键作用。乳腺癌细胞的增殖，迁移和生存力。我们已结合使用生物素化，Ca2 +成像以及蛋白敲低和显性负性TRPC6突变体（TRPC6dn）的过度表达来证明，在静息条件下，ERPC +中需要TRPC6和STIM2来维持胞质和内质网Ca2 +含量乳腺癌MCF7细胞。这些细胞在静止条件下比非肿瘤乳腺上皮细胞表现出更高的质膜表达。单独或组合使用STIM2，TRPC6和Orai3时，均会导致静息的胞质和内质网Ca2 +稳态破坏。当用TRPC6dn的表达质粒转染细胞时，观察到相似的结果。TRPC6在静止的MCF7细胞中与STIM2共同免疫沉淀，该过程因胞质Ca2 +浓度升高而受损。TRPC6功能受损导致异常的Ca2 +稳态和内质网应激，因此，表明TRPC6可能是抗肿瘤疗法发展的潜在靶标。导致静息的胞质和内质网Ca2 +稳态破坏。当用TRPC6dn的表达质粒转染细胞时，观察到相似的结果。TRPC6在静止的MCF7细胞中与STIM2共同免疫沉淀，该过程因胞质Ca2 +浓度升高而受损。TRPC6功能受损导致异常的Ca2 +稳态和内质网应激，因此，表明TRPC6可能是抗肿瘤疗法发展的潜在靶标。导致静息的胞质和内质网Ca2 +稳态破坏。当用TRPC6dn的表达质粒转染细胞时，观察到相似的结果。TRPC6在静止的MCF7细胞中与STIM2共同免疫沉淀，该过程因胞质Ca2 +浓度升高而受损。TRPC6功能受损导致异常的Ca2 +稳态和内质网应激，因此，表明TRPC6可能是抗肿瘤疗法发展的潜在靶标。