Survivin-directed RNA interference cocktail is a potent suppressor of tumour growth in vivo

Fusion-negative rhabdomyosarcoma 3D organoids to predict effective drug combinations: A proof-of-concept on cell death inducers

Rhabdomyosarcoma (RMS) is the main form of pediatric soft-tissue sarcoma. Its cure rate has not notably improved in the last 20 years following relapse, and the lack of reliable preclinical models has hampered the design of new therapies. This is particularly true for highly heterogeneous fusion-negative RMS (FNRMS). Although methods have been proposed to establish FNRMS organoids, their efficiency remains limited to date, both in terms of derivation rate and ability to accurately mimic the original tumor. Here, we present the development of a next-generation 3D organoid model derived from relapsed adult and pediatric FNRMS. This model preserves the molecular features of the patients' tumors and is expandable for several months in 3D, reinforcing its interest to drug combination screening with longitudinal efficacy monitoring. As a proof-of-concept, we demonstrate its preclinical relevance by reevaluating the therapeutic opportunities of targeting apoptosis in FNRMS from a streamlined approach based on transcriptomic data exploitation.

Advances in immunotherapeutic targets for childhood cancers: A focus on glypican-2 and B7-H3

Cancer immunotherapies have revolutionized how we can treat adult malignancies and are being translated to pediatric oncology. Chimeric antigen receptor T-cell therapy and bispecific antibodies targeting CD19 have shown success for the treatment of pediatric patients with B-cell acute lymphoblastic leukemia. Anti-GD2 monoclonal antibody has demonstrated efficacy in neuroblastoma. In this review, we summarize the immunotherapeutic agents that have been approved for treating childhood cancers and provide an updated review of molecules expressed by pediatric cancers that are under study or are emerging candidates for future immunotherapies. Advances in our knowledge of tumor immunology and in genome profiling of cancers has led to the identification of new tumor-specific/associated antigens. While cell surface antigens are normally targeted in a major histocompatibility complex (MHC)-independent manner using antibody-based therapies, intracellular antigens are normally targeted with MHC-dependent T cell therapies. Glypican 2 (GPC2) and B7-H3 (CD276) are two cell surface antigens that are expressed by a variety of pediatric tumors such as neuroblastoma and potentially can have a positive impact on the treatment of pediatric cancers in the clinic.

Challenges and advances in clinical applications of mesenchymal stromal cells

Mesenchymal stromal cells (MSCs), also known as mesenchymal stem cells, have been intensely investigated for clinical applications within the last decades. However, the majority of registered clinical trials applying MSC therapy for diverse human diseases have fallen short of expectations, despite the encouraging pre-clinical outcomes in varied animal disease models. This can be attributable to inconsistent criteria for MSCs identity across studies and their inherited heterogeneity. Nowadays, with the emergence of advanced biological techniques and substantial improvements in bio-engineered materials, strategies have been developed to overcome clinical challenges in MSC application. Here in this review, we will discuss the major challenges of MSC therapies in clinical application, the factors impacting the diversity of MSCs, the potential approaches that modify MSC products with the highest therapeutic potential, and finally the usage of MSCs for COVID-19 pandemic disease.

Targeted-delivery of siRNA via a polypeptide-modified liposome for the treatment of gp96 over-expressed breast cancer

Targeted gene therapy has led to significant breakthroughs in cancer treatment. Heat shock protein gp96 is an emerging target for tumor treatment because of its transfer ability from reticulum to tumor cell surface. CDO14 is a peptide cationic liposome developed in our laboratory with higher gene transfection efficiency and lower toxicity compared with the existing cationic liposomes. In this study, gp96-targeted liposome p37-CDO14 was constructed by modifying cationic liposome CDO14 with a gp96 inhibitor, helical polypeptide p37. Liposome p37-CDO14 could specifically bind to breast cancer cells with gp96-overexpression on the cell membrane. Both liposomes CDO14 and p37-CDO14 showed high delivery efficiency for survivin siRNA (siSuvi) to SK-BR-3 and MCF-7 cells via obviously decreased survivin expression level and cell viability. P37-CDO14 significantly increased the accumulation of FAM-siRNA in tumor compared with CDO14. SiSuvi transfected by CDO14 and p37-CDO14 could inhibit the growth of xenograft in mice and the expression of survivin in tumor tissues. The anti-tumor effect of siSuvi delivered by p37-CDO14 was much higher than that delivered by CDO14. This suggests that targeted liposome p37-CDO14 is a potential gene vector for the therapy of gp96 overexpressed breast cancer.

Multiomics global landscape of stemness-related gene clusters in adipose-derived mesenchymal stem cells

Background

Adipose-derived mesenchymal stem cells (AD-MSCs) are a type of stem cell that is abundant and widely used. The molecular characteristics of AD-MSCs from different passages from donors of different ages have not been well elucidated.

Methods

Six kinds of AD-MSCs ((E1, E2, E3, Y1, Y2, and Y3) with E denoting cells derived from an elderly patient, Y denoting cells derived from a young patient, and 1, 2, and 3 representing passages 3, 6, and 10) were obtained from human abdominal adipose tissue. We obtained the protein expression profile, the mRNA expression profile, the lncRNA expression profile, and the methylation profile of each kind of AD-MSC by sequencing. After calculating the stemness indices, genes related to stemness were extracted. The multiomics correlation analysis was performed in the stemness-related genes. In addition, short time-series expression miner (STEM) analysis was performed for all cell passages and donor ages. To further explore the biological functions of the stemness-related genes, we performed Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Finally, the lncRNA-KEGG network and transcription factor (TF)-KEGG network were constructed based on the RNAInter database and TRRUST v2 database.

Results

The stemness of the Y1, E1, and Y2 cells was higher than that of the E2, Y3, and E3 cells. The stemness was the highest for Y1 cells and the lowest for E3 cells. STEM analysis showed that five stemness-related gene clusters were associated with the cell passages, and only one gene cluster was associated with age. The enrichment analysis results showed that the biological processes (BPs) and KEGG pathways were mainly involved in the proliferation, differentiation, and migration of cells. The global regulatory landscape of AD-MSCs was constructed: 25 TFs and 16 lncRNAs regulated 21 KEGG pathways through 27 mRNAs. Furthermore, we obtained a core stemness-related gene set consisting of ITGAV, MAD2L1, and PCNA. These genes were expressed at higher levels in Y1 cells than in E3 cells.

Conclusion

The multiomics global landscape of stemness-related gene clusters was determined for AD-MSCs, which may be helpful for selecting AD-MSCs with increased stemness.

Destined to Die: Apoptosis and Pediatric Cancers

Apoptosis (programmed cell death) is a systematic and coordinated cellular process that occurs in physiological and pathophysiological conditions. Sidestepping or resisting apoptosis is a distinct characteristic of human cancers including childhood malignancies. This review dissects the apoptosis pathways implicated in pediatric tumors. Understanding these pathways not only unraveled key molecules that may serve as potential targets for drug discovery, but also molecular nodes that integrate with other signaling networks involved in processes such as development. This review presents current knowledge of the complex regulatory system that governs apoptosis with respect to other processes in pediatric cancers, so that fresh insights may be derived regarding treatment resistance or for more effective treatment options.

Synergistic effects of 7-O-geranylquercetin and siRNAs on the treatment of human breast cancer

AIMS

To investigate the antitumor effect of 7-O-geranylquercetin (GQ) combining with survivin siRNA (siSuvi) or IL-10 siRNA (siIL-10) to breast cancer.

MAIN METHODS

Xenograft tumor model was established by subcutaneously inoculating human breast cancer MCF-7 cells in BALB/c nude mice. Transfection efficiency of siRNA mediated by cationic liposome CDO14 in MCF-7 cells and tumor bearing mice was measured by flow cytometer and living imaging sysytem, respectively. Cell viability was detected using CCK-8 assay. Cell apoptosis was determined by Hoechst33342 staining and AV-PI staining. Tumors bearing mice were administered with GQ by gavage, and/or with liposome CDO14 mediated siRNAs via tail intravenous injection. Expression levels of proteins and cytokines were detected by western blot and ELISA, respectively.

KEY FINDINGS

Liposome CDO14 could deliver siRNA to tumor effectively. Combination of GQ and siSuvi promoted the antiproliferation and pro-apoptosis effects of GQ or siSuvi to MCF-7 cells, and reduced the level of survivin and raised the level of caspase-7 in cells. GQ combining with siSuvi inhibited the growth of tumor, down-regulated the expression of survivin and up-regulated the expression of caspase-7 in tumor tissue. Similarly, GQ combining with siIL-10 inhibited the growth of tumor, decreased the level of IL-10 and increased the level of TNF-α. These results revealed that GQ enhanced the pro-apoptosis effect of siSuvi on tumor cells and the modulating effect of siIL-10 on tumor microenvironment.

SIGNIFICANCES

Synergistic anti-tumor effect of GQ and siRNAs against breast cancer proved that chemical drugs combining with siRNAs is a promising antitumor strategy.

Tumor expression of survivin, p53, cyclin D1, osteopontin and fibronectin in predicting the response to neo-adjuvant chemotherapy in children with advanced malignant peripheral nerve sheath tumor

PURPOSE

Selected cell-cycle regulators and extracellular matrix proteins were found to play roles in malignant peripheral nerve sheath tumor (MPNST) biology. We aimed to analyze whether initial tumor tissue expressions of survivin, p53, cyclin D1, osteopontin (OPN) and fibronectin (FN) correlate with the response to neo-adjuvant CHT (naCHT) in children with advanced inoperable MPNST.

METHODS

The study included 26 children with MPNST (M/F 14/12, median age 130 months) treated in Polish centers of pediatric oncology between 1992 and 2013. Tissue expression of markers was studied immunohistochemically in the manually performed tissue microarrays and assessed semi-quantitatively as low and high, based on the rate of positive cells and staining intensity.

RESULTS

Good response to naCHT was noted in 47.6%, while poor-in 52.4% of patients. The response to naCHT was influenced negatively by the presence of neurofibromatosis NF1 and high initial tumor tissue expression of OPN, survivin, p53 and cyclin D1. Patients with high tumor expression of either OPN, survivin or p53 and those with simultaneous high expression of ≥ 3 of the markers, responded significantly worse to naCHT, than patients, in whom expression of ≤ 2 markers were detected at diagnosis. Nearly, 85% of patients expressing ≥ 3 markers, responded poor to CHT; while 87.5% of children, expressing ≤ 2 markers, were good responders.

CONCLUSION

The initial tumor tissue expression of OPN, survivin, p53 and cyclin D1 may serve as markers to predict response to naCHT in pediatric advanced MPNST. Future studies in more numerous group of patients are needed to confirm these preliminary results.

Synergistic Antitumour Properties of viscumTT in Alveolar Rhabdomyosarcoma

Aqueous mistletoe extracts from the European mistletoe (Viscum album) contain mainly mistletoe lectins and viscotoxins as cytotoxic compounds. Lipophilic triterpene acids, which do not occur in conventional mistletoe preparations, were solubilised with β-cyclodextrins. The combination of an aqueous extract (viscum) and a triterpene-containing extract (TT) recreated a whole mistletoe extract (viscumTT). These extracts were tested on rhabdomyosarcoma in vitro, ex vivo, and in vivo with regard to anticancer effects. Viscum and viscumTT inhibited cell proliferation and induced apoptosis effectively in a dose-dependent manner in vitro and ex vivo, whereas TT showed only moderate inhibitory effects. viscumTT proved to be more effective than the single extracts and displayed a synergistic effect in vitro and a stronger effect in vivo. viscumTT induced apoptosis via the extrinsic and intrinsic pathways, evidenced by the loss of mitochondrial membrane potential and activation of CASP8 and CASP9. CASP10 inhibitor inhibited apoptosis effectively, emphasising the importance of CASP10 in viscumTT-induced apoptosis. Additionally, viscumTT changed the ratio of apoptosis-associated proteins by downregulation of antiapoptotic proteins such as XIAP and BIRC5, thus shifting the balance towards apoptosis. viscumTT effectively reduced tumour volume in patient-derived xenografts in vivo and may be considered a promising substance for rhabdomyosarcoma therapy.

Antitumor effect of YM155, a novel small-molecule survivin suppressant, via mitochondrial apoptosis in human MFH/UPS

Survivin is a member of the inhibitor of apoptosis family, which is known to inhibit mitochondrial apoptosis. Survivin is highly expressed in cancers and plays an important role in cancer cell survival, and increased survivin expression is an unfavorable prognostic marker in cancer patients. YM155, a novel small-molecule survivin suppressant, selectively suppresses survivin expression, resulting in the induction of apoptosis in various malignancies. However, the roles of survivin in human malignant fibrous histiocytoma/undifferentiated pleomorphic sarcoma (MFH/UPS) have not been studied. In the present study, we examined survivin expression in human musculoskeletal tumor tissues, and the effect of survivin inhibition by siRNA or YM155 on apoptotic activity in human MFH/UPS cell lines. In tumor tissues, mRNA expression of survivin was significantly higher in MFH/UPS samples than in benign schwannomas. Moreover, in vitro studies revealed that both survivin siRNA and YM155 suppressed survivin expression and inhibited MFH/UPS cell proliferation in a dose- and a time-dependent manner. Further, the numbers of apoptotic cells significantly increased with YM155 treatment. In vivo, tumor volume in YM155-treated groups was significantly reduced without significant bodyweight loss. Increased apoptotic activity along with decreased survivin expression was also observed in YM155-treated tumors. The findings in this study strongly suggest that survivin suppressants, including YM155, contribute to the suppression of human MFH/UPS cell growth via promoting mitochondrial apoptosis, and that survivin may be a potent therapeutic target for the novel treatment of human MFH/UPS.

Rb1 loss modifies but does not initiate alveolar rhabdomyosarcoma

Background

Alveolar rhabdomyosarcoma (aRMS) is a myogenic childhood sarcoma frequently associated with a translocation-mediated fusion gene, Pax3:Foxo1a.

Methods

We investigated the complementary role of Rb1 loss in aRMS tumor initiation and progression using conditional mouse models.

Results

Rb1 loss was not a necessary and sufficient mutational event for rhabdomyosarcomagenesis, nor a strong cooperative initiating mutation. Instead, Rb1 loss was a modifier of progression and increased anaplasia and pleomorphism. Whereas Pax3:Foxo1a expression was unaltered, biomarkers of aRMS versus embryonal rhabdomyosarcoma were both increased, questioning whether these diagnostic markers are reliable in the context of Rb1 loss. Genome-wide gene expression in Pax3:Foxo1a,Rb1 tumors more closely approximated aRMS than embryonal rhabdomyosarcoma. Intrinsic loss of pRb function in aRMS was evidenced by insensitivity to a Cdk4/6 inhibitor regardless of whether Rb1 was intact or null. This loss of function could be attributed to low baseline Rb1, pRb and phospho-pRb expression in aRMS tumors for which the Rb1 locus was intact. Pax3:Foxo1a RNA interference did not increase pRb or improve Cdk inhibitor sensitivity. Human aRMS shared the feature of low and/or heterogeneous tumor cell pRb expression.

Conclusions

Rb1 loss from an already low pRb baseline is a significant disease modifier, raising the possibility that some cases of pleomorphic rhabdomyosarcoma may in fact be Pax3:Foxo1a-expressing aRMS with Rb1 or pRb loss of function.

MYCN and survivin cooperatively contribute to malignant transformation of fibroblasts

The oncogenes MYCN and survivin (BIRC5) maintain aggressiveness of diverse cancers including sarcomas. To investigate whether these oncogenes cooperate in initial malignant transformation, we transduced them into Rat-1 fibroblasts. Indeed, survivin enhanced MYCN-driven contact-uninhibited and anchorage-independent growth in vitro. Importantly, upon subcutaneous transplantation into mice, cells overexpressing both instead of either one of the oncogenes generated tumors with shortened latency, marked anaplasia and an increased proliferation-to-apoptosis ratio resulting in accelerated growth. Mechanistically, the increased tumorigenicity was associated with an enhanced Warburg effect and a hypoxia inducible factor 1α linked vascular remodeling. This cooperation between MYCN and survivin may be important in the genesis of several cancers.

On-chip selective capture of cancer cells and ultrasensitive fluorescence detection of survivin mRNA in a single living cell

The rapid recognition of cancer cells and detection of tumor biomarker survivin mRNA plays a critical role in the early diagnosis of many cancers. Based on the integration of specific cancer cell capture and intracellular survivin mRNA detection, this work presents a novel and sensitive on-chip approach for the bioanalysis of survivin mRNA in a single living cell. The microchannel surface was firstly modified with a prostate stem cell antigen (PSCA) monoclonal antibody as the recognition element for prostate cancer cells (PC-3). As a result of the antigen-antibody specific affinity interactions, PC-3 cells could be selectively captured on the microchannel surface. After cell capture, nano-sized graphene oxide-poly(ethylene glycol) bis(amine) (NGO-PEG) was employed as a quencher and carrier of a signal tag, fluorescein isothiocyanate (FITC)-labeled antisense oligonucleotide (F-S1), which is complementary to part of survivin mRNA (target survivin mRNA), to transfect into the captured PC-3 cells. Upon the selective binding of S1 to intracellular survivin mRNA, F-S1 will be released from the NGO-PEG, inducing the fluorescence recovery of FITC. This antibody-based microfluidic device enables simple and inexpensive monitoring of the amount of survivin mRNA in single captured cell without the need for sample pretreatment. The survivin mRNA content in each PC-3 cell was estimated to be (4.8 ± 1.8) × 10(6) copies. This strategy opens a different perspective for ultrasensitive survivin mRNA detection, which may facilitate the early screening for malignancy.

Survivin blockade sensitizes rhabdomyosarcoma cells for lysis by fetal acetylcholine receptor-redirected T cells

Cellular immunotherapy may provide a strategy to overcome the poor prognosis of metastatic and recurrent rhabdomyosarcoma (RMS) under the current regimen of polychemotherapy. Because little is known about resistance mechanisms of RMS to cytotoxic T cells, we investigated RMS cell lines and biopsy specimens for expression and function of immune costimulatory receptors and anti-apoptotic molecules by RT-PCR, Western blot analysis, IHC, and cytotoxicity assays using siRNA or transfection-modified RMS cell lines, together with engineered RMS-directed cytotoxic T cells specific for the fetal acetylcholine receptor. We found that costimulatory CD80 and CD86 were consistently absent from all RMSs tested, whereas inducible T-cell co-stimulator ligand (ICOS-L; alias B7H2) was expressed by a subset of RMSs and was inducible by tumor necrosis factor α in two of five RMS cell lines. Anti-apoptotic survivin, along with other inhibitor of apoptosis (IAP) family members (cIAP1, cIAP2, and X-linked inhibitor of apoptosis protein), was overexpressed by RMS cell lines and biopsy specimens. Down-regulation of survivin by siRNA or pharmacologically in RMS cells increased their susceptibility toward a T-cell attack, whereas induction of ICOS-L did not. Treatment of RMS-bearing Rag(-/-) mice with fetal acetylcholine receptor-specific chimeric T cells delayed xenograft growth; however, this happened without definitive tumor eradication. Combined blockade of survivin and application of chimeric T cells in vivo suppressed tumor proliferation during survivin inhibition. In conclusion, survivin blockade provides a strategy to sensitize RMS cells for T-cell-based therapy.

Study of the UTMD-based delivery system to induce cervical cancer cell apoptosis and inhibit proliferation with shRNA targeting Survivin

Apoptosis induction by short hairpin RNA (shRNA) expression vectors could be an efficient and promising strategy for cancer gene therapy. Ultrasound-targeted microbubble destruction (UTMD) is an appealing technique. In this study, we investigated the apoptosis induction and suppression of cell proliferation in vivo transfected by the UTMD-based shRNA delivery system. Nude mice with transplanted tumors of cervical cancer were randomly arranged into three groups: control group, plasmid injection and ultrasound (P + US), P + UTMD group. Expressions of Survivin and proliferating cell nuclear antigen (PCNA), Bcl-2, Bax, Caspase-3, Ki-67, nucleostemin (NS) were investigated by immunohistochemistry. Furthermore, microvessel density (MVD) was detected by CD34 protein expressions and apoptotic index (AI) was measured by TUNEL. As compared with those in the control and P + US groups, protein expressions of PCNA, Ki-67, Bcl-2, Survivin and NS in P + UTMD groups were down-regulated markedly, while those of Bax, Caspase-3 were up-regulated significantly (p < 0.05). MVD decreased significantly, whereas AI increased remarkably (p < 0.05). We suggested that UTMD-based shRNA delivery system could induce apoptosis and inhibit proliferation significantly, without causing any apparently adverse effect, representing a new, promising technology that would be used in the future gene therapy and research.

Optimization and apoptosis induction by RNAi with UTMD technology in vitro

Apoptosis induction by short hairpin RNA (shRNA) expression vectors may be an efficient and promising strategy for cancer gene therapy. Ultrasound-targeted microbubble destruction (UTMD) is an appealing technique; however, there few data are available to demonstrate the feasibility and to optimize the methodology for this technology. The aim of this study was to optimize this technique and to elucidate the effects on gene inhibition and apoptosis induction in vitro. Human cervical cancer cell lines were obtained and cultured.shRNA vectors were constructed, and the UTMD technique was examined to determine whether or not it was suitable for shRNA transfection into cells. Cells were then examined using flow cytometry. The results revealed that the optimal irradiation parameters obtained higher transfection efficiency and did not affect the integrity of plasmid DNA. We concluded that survivin downregulation with shRNA expression vectors, mediated by the optimal UTMD parameters, markedly induced cell apoptosis and caused cell cycle arrest, laying a foundation for further investigation of this cancer therapy.

RNA interference targeting survivin exerts antitumoral effects in vitro and in established glioma xenografts in vivo

Malignant glioma represents the most common primary adult brain tumor in Western industrialized countries. Despite aggressive treatment modalities, the median survival duration for patients with glioblastoma multiforme (GBM), the highest grade malignant glioma, has not improved significantly over past decades. One promising approach to deal with GBM is the inactivation of proteins essential for survival or progression of glioma cells by means of RNA interference (RNAi) techniques. A likely candidate for an RNAi therapy of gliomas is the inhibitor of apoptosis protein survivin. Survivin is involved in 2 main cellular processes-cell division and inhibition of apoptosis. We show here that stable RNAi of survivin induced polyploidy, apoptosis, and impaired proliferation of human U343-MG, U373-MG, H4, and U87-MG cells and of primary glioblastoma cells. Proteome profiler arrays using U373-MG cells identified a novel set of differentially expressed genes upon RNAi-mediated survivin knockdown. In particular, the death receptor TRAIL R2/DR5 was strongly upregulated in survivin-depleted glioma cells, inducing an enhanced cytotoxic response of allogeneic human NK cells. Moreover, an experimental in vivo therapy using polyethylenimine (PEI)/siRNA complexes for survivin knockdown efficiently blocked tumor growth of established subcutaneous U373-MG tumors and enhanced survival of NMRI(nu/nu) mice orthopically transplanted with U87-MG cells. We conclude that survivin is functionally relevant in gliomas and that PEI-mediated exogenous delivery of siRNA targeting survivin is a promising strategy for glioblastoma therapy.

Impaired Wnt signaling in embryonal rhabdomyosarcoma cells from p53/c-fos double mutant mice

Rhabdomyosarcoma is a primitive neoplasm with a poorly understood etiology that exhibits features of fetal skeletal muscle. It represents the most frequent malignant soft tissue sarcoma affecting the pediatric population and is often treated very aggressively. Embryonal rhabdomyosarcoma (ERMS) and alveolar rhabdomyosarcoma constitute the two major subtypes and exhibit different molecular features. We investigated one potential molecular basis for ERMS by using cells derived from tumors produced in p53(-/-)/c-fos(-/-) mice. This model closely recapitulates the timing, location, molecular markers, and histology seen in human ERMS. A combined chromatin immunoprecipitation/promoter microarray approach was used to identify promoters bound by the c-Jun-containing AP-1 complex in the tumor-derived cells that lacked c-Fos. Identification of the Wnt2 gene and its overexpression in ERMS cells was confirmed in human rhabdomyosarcoma cell lines and prompted further analysis of the Wnt signaling pathway. Contrary to our expectations, the canonical Wnt/β-catenin signaling pathway was down-regulated in ERMS cells compared with normal myoblasts, and activating this pathway promoted myogenic differentiation. Furthermore, the identification of both survivin and sfrp2 through promoter and expression analyses suggested that increased resistance to apoptosis was associated with the inhibition of the Wnt signaling pathway. These results suggest that altered AP-1 activity that leads to the down-regulation of the Wnt pathway may contribute to the inhibition of myogenic differentiation and resistance to apoptosis in ERMS cases.

Zebrafish models of p53 functions

Zebrafish models have significantly contributed to our understanding of vertebrate development and, more recently, human disease. The growing number of genetic tools available in zebrafish research has resulted in the identification of many genes involved in developmental and disease processes. In particular, studies in the zebrafish have clarified roles of the p53 tumor suppressor in the formation of specific tumor types, as well as roles of p53 family members during embryonic development. The zebrafish has also been instrumental in identifying novel mechanisms of p53 regulation and highlighting the importance of these mechanisms in vivo. This article will summarize how zebrafish models have been used to reveal numerous, important aspects of p53 function.

Targets for cancer therapy in childhood sarcomas

Development of chemotherapeutic treatment modalities resulted in a dramatic increase in the survival of children with many types of cancer. Still, in case of some pediatric cancer entities including rhabdomyosarcoma, osteosarcoma and Ewing's sarcoma, survival of patients remains dismal and novel treatment approaches are urgently needed. Therefore, based on the concept of targeted therapy, numerous potential targets for the treatment of these cancers have been evaluated pre-clinically or in some cases even clinically during the last decade. This review gives an overview over many different potential therapeutic targets for treatment of these childhood sarcomas, including receptor tyrosine kinases, intracellular signaling molecules, cell cycle and apoptosis regulators, proteasome, hsp90, histone deacetylases, angiogenesis regulators and sarcoma specific fusion proteins. The large number of potential therapeutic targets suggests that improved comparability of pre-clinical models might be necessary to prioritize the most effective ones for future clinical trials.

Expression of survivin detected by immunohistochemistry in the cytoplasm and in the nucleus is associated with prognosis of leiomyosarcoma and synovial sarcoma patients

Background

Survivin, a member of the inhibitor of apoptosis-protein family suppresses apoptosis and regulates cell division. It is strongly overexpressed in the vast majority of cancers. We were interested if survivin detected by immunohistochemistry has prognostic relevance especially for patients of the two soft tissue sarcoma entities leiomyosarcoma and synovial sarcoma.

Methods

Tumors of leiomyosarcoma (n = 24) and synovial sarcoma patients (n = 26) were investigated for their expression of survivin by immunohistochemistry. Survivin expression was assessed in the cytoplasm and the nucleus of tumor cells using an immunoreactive scoring system (IRS).

Results

We detected a survivin expression (IRS > 2) in the cytoplasm of 20 leiomyosarcomas and 22 synovial sarcomas and in the nucleus of 12 leiomyosarcomas and 9 synovial sarcomas, respectively. There was no significant difference between leiomyosarcoma and synovial sarcoma samples in their cytoplasmic or nuclear expression of survivin. Next, all sarcoma patients were separated in four groups according to their survivin expression in the cytoplasm and in the nucleus: group 1: negative (IRS 0 to 2); group 2: weak (IRS 3 to 4); group 3: moderate (IRS 6 to 8); group 4: strong (IRS 9 to 12). In a multivariate Cox's regression hazard analysis survivin expression detected in the cytoplasm or in the nucleus was significantly associated with overall survival of patients in group 3 (RR = 5.7; P = 0.004 and RR = 5.7; P = 0.022, respectively) compared to group 2 (reference). Patients whose tumors showed both a moderate/strong expression of survivin in the cytoplasm and a moderate expression of survivin in the nucleus (in both compartments IRS ≥ 6) possessed a 24.8-fold increased risk of tumor-related death (P = 0.003) compared to patients with a weak expression of survivin both in the cytoplasm and in the nucleus.

Conclusion

Survivin protein expression in the cytoplasma and in the nucleus detected by immunohistochemistry is significantly associated with prognosis of leiomyosarcoma and synovial sarcoma patients.

Mice lacking dystrophin or alpha sarcoglycan spontaneously develop embryonal rhabdomyosarcoma with cancer-associated p53 mutations and alternatively spliced or mutant Mdm2 transcripts

Altered expression of proteins in the dystrophin-associated glycoprotein complex results in muscular dystrophy and has more recently been implicated in a number of forms of cancer. Here we show that loss of either of two members of this complex, dystrophin in mdx mice or alpha sarcoglycan in Sgca(-/-) mice, results in the spontaneous development of muscle-derived embryonal rhabdomyosarcoma (RMS) after 1 year of age. Many mdx and Sgca(-/-) tumors showed increased expression of insulin-like growth factor 2, retinoblastoma protein, and phosphorylated Akt and decreased expression of phosphatase and tensin homolog gene, much as is found in a human RMS. Further, all mdx and Sgca(-/-) RMS analyzed had increased expression of p53 and murine double minute (mdm)2 protein and contained missense p53 mutations previously identified in human cancers. The mdx RMS also contained missense mutations in Mdm2 or alternatively spliced Mdm2 transcripts that lacked an exon encoding a portion of the p53-binding domain. No Pax3:Fkhr or Pax7:Fkhr translocation mRNA products were evident in any tumor. Expression of natively glycosylated alpha dystroglycan and alpha sarcoglycan was reduced in mdx RMS, whereas dystrophin expression was absent in almost all human RMS, both for embryonal and alveolar RMS subtypes. These studies show that absence of members of the dystrophin-associated glycoprotein complex constitutes a permissive environment for spontaneous development of embryonal RMS associated with mutation of p53 and mutation or altered splicing of Mdm2.

Molecular and cellular biology of rhabdomyosarcoma

Rhabdomyosarcoma is a group of soft-tissue sarcomas that share features of skeletal myogenesis, but show extensive heterogeneity in histology, age and site of onset, and prognosis. This review matches recent molecular data with biological features of rhabdomyosarcoma. Alterations in molecular pathways, animal models, cell of origin and potential new therapeutic targets are discussed.

Small interfering RNA library screen of human kinases and phosphatases identifies polo-like kinase 1 as a promising new target for the treatment of pediatric rhabdomyosarcomas

Rhabdomyosarcoma, consisting of alveolar (aRMS) and embryonal (eRMS) subtypes, is the most common type of sarcoma in children. Currently, there are no targeted drug therapies available for rhabdomyosarcoma. In searching for new molecular therapeutic targets, we carried out genome-wide small interfering RNA (siRNA) library screens targeting human phosphatases (n = 206) and kinases (n = 691) initially against an aRMS cell line, RH30. Sixteen phosphatases and 50 kinases were identified based on growth inhibition after 72 hours. Inhibiting polo-like kinase 1 (PLK1) had the most remarkable impact on growth inhibition (approximately 80%) and apoptosis on all three rhabdomyosarcoma cell lines tested, namely, RH30, CW9019 (aRMS), and RD (eRMS), whereas there was no effect on normal muscle cells. The loss of PLK1 expression and subsequent growth inhibition correlated with decreased p-CDC25C and Cyclin B1. Increased expression of WEE 1 was also noted. The induction of apoptosis after PLK1 silencing was confirmed by increased p-H2AX, propidium iodide uptake, and chromatin condensation, as well as caspase-3 and poly(ADP-ribose) polymerase cleavage. Pediatric Ewing's sarcoma (TC-32), neuroblastoma (IMR32 and KCNR), and glioblastoma (SF188) models were also highly sensitive to PLK1 inhibition. Finally, based on cDNA microarray analyses, PLK1 mRNA was overexpressed (>1.5 fold) in 10 of 10 rhabdomyosarcoma cell lines and in 47% and 51% of primary aRMS (17 of 36 samples) and eRMS (21 of 41 samples) tumors, respectively, compared with normal muscles. Similarly, pediatric Ewing's sarcoma, neuroblastoma, and osteosarcoma tumors expressed high PLK1. We conclude that PLK1 could be a promising therapeutic target for the treatment of a wide range of pediatric solid tumors including rhabdomyosarcoma.

Enhancement of survivin gene downregulation and cell apoptosis by a novel combination: liposome microbubbles and ultrasound exposure

Ultrasound-mediated microbubble destruction (sonoporation) is an efficient and safe nonviral technique for gene delivery. In the present work, we hypothesized that short hairpin RNA (shRNA) interference therapy targeting human Survivin gene could be transfected by the novel combination of ultrasound exposure (USE) and liposome microbubbles (LM). ShRNA vectors targeting Survivin were constructed and transfected under USE and LM conditions. The optimal transfection efficiency and cell injury were compared with those of polyethylenimine (PEI)-mediated transfection in different cancer cell lines (HeLa, HepG2, Ishikawa, MCF-7, and B16-F10). The effects of gene downregulation and cell apoptosis were further investigated. The results indicated that P + USE + LM group could significantly increase the gene expression as compared with plasmid group, plasmid + USE group, plasmid + LM group (P < 0.001). The transfection efficiency of the novel combination was nearly equal to PEI-mediated transfection in some cancer cell lines while the cell viability did not decrease markedly. Reverse transcription-polymerase chain reaction (RT-PCR) and western blot analysis also confirmed that Survivin mRNA and protein expression could be knocked down significantly by shRNA transfection under USE and LM condition (P < 0.001). This is the first study to verify the role of shRNA therapy in vitro with novel combination of USE and LM. We concluded that this nonviral technique would be valuable in the gene transfection of shRNA and Survivin gene downregulation would lead to apparent cell apoptosis.

Induced apoptosis with ultrasound-mediated microbubble destruction and shRNA targeting survivin in transplanted tumors

INTRODUCTION

This study was designed to evaluate the consequences of survivin down-modulation on tumor growth in a nude mice model combined with short hairpin RNA recombinant vector (shRNA) and ultrasound-mediated microbubble destruction (UMMD).

METHODS

BALB/c nude mice were inoculated subcutaneously with cervical cancer cells (HeLa) and tumors (5-10 mm) developed. A shRNA recombinant vector that targeted the survivin gene (survivin-shRNA) was constructed. The mice were divided into three groups (n=6 in each group) and injected with survivin-shRNA: plasmid group (P), plasmid+ultrasound exposure group (P+US), and plasmid+microbubble (SonoVue(R))+ultrasound group (P+UMMD). Protein expression of survivin, proliferating cell nuclear antigen (PCNA), and caspase-3 were investigated by immunohistochemistry, and proliferation index (PI) and apoptotic index (AI) were measured.

RESULTS

The protein expression of survivin and PCNA was markedly downregulated, while caspase-3 was markedly upregulated in the P+UMMD group as compared with that of the P group and P+US group. PI decreased significantly (P<0.05), whereas AI increased remarkably (P<0.01) in the P+UMMD group as compared with that of the P group and P+US group. These data indicate that the combined strategy of UMMD and survivin-shRNA effectively induces silencing of the survivin gene, resulting in inhibition of proliferation and induction of apoptosis in nude mice.

CONCLUSIONS

Survivin could be regarded as an ideal target for anticancer intervention of cervical cancer. The combination of shRNA and UMMD could enhance antitumor efficacy as a result of synergism. This may be a powerful, promising non-viral technology that could be used in tumor gene therapy.

Experimental cancer gene therapy by multiple anti-survivin hammerhead ribozymes

To improve the efficacy of gene therapy for cancer, we designed four hammerhead ribozyme adenoviruses (R1 to R4) targeting the exposed regions of survivin mRNA. In addition to the in vitro characterization, which included a determination of the sequence specificity of cleavage by primer extension, assays for cell proliferation and for in vivo tumor growth were used to score for ribozyme efficiency. The resulting suppression of survivin expression induced mitotic catastrophe and cell death via the caspase-3-dependent pathway. Importantly, administration of the ribozyme adenoviruses inhibited tumor growth in a hepatocellular carcinoma xenograft mouse model. Co-expression of R1, R3 and R4 ribozymes synergistically suppressed survivin and, as this combination targets all major forms of the survivin transcripts, produced the most potent anti-cancer effects. The adenoviruses carrying the multiple hammerhead ribozymes described in this report offered a robust gene therapy strategy against cancer.

Applications of RNA interference in mammalian systems

RNA interference (RNAi) can mediate the long- or short-term silencing of gene expression at the DNA, RNA, and/or protein level. Although several triggers of RNAi have been identified, the best characterized of these are small interfering RNAs (siRNAs), which can decrease gene expression through mRNA transcript cleavage, and endogenous microRNAs (miRNAs), which primarily inhibit protein translation. An improved understanding of RNAi has provided new, powerful tools for conducting functional studies in a gene-specific manner. In various applications, RNAi has been used to create model systems, to identify novel molecular targets, to study gene function in a genome-wide fashion, and to create new avenues for clinical therapeutics. Here, we review many of the ongoing applications of RNAi in mammalian and human systems, and discuss how advances in our knowledge of the RNAi machinery have enhanced the use of these technologies.

RNAi-mediated knockdown of target genes: a promising strategy for pancreatic cancer research

Pancreatic cancer is one of the most aggressive malignancies with a very poor prognosis, partially due to its very low accessibility to resection and resistance to chemoradiotherapy. As such, it is reasonable to find more effective, specific therapies and the related therapeutic targets. The identification of certain genes contributing to the tumorigenesis and poor prognosis provides the specific targets for efficient silencing by RNA interference (RNAi). As a powerful tool to suppress gene expression in mammalian cells, RNAi can be directed against pancreatic cancer through various pathways, including the inhibition of overexpressed oncogenes, suppression of tumor growth, metastasis and enhancement of apoptosis. In combination with chemoradiotherapy agents, RNAi can also attenuate the chemoradiation resistance of pancreatic cancer. In addition, RNAi has been used to define the 'loss of function' of endogenous genes in pancreatic cancer. This review provides a brief introduction to recent developments of RNAi applications in pancreatic cancer studies and suggestions for further exploration. It substantially demonstrates that RNAi holds a promising therapeutic potential as a future treatment for pancreatic cancer.

Effects of RAS on the genesis of embryonal rhabdomyosarcoma

Embryonal rhabdomyosarcoma (ERMS) is a devastating cancer with specific features of muscle differentiation that can result from mutational activation of RAS family members. However, to date, RAS pathway activation has not been reported in a majority of ERMS patients. Here, we have created a zebrafish model of RAS-induced ERMS, in which animals develop externally visible tumors by 10 d of life. Microarray analysis and cross-species comparisons identified two conserved gene signatures found in both zebrafish and human ERMS, one associated with tumor-specific and tissue-restricted gene expression in rhabdomyosarcoma and a second comprising a novel RAS-induced gene signature. Remarkably, our analysis uncovered that RAS pathway activation is exceedingly common in human RMS. We also created a new transgenic coinjection methodology to fluorescently label distinct subpopulations of tumor cells based on muscle differentiation status. In conjunction with fluorescent activated cell sorting, cell transplantation, and limiting dilution analysis, we were able to identify the cancer stem cell in zebrafish ERMS. When coupled with gene expression studies of this cell population, we propose that the zebrafish RMS cancer stem cell shares similar self-renewal programs as those found in activated satellite cells.

Survivin: Potential role in diagnosis, prognosis and targeted therapy of gastric cancer

Survivin is a protein that is highly expressed in a vast number of malignancies, but is minimally expressed in normal tissues. It plays a role as an inhibitor of cell death in cancer cells, thus facilitating the growth of these cells. In the case of gastric cancer, survivin is over-expressed in tumor cells and plays a role in the carcinogenesis process. Several studies on gastric cancer have indicated that there is a relationship between survivin expression and the ultimate behavior of the carcinoma. Since the expression pattern of survivin is selective to cancer cells, it has been described as an “ideal target” for cancer therapy. Currently, several pre-clinical and clinical trials are on-going to investigate the effects of interfering with survivin function in cancer cells as a biologic therapy. Survivin is a potentially significant protein in the diagnosis, prognosis and treatment of gastric tumors.

Human bone marrow stromal cells enhance breast cancer cell growth rates in a cell line-dependent manner when evaluated in 3D tumor environments

Our understanding of the impact that fibroblasts have on cancer cell behavior in vivo has been limited by the complexities of in vivo tumor microenvironments, which contain many distinct cell populations that influence tumor growth and survival. Herein, we describe a novel, three-dimensional (3D), in vitro, fluorometric, Tumor Growth Assay (TGA) that allows for non-invasive measurements of cancer cell expansion in the presence of multiple tumor-associated cell types or soluble factors, while embedded in Cultrex or Matrigel Basement Membrane Extract (BME). Using this assay, we investigated the direct biological impact of primary human bone marrow stromal cells (hMSC) on the growth rates of a panel of metastatic breast cancer cell lines. Human MSC can be readily isolated from bone marrow, a principle site of breast cancer metastasis, and were found to significantly enhance the growth rate of MCF-7 (P-value<0.0001), an estrogen receptor-alpha (ERalpha) positive breast cancer cell line, in a soluble factor-dependent manner. MSC paracrine factors also enhanced the growth of other ERalpha positive breast cancer cell lines including T47D, BT474, and ZR-75-1 (P-value<0.05). In contrast, the ERalpha negative cell line MDA-MB-231 was unaffected by hMSC and the growth rate of another ERalpha negative cell line MDA-MB-468 was elevated in the presence of hMSC, albeit to a lesser extent than MCF-7 or the other ERalpha positive cell lines tested.

Adult human sarcomas. II. Medical oncology

Human sarcoma cells can be killed by radio- and chemotherapy, but tumor cells acquiring resistance frequently kill the patient. A keen understanding of the intracellular course of oncogenic cascades leads to the discovery of small molecular inhibitors of the involved phosphorylated kinases. Targeted therapy complements chemotherapy. Oncogene silencing is feasible by small interfering RNA. The restoration of some of the mutated or deleted tumor-suppressor genes (p53, Rb, PTEN, hSNF, INK/ARF and WT) by demethylation or reacetylation of their histones has been accomplished. Genetically engineered or naturally oncolytic viruses selectively lyse tumors and leave healthy tissues intact. Adeno- or retroviral vectors deliver genes of immunological costimulators, tumor antigens, chemo- or cytokines and/or tumor-suppressor proteins into tumor (sarcoma) cells. Suicide gene delivery results in apoptosis induction. Genes of enzymes that target prodrugs as their substrates render tumor cells highly susceptible to chemotherapy, with the prodrug to be targeted intracellularly. It will be combinations of sophisticated surgical removal of the nonencapsulated and locally invasive primary sarcomas, advanced forms of radiotherapy to the involved sites and immunotherapy with sarcoma vaccines that will cure primary sarcomas. Adoptive immunotherapy with immune lymphocytes will be operational in metastatic disease only when populations of regulatory T cells are controlled. Targeted therapy with small molecular inhibitors of oncogene cascades, the driving forces of sarcoma cells, alteration of the tumor stroma from a supportive to a tumor-hostile environment, reactivation or replacement of wild-type tumor-suppressor genes, and radio-chemotherapy (with much reduced toxicity) will eventually accomplish the cure of metastatic sarcomas.

RNA interference: implications for cancer treatment

RNA interference (RNAi) has emerged as one of the most important discoveries of the last years in the field of molecular biology. Following clarification of this highly conserved endogenous gene silencing mechanism, RNAi has largely been exploited as a powerful tool to uncover the function of specific genes and to understand the effects of selective gene silencing in mammalian cells both in vitro and in vivo. RNAi can be induced by direct introduction of chemically synthesized siRNAs into the cell or by the use of plasmid and viral vectors encoding for siRNA allowing a more stable RNA knockdown. Potential application of this technique both as a research tool and for therapeutic purposes has led to an extensive effort to overcome some critical constraints which may limit its successful application in vivo, including off-target and non-specific effects, as well as the relatively poor stability of siRNA. This review provides a brief overview of the RNAi mechanism and of its application in preclinical animal models of cancer.

Dissecting the role of endothelial SURVIVIN DeltaEx3 in angiogenesis

The identification of alternative splice variants of Survivin that possess distinct functions from those originally identified for the main Survivin isoform has greatly increased the complexity of our understanding of the role of Survivin in different cells. Previous functional studies of the Survivin splice variants have been performed almost exclusively in cancer cells. However, Survivin has increasingly been implicated in other normal physiologic and pathophysiologic processes, including angiogenesis. In this study, we dissect the involvement of Survivin DeltaEx3 in angiogenesis. We show by confocal microscopy that a pool of endothelial Survivin DeltaEx3 is localized to membrane ruffles. We also demonstrate that Survivin DeltaEx3 is the Survivin splice variant responsible for modulating angiogenesis in vitro, in tube formation assays, and in vivo, in an in vivo angiogenesis assay. Our data indicate that Survivin DeltaEx3 may regulate angiogenesis via several mechanisms including cell invasion, migration, and Rac1 activation. Our findings identify a novel pathway regulating angiogenesis through Survivin DeltaEx3 and a novel mechanism for Rac1 activation during angiogenesis. In conclusion, our results provide new insights into the regulation of endothelial cell homeostasis and angiogenesis by the Survivin proteins.

Survivin, a cancer target with an emerging role in normal adult tissues

Survivin, an inhibitor of apoptosis protein, is highly expressed in most cancers and associated with chemotherapy resistance, increased tumor recurrence, and shorter patient survival, making antisurvivin therapy an attractive cancer treatment strategy. However, growing evidence indicates that survivin is expressed in normal adult cells, particularly primitive hematopoietic cells, T lymphocytes, polymorphonuclear neutrophils, and vascular endothelial cells, and may regulate their proliferation or survival. In preclinical animal models, targeted antisurvivin therapies show efficacy without overt toxicity. However, consequences of prolonged survivin disruption in normal cells, particularly those associated with continuous renewal, have not been clearly determined. Understanding the role of survivin in normal versus malignant cells will be important in identifying strategies that maximally disrupt survivin in cancer cells with minimal effect on normal tissues. In this review, we summarize the prognostic relevance of survivin in cancer that justifies the pursuit of antisurvivin therapies and discuss differences in survivin expression between normal and cancer cells. We subsequently review expression of survivin in normal adult tissues and evaluate preclinical antisurvivin therapies reported to date in light of emerging roles for survivin in normal physiology, particularly hematopoiesis, angiogenesis, and immune function.

Survivin: an inhibitor of apoptosis in pediatric cancer

Survivin is an inhibitor of apoptosis protein (IAP) expressed in a large number of adult malignancies. Its expression levels correlate with more aggressive disease and poor clinical outcome in many of these tumors. As its expression is restricted in normal adult differentiated tissues, it has become of great interest as both a tumor prognostic marker and as a potential biologic target for future anti-cancer therapies. Survivin expression and Survivin-based therapies have been examined in many of the more common pediatric malignancies. We present an overview of Survivin function and current research exploring its biologic and therapeutic roles in pediatric tumors.

Targeted therapy by disabling crossroad signaling networks: the survivin paradigm

Embedded in the concept of targeted cancer therapy is the expectation that disabling a single oncogenic pathway will eliminate the tumor cells and leave the normal tissues unscathed. Although validated by clinical responses in certain malignancies, challenges exist to generalize this approach to most tumors, as multiple genetic lesions, chromosomal instability, insensitivity of the cancer stem cell compartment, and emergence of drug resistance complicate the identification and therapeutic exploitation of a single, driving oncogenic pathway. Instead, broader therapeutic prospects may be offered by targeting crossroad signaling networks that are selectively exploited in cancer and oversee multiple aspects of tumor cell maintenance. One such pathway is centered on survivin, a cancer gene that intersects cell proliferation, cell survival, and the cellular stress response. Several clinical trials targeting survivin with a collection of approaches from immunotherapy to small-molecule antagonists are currently under way. By simultaneously disabling multiple signaling circuitries, targeting survivin may provide a novel perspective in rational cancer therapy selective for specific cancer mechanisms but broadly applicable to disparate tumors regardless of their genetic makeup.

RNA interference in cancer

In the recent years, RNA interference (RNAi) has emerged as a major regulatory mechanism in eukaryotic gene expression. The realization that changes in the levels of microRNAs are directly associated with cancer led to the recognition of a new class of tumor suppressors and oncogenes. Moreover, RNAi has been turned into a potent tool for artificially modulating gene expression through the introduction of short interfering RNAs. A plethora of individual inhibitory RNAs as well as several large collections of these reagents have been generated. The systems for stable and regulated expression of these molecules emerged as well. These tools have helped to delineate the roles of various cellular factors in oncogenesis and tumor suppression and laid the foundation for new approaches in gene discovery. Furthermore, successful inhibition of tumor cell growth by RNAi aimed at oncogenes in vitro and in vivo supports the enthusiasm for potential therapeutic applications of this technique. In this article we review the evidence of microRNA involvement in cancer, the use of short interfering RNAs in forward and reverse genetics of this disease, and as well as both the benefits and limitations of experimental RNAi.

The therapeutic potential of RNA interference

In recent years, we have witnessed the discovery of a new mechanism of gene regulation called RNA interference (RNAi), which has revitalized interest in the development of nucleic acid‐based technologies for therapeutic gene suppression. This review focuses on the potential therapeutic use of RNAi, discussing the theoretical advantages of RNAi‐based therapeutics over previous technologies as well as the challenges involved in developing RNAi for clinical use. Also reviewed, are the in vivo proof‐of principle experiments that provide the preclinical justification for the continued development of RNAi‐based therapeutics.