INSERM U1240 IMoST, University of Clermont Auvergne, Clermont-Ferrand, F-63000, France.
Département d'Oncogénétique, Centre Jean Perrin, F-63011 Clermont-Ferrand, France.
Int J Med Sci. 2020 Oct 1;17(17):2799-2808. doi: 10.7150/ijms.43101. eCollection 2020.
Basal-like breast cancer is among the most aggressive cancers and there is still no effective targeted treatment. In order to identify new therapeutic targets, we performed mRNA-Seq on eight breast cancer cell lines. Among the genes overexpressed in basal-like tumors, we focused on the RhoA and RhoB genes, which encode small GTPases known to play a role in the actin cytoskeleton, allowing cells to migrate. qRT-PCR and Western blotting were used for expression studies. Migratory and invasive properties were analysed by wound healing and Boyden chambers assays. Stress fibers formation was evaluated by fluorescent actin labeling. Rho siRNA, small inhibitor Rhosin treatment and BRCA1 transfection were performed to study the role of Rho and BRCA1 proteins. We showed that strong expression of RhoA and low expression of RhoB was associated with the basal-like subtype of breast cancer. Decreasing RhoA expression reduced the migratory and invasive capacities of basal-like cell lines, while decreasing RhoB expression increased these capacities. Rhosin, an inhibitor of RhoA, could also reduce the migration of basal-like cell lines. Rho proteins are involved in the formation of stress fibers, a conformation of the actin cytoskeleton found in migrating cells: inhibition of RhoA expression decreased the formation of these fibers. , a gene frequently inactivated in basal-like tumors, appears to play a role in the differential expression of RhoA and RhoB in these tumors, as the restoration of BRCA1 expression in a BRCA1-mutated basal-like cell line decreased expression of RhoA and increased expression of RhoB, resulting in reduced migratory capacity. These results suggest Rho proteins as potential therapeutic targets for basal-like and BRCA1-mutated breast cancer, as migration and acquisition of mesenchymal properties are key functional pathways in these tumors with high metastatic potential.
基底样乳腺癌是最具侵袭性的癌症之一，目前仍没有有效的靶向治疗方法。为了寻找新的治疗靶点，我们对 8 种乳腺癌细胞系进行了 mRNA-Seq 分析。在基底样肿瘤中过表达的基因中，我们重点关注 RhoA 和 RhoB 基因，它们编码已知在肌动蛋白细胞骨架中起作用的小 GTPase，使细胞能够迁移。使用 qRT-PCR 和 Western blot 进行表达研究。通过划痕愈合和 Boyden 室测定分析迁移和侵袭特性。通过荧光肌动蛋白标记评估应力纤维形成。进行 Rho siRNA、小分子抑制剂 Rhosin 处理和 BRCA1 转染以研究 Rho 和 BRCA1 蛋白的作用。我们表明，RhoA 的强表达和 RhoB 的低表达与乳腺癌的基底样亚型相关。降低 RhoA 的表达降低了基底样细胞系的迁移和侵袭能力，而降低 RhoB 的表达增加了这些能力。Rho 蛋白抑制剂 Rhosin 也可以减少基底样细胞系的迁移。Rho 蛋白参与应激纤维的形成，应激纤维是迁移细胞中肌动蛋白细胞骨架的一种构象：抑制 RhoA 的表达减少了这些纤维的形成。, 一种在基底样肿瘤中经常失活的基因，似乎在这些肿瘤中 RhoA 和 RhoB 的差异表达中起作用，因为在 BRCA1 突变的基底样细胞系中恢复 BRCA1 的表达降低了 RhoA 的表达并增加了 RhoB 的表达，从而降低了迁移能力。这些结果表明 Rho 蛋白可能成为基底样和 BRCA1 突变型乳腺癌的潜在治疗靶点，因为迁移和获得间质特性是这些具有高转移潜能的肿瘤中的关键功能途径。
