Wilms' tumor 1 silencing decreases the viability and chemoresistance of glioblastoma cells in vitro: a potential role for IGF-1R de-repression

Upregulation of HOXA3 by isoform-specific Wilms tumour 1 drives chemotherapy resistance in acute myeloid leukaemia

Upregulation of the Wilms' tumour 1 (WT1) gene is common in acute myeloid leukaemia (AML) and is associated with poor prognosis. WT1 generates 12 primary transcripts through different translation initiation sites and alternative splicing. The short WT1 transcripts express abundantly in primary leukaemia samples. We observed that overexpression of short WT1 transcripts lacking exon 5 with and without the KTS motif (sWT1+/- and sWT1-/-) led to reduced cell growth. However, only sWT1+/- overexpression resulted in decreased CD71 expression, G1 arrest, and cytarabine resistance. Primary AML patient cells with low CD71 expression exhibit resistance to cytarabine, suggesting that CD71 may serve as a potential biomarker for chemotherapy. RNAseq differential expressed gene analysis identified two transcription factors, HOXA3 and GATA2, that are specifically upregulated in sWT1+/- cells, whereas CDKN1A is upregulated in sWT1-/- cells. Overexpression of either HOXA3 or GATA2 reproduced the effects of sWT1+/-, including decreased cell growth, G1 arrest, reduced CD71 expression and cytarabine resistance. HOXA3 expression correlates with chemotherapy response and overall survival in NPM1 mutation-negative leukaemia specimens. Overexpression of HOXA3 leads to drug resistance against a broad spectrum of chemotherapeutic agents. Our results suggest that WT1 regulates cell proliferation and drug sensitivity in an isoform-specific manner.

Non-coding RNAs (ncRNAs) and multidrug resistance in glioblastoma: Therapeutic challenges and opportunities

Non-coding RNAs (ncRNAs) have been recognized as pivotal regulators of transcriptional and post-transcriptional gene modulation, exerting a profound influence on a diverse array of biological and pathological cascades, including the intricate mechanisms underlying tumorigenesis and the acquisition of drug resistance in neoplastic cells. Glioblastoma (GBM), recognized as the foremost and most aggressive neoplasm originating in the brain, is distinguished by its formidable resistance to the cytotoxic effects of chemotherapeutic agents and ionizing radiation. Recent years have witnessed an escalating interest in comprehending the involvement of ncRNAs, particularly lncRNAs, in GBM chemoresistance. LncRNAs, a subclass of ncRNAs, have been demonstrated as dynamic modulators of gene expression at the epigenetic, transcriptional, and post-transcriptional levels. Disruption in the regulation of lncRNAs has been observed across various human malignancies, including GBM, and has been linked with developing multidrug resistance (MDR) against standard chemotherapeutic agents. The potential of targeting specific ncRNAs or their downstream effectors to surmount chemoresistance is also critically evaluated, specifically focusing on ongoing preclinical and clinical investigations exploring ncRNA-based therapeutic strategies for glioblastoma. Nonetheless, targeting lncRNAs for therapeutic objectives presents hurdles, including overcoming the blood-brain barrier and the brief lifespan of oligonucleotide RNA molecules. Understanding the complex relationship between ncRNAs and the chemoresistance characteristic in glioblastoma provides valuable insights into the fundamental molecular mechanisms. It opens the path for the progression of innovative and effective therapeutic approaches to counter the therapeutic challenges posed by this aggressive brain tumor. This comprehensive review highlights the complex functions of diverse ncRNAs, including miRNAs, circRNAs, and lncRNAs, in mediating glioblastoma's chemoresistance.

Application of Bioinformatics Analysis to Identify Important Pathways and Hub Genes in Ovarian Cancer Affected by WT1

Wilms tumor gene (WT1) is used as a marker for the diagnosis and prognosis of ovarian cancer. However, the molecular mechanisms involving WT1 in ovarian cancer require further study. Herein, we used bioinformatics and other methods to identify important pathways and hub genes in ovarian cancer affected by WT1. The results showed that WT1 is highly expressed in ovarian cancer and is closely related to the overall survival and progression-free survival (PFS) of ovarian cancer. In ovarian cancer cell line SKOV3, WT1 downregulation increased the mRNA expression of 638 genes and decreased the mRNA expression of 512 genes, which were enriched in the FoxO, AMPK, and the Hippo signaling pathways. The STRING online tool and Cytoscape software were used to construct a Protein-protein interaction (PPI) network and for Module analysis, and 18 differentially expressed genes (DEGs) were selected. Kaplan-Meier plotter analysis revealed that 16 of 18 genes were related to prognosis. Analysis of GEPIA datasets indicated that 7 of 16 genes were differentially expressed in ovarian cancer tissues and in normal tissues. The expression of IGFBP1 and FBN1 genes increased significantly after WT1 interference, while the expression of the SERPINA1 gene decreased significantly. The correlation between WT1 expression and that of these three genes was consistent with that of ovarian cancer tissues and normal tissues. According to the GeneMANIA online website analysis, there were complex interactions between WT1, IGFBP1, FBN1, SERPINA1, and 20 other genes. In conclusion, we have identified important signaling pathways involving WT1 that affect ovarian cancer, and distinguished three differentially expressed genes regulated by WT1 associated with the prognosis of ovarian cancer. Our findings provide evidence outlining mechanisms involving WT1 gene expression in ovarian cancer and provides a rational for novel treatment of ovarian cancer.

Ribosomal protein QM/RPL10 positively regulates defence and protein translation mechanisms during nonhost disease resistance

Ribosomes play an integral part in plant growth, development, and defence responses. We report here the role of ribosomal protein large (RPL) subunit QM/RPL10 in nonhost disease resistance. The RPL10-silenced Nicotiana benthamiana plants showed compromised disease resistance against nonhost pathogen Pseudomonas syringae pv. tomato T1. The RNA-sequencing analysis revealed that many genes involved in defence and protein translation mechanisms were differentially affected due to silencing of NbRPL10. Arabidopsis AtRPL10 RNAi and rpl10 mutant lines showed compromised nonhost disease resistance to P. syringae pv. tomato T1 and P. syringae pv. tabaci. Overexpression of AtRPL10A in Arabidopsis resulted in reduced susceptibility against host pathogen P. syringae pv. tomato DC3000. RPL10 interacts with the RNA recognition motif protein and ribosomal proteins RPL30, RPL23, and RPS30 in the yeast two-hybrid assay. Silencing or mutants of genes encoding these RPL10-interacting proteins in N. benthamiana or Arabidopsis, respectively, also showed compromised disease resistance to nonhost pathogens. These results suggest that QM/RPL10 positively regulates the defence and translation-associated genes during nonhost pathogen infection.

WT1 Clone 6F-H2 Cytoplasmic Expression Differentiates Astrocytic Tumors from Astrogliosis and Associates with Tumor Grade, Histopathology, IDH1 Status, Apoptotic and Proliferative Indices: A Tissue Microarray Study

OBJECTIVES

This tissue microarray (TMA) immunohistochemical (IHC) study elucidates the role of Wilms' tumor 1 protein (WT1) in diagnosis and prognostication of astrocytic tumors.

METHODS

IHC was applied to 75 astrocytic lesions (18 astrogliosis and 57 astrocytic tumors) using antibodies directed against WT1 clone 6F-H2, isocitrate dehydrogenase 1(IDH1), Bcl2 and Ki67. WT1 IHC staining was evaluated and scored blindly by 2 pathologists. Bcl2 and Ki67 scores and labelling indices were assessed and IDH1 status determined. Statistical analysis was performed using the appropriate methodology.

RESULTS

WT1 cytoplasmic expression was detected in 89.5% of astrocytic tumors but not in astrogliosis. Positive WT1 differentiated astrocytic tumors (92.6% accuracy) and grade II diffuse astrocytomas (93.5% accuracy) from astrogliosis with high sensitivity, specificity and positive predictive values (p<0.001). Increased WT1 score significantly associated higher Bcl2 and Ki67 labelling indices, increasing WHO tumor grade and tumor's histopathologic type (p<0.05) showing staining pattern variability by tumor entity and cell type. Glioblastomas, gliosarcomas and subependymal giant cell astrocytomas were the most frequently WT1 expressing tumors with frequent +3 WT1 score. About 21.4% of pilocytic astrocytomas had +3WT1 score in association with increased Bcl2 and Ki67 indices. Low WT1 scores in grade II and III diffuse astrocytomas were linked to the high frequency of IDH1 positivity, and were associated with low Bcl2 and Ki67 labelling indices. In glioblastomas, WT1 significantly associated poor prognostic variables: older age, negative-IDH1 status, high Bcl2 and Ki67 labelling indices (p=0.04, <0.001, =0.001 and.

An Interplay between Senescence, Apoptosis and Autophagy in Glioblastoma Multiforme-Role in Pathogenesis and Therapeutic Perspective

Autophagy, cellular senescence, programmed cell death and necrosis are key responses of a cell facing a stress. These effects are partly interconnected, but regulation of their mutual interactions is not completely clear. That regulation seems to be especially important in cancer cells, which have their own program of development and demand more nutrition and energy than normal cells. Glioblastoma multiforme (GBM) belongs to the most aggressive and most difficult to cure cancers, so studies on its pathogenesis and new therapeutic strategies are justified. Using an animal model, it was shown that autophagy is required for GBM development. Temozolomide (TMZ) is the key drug in GBM chemotherapy and it was reported to induce senescence, autophagy and apoptosis in GBM. In some GBM cells, TMZ induces small toxicity despite its significant concentration and GBM cells can be intrinsically resistant to apoptosis. Resveratrol, a natural compound, was shown to potentiate anticancer effect of TMZ in GBM cells through the abrogation G2-arrest and mitotic catastrophe resulting in senescence of GBM cells. Autophagy is the key player in TMZ resistance in GBM. TMZ can induce apoptosis due to selective inhibition of autophagy, in which autophagic vehicles accumulate as their fusion with lysosomes is blocked. Modulation of autophagic action of TMZ with autophagy inhibitors can result in opposite outcomes, depending on the step targeted in autophagic flux. Studies on relationships between senescence, autophagy and apoptosis can open new therapeutic perspectives in GBM.

Function of insulin-like growth factor 1 receptor in cancer resistance to chemotherapy

Drug resistance is a primary cause of chemotherapeutic failure; however, how this resistance develops is complex. A comprehensive understanding of chemotherapeutic resistance mechanisms may aid in identifying more effective drugs and improve the survival rates of patients with cancer. Insulin-like growth factor 1 receptor (IGF1R), a member of the insulin receptor family, has been extensively assessed for biological activity, and its putative contribution to tumor cell development and progression. Furthermore, researchers have attended to drugs that target IGF1R since IGF1R functions as a membrane receptor. However, how IGF1R participates in chemotherapeutic resistance remains unclear. Therefore, the present study described the IGF1R gene and its associated signaling pathways, and offered details of IGF1R-induced tumor chemoresistance associated with promoting cell proliferation, inhibition of apoptosis, regulation of ATP-binding cassette transporter proteins and interactions with the extracellular matrix. The present study offered additional explanations for tumor chemotherapy resistance and provided a theoretical basis of IGF1R and its downstream pathways for future possible chemotherapy treatment options.

Turning back the Wheel: Inducing Mesenchymal to Epithelial Transition via Wilms Tumor 1 Knockdown in Human Mesothelioma Cell Lines to Influence Proliferation, Invasiveness, and Chemotaxis

Malignant pleural mesothelioma (MPM) is a highly aggressive tumor that arises from the surface of the pleura and is associated with a history of asbestos exposure. The tumor is characterized by a strong local invasiveness and a poor response to any single modality therapy. Therefore clinical outcome of patients with MPM is poor and median survival time of untreated patients with MPM is 7 months from initial diagnosis. The Wilms Tumor Protein 1 (WT1) is a transcription factor which is highly expressed by MPM and is involved in cellular development and survival. We evaluated the role of WT1 in two human MPM cell lines (MSTO and H2052) expressing high levels of WT1. We performed a knockdown of WT1 using siRNA. Knockdown of WT1 was confirmed by Westernblotting. After knockdown of WT1 we investigated the effect on proliferation, chemoresistance, chemotaxis and migration. We could demonstrate that knockdown of WT1 suppresses chemoresistance in both cell lines compared with control (scrambled siRNA). Additionally, WT1 knockdown reduces proliferation, chemotaxis and invasiveness of mesothelioma cell lines. WT1 reduces malignancy of malignant mesothelioma cell lines and might be a new molecular target in mesothelioma therapy. Further investigations are needed to discover the mechanisms of chemoresistance depending on WT1.

Phase I/II trial of combination of temozolomide chemotherapy and immunotherapy with fusions of dendritic and glioma cells in patients with glioblastoma

BACKGROUND

This trial was designed to evaluate the safety and clinical responses to a combination of temozolomide (TMZ) chemotherapy and immunotherapy with fusions of DCs and glioma cells in patients with glioblastoma (GBM).

METHOD

GBM patients were assigned to two groups: a group of recurrent GBMs after failing TMZ-chemotherapy against the initially diagnosed glioma (Group-R) or a group of newly diagnosed GBMs (Group-N). Autologous cultured glioma cells obtained from surgical specimens were fused with autologous DCs using polyethylene glycol. The fusion cells (FC) were inoculated intradermally in the cervical region. Toxicity, progression-free survival (PFS), and overall survival (OS) of this trial were evaluated. Expressions of WT-1, gp-100, and MAGE-A3, recognized as chemoresistance-associated peptides (CAP), were confirmed by immunohistochemistry of paraffin-embedded tumor samples. Patient's PBMCs of pre- and post-vaccination were evaluated by tetramer and ELISPOT assays.

RESULTS

FC-immunotherapy was well tolerated in all patients. Medians of PFS and OS of Group-R (n = 10) were 10.3 and 18.0 months, and those of Group-N (n = 22) were 18.3 and 30.5 months, respectively. Up-regulation and/or cytoplasmic accumulation of CAPs was observed in the recurrent tumors of Group-R patients compared with their initially excised tumors. Specific immune responses against CAPs were observed in the tetramer and ELISPOT assays.

CONCLUSIONS

The combination of TMZ-treatment leading to up-regulation and/or cytoplasmic accumulation of CAPs, with FC-immunotherapy as a means of producing specific immunity against CAPs, may safely induce anti-tumor effects in patients with GBM.

WT1 shRNA delivery using transferrin-conjugated PEG liposomes in an in vivo model of melanoma

The global incidence of melanoma is increasing. Mortality from melanoma is influenced primarily by metastasis in advanced stages of the disease. Current treatments are largely ineffective; thus, novel gene delivery approaches that target tumor-specific markers may be useful for the treatment of melanoma. Systemic administration of encapsulated RNA-interference plasmids targeted against tumor cells is a potential alternative therapy for cancer. Formulations of transferrin (Tf)-conjugated polyethylene glycol (PEG) liposomes loaded with short hairpin RNA (shRNA) against WT1 (Lip + RNAi + Tf), PEG liposomes loaded with shRNA against WT1 (Lip + RNAi), Tf-conjugated PEG liposomes loaded with pEGFP-N3 (Lip + GFP + Tf) and saline solution as negative control (untreated) were administered systemically to C57BL/6 mice implanted subcutaneously with a melanoma cell line. Tumor volume, body weight, tumor weight, survival and relative expression of WT1 were evaluated. No significant differences in net body weight were identified between groups. The tumor volume decreased from 7,871 mm³ (SD±2,087) in the untreated group to 5,981 mm³ (SD±2,099) in the Lip + RNAi + Tf group. The tumor weight was reduced, from 8.8 g (SD±0.30) in the untreated group to 5.5 g (SD±0.87) in the Lip + RNAi + Tf group. An increase of 37% in survival was also observed in the group treated with Lip + RNAi + Tf in comparison to the untreated group. Tumors treated with Lip + RNAi + Tf also showed a decrease in the mean relative expression of WT1 of 0.21 (SD±0.28) folds compared with 1.8 (SD±2.49) folds in untreated group, 1.34 (SD±0.43) folds in Lip + RNAi group and of 1.89 (SD±0.69) folds in Lip + GFP + Tf group. Systemic administration of transferrin-conjugated PEG liposomes loaded with shRNA against WT1 reduced WT1 expression and tumor size and increased survival.

Wilms tumor 1 gene, CD97, and the emerging biogenetic profile of glioblastoma

Glioblastoma multiforme (GBM) is the most common type of primary brain tumor, and current treatment regimens are only marginally effective. One of the most vexing and malignant aspects of GBM is its pervasive infiltration into surrounding brain tissue. This review describes the role of the Wilms tumor 1 gene (WT1) and its relationship to GBM. WT1 has several alternative splicing products, one of which, the KTS(+) variant, has been demonstrated to be involved in the transcriptional activation of a variety of oncogenes as well as the inhibition of tumor suppressor genes. Further, this paper will examine the relationship of WT1 with CD97, a gene that codes for an epidermal growth factor receptor family member, an adhesion G-protein-coupled receptor, thought to promote tumor invasiveness and migration. The authors suggest that further research into WT1 and CD97 will allow clinicians to begin to deal more effectively with the infiltrative behavior displayed by GBM and design new therapies that target this deadly disease.

Insulin-like growth factor (IGF) signaling in tumorigenesis and the development of cancer drug resistance

One of the greatest obstacles to current cancer treatment efforts is the development of drug resistance by tumors. Despite recent advances in diagnostic practices and surgical interventions, many neoplasms demonstrate poor response to adjuvant or neoadjuvant radiation and chemotherapy. As a result, the prognosis for many patients afflicted with these aggressive cancers remains bleak. The insulin-like growth factor (IGF) signaling axis has been shown to play critical role in the development and progression of various tumors. Many basic science and translational studies have shown that IGF pathway modulators can have promising effects when used to treat various malignancies. There also exists a substantial body of recent evidence implicating IGF signaling dysregulation in the dwindling response of tumors to current standard-of-care therapy. By better understanding both the IGF-dependent and -independent mechanisms by which pathway members can influence drug sensitivity, we can eventually aim to use modulators of IGF signaling to augment the effects of current therapy. This review summarizes and synthesizes numerous recent investigations looking at the role of the IGF pathway in drug resistance. We offer a brief overview of IGF signaling and its general role in neoplasia, and then delve into detail about the many types of human cancer that have been shown to have IGF pathway involvement in resistance and/or sensitization to therapy. Ultimately, our hope is that such a compilation of evidence will compel investigators to carry out much needed studies looking at combination treatment with IGF signaling modulators to overcome current therapy resistance.

The transcription factors Ik-1 and MZF1 downregulate IGF-IR expression in NPM-ALK⁺ T-cell lymphoma

Background

The type I insulin-like growth factor receptor (IGF-IR) tyrosine kinase promotes the survival of an aggressive subtype of T-cell lymphoma by interacting with nucleophosmin-anaplastic lymphoma kinase (NPM-ALK) oncogenic protein. NPM-ALK⁺ T-cell lymphoma exhibits much higher levels of IGF-IR than normal human T lymphocytes. The mechanisms underlying increased expression of IGF-IR in this lymphoma are not known. We hypothesized that upregulation of IGF-IR could be attributed to previously unrecognized defects that inherently exist in the transcriptional machinery in NPM-ALK⁺ T-cell lymphoma.

Methods and results

Screening studies showed substantially lower levels of the transcription factors Ikaros isoform 1 (Ik-1) and myeloid zinc finger 1 (MZF1) in NPM-ALK⁺ T-cell lymphoma cell lines and primary tumor tissues from patients than in human T lymphocytes. A luciferase assay supported that Ik-1 and MZF1 suppress IGF-IR gene promoter. Furthermore, ChIP assay showed that these transcription factors bind specific sites located within the IGF-IR gene promoter. Forced expression of Ik-1 or MZF1 in the lymphoma cells decreased IGF-IR mRNA and protein. This decrease was associated with downregulation of pIGF-IR, and the phosphorylation of its interacting proteins IRS-1, AKT, and NPM-ALK. In addition, overexpression of Ik-1 and MZF1 decreased the viability, proliferation, migration, and anchorage-independent colony formation of the lymphoma cells.

Conclusions

Our results provide novel evidence that the aberrant decreases in Ik-1 and MZF1 contribute significantly to the pathogenesis of NPM-ALK⁺ T-cell lymphoma through the upregulation of IGF-IR expression. These findings could be exploited to devise new strategies to eradicate this lymphoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-015-0324-2) contains supplementary material, which is available to authorized users.

Wilms' tumor gene 1 (WT1) silencing inhibits proliferation of malignant peripheral nerve sheath tumor sNF96.2 cell line

Wilms’ tumor gene 1 (WT1) plays complex roles in tumorigenesis, acting as tumor suppressor gene or an oncogene depending on the cellular context. WT1 expression has been variably reported in both benign and malignant peripheral nerve sheath tumors (MPNSTs) by means of immunohistochemistry. The aim of the present study was to characterize its potential pathogenetic role in these relatively uncommon malignant tumors. Firstly, immunohistochemical analyses in MPNST sNF96.2 cell line showed strong WT1 staining in nuclear and perinuclear areas of neoplastic cells. Thus, we investigated the effects of silencing WT1 by RNA interference. Through Western Blot analysis and proliferation assay we found that WT1 knockdown leads to the reduction of cell growth in a time- and dose-dependent manner. siWT1 inhibited proliferation of sNF96.2 cell lines likely by influencing cell cycle progression through a decrease in the protein levels of cyclin D1 and inhibition of Akt phosphorylation compared to the control cells. These results indicate that WT1 knockdown attenuates the biological behavior of MPNST cells by decreasing Akt activity, demonstrating that WT1 is involved in the development and progression of MPNSTs. Thus, WT1 is suggested to serve as a potential therapeutic target for MPNSTs.

A subtraction tolerization method of immunization allowed for Wilms' tumor protein-1 (WT1) identification in melanoma and discovery of an antitumor peptide sequence

On searching for melanoma transcription factors in a project focusing on internal antitumor peptide sequences from transcription factors, we found that a highly immunogenic component emerged upon using a subtraction tolerization method of immunization. While several conventional immunization procedures using whole melanoma cells induced a plethora of low affinity antibodies of various specificities, the subtraction tolerization method efficiently elicited mono-specific antibodies that recognized Wilms' tumor protein 1 (WT1), which is known as an important marker in melanoma prognosis and treatment. For the tolerization step, pre-immunization of Balb/c mice with a membrane-rich preparation of glioblastoma U87 cells was used. The subsequent immunizations with SK-MEL-28 melanoma cells elicited antibodies strongly reacting with 50 and 55 kDa proteins, identified as WT1. Remarkably, this was the only component strongly reactive with these antibodies in a melanoma cell lysate. WT1 was then chosen as a target for selecting internally bioactive peptides. A hydrophilic Trojan peptide containing most of the zinc finger-2 domain of WT1 was synthesized and shown to inhibit SK-MEL-28 melanoma growth in vitro. The peptide WT1-pTj was also protective in vivo in a metastatic melanoma model and peptide-stimulated syngeneic dendritic cells reproduced the anti-melanoma effect of the unprotected peptide. Identification of antitumor peptides derived from major transcription factors represents a new tool to be explored in cancer research aiming at new therapeutic drugs.

Synthesis and in vitro evaluation of [18F]BMS-754807: a potential PET ligand for IGF-1R

Radiosynthesis and in vitro evaluation of [(18)F](S)-1-(4-((5-cyclopropyl-1H-pyrazol-3-yl)amino)pyrrolo[2,1-f][1,2,4]triazin-2-yl)-N-(6-fluoropyridin-3-yl)-2-methylpyrrolidine-2-carboxamide ([(18)F]BMS-754807 or [(18)F]1) a specific IGF-1R inhibitor was performed. [(18)F]1 demonstrated specific binding in vitro to human cancer tissues. Synthesis of reference standard 1 and corresponding bromo derivative (1a), the precursor for radiolabeling were achieved from 2,4-dichloropyrrolo[2,1-f][1,2,4]triazine (4) in three steps with 50% overall yield. The radioproduct was obtained in 8% yield by reacting 1a with [(18)F]TBAF in DMSO at 170°C at high radiochemical purity and specific activity (1-2Ci/μmol, N=10). The proof of concept of IGF-IR imaging with [(18)F]1 was demonstrated by in vitro autoradiography studies using pathologically identified surgically removed grade IV glioblastoma, breast cancer and pancreatic tumor tissues. These studies indicate that [(18)F]1 can be a potential PET tracer for monitoring IGF-1R.

Targeting the insulin growth factor receptor 1

The IGF axis is a tightly controlled endocrine system that regulates cell growth and development, known to have an important function in cancer biology. IGF1 and IGF2 can promote cancer growth in a GH-independent manner both through paracrine and autocrine secretion and can also confer resistance to chemotherapy and radiation. Many alterations of this system have been found in neoplasias, including increased expression of ligands and receptors, loss of heterozygosity of the IGF2 locus and increased IGF1R gene copy number. The IGF1 network is an attractive candidate for targeted therapy, including receptor blockade with monoclonal antibodies and small molecule inhibitors of receptor downstream signaling. This article reviews the role of the IGF axis in the initiation and progression of cancer, and describes the recent advances in IGF inhibition as a therapeutic tool.

Novel report of expression and function of CD97 in malignant gliomas: correlation with Wilms tumor 1 expression and glioma cell invasiveness

OBJECT

The Wilms tumor 1 (WT1) protein-a developmentally regulated transcription factor-is aberrantly expressed in gliomas and promotes their malignant phenotype. However, little is known about the molecular allies that help it mediate its oncogenic functions in glioma cells.

METHODS

The authors used short interfering RNA (siRNA) to suppress WT1 expression in glioblastoma (GBM) cells and evaluated the effect of this on GBM cell invasiveness. Gene expression analysis was then used to identify the candidate genes that were altered as a result of WT1 silencing. One candidate target, CD97, was then selected for further investigation into its role by suppressing its expression using siRNA silencing, followed by proliferation and invasion assays.

RESULTS

WT1 levels were reliably and reproducibly suppressed by siRNA application. This resulted in a significant decrease in cellular invasiveness. Microarray analyses identified the gene products that were consistently downregulated (27) and upregulated (11) with WT1 silencing. Of these, CD97 expression was consistently suppressed across the 3 different GBM cell lines studied and was found on further investigation to significantly impact GBM cell invasiveness.

CONCLUSIONS

Although CD97 expression in gliomas has not been described previously, we conclude that the possible upregulation of CD97 mediated by WT1 promotes cellular invasiveness-one of the most characteristic and challenging aspects of glial tumor cells. Further studies are needed to clarify the nature of this regulation and its impact, as CD97 could represent a novel target for antiglioma therapies.