Kennedy Amy L, Rai Rajani, Isingizwe Zitha Redempta, Zhao Yan Daniel, Lightfoot Stanley A, Benbrook Doris M
Department of Pathology, College of Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
Stephenson Cancer Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104, USA.
Cancers (Basel). 2020 May 17;12(5):1269. doi: 10.3390/cancers12051269.
Cervical cancer is caused by high-risk human papillomavirus (HPV) types and treated with conventional chemotherapy with surgery and/or radiation. HPV E6 and E7 proteins increase phosphorylation of retinoblastoma (Rb) by cyclin D1/cyclin dependent kinase (CDK)4/6 complexes. We hypothesized that cyclin D1 degradation by the SHetA2 drug in combination with palbociclib inhibition of CDK4/6 activity synergistically reduces phosphorylated Rb (phospho-Rb) and inhibits cervical cancer growth. The effects of these drugs, alone, and in combination, were evaluated in SiHa and CaSki HPV-positive and C33A HPV-negative cervical cancer cell lines using cell culture, western blots and ELISA, and in a SiHa xenograft model. Endpoints were compared by isobolograms, ANOVA, and Chi-Square. In all cell lines, combination indexes documented synergistic interaction of SHetA2 and palbociclib in association SHetA2 reduction of cyclin D1 and phospho-Rb, palbociclib reduction of phospho-Rb, and enhanced phospho-Rb reduction upon drug combination. Both drugs significantly reduced phospho-Rb and growth of SiHa xenograft tumors as single agents and acted additively when combined, with no evidence of toxicity. Dilated CD31-negative blood vessels adjacent to, or within, areas of necrosis and apoptosis were observed in all drug-treated tumors. These results justify development of the SHetA2 and palbociclib combination for targeting phospho-Rb in cervical cancer treatment.
宫颈癌由高危型人乳头瘤病毒（HPV）引起，采用手术和/或放疗的传统化疗方法进行治疗。HPV E6和E7蛋白通过细胞周期蛋白D1/细胞周期蛋白依赖性激酶（CDK）4/6复合物增加视网膜母细胞瘤（Rb）的磷酸化。我们假设，SHetA2药物介导的细胞周期蛋白D1降解与帕博西尼对CDK4/6活性的抑制协同降低磷酸化Rb（p-Rb），并抑制宫颈癌生长。使用细胞培养、蛋白质免疫印迹和酶联免疫吸附测定法，以及在SiHa异种移植模型中，评估了这些药物单独使用和联合使用时的效果。通过等效线图、方差分析和卡方检验比较终点指标。在所有细胞系中，联合指数证明SHetA2和帕博西尼之间存在协同相互作用，这与SHetA2降低细胞周期蛋白D1和p-Rb、帕博西尼降低p-Rb以及联合用药后增强的p-Rb降低有关。两种药物作为单一药物均显著降低p-Rb和SiHa异种移植肿瘤的生长，联合使用时具有相加作用，且无毒性证据。在所有经药物治疗的肿瘤中，均观察到坏死和凋亡区域附近或内部扩张的CD31阴性血管。这些结果证明开发SHetA2和帕博西尼联合用药方案用于靶向p-Rb治疗宫颈癌是合理的。
