Combined treatment of XIAP-targeting shRNA and celecoxib synergistically inhibits the tumor growth of non-small cell lung cancer cells in vitro and in vivo

Abstract

Abstract. X-linked inhibitor of apoptosis protein (XIAP) has been shown to be highly expressed in lung cancer, but not in normal lung tissue, which makes it an attractive target for lung cancer treatment. Celecoxib (CXB), a cyclooxygenase-2 inhibitor, is in wide clinical use for the treatment and prevention of non-small cell lung cancer (NSCLC). Therefore, in our study, we combined short hairpin RNA (shRNA) targeted to XIAP (XIAP-shRNA) with CXB and tested the effects of this combination on lung cancer cells to identify more effective therapeutics against lung cancer. An XIAP-shRNA plasmid was constructed and transfected into the A549 NSCLC cell line. The cells were then treated with CXB and XIAP-shRNA alone or in combination for indicated time periods, and the treatments were assessed for their effects on cell proliferation, apoptosis, migration, invasion and receptor signaling using the MTT, TUNEL, wound healing and Matrigel invasion assays and western blotting, respectively. In addition, an NSCLC xenograft model was prepared to observe tumor growth. It was found that both CXB and XIAP-shRNA significantly inhibited cell proliferation, migration and invasion, and induced cell apoptosis in vitro, as well as suppressed tumor growth in vivo. Moreover, the combination of the agents significantly enhanced these effects compared to the single agent treatments. We also found that the combination treatment significantly suppressed constitutive phosphorylation of PI3K and AKT, which may contribute to the inhibition of tumor growth. These findings suggest that the combination of XIAP-shRNA and CXB is a promising drug candidate for the treatment of NSCLC. IntroductionLung cancer is one of the most common neoplasms worldwide, and approximately 85-90% of lung cancer cases are non-small cell lung cancer (NSCLC) (1). Despite the fact that chemotherapy and radiotherapy have been widely used in the treatment of advanced NSCLC, the outcome remains poor, with less than 15% of patients surviving beyond 5 years due to the lack of early diagnosis and effective treatment methods (2,3). Therefore, it is urgent to identify new therapeutics to combat this disease.With the recent advances in the understanding of the molecular pathways involved in NSCLC progression, targeted therapies that are designed to interfere with the mechanisms of cancer cell growth and survival offer new hope in NSCLC therapeutics. X-linked inhibitor of apoptosis protein (XIAP) has been identified as one of the most potent inhibitors of caspases and apoptosis to date and is known to play an important role in cell apoptosis, cell migration and cell invasion (4,5). It is highly expressed in various malignancies, while its expression is very low or absent in normal cells, which makes it an attractive target for cancer therapeutics (6)(7)(8). A large number of studies have demonstrated that inhibition of XIAP expression using antisense oligonucleotides or small interfering RNA (siRNA) could suppress the proliferation of tumor cells, induce cell apoptosis, and sensitiz...

Synergistic combination of flavopiridol and carfilzomib targets commonly dysregulated pathways in adrenocortical carcinoma and has biomarkers of response

“…The combination of flavopiridol and bortezomib, another proteasome inhibitor, was found to be a tolerable regimen in patients with heavily pre-treated refractory/recurrent B-cell malignancies in a Phase I clinical trial and resulted in a 33% response rate with 8% complete remission [ 22 ]. The other combination therapy that synergistically targets XIAP was demonstrated in non-small cell lung cancer preclinical studies using XIAP-targeting short hairpin RNA (shRNA) and celecoxib [ 23 ]. However, the clinical application of shRNA in cancer treatment is limited with no known toxicity or proven efficacy.…”

Upregulation of XIAP promotes lung adenocarcinoma brain metastasis by modulating ceRNA network

“…that XIAP-shRNA significantly inhibited cell migration and invasion through a non-small cell lung cancer (NSCLC) xenograft model (26). Ceramide analog LCL85 targeting XIAP and CIAP1 overcomes apoptosis-induced resistance in metastatic colon and breast cancer, thereby inhibiting metastasis in vivo (27).…”

“…Inhibition of XIAP or Survivin enhances postradiotherapy cell survival in lung cancer cells H460 compared to controls (29). XIAP-targeted shRNA and celecoxib synergistically reduce the growth of NSCLC (26). And XIAP-mediated protection of H460 lung cancer cells against cisplatin (30).…”

Effects of silencing Rab27a gene on biological characteristics and chemosensitivity of non-small cell lung cancer

“…shRNA (short hairpin RNA) is a expression vector in which double-stranded RNA degrades its homological mRNA and leads to sequence specific post-transcriptional gene silencing in an organism [ 7 ]. With the development of technology, silencing targeted genes associated with the progress of lung cancer is a new hope for patients with lung cancer [ 8 ].…”