Department of Pathology and Simmons Cancer Center, UT Southwestern Medical Center, Dallas, Texas, United States of America.
PLoS One. 2013 Sep 25;8(9):e73449. doi: 10.1371/journal.pone.0073449. eCollection 2013.
Germline mutations in the LKB1 gene (also known as STK11) cause the Peutz-Jeghers Syndrome, and somatic loss of LKB1 has emerged as causal event in a wide range of human malignancies, including melanoma, lung cancer, and cervical cancer. The LKB1 protein is a serine-threonine kinase that phosphorylates AMP-activated protein kinase (AMPK) and other downstream targets. Conditional knockout studies in mouse models have consistently shown that LKB1 loss promotes a highly-metastatic phenotype in diverse tissues, and human studies have demonstrated a strong association between LKB1 inactivation and tumor recurrence. Furthermore, LKB1 deficiency confers sensitivity to distinct classes of anticancer drugs. The ability to reliably identify LKB1-deficient tumors is thus likely to have important prognostic and predictive implications. Previous research studies have employed polyclonal antibodies with limited success, and there is no widely-employed immunohistochemical assay for LKB1. Here we report an assay based on a rabbit monoclonal antibody that can reliably detect endogenous LKB1 protein (and its absence) in mouse and human formalin-fixed, paraffin-embedded tissues. LKB1 protein levels determined through this assay correlated strongly with AMPK phosphorylation both in mouse and human tumors, and with mRNA levels in human tumors. Our studies fully validate this immunohistochemical assay for LKB1 in paraffin-embedded formalin tissue sections. This assay should be broadly useful for research studies employing mouse models and also for the development of human tissue-based assays for LKB1 in diverse clinical settings.
LKB1 基因（也称为 STK11）的种系突变导致 Peutz-Jeghers 综合征，而 LKB1 的体细胞缺失已成为多种人类恶性肿瘤的因果事件，包括黑色素瘤、肺癌和宫颈癌。LKB1 蛋白是一种丝氨酸-苏氨酸激酶，可磷酸化 AMP 激活的蛋白激酶（AMPK）和其他下游靶标。在小鼠模型中的条件敲除研究一致表明，LKB1 缺失促进了多种组织中的高度转移性表型，而人类研究表明 LKB1 失活与肿瘤复发之间存在很强的关联。此外，LKB1 缺乏赋予对不同类别的抗癌药物的敏感性。因此，能够可靠地识别 LKB1 缺陷型肿瘤可能具有重要的预后和预测意义。先前的研究使用具有有限成功的多克隆抗体，并且没有广泛使用的 LKB1 免疫组织化学检测方法。在这里，我们报告了一种基于兔单克隆抗体的检测方法，该方法可在小鼠和人类福尔马林固定、石蜡包埋组织中可靠地检测内源性 LKB1 蛋白（及其缺失）。通过该检测方法确定的 LKB1 蛋白水平与小鼠和人类肿瘤中的 AMPK 磷酸化以及人类肿瘤中的 mRNA 水平密切相关。我们的研究充分验证了该用于石蜡包埋福尔马林组织切片的 LKB1 免疫组织化学检测方法。该检测方法应该在使用小鼠模型的研究中广泛有用，并且还可以在不同临床环境中开发用于 LKB1 的基于人组织的检测方法。
