Zhao Ming, Zhuo Ming-Lei, Zheng Xiaofeng, Su Xiaoping, Meric-Bernstam Funda
Department of Investigational Cancer Therapeutics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
Key Laboratory of Carcinogenesis and Translational Research, Department of Thoracic Medical Oncology-I, Peking University Cancer Hospital and Institute, Beijing, China.
Oncotarget. 2019 Jan 1;10(1):30-44. doi: 10.18632/oncotarget.26530.
Abnormal FGFR1 alternative splicing is correlated with tumorigenicity and poor prognosis in several tumor types. We sought to determine the roles of FGFR1α and FGFR1β variants in breast cancer. TCGA samples and cell lines were analyzed for FGFR1α/FGFR1β expression. MCF-10A cells were used to overexpress these variants. Cell growth and transformation were assessed by SRB, colony formation, 3D-Matrigel, soft agar, cell motility assays. In TCGA, compared to FGFR1 non-amplified samples, FGFR1-amplified samples had significantly higher FGFR1α but not FGFR1β levels. FGFR1β expression levels and FGFR1β/FGFR1α ratio were higher in basal subtype samples than in ER-positive/luminal samples in both TCGA and breast cancer cell lines. Both FGFR1α and FGFR1β induced transformation of MCF-10A cells. However, only FGFR1β-expressing cells, not FGFR1α, enhanced cell growth and cell motility. Cells with higher FGFR1β levels and FGFR1β/FGFR1α ratio were more sensitive to FGFR inhibitor BGJ-398. Interestingly, in ER-negative cells, FGFR inhibitors decreased FGFR1β levels, likely by increasing expression of splicing repressor PTBP1. In ER-positive cells, estrogen treatment increased FGFR1β levels by decreasing PTBP1 expression, which was blocked by 4-OHT. Lastly, combination treatment with BGJ-398 and 4-OHT synergistically inhibited cell survival. These findings suggest that FGFR1 alternative FGFR1α/FGFR1β splicing plays an important role in breast cancer.
异常的FGFR1可变剪接与多种肿瘤类型的致瘤性和不良预后相关。我们试图确定FGFR1α和FGFR1β变体在乳腺癌中的作用。对TCGA样本和细胞系进行FGFR1α/FGFR1β表达分析。使用MCF-10A细胞过表达这些变体。通过SRB、集落形成、3D-基质胶、软琼脂、细胞运动性实验评估细胞生长和转化。在TCGA中，与FGFR1未扩增样本相比，FGFR1扩增样本的FGFR1α水平显著更高，但FGFR1β水平并非如此。在TCGA样本和乳腺癌细胞系中，基底亚型样本的FGFR1β表达水平以及FGFR1β/FGFR1α比值均高于雌激素受体阳性/管腔型样本。FGFR1α和FGFR1β均诱导MCF-10A细胞发生转化。然而，只有表达FGFR1β的细胞，而非表达FGFR1α的细胞，能增强细胞生长和细胞运动性。FGFR1β水平和FGFR1β/FGFR1α比值较高的细胞对FGFR抑制剂BGJ-398更敏感。有趣的是，在雌激素受体阴性细胞中，FGFR抑制剂可能通过增加剪接抑制因子PTBP1的表达来降低FGFR1β水平。在雌激素受体阳性细胞中，雌激素处理通过降低PTBP1表达来增加FGFR1β水平，而这一作用被4-羟基他莫昔芬阻断。最后，BGJ-398与4-羟基他莫昔芬联合治疗可协同抑制细胞存活。这些发现表明FGFR1的可变剪接FGFR1α/FGFR1β在乳腺癌中起重要作用。
