Markaverich Barry M, Vijjeswarapu Mary
Department of Molecular and Cellular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
Int J Biomed Sci. 2012 Dec;8(4):219-32.
Type II [(3)H]estradiol binding site ligands including luteolin (a naturally occurring bioflavonoid) and synthetic compounds such as 2,6-bis((3-methoxy-4-hydroxyphenyl)methylene)cyclohexanone (BMHPC) inhibit normal and malignant prostate cell (PC-3, LNCaP, DU-145) proliferation in vitro and in vivo. Type II sites represent a binding domain on histone H4 possibly involved in an epigenetic mechanism for controlling gene transcription. Treatment of PC-3 human prostate cancer cells with luteolin or BMHPC modulated the expression of a number of genes in the epidermal growth factor receptor signaling pathway (EGFRSP) and cell cycle pathway (CCP). Pronounced stimulation (400-2000% of control) of c-FOS and p21 RNA expression was observed, suggesting that these were primary sites of action. Both compounds also caused irreversible G2/M arrest (p<0.001). siRNA's for c-FOS or p21 reduced the RNA expression of their respective targets by 85-95%, with minimal effects on cell proliferation. Furthermore, neither siRNA alone (single knockdown), or in combination (double knockdown), blocked luteolin or BMHPC inhibition of PC-3 cell proliferation. Thus, although c-FOS and p21 are known to modulate the expression of genes in the ESGRSP (EGFR, SOS, GRB2, JNK1, MKK4, RasGAP) and CCP (CCNA2, CCNE2, CDC25A, CDKN1A, CDKN1B, p27, PLK1) involved in the regulation of cell proliferation by luteolin and BMHPC, the c-FOS and p21 siRNA knockdown studies reported here suggest that c-FOS and p21 may be secondary bystanders in the overall response to these ligands in the regulation of PC-3 cell proliferation.
II型[(3)H]雌二醇结合位点配体，包括木犀草素（一种天然存在的生物黄酮）和合成化合物，如2,6-双((3-甲氧基-4-羟苯基)亚甲基)环己酮（BMHPC），在体外和体内均可抑制正常和恶性前列腺细胞（PC-3、LNCaP、DU-145）的增殖。II型位点代表组蛋白H4上的一个结合结构域，可能参与控制基因转录的表观遗传机制。用木犀草素或BMHPC处理PC-3人前列腺癌细胞，可调节表皮生长因子受体信号通路（EGFRSP）和细胞周期通路（CCP）中许多基因的表达。观察到c-FOS和p21 RNA表达有明显的刺激（对照的400 - 2000%），表明这些是主要作用位点。两种化合物还导致不可逆的G2/M期阻滞（p<0.001）。针对c-FOS或p21的小干扰RNA（siRNA）使各自靶点的RNA表达降低了85 - 95%，对细胞增殖的影响最小。此外，单独的siRNA（单敲低）或联合使用（双敲低）均未阻断木犀草素或BMHPC对PC-3细胞增殖的抑制作用。因此，尽管已知c-FOS和p21可调节木犀草素和BMHPC参与细胞增殖调控的ESGRSP（EGFR、SOS、GRB2、JNK1、MKK4、RasGAP）和CCP（CCNA2、CCNE2、CDC25A、CDKN1A、CDKN1B、p27、PLK1）中的基因表达，但本文报道的c-FOS和p21 siRNA敲低研究表明，在PC-3细胞增殖调控中，c-FOS和p21可能是这些配体总体反应中的次要旁观者。
