Data for: L-type amino acid transporter 1, LAT1, in growth hormone-producing pituitary tumor cells

The data show the roles of LAT1 in growth hormone (GH)-producing pituitary tumor cells, GH4 cells. Briefly, GH4 cells express higher LAT1 gene levels compared to rat normal pituitary tissues (Fig. 1A). A selective LAT1 inhibitor, JPH203, does not change LATs expression profiles in GH4 cells (Fig.1B and C), and pharmacological LAT1 inhibition by JPH203 suppresses leucine uptake and cell growth in GH4 cells (Fig. 2A and C, and Supplemental Fig. 1). Deprivation of leucine reduces cell growth in GH4 cells (Fig 2B). JPH203 suppresses GH production and secretion in GH4 cells (Fig. 3A, B, and C). JPH203 also reduces prolactin gene expression levels. Genetic downregulation of LAT1 shows similar effects on cell growth and hormone production (Fig. 4A, B, and C, and Supplemental Fig 3). JPH203 does not alter the activity of the mTOR pathway (Fig. 5A, B, and C). Pharmacological mTOR inhibition by rapamycin suppresses cell growth but does not alter GH production in GH4 cells (Fig. 6A, B, and C). JPH203 does not induce apoptosis in GH4 cells (Fig. 7). A combination of JPH203 and rapamycin shows additive anti-tumor effects on cell growth in GH4 cells (Supplemental Fig. 4) .

本研究数据揭示了LAT1在生长激素（GH）分泌性垂体肿瘤细胞，即GH4细胞中的功能。简言之，与大鼠正常垂体组织相比，GH4细胞中LAT1基因的表达水平较高（图1A）。选择性LAT1抑制剂JPH203对GH4细胞中LATs的表达谱无显著影响（图1B和C），而JPH203通过药理学抑制LAT1能够抑制GH4细胞中的亮氨酸摄取和细胞生长（图2A和C，及补充图1）。亮氨酸剥夺可降低GH4细胞的细胞生长（图2B）。JPH203能够抑制GH4细胞中GH的生成和分泌（图3A、B和C）。此外，JPH203亦能降低催乳素基因的表达水平。遗传性降低LAT1的表达对细胞生长和激素生成表现出类似的影响（图4A、B和C，及补充图3）。JPH203不改变mTOR通路的活动（图5A、B和C）。通过拉帕霉素药理学抑制mTOR能够抑制细胞生长，但不会改变GH的生成（图6A、B和C）。JPH203不诱导GH4细胞的凋亡（图7）。JPH203与拉帕霉素联合应用对GH4细胞的细胞生长展现出协同的抗肿瘤效应（补充图4）。