Therapeutic potential of siRNA-mediated combined knockdown of the IAP genes (Livin, XIAP, and Survivin) on human bladder cancer T24 cells

Livin expression promotes keratinocyte release of inflammatory mediators in psoriasis

BACKGROUND

Psoriasis is a prevalent, long-term skin condition characterized by inflammation. Keratinocytes (KCs) are important effector cells that release inflammatory factors and chemokines to promote the inflammatory cascade in psoriasis. However, the mechanisms underlying the activation of KCs in psoriasis remain unclear. Livin suppresses apoptotic proteins and directly affects the growth and spread of cancer cells. Livin expression reportedly increases significantly in lesions of patients with psoriasis; however, its specific role in KC activation remains unknown. This study aimed to examine the impact of Livin on KC activation and the subsequent release of inflammatory mediators.

METHODS

Immunofluorescence staining, reverse transcription-quantitative polymerase chain reaction, enzyme-linked immunosorbent assay (ELISA), and western blotting were used to assess Livin expression in patients with psoriasis, an imiquimod (IMQ)-induced psoriasis-like mouse model, and M5-treated HaCaT cells. To investigate the role of Livin in KCs, we performed RNA sequencing and proteomic analysis of Livin-knockdown (knockdown-HaCaT) and negative control (NC-HaCaT) cells. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes were used for enrichment analyses. Moreover, the effect of Livin expression on the release of inflammatory mediators in KCs was verified using ELISA.

RESULTS

Livin expression was higher in KCs of patients with psoriasis than in those healthy controls. Livin expression in HaCaT cells treated with M5 increased significantly over time. Livin expression was higher in the skin lesions of the IMQ mouse model than in the control group. Proteomic analysis and RNA sequencing used to investigate the function of Livin in HaCaT cells revealed its potential role in mediating KC activation and inflammatory mediator release, which affected the pathology of psoriasis.

CONCLUSIONS

Livin expression played an effect on KCs activation, which induced release of inflammatory mediators and up-regulation of keratin. This study provides a new effector molecule for the mechanism of inflammatory response in psoriasis.

Role of Survivin in Bladder Cancer: Issues to Be Overcome When Designing an Efficient Dual Nano-Therapy

Bladder cancer is the 10th most diagnosed cancer, with almost 10 M cancer deaths last year worldwide. Currently, chemotherapy is widely used as adjuvant therapy after surgical transurethral resection. Paclitaxel (PTX) is one of the most promising drugs, but cancer cells acquire resistance, causing failure of this treatment and increasing the recurrence of the disease. This poor chemotherapeutic response has been associated with the overexpression of the protein survivin. In this work, we present a novel dual nano-treatment for bladder cancer based on the hypothesis that the inhibition of survivin in cancer cells, using a siRNA gene therapy strategy, could decrease their resistance to PTX. For this purpose, two different polymeric nanoparticles were developed to encapsulate PTX and survivin siRNA independently. PTX nanoparticles showed sizes around 150 nm, with a paclitaxel loading of around 1.5%, that produced sustained tumor cell death. In parallel, siRNA nanoparticles, with similar sizes and loading efficiency of around 100%, achieved the oligonucleotide transfection and knocking down of survivin expression that also resulted in tumor cell death. However, dual treatment did not show the synergistic effect expected. The root cause of this issue was found to be the cell cycle arrest produced by nuclear survivin silencing, which is incompatible with PTX action. Therefore, we concluded that although the vastly reported role of survivin in bladder cancer, its silencing does not sensitize cells to currently applied chemotherapies.

Multi-Drug/Gene NASH Therapy Delivery and Selective Hyperspectral NIR Imaging Using Chirality-Sorted Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWCNTs) can serve as drug delivery/biological imaging agents, as they exhibit intrinsic fluorescence in the near-infrared, allowing for deeper tissue imaging while providing therapeutic transport. In this work, CoMoCAT (Cobalt Molybdenum Catalyst) SWCNTs, chirality-sorted by aqueous two-phase extraction, are utilized for the first time to deliver a drug/gene combination therapy and image each therapeutic component separately via chirality-specific SWCNT fluorescence. Each of (7,5) and (7,6) sorted SWCNTs were non-covalently loaded with their specific payload: the PI3 kinase inhibitor targeting liver fibrosis or CCR5 siRNA targeting inflammatory pathways with the goal of addressing these processes in nonalcoholic steatohepatitis (NASH), ultimately to prevent its progression to hepatocellular carcinoma. PX-866-(7,5) SWCNTs and siRNA-(7,6) SWCNTs were each imaged via characteristic SWCNT emission at 1024/1120 nm in HepG2 and HeLa cells by hyperspectral fluorescence microscopy. Wavelength-resolved imaging verified the intracellular transport of each SWCNT chirality and drug release. The therapeutic efficacy of each formulation was further demonstrated by the dose-dependent cytotoxicity of SWCNT-bound PX-866 and >90% knockdown of CCR5 expression with SWCNT/siRNA transfection. This study verifies the feasibility of utilizing chirality-sorted SWCNTs for the delivery and component-specific imaging of combination therapies, also suggesting a novel nanotherapeutic approach for addressing the progressions of NASH to hepatocellular carcinoma.

The effect of polymorphisms in the promoter of the BIRC5 gene on the risk of oesophageal squamous cell carcinoma and patient’s outcomes

Baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5) is an inhibitor of apoptosis proteins and plays a key role in apoptosis or programmed cell death. In the present study, we evaluated the effect of BIRC5 gene polymorphisms on the risk of developing oesophageal squamous cell carcinoma (ESCC) and patients’ outcomes in a high-incidence population from northern China. A population-based case-control study was performed in 597 ESCC patients and 597 control subjects.Survival data were available for 211 patients who received platinum-based chemotherapy after surgery. Five polymorphisms (-31 C>G, -241 C>T, -625 G>C, -644 T>C and -1547 A>G) in the promoter of the BIRC5 gene were genotyped by the polymerase chain reaction-ligase detection reaction (PCR-LDR) method. Compared with the -31 CC genotype, the -31 CG/GG genotype of -31 C>G single nucleotide polymorphism (SNP) was associated with a significant elevated risk of ESCC [adjusted odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.07–1.84]. Interestingly, this association was stronger among females, younger patients and non-smokers in stratified analyses (adjusted OR = 1.72, 95% CI = 1.07–2.75; adjusted OR = 1.61, 95% CI = 1.10–2.36; adjusted OR = 1.80, 95% CI = 1.26–2.58, respectively]. Survival analyses showed that the T allele of -241 C>T SNP was associated with poor prognosis [hazard ratio (HR) = 2.99, 95% CI = 1.09–8.19) and that the C allele of -625 G>C SNP was associated with good prognosis (HR = 0.62, 95% CI = 0.38–0.99) in ESCC patients. The -31 C>G polymorphism may be involved in the development of ESCC, and the -241 C>T and -625 G>C polymorphisms may be useful prognostic markers for ESCC.

Inhibitors of apoptosis: clinical implications in cancer

Inhibitor of apoptosis (IAP) family comprises a group of endogenous proteins that function as main regulators of caspase activity and cell death. They are considered the main culprits in evasion of apoptosis, which is a fundamental hallmark of carcinogenesis. Overexpression of IAP proteins has been documented in various solid and hematological malignancies, rendering them resistant to standard chemotherapeutics and radiation therapy and conferring poor prognosis. This observation has urged their exploitation as therapeutic targets in cancer with promising pre-clinical outcomes. This review describes the structural and functional features of IAP proteins to elucidate the mechanism of their anti-apoptotic activity. We also provide an update on patterns of IAP expression in different tumors, their impact on treatment response and prognosis, as well as the emerging investigational drugs targeting them. This aims at shedding the light on the advances in IAP targeting achieved to date, and encourage further development of clinically applicable therapeutic approaches.

Dual targeting of survivin and X-linked inhibitor of apoptosis protein suppresses the growth and promotes the apoptosis of gastric cancer HGC-27 cells

Gastric cancer can be a fatal tumor and therefore represents one of the primary challenges in modern oncology. Survivin and X-linked inhibitor of apoptosis protein (XIAP) are members of the IAP family, which exerts a strong inhibitory effect on cellular apoptosis. In previous studies, the expression levels of survivin and XIAP have been demonstrated to influence the prognosis of patients with gastric cancer; therefore, the present study investigated the effect of silencing survivin and XIAP on the biological activity of the gastric cancer HGC-27 cell line. It was demonstrated that the expression levels of survivin and XIAP were significantly increased in gastric cancer tissues, compared with the adjacent non-tumor tissues. Furthermore, it was observed that the expression levels of survivin and XIAP were similarly elevated in gastric cancer HGC-27 cells, compared with normal gastric epithelial GES-1cells. Furthermore, small interfering RNA-mediated surviving- or XIAP-knockdown, in addition to the dual knockdown of survivin and XIAP, inhibited the proliferation and promoted the apoptosis of HGC-27 cells. Simultaneous inhibition of XIAP and survivin expression was more effective, compared with inhibition of XIAP or survivin alone. These results indicated that the dual knockdown of survivin and XIAP may be an effective strategy for treating gastric cancer in the future.

Transfection with Livin and Survivin shRNA inhibits the growth and proliferation of non‑small cell lung cancer cells

Lung cancer is reported to be a major public health issue worldwide and the overall prognosis of patients remains poor. The expression levels of Livin and Survivin, of the inhibitors of apoptosis (IAP) family, are associated with prognostic significance in the majority of solid tumors. Therefore, in the presents study, short hairpin (sh)RNA expression vectors inhibiting the Livin and Survivin genes were constructed to examine the effects of the transfection of Livin shRNA and/or Survivin shRNA on the biological functions of tumor cells. The transfection efficiency was measured using fluorescence reverse transcription‑quantitative polymerase chain reaction and western blot analyses. The cell growth inhibition ratio was measured using a CCK assay. Cell apoptosis following transfection and in tumor tissues were measured using a TUNEL assay, and a cancer xenograft model was used to investigate the effect of Livin shRNA and/or Survivin shRNA on tumor growth. The results indicated that the mRNA and protein expression levels were suppressed following the transfection of Livin and Survivin shRNA into tumor cells (P<0.05, compared with control group). The growth of tumor cells in vivo and in vitro was significantly inhibited following transfection with Livin and Survivin shRNA, compared with that in the other groups (P<0.05). Taken together, the transfection of cells with Livin and Survivin inhibited tumor growth in vivo and in vitro, with the co‑transfection of Livin and Survivin shRNA showing increased efficiency, compared with transfection of either the Livin vector or Survivin vector alone. The combined inhibition of Livin and Survivin may be a promising multitargeted gene therapeutic strategy in cancer treatment.

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.

Inhibition of livin expression suppresses cell proliferation and enhances chemosensitivity to cisplatin in human lung adenocarcinoma cells

Livin is a novel member of the inhibitor of apoptosis protein family that has been reported to be overexpressed in various types of human malignancy. Although several studies have demonstrated that livin may be used as an effective target for tumor therapy, few studies have investigated its role in human lung adenocarcinoma. In the present study, two different methods were used in order to investigate the tumor‑suppressing effect of livin in human lung adenocarcinoma cells. Firstly, small interfering (si)RNA technology was used to down regulate livin expression; siRNA-mediated knockdown of livin was confirmed using reverse transcription quantitative polymerase chain reaction and western blot analysis, and cell proliferations was assessed using an MTT assay in vitro. Secondly, inhibition of livin expression was induced through the synergistic inhibitory effect between flavopiridol and tumor necrosis factor‑related apoptosis-inducing ligand (TRAIL). Experimental results revealed that, following transfection of the livin gene-silencing vector, the gene expression of livin was markedly decreased, SPC-A1 cell proliferation was significantly reduced and the therapeutic effect of the chemotherapy drug cisplatin was markedly improved. This growth inhibitory effect was also observed in the flavopiridol and TRAIL combination treatment group. In the flavopiridol and TRAIL combination treatment group, the protein expression of livin was significantly reduced and the survival rate of SPC‑A1 cells was significantly lower than the flavopiridol and TRAIL single operation group. In conclusion, the RNA silencing and the synergistic inhibitory effect between flavopiridol with TRAIL was able to effectively inhibit the expression of livin, significantly decrease SPC-A1 tumor cell proliferation and significantly enhance sensitivity to the chemotherapy drug cisplatin. These findings suggest that livin may be used as a novel target for tumor gene therapy.

Inhibition of cell proliferation and increase of chemosensitivity by simultaneous knockdown of XIAP and survivin in pancreatic carcinoma cells

At present, classic therapies provide limited benefits to the survival of patients with pancreatic cancer. However, clinically available gene therapy strategies have not been well established. This study investigates the effect of shRNA-mediated inhibition of XIAP and survivin expression on the proliferation, apoptosis, and chemosensitivity of pancreatic cancer cells. Stable inhibition of XIAP and survivin expression in SW1990 and Panc-1 pancreatic cancer cells was established by lentivirus-carried shRNAs. The mRNA and protein expression of XIAP and survivin were detected by real-time PCR and Western blot, respectively. Cell proliferation was measured by MTT assay, and apoptosis was detected by caspase-3/7 activity and Hoechst33342 staining. The lentivirus-carried shRNA significantly inhibited XIAP and survivin expression. Simultaneous inhibition of XIAP and survivin expression in pancreatic cells significantly reduced cell proliferation, increased caspase-3/7 activity, and increased cell sensitization to 5-FU and gemcitabine treatments compared to inhibition of XIAP or survivin expression alone. However, simultaneous silencing of XIAP and survivin showed no significant difference in inducing cell apoptosis compared to silencing of XIAP or survivin expression alone. Simultaneous inhibition of XIAP and survivin expression may be an effective strategy for gene therapy of pancreatic cancer.

Prognostic significance of survivin in breast cancer: meta-analysis

Survivin, an inhibitor of apoptosis protein, is a potentially prognostic factor and therapeutic target in breast carcinoma, but no consensus exists based on heterogeneous data. The aim of this present study is to clarify the prognostic relevance of survivin in breast cancer patients. Relevant articles were screened in PubMed and EMBASE databases. Patients' clinical characteristics, overall survival (OS), disease/recurrence-free survival (DFS/RFS) and positive expressed survivin rates were extracted for further analysis. Statistics extracted from Kaplan-Meier survival curves were calculated indirectly with methods developed by Parmar, Williamson, and Tierney. Multivariate Cox hazard regression analysis data were used directly in Stata 11.0. Pooled hazard ratio (HR) and 95% confidence interval (CI) were calculated to evaluate the prognostic role of survivin in breast cancer. Online literature search identified 23 articles containing 3,259 breast cancer patients. Our meta-analysis of all included studies about survival outcomes showed positive correlation between poor prognosis and survivin expression. Pooled HRs (95% CIs) for OS and DFS/RFS were 1.37 (1.12-1.68) and 1.34 (1.02-1.76), respectively. Subgroup analyses considering methods used to detect survivin (immunohistochemistry or not) and localization of survivin (whole, nuclear or cytoplasm of the cell) were also conducted, and all the above analyses supported the stability of the prognostic role of survivin. In addition, our study revealed a significant association between survivin expression and lymph node metastasis (OR: 2.74; 95% CI: 1.27-5.93) or stage of breast cancer (OR: 2.01; 95% CI: 1.29-3.13). Positive expression of survivin demonstrated a significantly higher risk of recurrence and decreased OS rates in breast cancer.

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.

Surface-modified nanoparticles enhance transurothelial penetration and delivery of survivin siRNA in treating bladder cancer

Penetration of the bladder permeability barrier (BPB) is a major challenge when treating bladder diseases via intravesical delivery. To increase transurothelial migration and tissue and tumor cell uptake, poly(lactic-co-glycolic acid; PLGA) nanoparticles (NP) were modified by addition of a low molecular weight (2.5 or 20 kDa) positively charged mucoadhesive polysaccharide, chitosan, to the NP surface. In designing these NPs, we balanced the adhesive properties of chitosan with the release and bioactivity of the siRNA. Chitosan-functionalized NPs demonstrated increased binding to and uptake in intravesically instilled mouse bladders and human ureter at 10 times the level of unmodified NPs. Furthermore, we extended the bioactivity of survivin siRNA in vitro for up to 9 days and demonstrated a decrease in proliferation when using chitosan-modified NPs relative to unmodified NPs. In addition, treatment of xenograft tumors with chitosan-modified NPs that encapsulate survivin siRNA (NP-siSUR-CH2.5) resulted in a 65% reduction in tumor volume and a 75% decrease in survivin expression relative to tumors treated with blank chitosan NPs (NP-Bk-CH2.5). Our low molecular weight chitosan delivery system has the capacity to transport large amounts of siRNA across the urothelium and/or to the tumor site, thus increasing therapeutic response.

Double siRNA-targeting of cIAP2 and LIVIN results in synergetic sensitization of HCT-116 cells to oxaliplatin treatment

Purpose

Most colon cancers show low sensitivity to treatment with oxaliplatin and a specific strategy is needed to overcome this problem. Our approach uses RNA interference to silence the expression of target genes responsible for the development of oxaliplatin resistance. Profile analysis of genes related to the regulation of apoptosis allowed identification of target genes showing the greatest degree of upregulation in response to oxaliplatin exposure.

Methods

We designed a panel of genes with functions closely related to inactivation of the caspase cascade, endoplasmic reticulum stress reduction, and drug metabolism. The candidate genes were silenced by means of specific small interfering RNA (siRNA) oligonucleotides.

Results

The caspase 3 and 9 inhibitors of apoptosis 2 (cIAP2) and LIVIN were found to be the most dose-responsive genes during the period of oxaliplatin treatment. Two-fold sensitization of cells to oxaliplatin was observed with independent knockdown of either cIAP2 or LIVIN expression. siRNA-silencing of both targets produced a five-fold increase in oxaliplatin sensitivity of HCT-116 cells.

Conclusion

A dose-dependent approach revealed reliable targets for siRNA-silencing under low doses of oxaliplatin. Targeting the key proapoptotic chain with several specific siRNAs resulted in synergetic sensitization of HCT-116 cells to oxaliplatin treatment.

A novel mechanism of XIAP degradation induced by timosaponin AIII in hepatocellular carcinoma

Inducing tumor cell death is one of the major therapeutic strategies in treating cancer. The aim of this study is to investigate the mechanism underlying the involvement of autophagy in cell death induced by timosaponin AIII (TAIII). Cell viability was determined by MTT and cologenic assay; apoptosis was determined by flow cytometry and TUNEL assay; autophagy was examined by immunoblotting and immunofluorescence; ubiquitination was detected by co-immunoprecipitation; mRNA expression was detected by real-time PCR; and determination of necrotic cell death was approached with LDH assay. The in vivo tumor growth inhibition was determined by xenograft model. TAIII exhibits potent cytotoxicity on human hepatocellular carcinoma (HCC) cells without severe hepatic toxicity. TAIII induced caspase-dependent apoptosis in HCC, and the induction of apoptosis was attributed to the inhibition of TAIII on XIAP expression. Repressing XIAP expression allowed cell tolerance toward the treatment with TAIII. The suppression of XIAP by TAIII is under post-transcriptional control and independent of proteasomal-driven proteolysis. Instead, TAIII-induced AMPKα/mTOR-dependent autophagy was responsible for XIAP suppression and triggered the XIAP heading lysosomal degradation pathway. Ubiquitination of IAPs is required for the autophagic degradation induced by TAIII. Blockade of autophagy turns on the switch of necrotic cell death in TAIII-treated cells. Timosaponin AIII induces HCC cell apoptosis through a p53-independent mechanism involving XIAP degradation through autophagy-lysosomal pathway. The possibility of developing TAIII as a new anti-tumor agent is worth considering.

Enhanced inhibition of bladder cancer cell growth by simultaneous knockdown of antiapoptotic Bcl-xL and survivin in combination with chemotherapy

The overexpression of antiapoptotic genes, such as Bcl-xL and survivin, contributes to the increased survival of tumor cells and to the development of treatment resistances. In the bladder cancer cell lines EJ28 and J82, the siRNA-mediated knockdown of survivin reduces cell proliferation and the inhibition of Bcl-xL sensitizes these cells towards subsequent chemotherapy with mitomycin C and cisplatin. Therefore, the aim of this study was to analyze if the simultaneous knockdown of Bcl-xL and survivin might represent a more powerful treatment option for bladder cancer than the single inhibition of one of these target genes. At 96 h after transfection, reduction in cell viability was stronger after simultaneous inhibition of Bcl-xL and survivin (decrease of 40%-48%) in comparison to the single target treatments (decrease of 29% at best). Furthermore, simultaneous knockdown of Bcl-xL and survivin considerably increased the efficacy of subsequent chemotherapy. For example, cellular viability of EJ28 cells decreased to 6% in consequence of Bcl-xL and survivin inhibition plus cisplatin treatment whereas single target siRNA plus chemotherapy treatments mediated reductions down to 15%-36% only. In conclusion, the combination of simultaneous siRNA-mediated knockdown of antiapoptotic Bcl-xL and survivin-a multitarget molecular-based therapy-and conventional chemotherapy shows great potential for improving bladder cancer treatment.

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.

Zinc sensitizes prostate cancer cells to sorafenib and regulates the expression of Livin

In prostate carcinogenesis, normal zinc-accumulating epithelial cells are transformed into malignant cells that do not accumulate zinc. Increased levels of zinc have been shown to induce apoptosis through a caspase-dependent mechanism with down-regulated anti-apoptotic proteins in prostate cancer cells. Our previous study showed that, as a member of the inhibitor of apoptosis proteins (IAPs) family, Livin could play an important role in the initiation of human prostate cancer and promote cell proliferation by altering the G1-S cell cycle transition. In the present study, we measured the apoptosis sensitivity of prostate cancer cells to zinc and sorafenib and found that zinc sensitized prostate cancer cells to sorafenib-induced apoptosis. Surprisingly, we also found that, unlike its counterparts Survivin and cIAP2, Livin was not decreased all the time; instead, it was compensatively increased in zinc-mediated apoptosis at 48 h in prostate cancer cells. Our results offer potential treatment combinations that may augment the effect of sorafenib, and also reveal, for the first time, that increased Livin expression may play a role in the early cell death response of prostate cancer cells to zinc.

Expression of the IAP protein family acts cooperatively to predict prognosis in human bladder cancer patients

The inhibitors of apoptosis (IAPs) are a group of anti-apoptotic factors in the apoptotic pathway that render cancer cells insensitive to apoptotic stimulation. Recently, several members of the IAP family have been investigated in the context of bladder cancer, and some of these have been associated with specific clinical and pathological tumor features, and with prognosis. These data suggested that the expression of an individual nuclear IAP has an important relationship with the progression of bladder cancer. To date, there are no studies concerning the overall tendencies of IAPs and their comparative therapeutic values in bladder cancer. In this study, we investigated the overall expression trends of the five tumor-related proteins, Survivin, cIAP1, cIAP2, XIAP and Livin, in normal bladder tissues and bladder cancer tissues. We classified and compared the gene expression data of these IAPs with the corresponding clinical and pathological tumor features, and with prognosis, in the development and progression of bladder cancer. The differences in IAP expression levels between archival bladder specimens from 36 normal controls and 105 patients who underwent surgery at our facility were examined using western blot analysis. The localization and expression level of each protein in low- and high-grade bladder cancer tissues were examined through immunohistochemistry. The cytoplasmic expression levels of each protein were scored as 0 (negative), +1 (weak), +2 (medium) or +3 (strong). The nuclear expression levels of cIAP1 and Survivin were scored as 0 (0%), +1 (1–25%), +2 (26–50%) or +3 (>50%). The results demonstrated that the expression of IAPs acted cooperatively to predict prognosis in human bladder cancer patients.

Small interfering RNA targeted to secretory clusterin blocks tumor growth, motility, and invasion in breast cancer

Clusterin/apolipoprotein J (Clu) is a ubiquitously expressed secreted heterodimeric glycoprotein that is implicated in several physiological processes. It has been reported that the elevated level of secreted clusterin (sClu) protein is associated with poor survival in breast cancer patients and can induce metastasis in rodent models. In this study, we investigated the effects of sClu inhibition with small interfering RNAs (siRNAs) on cell motility, invasion, and growth in vitro and in vivo. MDA-MB-231 cells were transfected with pSuper-siRNA/sClu. Cell survival and proliferation were examined by 3-(4,5-dimethyl-thiazol-2yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium and clonogenic survival assay. The results showed that sClu silencing significantly inhibited the proliferation of MDA-MB-231 cells. The invasion and migration ability were also dramatically decreased, which was detected by matrigel assays. TUNEL staining and caspase-3 activity assay demonstrated that sClu silencing also could increase the apoptosis rate of cells, resulting in the inhibition of cell growth. We also determined the effects of sClu silencing on tumor growth and metastatic progression in an orthotopic breast cancer model. The results showed that orthotopic primary tumors derived from MDA-MB-231/pSuper sClu siRNA cells grew significantly slower than tumors derived from parental MDA-MB-231 or MDA-MB-231/pSuper scramble siRNA cells, and metastasize less to the lungs. These data suggest that secretory clusterin plays a significant role in tumor growth and metastatic progression. Knocking-down sClu gene expression may provide a valuable method for breast cancer therapy.

Simultaneous siRNA-mediated knockdown of antiapoptotic BCL2, Bcl-xL, XIAP and survivin in bladder cancer cells

Bladder cancer (BCa) represents the ninth most common malignancy worldwide. Despite intensive treatment with surgery and chemotherapy the prognosis for BCa patients particularly at advanced stages is poor. The ability to evade apoptosis is a hallmark of cancer cells. Since the antiapoptotic genes BCL2, Bcl-xL, XIAP and survivin are frequently upregulated in BCa tissues, their combined siRNA-mediated knockdown might be more potent in decreasing BCa growth than the single inhibition of one target. Against each target two siRNAs were selected that specifically reduced the mRNA and protein levels of their appropriate target in EJ28 and J82 BCa cells. Inhibition of survivin provoked the strongest antiproliferative effect of all single target treatments, for example cell counts decreased by 50%. Simultaneous targeting of all four antiapoptotic genes downregulated expression levels of all targets and mediated significant reductions in cell viability and cell counts as well as induction of apoptosis. In EJ28 cells, combined knockdown of BCL2, Bcl-xL, XIAP and survivin caused a 2.5-fold enhancement in apoptosis rate and reduced cellular viability by 40%. Therefore, simultaneous knockdown of antiapoptotic BCL2, Bcl-xL, XIAP and survivin may represent a promising treatment option for bladder cancer.

Sensitization of human bladder tumor cells to TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis with a small molecule IAP antagonist

Urothelial carcinoma of the bladder accounts for approximately 5% of all cancer deaths in humans. The large majority of bladder tumors are non-muscle invasive at diagnosis, but even after local surgical therapy there is a high rate of local tumor recurrence and progression. Current treatments extend time to recurrence but do not significantly alter disease survival. The objective of the present study was to investigate the tumoricidal potential of combining the apoptosis-inducing protein TNF-related apoptosis-inducing ligand (TRAIL) with a small molecule inhibitor of apoptosis proteins (IAP) antagonist to interfere with intracellular regulators of apoptosis in human bladder tumor cells. Our results demonstrate that the IAP antagonist Compound A exhibits high binding affinity to the XIAP BIR3 domain. When Compound A was used at nontoxic concentrations in combination with TRAIL, there was a significant increase in the sensitivity of TRAIL-sensitive and TRAIL-resistant bladder tumor lines to TRAIL-mediated apoptosis. In addition, modulation of TRAIL sensitivity in the TRAIL-resistant bladder tumor cell line T24 with Compound A was reciprocated by XIAP small interfering RNA-mediated suppression of XIAP expression, suggesting the importance of XIAP-mediated resistance to TRAIL in these cells. These results suggest the potential of combining Compound A with TRAIL as an alternative therapy for bladder cancer.