Kearney Alper Y, Fan You-Hong, Giri Uma, Saigal Babita, Gandhi Varsha, Heymach John V, Zurita Amado J
Department of Genitourinary Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
Department of Thoracic & Head and Neck Medical Oncology, Division of Cancer Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America.
PLoS One. 2015 Aug 27;10(8):e0135962. doi: 10.1371/journal.pone.0135962. eCollection 2015.
The adenosine analog 8-chloroadenosine has been shown to deplete ATP and inhibit tumor growth in hematological malignancies as well as in lung and breast cancer cell lines. We investigated effects of 8-chloroadenosine on clear cell (cc) renal cell carcinoma (RCC) cell lines. 8-chloroadenosine was effective against ccRCC cell viability in vitro, with IC50 ranging from 2 μM in the most sensitive CAKI-1 to 36 μM in the most resistant RXF-393. Proteomic analysis by reverse-phase protein array revealed that 8-chloroadenosine treatment leads to inhibition of the mTOR pathway. In time-course experiments, 8-chloroadenosine treatment rapidly activated AMPK, measured by AMPK and ACC phosphorylation, and subsequently caused dephosphorylation of p70S6K and ribosomal protein RPS6 in the sensitive cell lines. However, in the resistant cell lines, AMPK activity and the mTOR pathway were unaffected by the treatment. We also noted that the resistant cell lines had elevated basal levels of phospho RPS6 and AKT. Inhibition of PI3K pathway enhanced the efficacy of 8-chloroadenosine across all cell lines. Our observations indicate that 8-chloroadenosine activity is associated with inhibition of the mTOR pathway, and that phospho RPS6 and PI3K pathway activation status may determine resistance. Among solid tumors, RCC is one of the few susceptible to mTOR inhibition. We thus infer that 8-chloroadenosine may be effective in RCC by activating AMPK and inhibiting the mTOR pathway.
腺苷类似物8-氯腺苷已被证明可消耗三磷酸腺苷（ATP），并抑制血液系统恶性肿瘤以及肺癌和乳腺癌细胞系中的肿瘤生长。我们研究了8-氯腺苷对透明细胞（cc）肾细胞癌（RCC）细胞系的影响。8-氯腺苷在体外对ccRCC细胞活力有效，半数抑制浓度（IC50）范围从最敏感的CAKI-1细胞系中的2μM到最耐药的RXF-393细胞系中的36μM。通过反相蛋白质阵列进行的蛋白质组学分析表明，8-氯腺苷处理可导致雷帕霉素靶蛋白（mTOR）通路受到抑制。在时间进程实验中，通过检测AMPK和乙酰辅酶A羧化酶（ACC）的磷酸化来衡量，8-氯腺苷处理可迅速激活AMPK，随后导致敏感细胞系中p70核糖体蛋白S6激酶（p70S6K）和核糖体蛋白RPS6的去磷酸化。然而，在耐药细胞系中，AMPK活性和mTOR通路不受该处理的影响。我们还注意到，耐药细胞系中磷酸化RPS6和蛋白激酶B（AKT）的基础水平升高。抑制磷脂酰肌醇-3激酶（PI3K）通路可增强8-氯腺苷在所有细胞系中的疗效。我们的观察结果表明，8-氯腺苷的活性与mTOR通路的抑制有关，并且磷酸化RPS6和PI3K通路的激活状态可能决定耐药性。在实体瘤中，RCC是少数对mTOR抑制敏感的肿瘤之一。因此，我们推断8-氯腺苷可能通过激活AMPK和抑制mTOR通路对RCC有效。
