Chen Xuejun, Gao Wen, Yin Gaofei, Guo Wei, Huang Junwei, Huang Zhigang, Zhang Yang
Department of Otolaryngology Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
Ann Transl Med. 2021 Sep;9(18):1455. doi: 10.21037/atm-21-4335.
Erlotinib is a commonly used epidermal growth factor receptor (EGFR)-targeted therapeutic choice for head and neck squamous cell carcinoma; however, its efficacy is largely compromised by cancer cell resistance. Understanding and targeting the erlotinib adaptive mechanisms of squamous cell carcinoma of the head and neck (HNSCC) cancer cells are still pressing challenges. This study aimed to elucidate the cooperative erlotinib-sensitizing mechanisms of histone deacetylase (HDAC) and phosphatidylinositol 3-kinase (PI3K) co-inhibition, which will be helpful in gaining a better understanding of the mechanism of EGFR-tyrosine kinase inhibitor (TKI) resistance in head and neck cancer cells.
High-content screening (HCS) was performed to analyze the cell counts of different treatment groups and their drug-sensitizing effect phenotype. Western blotting and immunofluorescence staining assays were used to measure and locate the expression of proteins in the FaDu and TU212 cells. Annexin V/PI and DAPI staining were also used to determine the ratio of apoptotic cells and different cell cycle phases.
The expression of phosphor-EGFRTyr992 was significantly increased in erlotinib-treated FaDu cells compared with dimethyl sulfoxide (DMSO)-treated FaDu cells. Meanwhile, erlotinib + vorinostat + copanlisib jointly attenuated the expression of phosphor-EGFRTyr1068 and phosphor-EGFRTyr992, but stimulated the expression of E-cadherin. Moreover, we found that the tri-drug group also impaired the expression of phosphor-STAT3Ser727 and its relevant activators, including phosphor-SrcTyr416.
These findings indicate that HDACs and PI3K co-inhibition sensitizes erlotinib via inactivation of the phosphor-EGFRTyr1068-induced RTK-STAT3 axis. However, PI3K inhibition was sufficient to sensitize TU212 cells to erlotinib, providing new perspectives for the further clinical study of erlotinib + vorinostat + copanlisib as a potential combination therapeutic solution for EGFR responsive reactivation-induced resistance to erlotinib.
厄洛替尼是头颈部鳞状细胞癌常用的表皮生长因子受体（EGFR）靶向治疗药物；然而，癌细胞耐药性在很大程度上削弱了其疗效。了解并针对头颈部鳞状细胞癌（HNSCC）癌细胞的厄洛替尼适应性机制仍是紧迫的挑战。本研究旨在阐明组蛋白去乙酰化酶（HDAC）和磷脂酰肌醇3激酶（PI3K）共同抑制对厄洛替尼的增敏机制，这将有助于更好地理解头颈部癌细胞中EGFR酪氨酸激酶抑制剂（TKI）耐药的机制。
进行高内涵筛选（HCS）以分析不同治疗组的细胞计数及其药物增敏效应表型。采用蛋白质印迹法和免疫荧光染色法检测和定位FaDu和TU212细胞中蛋白质的表达。Annexin V/PI和DAPI染色也用于确定凋亡细胞比例和不同细胞周期阶段。
与二甲基亚砜（DMSO）处理的FaDu细胞相比，厄洛替尼处理的FaDu细胞中磷酸化EGFR Tyr992的表达显著增加。同时，厄洛替尼+伏立诺他+库潘尼西共同减弱了磷酸化EGFR Tyr1068和磷酸化EGFR Tyr992的表达，但刺激了E-钙黏蛋白的表达。此外，我们发现三联药物组还削弱了磷酸化STAT3 Ser727及其相关激活因子的表达，包括磷酸化Src Tyr416。
这些发现表明，HDAC和PI3K共同抑制通过磷酸化EGFR Tyr^{1068}诱导的RTK-STAT3轴失活使厄洛替尼增敏。然而，PI3K抑制足以使TU212细胞对厄洛替尼敏感，为厄洛替尼+伏立诺他+库潘尼西作为EGFR反应性再激活诱导的厄洛替尼耐药的潜在联合治疗方案的进一步临床研究提供了新的视角。
