Genetic Loss-of-Function Studies of SETD2 in Kidney Tumorigenesis

最近的大规模癌症基因组测序研究发现，表观遗传调控因子是一种新的主要 癌症基因的类别。SETD2就是这样一个例子。SETD2编码非冗余H3K36 三甲基转移酶，在多种人类癌症中经常发生突变。基于TCGA数据集， 13%的肾透明细胞癌、8.9%的子宫内膜中有SETD2突变 肺癌8.7%，膀胱尿路上皮癌6.9%，胃癌5.5% 腺癌，结直肠癌5.4%，黑色素瘤5.2%，肝细胞癌4.6%， 在ccRCC和肺腺癌中发现的SETD2突变大多是截短突变 位于SRI结构域的上游，介导SETD2与RNA聚合酶II的相互作用。 SETD2所在的染色体3p在ccRCC和肺腺癌中普遍缺失。 总之，这些癌症基因组数据有力地支持了SETD2的肿瘤抑制作用。然而， SETD2的肿瘤抑制功能尚未完全确立以及SETD2功能丧失如何促进 肿瘤发生机制尚不清楚。在这里，我们产生了有条件的SETD2基因敲除小鼠来解决 SETD2在肾癌中的抑瘤作用/机制值得注意的是，SETD2突变经常同时发生 与其他公认的驱动程序突变，如肾细胞癌中的VHL和PBRM1，急性肾细胞癌的MLL融合 白血病和激活RTK/RAS/RAF通路的突变在肺腺癌中的作用 SETD2缺失可能与这些驱动突变协同促进肿瘤的发生。在中国的癌症中 在已报道的SETD2突变中，ccRCC的突变率最高。尽管中国铁路总公司有 长期以来一直被认为是一种VHL丢失驱动的疾病，在这种疾病中，VHL发生突变或沉默的比例高达80%-90% CcRCC，VHL单独缺失不足以诱发小鼠肾癌，这表明额外的基因 Event(S)需要配合VHL Lost进行肾脏肿瘤的发生。在这里，我们假设VHL损失 和SETD2丢失将合作促进ccRCC的发展，这将被用遗传学来询问 经过改造的老鼠模型。此外，我们的基因组研究表明SETD2突变与 与肾细胞癌的进展和转移有关。我们计划建立患者来源的转移性临床前模型 目的：探讨SETD2缺失在促进肿瘤转移中的作用。我们的目标是 以人类肿瘤基因组学为基础建立慢性肾细胞癌生理性临床前模型 理解SETD2缺失引起的表观遗传学失调如何促进肿瘤的发生和发展 转移，并发现与SETD2丢失相关的新的治疗脆弱性。

Recent large-scale cancer genome sequencing studies have uncovered epigenetic regulators as a new major class of cancer genes. SETD2 is one such example. SETD2 encodes a non-redundant H3K36 trimethyltransferase and is frequently mutated in a wide variety of human cancers. Based on TCGA datasets, SETD2 is mutated in 13% of clear cell renal cell carcinoma (ccRCC), 8.9% of uterine corpus endometrial carcinoma, 8.7% of lung adenocarcinoma, 6.9% of bladder urothelial carcinoma, 5.5% of stomach adenocarcinoma, 5.4% of colorectal adenocarcinoma, 5.2% of melanoma, 4.6 % of hepatocellular carcinoma, etc. The majority of SETD2 mutations identified in ccRCC and lung adenocarcinoma are truncating mutations located upstream of the SRI domain that mediates the interaction of SETD2 with RNA polymerase II. Notably, chromosome 3p where SETD2 resides is commonly deleted in both ccRCC and lung adenocarcinoma. Altogether, these cancer genomics data strongly support a tumor suppressor role of SETD2. However, the tumor suppressor function of SETD2 has not been fully established and how SETD2 loss-of-function promotes tumorigenesis remains unclear. Herein, we have generated conditional Setd2 knockout mice to address the tumor suppressor function/mechanisms of SETD2 in kidney cancer. Notably, SETD2 mutations often co-occur with other well-established driver mutations, such as VHL and PBRM1 in ccRCC, MLL-fusions in acute leukemia, and mutations activating the RTK/RAS/RAF pathway in lung adenocarcinomas, suggesting that SETD2 loss probably cooperates with these driver mutations to promote tumorigenesis. Among cancers in which SETD2 mutations have been reported, ccRCC shows the highest mutation rate. Although ccRCC has long been recognized as a VHL loss-driven disease in which VHL is mutated or silenced in up to 80-90% of ccRCC, deletion of Vhl alone is insufficient to induce kidney cancer in mice, indicating that additional genetic event(s) is required to cooperate with VHL loss for kidney tumorigenesis. Here, we hypothesize that VHL loss and SETD2 loss will cooperate to promote ccRCC development, which will be interrogated using genetically engineered mouse models. Furthermore, our genomic studies indicate that SETD2 mutations are associated with ccRCC progression and metastasis. We plan to establish patient-derived preclinical models of metastatic SETD2 mutant ccRCC to investigate the role of SETD2 loss in promoting tumor metastasis. Our goals are to establish physiological preclinical models of ccRCC based on human cancer genomics, to provide mechanistic understanding of how dysregulated epigenetics conferred by SETD2 loss promotes tumor initiation and metastasis, and to discover novel therapeutic vulnerabilities associated with loss of SETD2.