The effects of Livin shRNA on the response to cisplatin in HepG2 cells

Silencing Livin gene expression by RNA interference enhanced the chemotherapeutic sensitivity of drug-resistant osteosarcoma cells to doxorubicin

BACKGROUND

Osteosarcoma is one of the most common malignant tumors in children and adolescents. It occurs in the metaphysis of long bones and is a type of aggressive malignant tumor. Although there are treatment methods such as surgery and chemotherapy, the mortality and disability of osteosarcoma patients are still high. With the emergence of more and more chemotherapy resistance, it is necessary to find new therapies to improve the chemotherapy sensitivity of osteosarcoma.

METHODS

Drug-resistant MG-63 and U2OS cell strain was established in vitro by continuous exposure of human osteosarcoma cells to doxorubicin at gradually increasing concentrations，then determined for resistance index to doxorubicin by MTT method，for transcriptions of Livin mRNA by real-time polymerase chain reaction（RT⁃PCR），and for expressions of Livin proteins by Western blot．The technology of gene recombination was used to construct the eukaryotic expression vector pSilencer3.1-H1 neo-Livin. Then the pSilencer3.1-H1 neo-Livin was transfected into drug-resistant MG-63 cell by using Lipofectmine 2000. Expressions of Livin mRNA and protein in the transfected cells were respectively measured by RT-PCR and Western blot. The distribution of cell cycle phase and apoptosis were determined by flow cytometry. The analysis of chemotherapeutic sensitivity of drug-resistant MG-63 cell to doxorubicin was performed by MTT.

RESULTS

The recombinant eukaryotic expression vector pSilencer3.1-H1 neo-Livin was successfully constructed. The result of inverted microscope revealed that the drug-resistant MG-63 cell were irregularity and morphological diversity. Compared with those in osteosarcoma cells，the transcription levels of Livin mRNA and protein in drug-resistant osteosarcoma cell increased（P＜0.05）．The flow cytometry analysis showed there was higher percentage of apoptosis in transfected drug-resistant MG-63 cell. Compared with control groups，the expression of Livin mRNA and protein were both significantly decreased in the transfected drug-resistant osteosarcomacell（P＜0.05）. We also observed that suppression of Livin expression in osteosarcoma cells increased their chemosensitivity to doxorubicin.

CONCLUSION

This study showed that Livin shRNA inhibited the proliferation level and increased the sensitivity of drug-resistant osteosarcoma cell to doxorubicin, suggested that Livin is involved in drug resistance of human osteosarcoma and may serve as a promising therapeutic target for osteosarcoma.

Livin enhances chemoresistance in head and neck squamous cell carcinoma

The responsiveness of head and neck squamous cell carcinoma (HNSCC) to chemotherapy widely affects prognosis. Overcoming chemoresistance is necessary to improve prognoses in patients with advanced HNSCC. Evasion of apoptosis by cancer cells is a major cause of chemoresistance. Livin, a member of the human inhibitors of apoptosis protein family, is highly expressed in various human cancer tissues and is associated with tumor progression and poor prognosis in human cancers. The aim of the present study was to evaluate the role of Livin in the susceptibility to popularly used chemotherapeutic drugs such as cisplatin, 5-fluorouracil (FU) and docetaxel in human HNSCC cell lines (SNU1041, PCI1 and PCI50 cells). Reverse transcription polymerase chain reaction and western blotting were performed to determine mRNA and protein expression levels. Cell viability and apoptosis assays were used to assess the functional effects of small-interfering RNA-mediated knockdown of Livin. Each HNSCC cell line had different sensitivity to chemotherapeutic drugs. Livin knockdown significantly enhanced cytotoxicity to cisplatin, 5-FU and docetaxel in human HNSCC cells. Livin knockdown induced apoptosis and enhanced chemotherapy-induced apoptosis to cisplatin, 5-FU and docetaxel. Consistent with this, Livin-knockdown cells showed greater expression of cleaved caspases-3 and -7 and poly(ADP-ribose)polymerase compared with that in control cells after cisplatin, 5-FU, or docetaxel treatment. In conclusion, our results suggest that siRNA-mediated Livin knockdown enhanced the chemosensitivity of the three HNSCC cell lines to cisplatin, 5-FU and docetaxel. Although further investigations are required to support these findings, our results demonstrated that novel therapeutic strategies with combined use of siRNA targeting Livin and chemotherapeutic agents may have applications in the treatment of advanced HNSCC.

Silencing the livin gene enhances the cytotoxic effects of anticancer drugs on colon cancer cells

Purpose

Livin is associated with drug response in several cancers. The aim of this study was to investigate the effect of silencing the livin gene expression on anticancer drug response in colorectal cancer.

Methods

siRNA was transfected at different concentrations (0, 10, and 30nM) into HCT116 cells, then cells were treated with either 5-fluorouracil (FU)/leucovorin (LV) or oxaliplatin (L-OHP)/5-FU/LV. Cellular viability and apoptosis were evaluated following silencing of livin gene expression combined with treatment with anticancer drugs.

Results

Livin gene expression was effectively suppressed by 30nM siRNA compared with control and 10nM siRNA. The 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay showed that proliferation was effectively inhibited in cells treated with a combination of both siRNA and an anticancer drug, compared to cells treated with siRNA-Livin or anticancer drug alone. In particular, the combination of 30nM siRNA and L-OHP/5-FU/LV resulted in a 93.8% and 91.4% decrease, compared to untreated control or L-OHP/5-FU/LV alone, respectively. Cellular proliferation was most effectively suppressed by a combination of 30nM of siRNA and L-OHP/5-FU/LV compared to other combinations.

Conclusion

siRNA-mediated down-regulation of livin gene expression could significantly suppress colon cancer growth and enhance the cytotoxic effects of anticancer drugs such as 5-FU and L-OHP. The results of this study suggest that silencing livin gene expression in combination with treatment with anticancer drugs might be a novel cancer therapy for colorectal cancer.

Silencing Livin induces apoptotic and autophagic cell death, increasing chemotherapeutic sensitivity to cisplatin of renal carcinoma cells

Renal cell carcinoma (RCC) accounts for 3 % of all adult malignancies and is the most lethal urological cancer. Livin is a member of the inhibitor of apoptosis protein (IAP) family, which is associated with tumor resistance to radiotherapy and chemotherapy. Clinical data also showed that patients with high tumor grades and stages have higher expression levels of Livin in RCC cells. Autophagy is a survival mechanism activated in response to nutrient deprivation. A possible role of Livin in the autophagy of RCC cells has not been investigated; therefore, this pioneer study was carried out. Livin was silenced in RCC cells (slow virus infection [SVI]-shLivin cells) by lentiviral transfection. Then, mRNA and protein expression levels in the transfected cells were assessed by quantitative fluorescence PCR and Western blotting, respectively. In addition, acridine orange staining and electron microscopy were used to assess autophagy in SVI-shLivin cells. The cisplatin IC50 values for RCC cells were measured by the CCK8 assay. Potent antitumor activities were observed in xenograft mouse models generated with Livin-silenced RCC cells in terms of delayed tumor onset and suppressed tumor growth. These results suggested that Livin silencing could increase the chemotherapeutic sensitivity of RCC cells to cisplatin and induce autophagic cell death. A possible mechanism of Bcl-2 and Akt pathway involvement was discussed specifically in this study. Overall, Livin silencing induces apoptotic and autophagic cell death and increases chemotherapeutic sensitivity of RCC cells to cisplatin.