Genomic Analyses Reveal Mutational Signatures and Frequently Altered Genes in Esophageal Squamous Cell Carcinoma

Ling Zhang, Yong Zhou, Caixia Cheng, Heyang Cui, Le Cheng, Pengzhou Kong, Jiaqian Wang, Yin Li, Wenliang Chen, Bin Song, Fang Wang, Zhiwu Jia, Lin Li, Yaoping Li, Bin Yang, Jing Liu, Ruyi Shi, Yanghui Bi, Yanyan Zhang, Juan Wang, Zhenxiang Zhao, Xiaoling Hu, Jie Yang, Hongyi Li, Zhibo Gao, Gang Chen, Xuanlin Huang, Xukui Yang, Shengqing Wan, Chao Chen, Bin Li, Yongkai Tan, Longyun Chen, Minghui He, Sha Xie, Xiangchun Li, Xuehan Zhuang, Mengyao Wang, Zhi Xia, Longhai Luo, Jie Ma, Bing Dong, Jiuzhou Zhao, Yongmei Song, Yunwei Ou, Enming Li, Liyan Xu, Jinfen Wang, Yanfeng Xi, Guodong Li, Enwei Xu, Jianfang Liang, Xiaofeng Yang, Jiansheng Guo, Xing Chen, Yanbo Zhang, Qingshan Li, Lixin Liu, Yingrui Li, Xiuqing Zhang, Huanming Yang, Dongxin Lin, Xiaolong Cheng, Yongjun Guo, Jun Wang, Qimin Zhan, Yongping Cui

Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers worldwide and the fourth most lethal cancer in China. However, although genomic studies have identified some mutations associated with ESCC, we know little of the mutational processes responsible. To identify genome-wide mutational signatures, we performed either whole-genome sequencing (WGS) or whole-exome sequencing (WES) on 104 ESCC individuals and combined our data with those of 88 previously reported samples. An APOBEC-mediated mutational signature in 47% of 192 tumors suggests that APOBEC-catalyzed deamination provides a source of DNA damage in ESCC. Moreover, PIK3CA hotspot mutations (c.1624G>A [p.Glu542Lys] and c.1633G>A [p.Glu545Lys]) were enriched in APOBEC-signature tumors, and no smoking-associated signature was observed in ESCC. In the samples analyzed by WGS, we identified focal (<100 kb) amplifications of CBX4 and CBX8. In our combined cohort, we identified frequent inactivating mutations in AJUBA, ZNF750, and PTCH1 and the chromatin-remodeling genes CREBBP and BAP1, in addition to known mutations. Functional analyses suggest roles for several genes (CBX4, CBX8, AJUBA, and ZNF750) in ESCC. Notably, high activity of hedgehog signaling and the PI3K pathway in approximately 60% of 104 ESCC tumors indicates that therapies targeting these pathways might be particularly promising strategies for ESCC. Collectively, our data provide comprehensive insights into the mutational signatures of ESCC and identify markers for early diagnosis and potential therapeutic targets.