Les traitements actuels de la leucémie myéloïde chronique (LMC) ne permettent pas d’éliminer la totalité des cellules leucémiques. Dans le but de développer un traitement curatif, il est donc nécessaire de parvenir à une meilleure compréhension des mécanismes sous-jacents des réponses partielles aux traitements, Dans ce travail, nous avons postulé qu’il existe des mécanismes de contrôle extrinsèques de la LMC pouvant influencer l’efficacité des différents traitements. Nous avons choisi d’étudier le rôle potentiel dans la LMC des lymphocytes iNKT, cellules T de type « inné » auxquelles la littérature attribue de nombreuses fonctions antitumorales et des facteurs moléculaires, la cytokine/alarmine IL-33, produite dans la niche hématopoïétique, et son récepteur ST2 à la surface des cellules hématopoïétiques comme cibles de l’IL-33.La première partie de notre travail a ainsi permis de mettre en évidence de profondes altérations fonctionnelles des lymphocytes iNKT chez les patients atteints de LMC ainsi qu’une correction partielle de ces défauts après traitement par l’Imatinib (IM) ou l’IFN-. L’ensemble de ces résultats permet de proposer que l’altération des fonctions des cellules iNKT au cours du développement de la LMC pourrait participer aux mécanismes d’échappement de la tumeur au contrôle par le système immunitaire. La deuxième partie de notre travail a permis de mettre en évidence une expression de la molécule ST2, chaîne spécifique du récepteur à l’IL-33, à la surface des cellules CD34+ de patients atteints de LMC, expression non décelée chez les sujets sains et les patients en rémission après traitement par l’IM. De plus, contrairement aux cellules CD34+ de sujets sains, les cellules progénititrices de patients en phase chronique prolifèrent en réponse à l’IL-33. Enfin, nous avons montré que l’IL-33 est capable de contrecarrer in vitro les effets antiprolifératifs de l’IM. Ainsi nous pouvons émettre l’hypothèse selon laquelle l’IL-33, une cytokine/alarmine, puisse participer aux phénomènes conduisant à la persistance de progéniteurs hématopoïétiques leucémiques chez les patients sous traitement par IM. / To date, treatment of Chronic Myeloid Leukaemia (CML) is not sufficient to completely eradicate leukaemia cells. Hence, in order to develop a curative treatment, it is necessary to have a better understanding of the underlying mechanisms explaining why response to treatment is only partial..We therefore addressed the question whether the extrinsic mechanisms of CML control can affect the effectiveness of different treatments. We first provided evidence of profound functional impairments of iNKT cells in patients with CML. Interestingly these impairments were partially corrected after treatment with Imatinib (IM) or IFN-. Consequently our results suggest that altered functions of iNKT cells during the development of CML could facilitate tumour escape from immune destruction. . The second part of our work revealed that CD34+ progenitors from CML patients upregulate their cell surface expression of the IL-33-specific receptor chain ST2, proliferate and produce cytokines in response to IL-33, conversely to CD34+ cells from healthy individuals. Moreover, ST2 overexpression is normalized following IM therapy, while IL-33 counteracts in vitro IM-induced growth arrest in CML CD34+ progenitors. From these findings, it can be surmised that IL-33, a cytokine/alarmin likely expressed in the hematopoietic niche, facilitates the development of CML and IM resistance.

Syftet med förevarande uppsats är att utreda hur det personliga ansvaret är utformat för nytillträdd styrelse, samt vilka möjligheter har nytillträdd styrelse att undgå ansvar. Styrelseledamöter i ett aktiebolag kan bli personligt betalningsansvariga om det i lagen givna handlingsmönstret när det finns skäl att anta att bolaget har kapitalbrist. Det personliga ansvaret är utformat som ett medansvar och träffar hela styrelsen. Möjligheterna för att undgå personligt betalningsansvar är dels genom ansvarsfrihetsgrunder, dels genom att läka kapitalbristen (inom en till två månader). Det personliga ansvaret för nytillträdd styrelse är inte lagreglerad och av lagstiftaren stadgas att frågan bör bedömas med beaktande av den nytillträdde ledamotens agerande i det enskilda fallet. Diskussion har förts kring vilken ansvarssituation som ska anses gälla för den nytillträdde styrelseledamoten vid tidpunkten för inträdet. Indikationer finns på att nytillträdd styrelseledamot "ärver" tidigare styrelses ansvar. Doktrins tolkning är nytillträdd styrelseledamot inte borde ådra sig något ansvar om denne vidtar adekvat åtgärd för rättelse så snart efter sitt inträde. Möjligheterna att undgå personligt betalningsansvar är tämligen begränsade. För egen del ansluter jag mig till doktrins tolkning, en ordning som innebär att styrelse ärver tidigare styrelses ansvar är alldeles för långtgående ansvar och oproportionerligt. Möjligheterna för nytillträdd styrelse att läka kapitalbrist är tämligen begränsade varför uppsatsförfattaren ställer frågan huruvida det inte vore rimligare att tillåta läkning i efterhand i speciella fall, t.ex. då en ny styrelse träder in i ett bolag. E contrario tolkningen har vidare av uppsatsförfattaren ifrågasatts om den stadgade tidpunkten verkligen borde utgöra den definitiva slutpunkten.

No description available.

The c-Jun NH2-terminal kinase (JNK) group of kinases include ten members that are created by alternative splicing of transcripts derived from Jnk1, Jnk2 and Jnk3 genes. The JNK1 and JNK2 protein kinases are ubiquitously expressed while JNK3 is expressed in a limited number of tissues. The JNK signaling pathway is implicated in multiple physiological processes including cell transformation. There is growing evidence that JNK signaling is involved in oncogenesis. Nevertheless, the role that JNK plays in malignant transformation is still unclear. The aim of this thesis is to examine the role of JNK in malignant transformation. For this purpose, I used the Bcr/Abl oncogene as a transforming agent. Bcr/Abl is a leukemogenic oncogene that is created by reciprocal translocation between chromosome 9 and 22. The translocation breakpoint is variable and several different Bcr/Abl isoforms have been identified such as Bcr/AblP185 and Bcr/AblP210, whose expression is associated with different types of leukemia. Bcr/Abl activates the JNK signaling pathway in hematopoietic cells and increases AP-1 transcription activity. Furthermore, dominant negative approaches demonstrate that inhibition of c-Jun or JNK prevents Bcr/ Abl-induced cell transformation in vitro. These data implicate the JNK signaling pathway in Bcr/Abl transformation although the role that JNK might have in this process is unclear. Thus, I examined the importance of JNK signaling in Bcr/Abl-induced lymphoid or myeloid transformation. For this purpose I compared Bcr/AblP185- and Bcr/AblP210- induced transformation of wild-type and JNK1-deficient cells using three approaches: in vitro, in vivo and ex vivo. The results obtained with the in vitro approach suggest that both Bcr/AblP185 and Bcr/AblP210 require JNK activity to induce lymphoid transformation. While JNK1-deficiency inhibits Bcr/AblP210 oncogenic potential in lymphoid cells both in vitro and in vivo, pharmacological inhibition of JNK activity (JNK1 and/or JNK2) blocked Bcr/AblP185 induced malignant proliferation in vitro. The differential requirement for JNK observed in the two Bcr/Abl isoforms can be ascribed to the presence in Bcr/AblP210 of the Dbl domain which can activate the JNK pathway in vitro. In the case of Bcr/AblP210, JNK1 is critical for the survival of the ex vivo derived transformed lymphoblasts upon growth factor removal. This result correlates with the fact that mice reconstituted with Bcr/AblP210 transformed Jnk1-l- bone marrow showed normal malignant lymphoid expansion in the bone marrow yet they had reduced numbers of lymphoblast in the bloodstream and lacked peripheral organ infiltration. Thus JNK1 is essential for the survival of the transformed lymphoblast outside the bone marrow microenvironment in Bcr/AblP210induced lymphoid leukemia. Interestingly, while JNK1 is essential for lymphoid transformation, it is dispensable for the proliferation of transformed myeloblasts. Taken together these results indicate that the JNK signaling pathway plays an essential role in the survival of Bcr/AblP210 lymphoblasts and that JNK-deficiency decreases the leukomogenic potential of Bcr/AblP210 in vivo. Thus, cell survival mediated by JNK may contribute to the pathogenesis of proliferative diseases.

CXCR4, récepteur de la chimiokine SDF-1 (stromal cell-derived factor 1) joue un rôle capital dans l’hématopoïèse normale mais aussi dans la biologie de la cellule leucémique. Ce récepteur est exprimé à la surface des blastes et participe à « l’ancrage » de la cellule souche leucémique (CSL) au sein de la niche médullaire. Les interactions de la CSL avec le micro-environnement sont source de signaux de survie et de résistance à l’apoptose. La première partie de ce travail correspond à deux analyses en cytométrie en flux de l’expression de CXCR4 et de molécules d’adhérence sur des échantillons diagnostiques de LAM (leucémie aiguë myéloïde). Ce travail confirme la valeur pronostique péjorative de l’expression de CXCR4 et propose un modèle de stratification pronostique des patients, en fonction de leur phénotype d’adhérence. La deuxième partie s’intéresse à l’identification de potentielles cibles thérapeutiques dans un modèle de LAL à chromosome Philadelphie, pathologie au pronostic sombre malgré les progrès thérapeutiques liés aux ITK (inhibiteurs de tyrosine kinase). L’inhibition de CXCR4 par l’AMD3100 permet de potentialiser l’efficacité de l’aracytine et du dasatinib dans un modèle de co-culture stromale avec la lignée SUPB15. Une deuxième piste de ciblage thérapeutique de la LAL Phi+ est l’inhibition de la protéine chaperone HSP90. Une expression forte de HSP90 (dans les LAL Phi+ par rapport aux LAL Phi-) s’associe à une plus grande cytotoxicité du 17-AAG. En conclusion, CXCR4 est un récepteur clé de la cellule leucémique. L’étude de son niveau d’expression permet des stratifications pronostiques des patients et son blocage en fait une cible thérapeutique prometteuse / CXCR4, receptor of the chemokine SDF-1 (stromal cell-derived factor 1) plays a major role in the normal hematopoiesis but also in the biology of the leukaemic cell. This receptor is expressed on the surface of blasts and is a key molecule in "the anchoring" of the leukaemic stem cell (LSC) within the bone marrow niche. The interactions of the LSC with the bone marrow microenvironment promote survival signals and drug resistance. The first part of this work consists of two flow cytometry analyses of CXCR4 and adhesion molecules expression in patients with AML (acute myeloid leukaemia) at diagnosis. The results confirm that CXCR4 expression is associated with poor prognosis and this work proposes to stratify patients, according to their adhesive phenotype, in order to establish risk-adapted strategies. The second part deals with the identification of potential therapeutic targets in a model of ALL with chromosome Philadelphia. Despite therapeutic improvements with the ITK (tyrosine kinase inhibitors) era, long term survival remains poor. The inhibition of CXCR4 by the AMD3100 enhances the sensitivity of SUPB15 cell line to cytarabine and dasatinib therapy in a model of stromal co-culture. A second way of therapeutic targeting of the ALL Phi + is the inhibition of the heat-shock protein HSP90. High percentage of HSP90-positive cells (in Ph+ ALL samples) is associated with high sensitivity to 17-AAG. In conclusion, CXCR4 appears as a key receptor of the leukaemic cell. The analysis of its level of expression allows prognostic stratifications and its blockade represents a promising therapeutic target

A leucemia mielóide crônica (LMC) é uma doença mieloproliferativa caracterizada citogeneticamente pela presença do cromossomo Philadelfia (Ph) e molecularmente pelo neogene bcr-abl1 que codifica a oncoproteína BCR-ABL com alta atividade de tirosina-quinase. A célula leucêmica BCR-ABL+ apresenta baixa adesão ao estroma medular, resistência à apoptose e potencial mitogênico exacerbado. A LMC possui curso evolutivo trifásico (fase crônica, acelerada e blástica) e seu tratamento pode ser realizado por meio de diferentes modalidades terapêuticas, destacando-se o mesilato de imatinibe (MI) que inibe a TK BCR-ABL induzindo altas taxas de remissão citogenética dos pacientes na fase crônica da doença. Apesar do MI ser eficiente, os pacientes na fase acelerada e blástica da doença são comumente refratários a essa terapia e na fase crônica há casos de resistência ao MI descritos. Nesse contexto, potenciais novos fármacos são investigados para melhorar a eficiência da terapia da LMC. Nesse estudo, investigamos o efeito do veneno bruto (VB) e da enzima L-amino-ácido-oxidase (LAAO) da Bothrops pirajai em desencadear apoptose em células BCR-ABL+. A apoptose das células HL-60 e HL-60.BCR-ABL foi quantificada pela detecção da percentagem de células com núcleos hipodiplóides pela da citometria de fluxo e confirmada pela observação da ativação das caspases 3, 8 e 9 por western-blot. Os resultados obtidos indicam que a LAAO é capaz de induzir apoptose em células HL-60 e HL-60.BCR-ABL por ativação das vias extrínseca e intrínseca. Além disso, foi verificado que a LAAO diminui a fosforilação de BCR-ABL em células HL-60.BCR-ABL e quando associada ao MI potencializou a inibição da atividade quinase de BCR-ABL. Os dados da presente investigação indicaram ainda que a LAAO é capaz de modular a expressão de bad, bak, bax, bid, bimel, fas,fasl, a1, bcl-2, bcl-xl, bcl-w e c-flip, genes reguladores da apoptose celular. Apesar do pouco conhecimento acerca do mecanismo de ação dessa toxina, os dados obtidos sugerem que a LAAO possui o potencial de estimular a apoptose nas linhagens HL-60 e HL-60.BCR-ABL e aumentar o efeito do inibidor da atividade quinase, MI, dados relevantes para estudos futuros associados a descrição de novos fármacos contra leucemia mielóide crônica. / Chronic myeloid leukemia (CML) is a myeloproliferative disorder cytogenetically characterized by the presence of Philadelphia chromosome (Ph) and molecularly by bcr-abl1 neogene that encodes the BCR-ABL oncoprotein with high tyrosine kinase (TK) activity. The leukemic cell BCR-ABL+ presents poor adhesion to bone marrow stroma, resistance to apoptosis and exacerbated mitogenic potential. The CML has a three-phase course (chronic, accelerated and blastic phase) and its treatment can be performed by different therapeutic modalities, especially the imatinib mesylate (IM) that inhibits the TK BCR-ABL inducing high rates of cytogenetic remission in chronic phase. Although MI is effective, patients in accelerated and blastic phases of the disease are often refractory to this therapy and there are also cases of resistance to MI described in chronic phase. In this context, potential new drugs are investigated to improve the efficiency of the therapy of CML. In this study, we investigated the effect of crude venom (CV) and of the enzyme L-amino acid oxidase (LAAO) from Bothrops pirajai in triggering apoptosis in BCR-ABL+. The apoptosis of HL-60 cells and HL-60. BCR-ABL was quantified by detecting the percentage of cells with hypodiploid nuclei by flow cytometry and confirmed by observation of the activation of caspases 3, 8 and 9 by Western blot. The results indicate that LAAO is able to induce apoptosis in HL-60 cells and HL-60. BCR-ABL by activation of the extrinsic and intrinsic pathways. Furthermore, it was found that LAAO decreases phosphorylation of BCR-ABL in HL-60 cells. BCR-ABL when associated with MI potencialized the inhibition of kinase activity of BCR-ABL. The data from this study also indicated that the LAAO is able to modulate the expression of bad, bak, bax, bid, bimel, fas, FasL, A1, bcl-2, bcl-xl, bcl-w and c-flip, regulatory genes of apoptosis. Even though there is little knowledge about the mechanism of action of this toxin, the data obtained suggests that LAAO has the potential to stimulate apoptosis in HL-60 lines and HL-60. BCR-ABL and increase the effect of the inhibitor of protein kinase activity, MI, relevant data for future studies associated with the description of new drugs against chronic myeloid leukemia.

A leucemia mielóide crônica (LMC) é uma doença mieloproliferativa e sua patogênese está associada à expressão de um neogene, bcr-abl, que codifica uma proteína tirosina quinase Bcr-Abl. Esse trabalho tem como objetivos o estudo dos mecanismos envolvidos na resistência à morte das células Bcr-Abl positivas e a identificação de alterações gênicas nessas células. Dados de expressão gênica global obtidos por \"microarray\" mostraram uma superexpressão nas células HL-60.Bcr-Abl com relação a HL-60 dos genes faim e nipa, que foi confirmada por qRT-PCR em diferentes linhagens celulares Bcr-Abl positivas. Já os genes de trail e osm, apresentaram uma diminuição significativa em HL-60.Bcr-Abl, que foi confirmada para trail, porém osm não teve seu resultado validado. A avaliação da expressão dos genes em células de pacientes portadores de LMC, em diferentes fases da doença também foi estudada. Com esses resultados, o presente estudo visa a melhor compreensão de como alterações na expressão desses genes contribuem na fisiopatologia da LMC. / Chronic myelogenous leukemia (CML) is a stem cell disease characterized by the presence of the Bcr-Abl oncoprotein, which is the cause of the malignant transformation and the extreme resistance to apoptosis displayed by CML patients. Our aim was to analyze the alteration in global gene expression in Bcr-Abl expressing cells. Data obtained from microarray analysis showed significant up-regulation of nipa and faim in HL60.Bcr-Abl and down-regulation of osm and trail. These results were further confirmed by Real-Time PCR to nipa, faim and trail, but not for osm expression in HL-60.Bcr-Abl cells. To evaluate the potential of some of the modified genes as therapeutic targets or prognostic markers for CML, we also analyzed the expression of these genes in samples from CML patients.

As leucemias cromossomo Ph-positivas estão intimamente associadas à expressão da tirosina-quinase Bcr-Abl. Esta oncoproteína promove independência de fatores de crescimento, alterações na adesão e inibição da apoptose por mecanismos ainda não totalmente elucidados. O objetivo desse estudo foi avaliar a contribuição da atividade quinase de Bcr-Abl para seu potencial anti-apoptótico e identificar alterações moleculares envolvidas na transformação celular induzida por essa proteína. Nossos resultados sugerem que a resistência à apoptose não depende da manutenção constante da atividade tirosina-quinase de Bcr-Abl, tampouco da presença de proteínas fosforiladas em tirosina. A comparação do proteoma de células HL-60.vetor e HL-60.Bcr-Abl revelou que a presença de Bcr-Abl causa alterações profundas no padrão de expressão protéica. As proteínas afetadas estão associadas a diversos processos celulares, como adesão, transdução de sinais, proliferação e morte celular. Esses achados devem contribuir para a identificação de novos marcadores de prognóstico e alvos terapêuticos. / Ph chromosome-positive leukemias are closely associated with the expression of Bcr-Abl tyrosine kinase. This oncoprotein promotes growth factor independence, alters cell adhesion and confers resistance to apoptosis by mechanisms that are not fully understood. The aim of this study was to evaluate the contribution of Bcr-Abl kinase activity for its antiapoptotic potential and identify molecular alterations involved in Bcr-Abl-induced cell malignant transformation. Our results suggest that Bcr-Abl is not required to be constantly active to maintain the resistance to apoptosis and pY-containing proteins may not be responsible for the antiapoptotic effect of Bcr-Abl. The comparison between the proteome of HL-60.vector and HL-60.Bcr-Abl cells revealed that the presence of Bcr-Abl alters the expression of a great variety of proteins. The affected molecules are associated with several cellular processes, including cell adhesion, signal transduction, proliferation and cell death. Our findings might help the identification of new prognostic markers and therapeutic targets.

A galectina-1 (LGALS1) participa em diferentes etapas da neoplasia, mas sua função na leucemia mielóide crônica (LMC) é desconhecida. Neste trabalho, a expressão etópica de BCR-ABL selvagem, mas não de BCR-ABL quinase deficiente, em linhagens celulares hematopoéticas, resultou em aumento de LGALS1. O efeito foi revertido com a inibição da tirosina quinase pelo mesilato de imatinibe. Este resultado indicou que a galectina-1 é modulada pela atividade tirosina-quinase de BCR-ABL. Em pacientes com LMC, a maior expressão de LGALS1 foi correlacionada a altos níveis de BCR-ABL, progressão da doença e a um tempo de sobrevida menor. Adicionalmente, as células K562 com LGALS1 inibida por RNA de interferência exibiram crescimento mais lento do que as células K562 com LGALS1 intacta, em camundongos nude. Portanto, o pior prognóstico de pacientes com altos níveis de galectina-1 sugere um efeito cooperativo de galectina-1 na tumorigênese de BCR-ABL reforçando o conceito de que a galectina-1 é um forte candidato para intervenção terapêutica na LMC. / Galectin-1 (LGALS1) participates in different steps of neoplasia but its role in chronic myeloid leukemia (CML) is unknown. In this work, ectopic expression of wild-type but not kinase-deficient BCR-ABL in different hematopoietic cells resulted in LGALS1 upregulation. Tyrosine-kinase inhibition by imatinib mesylate reversed this effect. This result indicate that galectin-1 is modulated by tyrosine kinase activity. In CML patients, the elevated expression of LGALS1 was correlated with high BCR-ABL levels, disease progression and shorter survival time. Additionally, in nude mice, LGALS1-deficient K562 cells obtained by RNA interference were less efficient in tumor formation than control K562 cells. Therefore, the worst prognosis in patients bearing high LGALS1 levels suggests a cooperative role for galectin-1 in BCR-ABL-positive leukemia and support the concept that galectin-1 is a strong candidate for CML therapeutic intervention.

Background: Therapy resistance is a great challenge in cancer treatment. Among numerous factors, cell adhesion to extracellular matrix is a well-known determinant of radiochemo-resistance. It has been shown that targeting focal adhesion proteins (FAPs), e.g. β1 integrin, enhances tumor cell radio(chemo)sensitivity in various entities such as head and neck squamous cell carcinoma (HNSCC), lung carcinoma, glioblastoma, breast carcinoma and leukemia. Previous studies demonstrated a functional crosstalk between specific FAPs and DNA repair processes; however, the molecular circuitry underlying this crosstalk remains largely unsolved. Hence, this study in HNSCC aimed to identify alternative FAPs associated with DNA damage repair mechanisms and radioresistance. Materials and Methods: A novel 3D High Throughput RNAi Screen (3DHT-RNAi-S) using laminin-rich extracellular matrix (lrECM) was established to determine radiation-induced re-sidual DNA double strand breaks (DSBs; foci assay) and clonogenic radiation survival. In the screen, we used UTSCC15 HNSSC cells stably expressing the DSB marker protein 53BP1 tagged to pEGFP. Validations were performed in 10 additional HNSCC cell lines (Cal33, FaDu, SAS, UTSCC5, UTSCC8, UTSCC14, UTSCC15, UTSCC45 and XF354fl2) grown in 3D lrECM. Immunofluorescence staining, immunoblotting, chromatin fractionation were utilized to evaluate protein expression, dynamics and kinetics post irradiation. Investigations of molecular mechanisms of DNA repair and radio(chemo)resistance employed DSB repair reporter assays for non-homologous end joining (NHEJ) and homologous recombination (HR), cell cycle analysis, chromatin fractionation levels evaluation and kinase activity profiling (PamGene) upon protein knockdown in combination with/-out X-ray exposure. Foci assay and clonogenic survival assay were performed after single or multiple knockdowns of synemin and associated proteins such as DNA-PKcs and c-Abl. Protein-protein interactions between synemin and associated proteins were determined using immunoprecipitation and proximity ligation assay. Mutant/depletion constructs of synemin (ΔLink-Tail, ΔHead-Link, Synemin_301-961, Synemin_962-1565, S1114A and S1159A) were generated in order to identify essential synemin’s sites controlling DNA repair functions. Results: Among the targets found in the 3DHT-RNAi-S, synemin was one of the most promising FAP candidates to determine HNSCC cell survival and DNA damage repair. Synemin silencing radiosensitized HNSCC cells, while its exogenous overexpression induced radio-protection. Radiation induced an increased synemin/chromatin interaction and a marked ac-cumulation of synemin in the perinuclear area. Intriguingly, synemin depletion elicited a 40% reduction in NHEJ activity without affecting HR or Alt-EJ. In line, ATM, DNA-PKcs and c-Abl phosphorylation as well as Ku70 expression strongly declined in synemin depleted and irra-diated cells relative to controls, whereas an opposite effect was observed under synemin overexpression. Single, double and triple depletion of synemin, DNA-PKcs and c-Abl resulted in a similar radiosensitizing effect and DSB levels as detected upon single knockdown of synemin, describing its upstream role. In kinome analysis, tyrosine kinases showed signifi-cantly reduced activity after synemin silencing relative to controls. Furthermore, immunoprecipitation assays revealed a protein complex formed between synemin, DNA-PKcs and c-Abl under pre- and post-irradiation conditions. This protein complex dispersed when ATM was pharmacologically inhibited, implying synemin function to be dependent on ATM kinase activity. By means of the different mutation/deletion constructs of synemin, the phosphorylation site at serine 1114 located on the distal portion of synemin’s tail was identified as essential protein-protein interaction site for synemin’s function in DNA repair. Conclusions: The established 3DHT-RNAi-S provides a robust screening platform for identifying novel targets involved in therapy resistance. Based on this screen and detailed mechanistic analyses, the intermediate filament synemin was discovered as a novel important determinant of DNA repair, tyrosine kinase activity and radiochemoresistance of HNSCC cells. These results further support the notion that DNA repair is controlled by cooperative interactions between nuclear and cytoplasmic proteins.