Laboratory of Hormonal Regulation, Cardiovascular and Metabolic Disorders Program, Duke-National University of Singapore Graduate Medical School, Singapore.
BMC Med Genomics. 2012 Aug 9;5:34. doi: 10.1186/1755-8794-5-34.
While there is strong evidence for phosphatidylinositol 3-kinase (PI3K) involvement in cancer development, there is limited information about the role of PI3K regulatory subunits. PIK3R3, the gene that encodes the PI3K regulatory subunit p55γ, is over-expressed in glioblastoma and ovarian cancers, but its expression in gastric cancer (GC) is not known. We thus used genetic and bioinformatic approaches to examine PIK3R3 expression and function in GC, the second leading cause of cancer mortality world-wide and highly prevalent among Asians.
Primary GC and matched non-neoplastic mucosa tissue specimens from a unique Asian patient gastric cancer library were comprehensively profiled with platforms that measured genome-wide mRNA expression, DNA copy number variation, and DNA methylation status. Function of PIK3R3 was predicted by IPA pathway analysis of co-regulated genes with PIK3R3, and further investigated by siRNA knockdown studies. Cell proliferation was estimated by crystal violet dye elution and BrdU incorporation assay. Cell cycle distribution was analysed by FACS.
PIK3R3 was significantly up-regulated in GC specimens (n = 126, p < 0.05), and 9.5 to 15% tumors showed more than 2 fold increase compare to the paired mucosa tissues. IPA pathway analysis showed that PIK3R3 promoted cellular growth and proliferation. Knockdown of PIK3R3 decreased the growth of GC cells, induced G0/G1 cell cycle arrest, decreased retinoblastoma protein (Rb) phosphorylation, cyclin D1, and PCNA expression.
Using a combination of genetic, bioinformatic, and molecular biological approaches, we showed that PIK3R3 was up-regulated in GC and promoted cell cycle progression and proliferation; and thus may be a potential new therapeutic target for GC.
尽管有强有力的证据表明磷脂酰肌醇 3-激酶（PI3K）参与癌症的发展，但关于 PI3K 调节亚基的作用的信息有限。PIK3R3 是编码 PI3K 调节亚基 p55γ 的基因，在神经胶质瘤和卵巢癌中过表达，但在胃癌（GC）中的表达情况尚不清楚。因此，我们使用遗传和生物信息学方法来研究 PIK3R3 在 GC 中的表达和功能，GC 是全球第二大癌症死亡原因，在亚洲人群中非常普遍。
我们使用了能够全面测量全基因组 mRNA 表达、DNA 拷贝数变异和 DNA 甲基化状态的平台，对来自独特的亚洲患者胃癌库的原发性 GC 和匹配的非肿瘤黏膜组织标本进行了综合分析。通过 IPA 通路分析与 PIK3R3 共同调控的基因，预测了 PIK3R3 的功能，并通过 siRNA 敲低研究进一步进行了研究。通过结晶紫染料洗脱和 BrdU 掺入测定来估计细胞增殖。通过 FACS 分析细胞周期分布。
PIK3R3 在 GC 标本中显著上调（n = 126，p <0.05），与配对的黏膜组织相比，9.5%至 15%的肿瘤显示上调超过 2 倍。IPA 通路分析表明 PIK3R3 促进细胞生长和增殖。PIK3R3 敲低降低了 GC 细胞的生长，诱导 G0/G1 细胞周期停滞，降低视网膜母细胞瘤蛋白（Rb）磷酸化、细胞周期蛋白 D1 和 PCNA 表达。
我们使用遗传、生物信息学和分子生物学方法的组合表明，PIK3R3 在 GC 中上调并促进细胞周期进程和增殖；因此，它可能是 GC 的一个潜在新的治疗靶点。
