EGFR activity addiction facilitates anti-ERBB based combination treatment of squamous bladder cancer. EGFR activity addiction facilitates anti-ERBB based combination treatment of squamous bladder cancer

Recent findings suggested a benefit of anti-EGFR therapy for basal-like muscle invasive bladder cancer (MIBC). However, impact on bladder cancer with substantial squamous differentiated (Sq-BLCA) and especially pure squamous cell carcinoma (SCC) remains unknown. Therefore, we comprehensively characterized pure and mixed Sq-BLCA (n=125) on genetic and protein expression level, and performed functional pathway and drug-response analyses with cell line models and isolated primary SCC (p-SCC) cells of the human urinary bladder. We identified abundant EGFR expression in 95% of Sq-BLCA without evidence for activating EGFR mutations. Both SCaBER and p-SCC cells were sensitive to EGFR tyrosine kinase inhibitors (TKIs: erlotinib and gefitinib). Combined treatment with anti-EGFR TKIs and varying chemotherapeutics led to a concentration-dependent synergism in SCC cells according to the Chou-Talalay method. In addition, siRNA knockdown of EGFR impaired SCaBER viability suggesting a putative ‘‘Achilles heel’’ of Sq-BLCA. The observed effects seem Sq-BLCA-specific since non-basal urothelial cancer cells were characterized by poor TKI sensitivity associated with a short-term feedback response by upregulating EGFR and ERBB3 expression. Hence, our findings give novel insights into a crucial, Sq-BLCA-specific role of the ERBB signaling pathway proposing improved effectiveness of combined anti-EGFR and chemotherapeutic regimens in squamous bladder cancers with wild-type EGFR-overexpression. Overall design: Tumor tissue of an individual diagnosed with a pure SCC was obtained from the RWTH centralized biomaterial bank (RWTH cBMB) for SCC-tumor cell (p-SCC) isolation. Primary cells derived from pure SCC (p-SCC) tissue were established as a cell culture ex vivo model. p-SCC cells (n=1) were characterized and compared with the original tumor tissue (n=1) by whole transcriptomic analysis. SCaBER (n=1) and J82 cell lines (n=1) served as squamous and urothelial-like controls.

近期研究表明，抗表皮生长因子受体（EGFR）治疗对基底样肌浸润性膀胱癌（MIBC）具有获益价值。然而，该疗法对伴显著鳞状分化的膀胱癌（Sq-BLCA），尤其是纯型鳞状细胞癌（SCC）的疗效仍不明确。为此，本研究从基因与蛋白表达层面全面表征了125例纯型与混合型鳞状分化膀胱癌（Sq-BLCA，n=125），并利用人膀胱来源的细胞系模型与分离得到的原代鳞状细胞癌（p-SCC）细胞开展功能通路及药物应答分析。研究发现，95%的Sq-BLCA中存在丰富的EGFR表达，且未检测到EGFR激活突变。SCaBER细胞与p-SCC细胞均对EGFR酪氨酸激酶抑制剂（TKIs，即厄洛替尼（erlotinib）与吉非替尼（gefitinib））敏感。采用Chou-Talalay法分析显示，抗EGFR TKI与多种化疗药物联合使用时，可在SCC细胞中产生浓度依赖性协同效应。此外，通过小干扰RNA（siRNA）敲低EGFR的表达会抑制SCaBER细胞的活力，提示Sq-BLCA存在潜在的“阿喀琉斯之踵”（Achilles heel）。上述效应似乎具有Sq-BLCA特异性，因为非基底型尿路上皮癌细胞对TKI的敏感性较差，且会通过上调EGFR与ERBB3的表达产生短期反馈应答。因此，本研究结果为ERBB信号通路在Sq-BLCA中的关键特异性作用提供了全新见解，并提出针对EGFR野生型且过表达的鳞状膀胱癌患者，联合抗EGFR治疗与化疗方案可获得更佳临床获益。研究整体设计：本研究从亚琛工业大学中心生物样本库（RWTH cBMB）获取1例确诊为纯型SCC患者的肿瘤组织，用于分离SCC肿瘤细胞（p-SCC）；将从纯型SCC组织中分离得到的原代细胞构建为体外细胞培养模型；通过全转录组分析，对1株p-SCC细胞（n=1）及其对应的原始肿瘤组织（n=1）进行表征与比对；以1株SCaBER细胞系（n=1）与1株J82细胞系（n=1）分别作为鳞状型与尿路上皮样对照。