Silencing Livin gene expression to inhibit proliferation and enhance chemosensitivity in tumor cells

BIRC7 and STC2 Expression Are Associated With Tumorigenesis and Poor Outcome in Extrahepatic Cholangiocarcinoma

Background:

Extrahepatic cholangiocarcinoma (EHCC) is a highly aggressive epithelial malignancy and has a poor prognosis for the insensitivity to therapies and difficulty in detection. Novel targets and biomarkers are urgently needed to develop for functional, diagnostic and prognostic application on EHCC.

Methods:

Immunohistochemical staining technique using the EnVision antibody complex was performed on the samples obtained from 100 EHCC, 30 peritumoral extrahepatic biliary tract (EHBT), 10 EHBT adenomas and 15 normal EHBT tissues.

Results:

The positive rates of BIRC7 and STC2 expression in tissues obtained from peritumoral EHBT, EHBT adenomas and normal EHBT were significantly lower than those in EHCC tissues. BIRC7 and STC2 proteins were expressed at significantly higher levels in patients with lymph node metastasis, invasion of adjacent tissues, and higher TNM stage (III and/or IV) and unable to undergo resection (biopsy only). Kaplan-Meier survival curves indicated that significantly decreased overall survival rate in patients with positive-BIRC7 or positive-STC2 expression compared with patients of negative-BIRC7 or negative-STC2 expression, respectively. Cox-proportional regression analysis demonstrated that positive-BIRC7 and positive-STC2 expression, along with poor differentiation of EHCC, tumor size >3 cm, lymph node metastasis, invasion of adjacent tissues and unable to undergo resection are independent prognostic factors of EHCC patients.

Conclusions:

The levels of BIRC7 and STC2 expression were correlated with clinicopathological characteristics of EHCC, and positive expression of BIRC7 and STC2 are associated with progression and poor clinical outcomes of EHCC. BIRC7 and STC2 might be a potential biomarker for EHCC in clinic.

The Multiple Roles of the IAP Super-family in cancer

The Inhibitor of Apoptosis proteins (IAPs) are a family of proteins that are mainly known for their anti-apoptotic activity and ability to directly bind and inhibit caspases. Recent research has however revealed that they have extensive roles in governing numerous other cellular processes. IAPs are known to modulate ubiquitin (Ub)-dependent signaling pathways through their E3 ligase activity and influence activation of nuclear factor κB (NF-κB). In this review, we discuss the involvement of IAPs in individual hallmarks of cancer and the current status of therapies targeting these critical proteins.

Methylation-mediated miR-214 regulates proliferation and drug sensitivity of renal cell carcinoma cells through targeting LIVIN

LIVIN, a member of the inhibitor of apoptosis proteins (IAPs), is reported playing important roles in the development and progression of multiple human cancers. However, its underlined mechanisms in human renal cell carcinoma (RCC) are still needed to be clarified. In the present study, we reported that inhibition of miR‐214 promoted the expression of LIVIN, then facilitated RCC cells growth and reduced the sensitivity of RCC cells to chemotherapeutic drugs. In constant, overexpression of miR‐214 had contradictory effects. Further investigation showed that miR‐214 was down‐regulated in RCC because of abnormal methylation. In addition, DNA methyltransferase DNMT1, miR‐214 and LIVIN are directly correlated in RCC patients. In conclusion, these results suggest that abnormal miR‐214 methylation negatively regulates LIVIN, which may promote RCC cells growth and reduced the sensitivity of RCC cells to chemotherapeutic drugs.

Lycopene Inhibits Reactive Oxygen Species-Mediated NF-κB Signaling and Induces Apoptosis in Pancreatic Cancer Cells

Generation of excess quantities of reactive oxygen species (ROS) caused by mitochondrial dysfunction facilitates rapid growth of pancreatic cancer cells. Elevated ROS levels in cancer cells cause an anti-apoptotic effect by activating survival signaling pathways, such as NF-κB and its target gene expression. Lycopene, a carotenoid found in tomatoes and a potent antioxidant, displays a protective effect against pancreatic cancer. The present study was designed to determine if lycopene induces apoptosis of pancreatic cancer PANC-1 cells by decreasing intracellular and mitochondrial ROS levels, and consequently suppressing NF-κB activation and expression of NF-κB target genes including cIAP1, cIAP2, and survivin. The results show that the lycopene decreased intracellular and mitochondrial ROS levels, mitochondrial function (determined by the mitochondrial membrane potential and oxygen consumption rate), NF-κB activity, and expression of NF-κB-dependent survival genes in PANC-1 cells. Lycopene reduced cell viability with increases in active caspase-3 and the Bax to Bcl-2 ratio in PANC-1 cells. These findings suggest that supplementation of lycopene could potentially reduce the incidence of pancreatic cancer.

Therapeutic Potency of Nanoformulations of siRNAs and shRNAs in Animal Models of Cancers

RNA Interference (RNAi) has brought revolutionary transformations in cancer management in the past two decades. RNAi-based therapeutics including siRNA and shRNA have immense scope to silence the expression of mutant cancer genes specifically in a therapeutic context. Although tremendous progress has been made to establish catalytic RNA as a new class of biologics for cancer management, a lot of extracellular and intracellular barriers still pose a long-lasting challenge on the way to clinical approval. A series of chemically suitable, safe and effective viral and non-viral carriers have emerged to overcome physiological barriers and ensure targeted delivery of RNAi. The newly invented carriers, delivery techniques and gene editing technology made current treatment protocols stronger to fight cancer. This review has provided a platform about the chronicle of siRNA development and challenges of RNAi therapeutics for laboratory to bedside translation focusing on recent advancement in siRNA delivery vehicles with their limitations. Furthermore, an overview of several animal model studies of siRNA- or shRNA-based cancer gene therapy over the past 15 years has been presented, highlighting the roles of genes in multiple cancers, pharmacokinetic parameters and critical evaluation. The review concludes with a future direction for the development of catalytic RNA vehicles and design strategies to make RNAi-based cancer gene therapy more promising to surmount cancer gene delivery challenges.

Silencing Livin improved the sensitivity of colon cancer cells to 5-fluorouracil by regulating crosstalk between apoptosis and autophagy

Colorectal cancer (CRC) is the third most common cause of cancer-associated mortality worldwide. Currently, 5-fluorouracil (5-FU) remains a widely used chemotherapeutic drug in the treatment of CRC; however, 5-FU resistance during treatment has become a common problem. Livin, a member of the inhibitor of apoptosis protein family, is considered to be associated with tumor resistance to chemotherapy. In the present study, Livin-silenced cells were generated by introducing a lentivirus into HCT116 and SW620 colon cancer cell lines. Acridine orange/ethidium bromide staining was used as an indicator of cell death. Western blot analysis was performed to detect protein expression levels, and transmission electron microscopy was used to assess autophagy. The half-maximal inhibitory concentration of 5-FU in colon cancer cells was evaluated using a Cell Counting Kit-8 assay. The results of the present study confirmed that silencing Livin significantly enhanced colon cancer cell death in the presence of 5-FU, increased expression levels of various apoptosis- and autophagy-associated proteins and augmented chemotherapeutic sensitivity to 5-FU. Furthermore, the present study demonstrated that this effect may be reversed when autophagy or apoptosis was inhibited, indicating that apoptosis and autophagy were involved in this process. The protein kinase B signaling pathway and B-cell lymphoma-2 expression levels significantly decreased following Livin knockdown, suggesting they may contribute to the regulation of apoptosis and autophagy crosstalk, which caused the Livin knockdown-induced cell death observed.

Livin/BIRC7 expression as malignancy marker in adrenocortical tumors

Livin/BIRC7 is a member of the inhibitors of apoptosis proteins family, which are involved in tumor development through the inhibition of caspases. Aim was to investigate the expression of livin and other members of its pathway in adrenocortical tumors and in the adrenocortical carcinoma (ACC) cell line NCI-H295R.

The mRNA expression of livin, its isoforms α and β, XIAP, CASP3 and DIABLO was evaluated by qRT-PCR in 82 fresh-frozen adrenal tissues (34 ACC, 25 adenomas = ACA, 23 normal adrenal glands = NAG). Livin protein expression was assessed by immunohistochemistry in 270 paraffin-embedded tissues (192 ACC, 58 ACA, 20 NAG). Livin, CASP3 and cleaved caspase-3 were evaluated in NCI-H295R after induction of livin overexpression.

Relative livin mRNA expression was significantly higher in ACC than in ACA and NAG (0.060 ± 0.116 vs 0.004 ± 0.014 and 0.002 ± 0.009, respectively, p < 0.01), being consistently higher in tumors than in adjacent NAG and isoform β more expressed than α. No significant differences in CASP3, XIAP and DIABLO levels were found among these groups. In immunohistochemistry, livin was localized in both cytoplasm and nuclei. The ratio between cytoplasmic and nuclear staining was significantly higher in ACC (1.51 ± 0.66) than in ACA (0.80 ± 0.35) and NAG (0.88 ± 0.27; p < 0.0001). No significant correlations were observed between livin expression and histopathological parameters or clinical outcome. In NCI-H295R cells, the livin overexpression slightly reduced the activation of CASP3, but did not correlate with cell viability.

In conclusion, livin is specifically over-expressed in ACC, suggesting that it might be involved in adrenocortical tumorigenesis and represent a new molecular marker of malignancy.

Inducing death in tumor cells: roles of the inhibitor of apoptosis proteins

The heterogeneous group of diseases collectively termed cancer results not just from aberrant cellular proliferation but also from a lack of accompanying homeostatic cell death. Indeed, cancer cells regularly acquire resistance to programmed cell death, or apoptosis, which not only supports cancer progression but also leads to resistance to therapeutic agents. Thus, various approaches have been undertaken in order to induce apoptosis in tumor cells for therapeutic purposes. Here, we will focus our discussion on agents that directly affect the apoptotic machinery itself rather than on drugs that induce apoptosis in tumor cells indirectly, such as by DNA damage or kinase dependency inhibition. As the roles of the Bcl-2 family have been extensively studied and reviewed recently, we will focus in this review specifically on the inhibitor of apoptosis protein (IAP) family. IAPs are a disparate group of proteins that all contain a baculovirus IAP repeat domain, which is important for the inhibition of apoptosis in some, but not all, family members. We describe each of the family members with respect to their structural and functional similarities and differences and their respective roles in cancer. Finally, we also review the current state of IAPs as targets for anti-cancer therapeutics and discuss the current clinical state of IAP antagonists.

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.

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

Hepatocellular carcinoma is a lethal malignancy with poor prognosis, partially due to tumor metastasis, recurrence and resistance to chemo- or radio-therapy. Cisplatin can inhibit cancer cell DNA replication, and is widely used in the clinical treatment of tumors. The present study aimed to generate eukaryotic expression vectors for Livin shRNA and to examine the effects of Livin shRNA on the chemosensitivity of HepG2 hepatocellular carcinoma cells. Eukaryotic expression vectors for Livin shRNA (pSD11-U6/Neo/GFP/Livin) were designed and constructed. The HepG2 hepatocellular carcinoma cell line was transfected with this vector using the liposome method. The expression levels of Livin mRNA and protein were measured by quantitative polymerase chain reaction and western blot analysis. The rate of cell growth inhibition was measured using MTT assay following treatment of the cells with cisplatin (2.0 mg/l). DNA sequencing confirmed that the construction of the eukaryotic expression vector for Livin shRNA had been successful. Transfection of these vectors into HepG2 cells led to a significant reduction in the expression levels of Livin mRNA and protein (P<0.05). Cisplatin treatment was associated with significantly higher rates of cell growth inhibition in HepG2 cells transfected with Livin shRNA compared with those that were not transfected (P<0.05). The vectors constructed in the present study produced effective inhibition of the Livin gene in HepG2 cells and increased the chemosensitivity of hepatocellular carcinoma cells.

Livin is associated with the invasive and oncogenic phenotypes of human hepatocellular carcinoma cells

AIM

Livin, a member of the inhibitors of apoptosis proteins, is expressed in variable cancers, and its expression is considered a poor prognostic marker. The aims of this study were to observe the effect of Livin on the behaviors of hepatocellular carcinoma (HCC) cells and to evaluate its expression in HCC tissues and its relation to prognosis.

METHODS

The biological effects of Livin on tumor cell behavior were investigated using siRNA in HepG2 and Chang cells. Migration, invasion and proliferation assays were performed. Flow cytometric analyses and western blotting were used to evaluate the impact of Livin on apoptosis and the cell cycle. In addition, western blotting and immunohistochemistry were used to investigate Livin expression in HCC tissues.

RESULTS

Livin knockdown suppressed tumor cell migration, invasion and proliferation in HCC cells, and increased the proportion of apoptotic cells as compared with scrambled siRNA-transfected HCC cells. Furthermore, Livin knockdown resulted in the activation of caspases and increased apoptosis. In addition, Livin knockdown modulated cell cycle regulatory protein levels such as decrease of cyclins and cyclin-dependent kinase (CDK) level, and increase of CDK inhibitor (CDKI) level in HCC cells. The Livin protein level was significantly elevated in HCC tissues as compared with normal hepatic tissues. However, Livin expression was not found to be associated with clinicopathological parameters, which included patient survival.

CONCLUSION

These results suggest that Livin is associated with invasive and oncogenic phenotypes of human HCC cells.

Relationship between expression of Livin and the biological behavior of human oral squamous cell carcinoma

Livin is one of the most important members of the inhibitor protein (IAP) family. It is overexpressed in several types of tumors and may have prognostic significance. The purpose of this study was to investigate Livin expression in human oral squamous cell carcinomas (OSCCs) and to determine whether Livin affects tumor cell behavior in OSCC cell lines and thus evaluate its potential usefulness in serving as a possible target for molecular-targeted therapy in a preclinical model. The expression of Livin protein was investigated in human OSCC tissues through immunohistochemistry and western blot analysis. To evaluate the impact of Livin knockdown on the behavior of human OSCC cell lines, invasion, migration, proliferation and apoptosis assays using small-interfering RNA (siRNA) were performed. RT-PCR and western blot analysis were used to assess alteration of Livin expression at the mRNA and protein levels. The results revealed that expression of Livin was increased in the human OSCC tissues compared with the adjacent normal mucosa. In addition, immunoreactivity of Livin was expressed in 8 OSCC tissues (44.4%). Knockdown of Livin resulted in significantly reduced cell invasion, migration and proliferation in the human OSCC cells. Livin knockdown induced cell apoptosis in the human OSCC cells. Moreover, Livin inhibited apoptosis by suppressing the activity of caspases in the human OSCC cells. In conclusion, livin is associated with invasive and oncogenic phenotypes such as tumor cell invasion, tumor cell migration, tumor cell proliferation, and resistance to apoptosis in human OSCC cells.

Impact of Co-transfection with Livin and survivin shRNA expression vectors on biological behavior of HepG2 cells

OBJECTIVE

To construct short hairpin RNA (shRNA) eukaryotic expression vectors targeting Livin and Survivin genes, and to explore the impact of co-transfection of Livin and Survivin shRNA expression vectors on the biological behavior of HepG2 cells.

METHODS

shRNA eukaryotic expression vectors pSD11-Livin and pSD11- Survivin were designed and constructed then transfected into HepG2 cells separately or in combination. mRNA and protein expression in transfected cells was assessed by quantitative fluorescence PCR and Western blotting, respectively. Cell proliferation was measured by MTT assay and cell apoptosis by TUNEL assay.

RESULTS

The Livin and Survivin shRNA eukaryotic expression vectors were successfully constructed and transfected into HepG2 cells. The relative mRNA expression levels of Livin and Survivin in HepG2 cells co-transfected with pSD11-Livin and pSD11-Survivin were 0.12 ± 0.02 and 0.33 ± 0.13, respectively, which was significantly lower than levels in cells transfected with either pSD11-Livin or pSD11-Survivin (P<0.05). The relative protein expression levels of Livin and Survivin in the co-transfected cells were also significantly decreased compared to single- transfection (P<0.05). The inhibition rate of cell growth in the co-transfection group was higher than that in the single-transfection groups at 48 h, 60 h, or 72 h after transfection (P<0.01). The apoptotic rate increased to the greatest extent in the co-transfection group relative to any other group (P<0.05).

CONCLUSIONS

Co-transfection with pSD11-Livin and pSD11-Survivin was more efficient than transfection with either vector alone in reducing the mRNA and protein expression of Livin and Survivin genes in HepG2 cells. Co-transfection also inhibited the proliferation of transfected cells more than the other groups, and induced cellular apoptosis more effectively.

Livin expression is an independent factor in rectal cancer patients with or without preoperative radiotherapy

BACKGROUND

This study was aimed to investigate the expression significance of Livin in relation to radiotherapy (RT), clinicopathological and biological factors of rectal cancer patients.

METHODS

This study included 144 primary rectal cancer patients who participated in a Swedish clinical trial of preoperative radiotherapy. Tissue microarray samples from the excised primary rectal cancers, normal mucosa and lymph node metastases were immunostained with Livin antibody. The proliferation of colon cancer cell lines SW620 and RKO was assayed after Livin knock-down.

RESULTS

The expression of Livin was significantly increased from adjacent (P = 0.051) or distant (P = 0.028) normal mucosa to primary tumors. 15.4% (2/13) and 39.7% (52/131) patients with Livin-negative and positive tumors died at 180 months after surgery, and the difference tended to be statistically significant (P = 0.091). In multivariate analyses, the difference achieved statistical significance, independent of TNM stage, local and distant recurrence, grade of differentiation, gender, and age (odds ratio = 5.09, 95% CI: 1.01-25.64, P = 0.048). The in vitro study indicated colon cancer cells with Livin knock-down exhibited decreased proliferation compared with controls after RT.

CONCLUSIONS

The expression of Livin was was independently related to survival in rectal cancer patients, suggesting Livin as a useful prognostic factor for rectal cancer patients.

RNA interference-mediated knockdown of Livin suppresses cell proliferation and invasion and enhances the chemosensitivity to cisplatin in human osteosarcoma cells

Livin is a novel member of the inhibitor of apoptosis protein (IAP) family that has been reported to be overexpressed in a variety of human malignancies, including osteosarcoma. However, the potential roles of Livin in tumorigenesis have not been elucidated. In the present study, we employed RNA interference (RNAi) technology to suppress endogenous Livin expression in osteosarcoma cells and successfully generated a U2-OS cell line with stably knockdown of Livin. Functional analysis showed that knockdown of Livin significantly reduced cell proliferation, colony formation, and invasion and migration capacities of U2-OS cells in vitro. Moreover, specific downregulation of Livin led to cell cycle arrest at the G0/G1 phase and eventual apoptosis. Meanwhile, western blot analysis revealed that cells with stably knockdown of Livin showed decreased expression levels of Cyclin D1, Bcl-2, matrix metalloproteinase (MMP)-2 and MMP-9, but increased expression levels of activated Caspase-3, Bax and cleaved poly (ADP-ribose) polymerase (PARP) compared to those transfected with a control vector. We also observed that suppression of Livin expression in osteosarcoma cells increased their chemosensitivity to cisplatin. Taken together, our data suggest that Livin is involved in tumorigenesis of human osteosarcoma and may serve as a promising therapeutic target for osteosarcoma.

Overexpression of the truncated form of Livin reveals a complex interaction with caspase-3

Disruption in apoptosis are involved in cancer development and progression. Livin-β, has been identified as a critical modulator for cell death in several tumor cell lines. It was demonstrated that a truncated fragment of Livin-β (tLivin) without its N-terminal 52 amino acids is produced in cells through protein cleavage. However, the biological consequence of the cleavage remains largely ignored. In the present study, we report that tLivin exerted a pro-apoptotic effect on cells. The subcellular localization of tLivin was mainly restricted to the cytoplasm. To explore the underlying mechanism, we observed an elevated caspase-3 activity which may account for the apoptosis. Furthermore, we observed that tLivin was further cleaved into a smaller fragment in cells. This second cleavage was possibly related to activated caspase-3. The resulted C-terminal fragment (livC) was an anti-apoptotic factor. Our study may help to deepen our understanding of the role of Livin in the regulation of cell death.

Upregulation of the antiapoptotic factor Livin contributes to cisplatin resistance in colon cancer cells

The antiapoptotic factor Livin has been considered critical for tumor progression and poor prognosis for variant types of tumors. However, there are only limited reports regarding its expression and biological functions in colon cancer. Here, we examined Livin expression in four colon cancer cell lines (HCT116, RKO, KM12C, and SW620) in the presence or absence of cisplatin that was used as a model reagent. We found the different response to cisplatin was related to endogenous Livin expression level. From among a panel of apoptosis-related factors (p53, Bcl-2, Bcl-XL, BAX, and survivin), the expression of Livin was upregulated after cisplatin treatment in a dose-dependent manner. Both immunocytochemistry and nuclear cytoplasmic fractionation indicated Livin remained in the cytoplasm after treatment with cisplatin. In an attempt to explore the mechanism, we found the elevated expression of Livin was not due to the decreased degradation by proteosome but was enhanced at the mRNA level. Besides, cisplatin treatment activated the mammalian target of rapamycin (mTOR) pathway as shown by increased phosphorylation of Akt1, mTOR, S6K, and 4E-BP1, together with the elevated Livin. The PI3K inhibitor LY294002 inhibited both the phosphorylation of mTOR and upregulation of Livin. The stable overexpression of Livin inhibited the activation of caspase-3 and led to resistance to cisplatin, while the knockdown of Livin by siRNA rendered colon cancer cells more sensitive to cisplatin. Our study, along with others, highlighted the potential of Livin for cancer therapy in colon cancer.

Role of melanoma inhibitor of apoptosis (ML-IAP) protein, a member of the baculoviral IAP repeat (BIR) domain family, in the regulation of C-RAF kinase and cell migration

Inhibitor of apoptosis (IAPs) proteins are characterized by the presence of evolutionarily conserved baculoviral inhibitor of apoptosis repeat (BIR) domains, predominantly known for their role in inhibiting caspases and, thereby, apoptosis. We have shown previously that multi-BIR domain-containing IAPs, cellular IAPs, and X-linked IAP can control tumor cell migration by directly regulating the protein stability of C-RAF kinase. Here, we extend our observations to a single BIR domain containing IAP family member melanoma-IAP (ML-IAP). We show that ML-IAP can directly bind to C-RAF and that ML-IAP depletion leads to an increase in C-RAF protein levels, MAPK activation, and cell migration in melanoma cells. Thus, our results unveil a thus far unknown role for ML-IAP in controlling C-RAF stability and cell migration.

Adenovirus-mediated Aurora A shRNA driven by stathmin promoter suppressed tumor growth and enhanced paclitaxel chemotherapy sensitivity in human breast carcinoma cells

Aurora A has multiple key functions in tumor initiation and progression and is overexpressed in many cancers. Several ongoing clinical trials are assessing the unique therapeutic potential of Aurora-based targeted therapy, but several severe adverse events such as hematopoietic toxicity have been observed in the early-phase clinical trials because Aurora A is also involved in normal cells proliferation process. The strategy to develop tumor-specific inhibition of this target may be an alteration for the treatment of Aurora A overexpression tumors. In this study, we developed a novel tumor-specific RNA interference adenovirus system targeting Aurora A by using stathmin promoter and investigated the effects of it on the proliferation, apoptosis and chemotherapy sensitivity in human breast carcinoma cells both in vitro and in vivo. The results showed that treatment of human breast carcinoma cells (SK-BR-3 and MDA-MB-231) by Aurora A short hairpin RNA (shRNA) driven by stathmin gene promoter not only inhibited the cells proliferation, but also enhanced the chemosensitivity to paclitaxel via downregulation of Aurora A mRNA and protein expression, which further decreased the phosphatidylinositol 3 kinase/Akt and p-BRCA1 protein expression. Furthermore, there were no obvious phenotypes changes observed in normally differentiated epithelial cells of MCF210. Therefore, stathmin promoter-driving Aurora A shRNA adenoviral system may have potential use, with targeted tumor gene silencing effect and as adjuvant tumor-specific therapy method, in the treatment of human breast carcinomas.

siRNA targeting Livin decreases tumor in a xenograft model for colon cancer

AIM: To evaluate the effect of silencing Livin gene expression with siRNA to apoptosis and proliferation in a colon cancer cell line.

METHODS: To investigate the anticancer effect of silencing Livin gene expression, we established an siRNA transfected cell line using the HCT116 colon cancer cell line. After confirming the successful transfection, MTT assay, flow cytometry and annexin V staining were employed to evaluate the antiapoptotic effect. To confirm the in vivo effect of Livin-siRNA, different doses of Livin-siRNA were injected into xenografted tumors in BALB/c nude mice model.

RESULTS: Livin expression was dramatically decreased after siRNA transfection, especially at 25 μmol/L of siRNA, but this suppression was not dose-dependent. The cell count at 18 h after transfection was significantly reduced as compared with controls (P < 0.01), but tended not to decrease proportionally depending on transfected dose or time. MTT assay revealed that silencing the Livin gene suppressed cellular proliferation at 18 h after transfection (P = 0.04); however, the inhibitory effect disappeared thereafter. Also, there was no significant difference in cellular proliferation depending on siRNA dose. The rate of apoptosis also increased with silencing of the Livin gene. In vivo, the tumor size significantly decreased after Livin-siRNA injection at 20 μmol/L concentration (P = 0.03). There were no significant body weight changes of mice after siRNA injection. Histologic examination revealed no significant toxic reaction in kidney, liver and brain of mice.

CONCLUSION: siRNA-mediated downregulation of Livin expression can induce apoptosis in colon cancer in vitro and in vivo, which suggests the possibility of new cancer therapeutics using siRNA.

DHA alters expression of target proteins of cancer therapy in chemotherapy resistant SW620 colon cancer cells

Diets rich in n-3 polyunsaturated fatty acids (PUFAs) have been associated with a reduced risk of several types of cancer. Recent reports have suggested that these PUFAs enhance the cytotoxic effect of cancer chemoradiotherapy. The effect of docosahexaenoic acid (DHA) on key cell cycle regulators and target proteins of cancer therapy was investigated in the human malign colon cancer cell line SW620. Cell cycle check point proteins such as p21 and stratifin (14-3-3 sigma) increased at mRNA and protein level, whereas cell cycle progression proteins such as cell division cycle 25 homolog and cyclin-dependent kinase 1 decreased after DHA treatment. Protein levels of inhibitors of apoptosis family members associated with chemotherapy resistance and cancer malignancy, survivin and livin, decreased after the same treatment: likewise the expression of NF-kappaB. Levels of the proapoptotic proteins phosphorylated p38 MAPK and growth arrest-inducible and DNA damage-inducible gene 153/C/EBP-homologous protein (CHOP) increased. The results indicate that DHA treatment causes simultaneous cell cycle arrest in both the G1 and G2 phase. In conclusion, DHA affects several target proteins of chemotherapy in a favorable way. This may explain the observed enhanced chemosensitivity in cancer cells supplemented with n-3 PUFAs and encourage further studies investigating the role of n-3 PUFAs as adjuvant to chemotherapy and radiotherapy in vivo.

Expression and functional role of inhibitor-of-apoptosis protein livin (BIRC7) in neuroblastoma

We evaluated the expression of the inhibitor-of-apoptosis protein (IAP)livin (BIRC7)in 59 cases ofneuroblastoma (NBL) by quantitative RT-PCR. We also examined the role of livin in protecting tumor cells from chemotherapy drugs. Livin expression varied significantly amongtumors. High levels of expression were observed in 17 of 39 patients with advanced stages (stages 3 and 4) and 6 of 20 patients with localized stages (stages 1 and 2). Livin-transfected, MYCN-amplified NBL cells showed increased resistance to doxorubicin and etoposide. Conversely, livin knockdown with siRNA enhanced spontaneous and drug-induced apoptosis in NBL cells. Multivariate analysis of prognostic factors showed that high livin expression worsened prognosis for patients with MYCN-amplified tumors. Our data suggest that (i) livin is frequently expressed in NBL and protects tumor cells with amplified MYCN oncogene from genotoxic agents; (ii) the antiapoptotic effect of livin in NBL is blocked by siRNA; (iii) in the sample studied, high livin expression enhanced the adverse prognostic impact of MYCN amplification. These findings suggest that livin may contribute to drug resistance in NBL.

Interaction of Beclin 1 with survivin regulates sensitivity of human glioma cells to TRAIL-induced apoptosis

We reported a novel interaction between Beclin 1, a key regulator of autophagy, and survivin, a member of the inhibitor of apoptosis protein family. We found that knock-down of Beclin 1 down-regulated survivin protein, and the turnover rate of survivin was increased when Beclin 1 expression was silenced. Knock-down of Beclin 1 sensitized glioma cells to TRAIL-induced apoptosis, and introduction of survivin antagonized the sensitizing effect, suggesting that down-regulation of survivin mediates the enhanced sensitivity to TRAIL-induced apoptosis. These results demonstrate a novel interaction between Beclin 1 and survivin, and may provide a potential mechanism underlying the cross-talk between autophagy and apoptosis.

Isolation of peptides blocking the function of anti-apoptotic Livin protein

Livin (ML-IAP) is a cancer-associated member of the inhibitor of apoptosis protein (IAP) family. By yeast two-hybrid screening of a randomized peptide expression library, we isolated short linear peptides that specifically bind to Livin, but not to other IAPs. Intracellular expression of the peptides sensitized livin-expressing cancer cells toward different pro-apoptotic stimuli. The bioactive peptides neither showed sequence homologies to Smac-derived IAP inhibitors, nor did they interfere with the binding of Livin to Smac. Intracellular expression of the peptides did not affect the levels or the subcellular distribution of Livin. Growth of livin-expressing tumor cells was inhibited in colony formation assays by the Livin-targeting peptides. These findings provide evidence that the targeted inhibition of Livin by peptides represents a viable approach for the apoptotic sensitization and growth inhibition of tumor cells. The inhibitory peptides isolated here could form a novel basis for the development of therapeutically useful Livin inhibitors.

Expression of inhibitor of apoptosis protein Livin in gastric cancer and adjacent non-cancerous tissue

AIM: To detect the expression of Livin protein in gastric cancer and adjacent non-cancerous tissue, and to analyze its prognostic significance by exploring the relationship between Livin expression and the biological behavior of gastric cancer.

METHODS: The expression of Livin was detected by immunohistochemistry (streptavidin-peroxidase method) in 50 gastric cancer and matched adjacent non-cancerous tissue samples. Quantitative analysis of Livin expression was performed with the Image-Pro Plus 6.0 software. The significance of Livin expression in gastric cancer was then analyzed.

RESULTS: The integrated absorbance (IA) value of Livin staining in gastric cancer tissue was significantly higher than that in adjacent non-cancerous tissue (283 270.55 ± 199 604.16 vs 6 878.08 ± 9 214.56, P < 0.01). The IA value was lower in well and moderately differentiated cancer tissue than in poorly and undifferentiated tissue (41 288.94 ± 27 891.09 vs 359 690.5 ± 166 583.17, P < 0.01), in cancer tissue not invading the serosal layer than in that invading the serosal layer (T_3-4) (85 529.62 ± 115 287.42 vs 360 174.77 ± 170 507.09, P < 0.01), and in gastric cancer without lymph node metastasis than in that with lymph node metastasis (148 547.51 ± 152 479.47 vs 380 949.72 ± 171 073.92, P < 0.01).

CONCLUSION: Livin protein is highly expressed in gastric cancer. Livin expression is significantly associated with tumor differentiation, infiltration and lymph node metastasis in gastric caner. Livin protein may be used as a prognostic marker for gastric cancer.

Livin gene plays a role in drug resistance of colon cancer cells

OBJECTIVE

The objective of this study was to investigate the effect of knockdown of Livin expression on reversing drug resistance phenotype of colon cancer HCT-8/V cells.

DESIGN AND METHODS

Specific short hairpin RNA (shRNA) was chosen and transfected in human colon cancer HCT-8/V cell line. Cell apoptosis and chemosensitivity were evaluated following downregulation of Livin expression.

RESULTS

In the current study, Livin was found to be highly expressed in the HCT-8/V colon cancer cells, which were resistant to several anti-tumor drugs. Knocking down of Livin expression in HCT-8/V cells by specific RNAi facilitated the apoptosis of HCT-8/V cells in response to vincristine (VCR), etoposide (VP-16), and 5-flourouracil (5-FU). Chemosensitivity assay confirmed the results and demonstrated the reversal of drug resistance phenotype of HCT-8/V cells.

CONCLUSION

These data suggest that specific silencing of Livin gene expression could be a promising target for further research in clinical chemotherapy of colon cancer.

The inhibitor of apoptosis protein Livin (ML-IAP) plays a dual role in tumorigenicity

The inhibitor of apoptosis protein (IAP) family can inhibit apoptosis induced by a variety of stimuli. We and others previously described the IAP Livin (ML-IAP). We found that Livin is unique among the IAP members as, on a strong apoptotic stimulus, it is specifically cleaved by caspases to produce a truncated protein with paradoxical proapoptotic activity (tLivin). We also showed that Livin encodes two splicing variants, termed Livin alpha and beta, with diverse antiapoptotic effects in vitro. In this study, we compared the Livin isoforms in vivo. An animal model was established and the effects of Livin alpha and beta on the initiation and development of tumors were compared. In the animal model, Livin alpha promotes tumor initiation in comparison with control. Interestingly, the growth of tumors originating from cells expressing Livin beta was inhibited. In these tumors, Livin beta was cleaved and produced a high level of the proapoptotic tLivin beta that repressed tumor development. When we eliminated the proapoptotic effect of Livin beta by point mutations, the resulting antiapoptotic Livin beta mutants contributed to tumor progression. In terms of mechanism, we show that Livin beta tumors develop only in mice lacking natural killer (NK) cell activity. Thus, from the animal model, we can conclude that Livin plays a major role in tumorigenicity and that NK cells induce cleavage of Livin to its proapoptotic truncated protein that in turn inhibits tumor growth. Therefore, Livin and tLivin may serve as potential targets for cancer therapy.

Effects of cIAP-1, cIAP-2 and XIAP triple knockdown on prostate cancer cell susceptibility to apoptosis, cell survival and proliferation

Background

Manipulating apoptotic resistance represents an important strategy for the treatment of hormone refractory prostate cancer. We hypothesised that the Inhibitor of Apoptosis (IAP) Proteins may be mediating this resistance and knockdown of cIAP-1, cIAP-2 and XIAP would increase sensitivity to apoptosis.

Methods

cIAP-1, cIAP-2 and XIAP where knocked down either individually or in combination using siRNA in androgen independent prostate cancer PC-3 cells as confirmed by real-time PCR and western blotting. Cells were then treated with TRAIL, Etoposide, or Tunicamycin, and apoptosis assessed by PI DNA staining. Apoptosis was confirmed with Annexin V labelling and measurement of PARP cleavage, and was inhibited using the pan-caspase inhibitor, zVAD.fmk. Clonogenic assays and assessment of ID-1 expression by western blotting were used to measure recovery and proliferation.

Results

PC-3 are resistant to TRAIL induced apoptosis and have elevated expression of cIAP-1, cIAP-2 and XIAP. Combined knockdown sensitised PC-3 to TRAIL induced apoptosis, but not to Etoposide or Tunicmycin, with corresponding increases in caspase activity and PARP cleavage which was inhibited by ZVAD.fmk. Triple knock down decreased proliferation which was confirmed by decreased ID-1 expression.

Conclusion

Simultaneous knock down of the IAPs not only sensitised the PC-3 to TRAIL but also inhibited their proliferation rates and clonogenic survival. The inability to alter sensitivity to other triggers of apoptosis suggests that this effect is specific for death receptor pathways and knock down might facilitate immune-surveillance mechanisms to counter cancer progression and, in combination with therapeutic approaches using TRAIL, could represent an important treatment strategy.