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Figure legends for Supplementary Figures

Caspase-8 dependent apoptosis induced by IR

IR-induced changes in cell surface expression of death receptors

Response of H460 and A549 cells to IR

Combination of SAHA with IR in H460 and A549 cells using different treatment schedules

AIMS Use bioinformatics methods to identify and validate associated proteins and genes in the SORL1 network. Generate a bank of patient derived cells in association with the Royal Preston Hospital BTNW tissue bank. Explore identified targets from the bioinformatics in patient derived cells. METHOD Proteins and genes associated with SORL1 and SORLA were identified on GeneCards. Connectivity mapping of known and predicted interactions linked to SORL1 was explored in STRING. For clinical validation differential expression was investigated by comparing genomic data from GTEX and TCGA, available at Xenabrowser. For survival analysis Kaplan-Meier curves were generated on cBioPortal. The five most differently expressed novel targets are taken forward for laboratory experiments using western blots for protein quantification and immunocytochemistry to identify and visualise target proteins. RESULTS A total of 73 genes (30 from GeneCards and 43 from STRING) were obtained. 63 genes from the generated SORL1-related network were shown to be differentially expressed whilst 40 were significantly different between low-surviving patients and high-surviving patients. The top five associated proteins are CKAP4, CTNND1, FN1, HSPA12A and SORCS3. CKAP4, CTNND1 and FN1 are highly expressed in both glioma and glioblastoma, but low expressed in healthy tissue. HSPA12A is low expressed in cancerous brain tissue and highly expressed in healthy samples. SORCS3 is differentially expressed in healthy samples and glioma, but significantly low expressed glioblastoma. CONCLUSION This project provides insight into SORL1 molecular relationships and function in tissue, cultured cells and serum from a patient cohort including demographics, disease progression and site.

AIMS Design and statistically optimize an in silico screening protocol; apply the screening protocol to a compound database; in vitro validation of selected inhibitors (isolated CDK5 enzyme binding assay). METHOD Two large compound databases, ZINC15 and Analyticon Discovery, were used to screen for potential CDK5 ATP-binding site inhibitors. They were first filtered using a generated pharmacophore model and then virtually screened using Glide SP docking with a solved CDK5-p25 structure (PDB: 3O0G). The selected candidates were validated using enzyme binding assays to determine their inhibitory activity on CDK5, as well as against a panel of kinases. RESULTS Over 17,000 compounds were screened during molecular docking studies and of these, ~11,600 compounds returned which are predicted to bind to CDK5. The top 10% of docked compounds were analysed and 30 candidates were selected for single concentration screening at 50 µM concentrations. The 9 most potent compounds were selected for IC50 determinations and revealed 6 compounds with IC50 CONCLUSION Low micromolar potent compounds have been identified through in silico screening and validated in using in vitro binding assays. One flavonoid compound in particular, cirsiliol (IC50 = 5.90 µM), displayed best selectivity towards CDK5, a challenge in kinase inhibitor design. The identified compounds will now pass to cellular studies to determine their effect on Glioblastoma cell lines.

AIMS Exploring how two proteins strongly associated with Alzheimer’s disease are expressed in glioma. Amyloid beta (Aβ) is a peptide cleaved from amyloid precursor protein (APP) that is shuttled around the cell by sorting-related receptor with A-type repeats (SorLA). Low expression of SorLA has been linked to increased risk of Alzheimer’s disease as APP processing shifts towards production of the plaque-forming Aβ42 rather than the more benign Aβ40. METHOD Expression of Aβ40, Aβ42 and SorLA was determined in immortalised cell lines (grade 4 glioblastoma U87MG, grade 2 astrocytoma 1321N1, foetal astrocytes SVGp12), glioblastoma patient-derived cells (PD301, PD304) and normal human astrocytes through western blotting or immunocytochemistry. RESULTS SorLA was present in all cells. Relative optical density was more than 60-fold higher for U87MG glioblastoma cells and approximately 10-fold higher for 1321N1 astrocytoma cells than SVGp12 cells. Similarly, SorLA had a significantly higher expression (p CONCLUSION These data suggest that SorLA is retained in glioblastoma and remains functional to drive APP processing away from Aβ42 production. Future work will determine how high SorLA expression contributes to the increased motility and invasiveness seen in glioblastoma cells by transfecting siRNA to knock down SorLA.

Resistance to radiotherapy due to insufficient cancer cell death is a significant cause of treatment failure in non–small cell lung cancer (NSCLC). The endogenous caspase-8 inhibitor FLIP is a critical regulator of cell death that is frequently overexpressed in NSCLC and is an established inhibitor of apoptotic cell death induced via the extrinsic death receptor pathway. Apoptosis induced by ionizing radiation (IR) has been considered to be mediated predominantly via the intrinsic apoptotic pathway; however, we found that IR-induced apoptosis was significantly attenuated in NSCLC cells when caspase-8 was depleted using RNA interference (RNAi), suggesting involvement of the extrinsic apoptosis pathway. Moreover, overexpression of wild-type FLIP, but not a mutant form that cannot bind the critical death receptor adaptor protein FADD, also attenuated IR-induced apoptosis, confirming the importance of the extrinsic apoptotic pathway as a determinant of response to IR in NSCLC. Importantly, when FLIP protein levels were downregulated by RNAi, IR-induced cell death was significantly enhanced. The clinically relevant histone deacetylase (HDAC) inhibitors vorinostat and entinostat were subsequently found to sensitize a subset of NSCLC cell lines to IR in a manner that was dependent on their ability to suppress FLIP expression and promote activation of caspase-8. Entinostat also enhanced the antitumor activity of IR in vivo. Therefore, FLIP downregulation induced by HDAC inhibitors is a potential clinical strategy to radiosensitize NSCLC and thereby improve response to radiotherapy. Overall, this study provides the first evidence that pharmacological inhibition of FLIP may improve response of NCSLC to IR. Mol Cancer Ther; 15(10); 2432–41. ©2016 AACR.

FLIP is a potential anti-cancer therapeutic target that inhibits apoptosis by blocking caspase 8 activation by death receptors. We report a novel interaction between FLIP and the DNA repair protein Ku70 that regulates FLIP protein stability by inhibiting its polyubiquitination. Furthermore, we found that the histone deacetylase (HDAC) inhibitor Vorinostat (SAHA) enhances the acetylation of Ku70, thereby disrupting the FLIP/Ku70 complex and triggering FLIP polyubiquitination and degradation by the proteasome. Using in vitro and in vivo colorectal cancer models, we further demonstrated that SAHA-induced apoptosis is dependant on FLIP downregulation and caspase 8 activation. In addition, an HDAC6-specific inhibitor Tubacin recapitulated the effects of SAHA, suggesting that HDAC6 is a key regulator of Ku70 acetylation and FLIP protein stability. Thus, HDAC inhibitors with anti-HDAC6 activity act as efficient post-transcriptional suppressors of FLIP expression and may, therefore, effectively act as 'FLIP inhibitors'.

Death receptor activation triggers recruitment of FADD, which via its death effector domain (DED) engages the DEDs of procaspase 8 and its inhibitor FLIP to form death-inducing signalling complexes (DISCs). The DEDs of FADD, FLIP and procaspase 8 interact with one another using two binding surfaces defined by α1/α4 and α2/α5 helices, respectively. Here we report that FLIP has preferential affinity for the α1/α4 surface of FADD, whereas procaspase 8 has preferential affinity for FADD's α2/α5 surface. These relative affinities contribute to FLIP being recruited to the DISC at comparable levels to procaspase 8 despite lower cellular expression. Additional studies, including assessment of DISC stoichiometry and functional assays, suggest that following death receptor recruitment, the FADD DED preferentially engages FLIP using its α1/α4 surface and procaspase 8 using its α2/α5 surface; these tripartite intermediates then interact via the α1/α4 surface of FLIP DED1 and the α2/α5 surface of procaspase 8 DED2.

Non-small cell lung carcinoma remains by far the leading cause of cancer-related deaths worldwide. Overexpression of FLIP, which blocks the extrinsic apoptotic pathway by inhibiting caspase-8 activation, has been identified in various cancers. We investigated FLIP and procaspase-8 expression in NSCLC and the effect of HDAC inhibitors on FLIP expression, activation of caspase-8 and drug resistance in NSCLC and normal lung cell line models. Immunohistochemical analysis of cytoplasmic and nuclear FLIP and procaspase-8 protein expression was carried out using a novel digital pathology approach. Both FLIP and procaspase-8 were found to be significantly overexpressed in tumours, and importantly, high cytoplasmic expression of FLIP significantly correlated with shorter overall survival. Treatment with HDAC inhibitors targeting HDAC1-3 downregulated FLIP expression predominantly via post-transcriptional mechanisms, and this resulted in death receptor- and caspase-8-dependent apoptosis in NSCLC cells, but not normal lung cells. In addition, HDAC inhibitors synergized with TRAIL and cisplatin in NSCLC cells in a FLIP- and caspase-8-dependent manner. Thus, FLIP and procaspase-8 are overexpressed in NSCLC, and high cytoplasmic FLIP expression is indicative of poor prognosis. Targeting high FLIP expression using HDAC1-3 selective inhibitors such as entinostat to exploit high procaspase-8 expression in NSCLC has promising therapeutic potential, particularly when used in combination with TRAIL receptor-targeted agents.

Failure to efficiently induce apoptosis contributes to cisplatin resistance in non-small-cell lung cancer (NSCLC). Although BCL-2-associated X protein (BAX) and BCL-2 antagonist killer (BAK) are critical regulators of the mitochondrial apoptosis pathway, their requirement has not been robustly established in relation to cisplatin. Here, we show that cisplatin can efficiently bypass mitochondrial apoptosis block caused by loss of BAX and BAK, via activation of the extrinsic death receptor pathway in some model cell lines. Apoptosis resistance following cisplatin can only be observed when both extrinsic and intrinsic pathways are blocked, consistent with redundancy between mitochondrial and death receptor pathways in cisplatin-induced apoptosis. In H460 NSCLC cells, caspase-8 cleavage was shown to be induced by cisplatin and is dependent on death receptor 4, death receptor 5, Fas-associated protein with death domain, acid sphingomyelinase and ceramide synthesis. In contrast, cisplatin-resistant cells fail to activate caspase-8 via this pathway despite conserving sensitivity to death ligand-driven activation. Accordingly, caspase-8 activation block acquired during cisplatin resistance, can be bypassed by death receptor agonism.

BACKGROUND:\ud Isolated limb perfusion with TNF-α and melphalan is used with remarkable efficiency to treat unresectable limb sarcomas. Here we tested the ability of TNF-α to directly induce apoptosis of sarcoma cells. In addition, we investigated the impact of p53 in the regulation of such effect.\ud \ud METHODOLOGY/PRINCIPAL FINDINGS:\ud We first analysed the ability of TNF-α to induce apoptosis in freshly isolated tumour cells. For this purpose, sarcoma tumours (n = 8) treated ex vivo with TNF-α were processed for TUNEL staining. It revealed substantial endothelial cell apoptosis and levels of tumour cell apoptosis that varied from low to high. In order to investigate the role of p53 in TNF-α-induced cell death, human sarcoma cell lines (n = 9) with different TP53 and MDM2 status were studied for their sensitivity to TNF-α. TP53(Wt) cell lines were sensitive to TNF-α unless MDM2 was over-expressed. However, TP53(Mut) and TP53(Null) cell lines were resistant. TP53 suppression in TP53(Wt) cell lines abrogated TNF-α sensitivity and TP53 overexpression in TP53(Null) cell lines restored it. The use of small molecules that restore p53 activity, such as CP-31398 or Nutlin-3a, in association with TNF-α, potentiated the cell death of respectively TP53(Mut) and TP53(Wt)/MDM2(Ampl). In particular, CP-31398 was able to induce p53 as well as some of its apoptotic target genes in TP53(Mut) cells. In TP53(Wt)/MDM2(Ampl) cells, Nutlin-3a effects were associated with a decrease of TNF-α-induced NF-κB-DNA binding and correlated with a differential regulation of pro- and anti-apoptotic genes such as TP53BP2, GADD45, TGF-β1 and FAIM.\ud \ud CONCLUSION/SIGNIFICANCE:\ud More effective therapeutic approaches are critically needed for the treatment of unresectable limb sarcomas. Our results show that restoring p53 activity in sarcoma cells correlated with increased sensitivity to TNF-α, suggesting that this strategy may be an important determinant of TNF-α-based sarcomas treatment.

Renal cell carcinoma (RCC) is the most common type of kidney cancer and recent developments in the molecular biology of RCC have identified multiple pathways associated with the development of this cancer. This study aimed at analyzing the expression pattern of cytokeratin 18 (CK18) in RCC patients and its prognostic relevance. We quantified CK18 mRNA expression and protein using real-time reverse transcription quantitative polymerase chain reaction (RT-QPCR) and immunohistochemistry, respectively, in paired tumor and non-tumor samples from 42 patients. Our data indicate that CK18 mRNA and proteins levels increased with advanced stage and grade of the disease. Using primary (RCC5) and metastatic renal cell carcinoma (RCC5 met) cell lines, we demonstrated that CK18 expression was 5-fold higher in the metastatic as compared to the primary RCC cell line and correlated with a migratory phenotype characterized by a distinct elongated morphology as revealed by Phalloidin staining. In addition, RCC5 met cells displayed an increased capacity to attach to fibronectin and collagen which was lost following CK18 knock-down. Our data also indicate that the expression of CK18 was associated with increased Snail expression which correlated positively with advanced disease in RCC patients. The present findings suggest that CK18 may play an important role in the progression of RCC and it may be used as a new predictor for RCC.

In order to exert their activity, transcription factors must be transported to the nucleus. Certain transcription factors have also been found on mitochondria. Here, the localization of RelB and NFATx in the mitochondrial fractions of normal thymocytes and thymic lymphoma cells is shown for the first time. CREB was only found in the nucleus, while p50 (NFκB) was found in both the nucleus and the cytoplasm, but outside the mitochondria. The translocation of transcription factors to the mitochondria is differentially regulated. Unlike RelB, which is always present in the mitochondrial fraction, NFATx appeared on the mitochondria in cells treated with ionomycin together with an immunosuppressant and inhibitor of calcineurin (FK506). This data reveals that the mitochondrial localization of some transcription factors is precisely controlled by a calcium signal sensitive to FK506 in T cells.

Malignant pleural mesothelioma (MPM) is a highly pro-inflammatory malignancy that is rapidly fatal and increasing in incidence. Cytokine signaling within the pro-inflammatory tumor microenvironment makes a critical contribution to the development of MPM and its resistance to conventional chemotherapy approaches. SMAC mimetic compounds (SMCs) are a promising class of anticancer drug that are dependent on tumor necrosis factor alpha (TNFa) signaling for their activity. As circulating TNFa expression is significantly elevated in MPM patients, we examined the sensitivity of MPM cell line models to SMCs. Surprisingly, all MPM cell lines assessed were highly resistant to SMCs either alone or when incubated in the presence of clinically relevant levels of TNFa. Further analyses revealed that MPM cells were sensitized to SMC-induced apoptosis by siRNA-mediated downregulation of the caspase 8 inhibitor FLIP, an antiapoptotic protein overexpressed in several cancer types including MPM. We have previously reported that FLIP expression is potently downregulated in MPM cells in response to the histone deacetylase inhibitor (HDACi) Vorinostat (SAHA). In this study, we demonstrate that SAHA sensitizes MPM cells to SMCs in a manner dependent on its ability to downregulate FLIP. Although treatment with SMC in the presence of TNFa promoted interaction between caspase 8 and the necrosis-promoting RIPK1, the cell death induced by combined treatment with SAHA and SMC was apoptotic and mediated by caspase 8. These results indicate that FLIP is a major inhibitor of SMC-mediated apoptosis in MPM, but that this inhibition can be overcome by the HDACi SAHA.

Background: Sarcomas are rare, poorly understood cancers, highly aggressive and refractory to standard therapies. In these tumors mutations of p53 or Mdm2 amplification are frequently found. Isolated limb perfusion (ILP) with TNFα and melphalan is an innovative approach to treat unresectable soft tissue sarcomas (STS) of extremities. TNF is known to increase endothelium permeability for melphalan, and to disrupt tumoral vessels. However, the direct apoptotic effect of TNF on sarcoma cells remains controversial. Several reports indicate an association of sensitivity to TNF with p53 activity in in vitro models. In the present study we attempted to test the ability of TNF to induce apoptosis of sarcoma cells and investigated the role of p53 in the regulation of this effect. Methods: Ex vivo study was performed on sarcoma tumor pieces from patients. Tumor slices were treated with TNF and cytotoxic effect was assessed with TUNEL method. In vitro studies were carried on human soft tissue sarcoma cell lines with different p53 status and Mdm2 expression, representing 5 histological types. Cytotoxic effect of TNF was assessed with DiOC6/PI test. Activation of p53 was verified by the detection of expression of proteins encoded by p53 target genes. Expression of TNF receptor was examined by flow cytometry. Results: In tumor slices treated ex vivo with TNF we observed apoptosis of not only endothelial, but also sarcoma cells. In vitro studies revealed that cell lines with active p53 were sensitive to TNF (80% and 40% of apoptosis), while 6 cell lines were resistant: 2 with wt p53 and Mdm2 amplification (2-4% of apoptosis), 2 with p53 mutation and 2 with p53 deletion (5-15% of apoptosis). TNFR I was expressed by all the cell lines. We next tested sensitivity to TNF after restoration of p53 activity. For this purpose we used either of two compounds: Nutlin-3a, an inhibitor of Mdm2, or CP-31398, a molecule restoring wild-type conformation to mutant TP53. In cell lines with Mdm2 amplification treatment with Nutlin alone resulted in decreased cell viability, while in combined treatment induced strong apoptosis synergistically with TNF. Similarly, treatment of cell lines expressing mutated p53 with CP-31398 led to a significant enhancement of sensitivity to TNF. Conclusions: The results of our ex vivo and in vitro studies suggest, that during ILP, TNF may directly kill sarcoma cells and its cytotoxic activity is correlated with the functionality of p53. Restoration of p53 activity may be advantageous not only in therapies based on DNA disruption, but also based on the use of TNFα. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1041.

The induction of thymocyte apoptosis through the Nur77-mediated intrinsic pathway can be of physiological importance in the clonal deletion of autoreactive thymocytes during negative selection in the thymus and/or in thymocytes undergoing oncogenic transformation. Ionomycin treatment induces endogenous Nur77 expression as well as apoptosis and cytochrome c release in thymocytes. Here it is shown for the first time that in normal thymocytes undergoing apoptosis, ionomycin induces translocation of endogenous Nur77 not only to the nucleus, but also to mitochondria. Immunosuppressant FK506 inhibits Nur77 NBRE and NurRE binding activity but has no effect on thymocytes apoptosis, the subcellular localization of Nur77, or cytochrome c release. This indicates that thymocytes can undergo apoptosis through the intrinsic Nur77-mediated mitochondrial pathway and that the transactivation activity of Nur77 monomers or dimers is not necessary for thymocyte apoptosis.