Repression of caspase-3 and RNA-binding protein HuR cleavage by cyclooxygenase-2 promotes drug resistance in oral squamous cell carcinoma.
Repression of caspase-3 and RNA-binding protein HuR cleavage by cyclooxygenase-2 promotes drug resistance in oral squamous cell carcinoma.
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DOI：
10.1038/onc.2016.451
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发表时间：
2017-06-01
期刊：
影响因子：
8
通讯作者：
Palanisamy V
中科院分区：
文献类型：
--
作者：
Janakiraman H;House RP;Talwar S;Courtney SM;Hazard ES;Hardiman G;Mehrotra S;Howe PH;Gangaraju V;Palanisamy V
RNA结合蛋白Hu抗原-R（HuR）在肿瘤细胞中控制转录后基因调控并经历应激激活的caspase-3依赖性切割。已知HuR的切割产物促进细胞死亡，然而，促进半胱天冬酶-3活化和HuR切割的潜在分子机制仍然未知。在这里，我们表明，HuR裂解与活性caspase-3在口腔癌细胞治疗电离辐射和化疗药物，紫杉醇。我们确定过表达环氧合酶-2（考克斯-2）的口腔癌细胞限制了caspase-3和HuR的裂解，从而降低了紫杉醇耐药口腔癌细胞的细胞死亡率。塞来昔布对考克斯-2的特异性抑制，通过激活caspase-3和切割HuR促进体内外紫杉醇耐药口腔癌细胞的凋亡。此外，与表达可裂解形式的HuR的细胞相比，过表达细胞HuR的口腔癌细胞增加了考克斯-2 mRNA的半衰期，促进了考克斯-2蛋白的表达，并表现出增强的体内肿瘤生长。最后，我们的核糖核蛋白免疫沉淀和测序（RIP-seq）分析的HuR在口腔癌细胞电离辐射（IR）处理，确定HuR裂解产物-1（HuR-CP 1）结合，并促进参与细胞凋亡的蛋白质编码的mRNA的表达。我们的结果表明，细胞不可切割的HuR控制着考克斯-2 mRNA的表达和酶活性。另外，过表达的考克斯-2蛋白可抑制caspase-3和HuR的裂解，从而促进肿瘤的耐药性和生长。总之，我们的观察结果支持使用考克斯-2抑制剂塞来昔布与紫杉醇联合治疗对紫杉醇耐药的口腔癌细胞。
A well-studied RNA-binding protein Hu Antigen-R (HuR), controls post-transcriptional gene regulation and undergoes stress-activated caspase-3 dependent cleavage in cancer cells. The cleavage products of HuR are known to promote cell death however, the underlying molecular mechanisms facilitating caspase-3 activation and HuR cleavage remains unknown. Here, we show that HuR cleavage associated with active caspase-3 in oral cancer cells treated with ionizing radiation and chemotherapeutic drug, paclitaxel. We determined that oral cancer cells overexpressing cyclooxygenase-2 (COX-2) limited the cleavage of caspase-3 and HuR, which reduced the rate of cell death in paclitaxel resistant oral cancer cells. Specific inhibition of COX-2 by celecoxib, promoted apoptosis through activation of caspase-3 and cleavage of HuR in paclitaxel-resistant oral cancer cells, both in vitro and in vivo. In addition, oral cancer cells overexpressing cellular HuR increased the half-life of COX-2 mRNA, promoted COX-2 protein expression and exhibited enhanced tumor growth in vivo in comparison with cells expressing a cleavable form of HuR. Finally, our ribonucleoprotein immunoprecipitation and sequencing (RIP-seq) analyses of HuR in oral cancer cells treated with ionizing radiation (IR), determined that HuR cleavage product-1 (HuR-CP1) bound and promoted the expression of mRNAs encoding proteins involved in apoptosis. Our results indicated that, cellular non-cleavable HuR controls COX-2 mRNA expression and enzymatic activity. In addition, overexpressed COX-2 protein repressed the cleavage of caspase-3 and HuR to promote drug resistance and tumor growth. Altogether, our observations support the use of the COX-2 inhibitor celecoxib, in combination with paclitaxel, for the management of paclitaxel resistant oral cancer cells.