Academic literature on the topic 'Lymphoma kinase inhibition therapy B-Cell Receptor'

Abstract Abstract 4918 Despite intensive efforts in developing new therapies, B-cell lymphoma remains essentially incurable with standard therapeutic approaches. Dynamic interactions between the lymphoma cell and its microenvironment play a critical role in lymphoma development and response to therapy. There is accumulating evidence pointing to an essential role of BCR signaling in B-cell lymphomas. Recently, inhibitors of BCR signaling have become an area of substantial clinical interest. We therefore studied the role of BCR signal pathways in stroma-mediated lymphoma cell survival. We demonstrated that adhesion of the various B-cell lymphoma cell lines to lymph node stromal cells enhanced activation of BCR signaling pathways: activation of phosphatidylinositol 3-kinase (PI3K), Bruton's tyrosine kinase (Btk) and extracellular signal-regulated kinase (ERK) pathways. Inhibition of Btk by PCI 32765 or PI3K by CAL101 significantly blocked BCR signal pathways, triggered lymphoma cell apoptosis and overcame stroma-mediated drug resistance. Furthermore, targeting BCR signal pathway disrupted microenvironmental stroma-lymphoma interaction through regulation of CXCR4 expression. Collectively, these data support that BCR activation not only controls intrinsic survival pathway related to B lymphoma cell but also regulates stroma-mediated extrinsic lymphoma cell survival as well as lymphoma cell homing and interplay with its microenvironment. As a result, this study suggests that targeting BCR signal pathway molecules is a promising therapeutic strategy to lymphoma therapy. Disclosures: No relevant conflicts of interest to declare.

Abstract Non-Hodgkin Lymphoma (NHL) is the most common hematological malignancy, with B-cell lymphoma (NHL-B) accounting for 85% of all lymphomas. In the United States, there are ~500,000 lymphoma patients currently living with this disease and ~20,000 lymphoma-related deaths occur annually. The current overall cure rate for B-cell lymphoma is estimated at ~30%, indicating that new innovative therapeutic approaches are needed to significantly reduce the high mortality rate, particularly of relapsed/refractory (r/r) NHL-B. The poor quality of life in patients suffering from chronic diseases like cancer has forced many patients to pursue alternative treatment options, including medicinal cannabinoids (CB), in order to improve their clinical prospect/outcomes. Medicinal cannabinoids have been legalized in 23 states and DC for several medical conditions such as cachexia, chronic pain, epilepsy and other similar disorders characterized by seizures, glaucoma, HIV- AIDS, Multiple Sclerosis, muscle spasticity and GI enteritis. Lately however, cannabis has been shown to have a broader biologic activity spectrum with various cannabis compounds functioning as ligands binding the two principle cannabinoid-specific G protein-coupled receptors (GPCR) CB1 (in neural cells), and CB2, in immune lymphoid, particularly B cells, but have also been identified, showing aberrant expression in a wide variety of important human cancers. This suggests not only a wider spectrum of cellular usage of cannabinoids and their cognate receptors, but also their potential utility as novel therapeutic targets. Gene expression profiling data has demonstrated, however, that B-cell lymphoma is one of the top three cancers (glioma and gastric are the other two) showing high expression of CB1 and CB2 receptors. Our studies showed that CB1 receptor is highly expressed in aggressive NHL-B, including mantle cell lymphoma (MCL) and diffuse large B-cell lymphoma (DLBCL) cells in comparison to normal unstimulated (G0) B cells, and that targeting CB1 using an siRNA approach leads to cell growth inhibition. Furthermore, pharmacological approaches targeting CB1 with small molecule antagonists (Rimonabant and Otenabant) inhibited lymphoma cell viability, leading to the induction of apoptosis and G2M cell cycle arrest. Using proteomic approach via reverse-phase protein array (RPPA), we have demonstrated that lymphoma cells treated with the CB1 antagonist Rimonabant showed a robust effect on apoptosis (increases in caspase 3 and 7, Bad, and bak), cell cycle (increases in p27 and cyclin D1), DNA damage (increases in gH2AX), and autophagy (increases in LC3A) associated proteins. In addition, Rimonabant treatment also inhibited several growth and survival pathways, including STAT3, SRC, and b-catenin, while enhancing the PI3K/ATK pathway. Of note, Rimonabant treatment also activated the DNA damage response (DDR) pathway through stimulating two checkpoint kinases (Chk1 and Chk2). Blocking Rimonabant-induced Chk1 and Chk2 with a selective ATP-competitive inhibitor of Chk1 and Chk2 leads to a robust synergistic effect on cell growth inhibition and apoptotic induction, suggesting that blocking the DDR pathway with Chk kinase inhibitors prevents cells recovering from rimonabant-induced DNA damage. These findings suggest that targeting the cannabinoid receptors and the DDR pathway represents a new therapeutic strategy against resistant r/r NHL-B cells. Disclosures Pham: Vyripharm Biopharmaceuticals: Research Funding. Bryant:Vyripharm Biopharmaceuticals: Equity Ownership. Yang:Vyripharm Biopharmaceuticals: Employment.

Abstract Abstract SCI-27 Targeted therapy in hematologic malignancies has achieved significant therapeutic success when relatively selective inhibition is attainable to a target dispensable to the majority of normal cells. The best appreciated example of this is imatinib in chronic myeloid leukemia (CML), in which a single translocation forms a fusion protein involving the tyrosine kinase ABL that molecularly defines the disease. Kinase inhibition of ABL in this setting by imatinib (or other second- and third-generation kinase inhibitors) promotes durable, long-term remission in CML patients. The great majority of B-cell malignancies lack a characteristic translocation, activating mutation, or other aberration that facilitates such targeted therapy as employed in CML. Nonetheless, a common global signaling pathway involving the B-cell receptor (BCR) pathway has emerged as one that might be important to the control of these diseases. Furthermore, mouse models of select kinase targets (phosphoinositide-3 kinase p110 isoform-delta and Bruton's tyrosine kinase [BTK]) have shown that these are dispensable relative to long-term survival. Indeed, knockout or mutation of BTK and p110 delta each have a modest phenotype outside of diminished B-cell development and function. Based upon these preclinical observations, several molecules targeting BCR signaling have come forward to the clinic with exciting results across a wide range of B-cell malignancies. GS-1101 is a selective phosphoinositide-3 kinase p100 delta inhibitor with a very favorable toxicity profile that has shown promising clinical activity in low-grade lymphoma and chronic lymphocytic leukemia (CLL). The toxicity of this orally administered agent is quite modest in the majority of patients and allows sustained continuous dosing. Similarly, ibrutinib is an irreversible inhibitor of BTK and has shown promising clinical potential in an even broader range of B-cell malignancies, including diffuse large B-cell lymphoma, mantle cell lymphoma, low-grade lymphoma, and CLL. Toxicity with ibrutinib has also been modest, allowing long-term continuous dosing. Notably, each of these agents also produces an atypical mobilization of malignant lymphocytes into the blood soon after treatment. This treatment lymphocytosis is BCR-target-related due to diminished CXCR4/SDF-1 interface between tumor cells and stromal cells in the bone marrow, with egress of these cells to the blood. GS-1101 and ibrutinib are now entering phase III studies for regulatory approval and offer great potential to change the treatment paradigm of both CLL and B-cell non-Hodgkin lymphoma (NHL). Questions moving forward with these agents will include molecular predictors of response, feasibility and efficacy of combining with other effective therapies, and mechanisms of resistance. The scientific session presentation will provide an overview of the most promising BCR signaling agents in CLL and NHL clinical trials. Disclosures: No relevant conflicts of interest to declare.

Abstract Current research in lymphoma is focused on two areas of lymphoma biology—the signal transduction pathways used to maintain the growth of malignant lymphocytes and the role of the tumor microenvironment in lymphoma growth and survival. This review focuses on three signaling pathways: the phosphatidylinositol 3-kinase/mammalian target of rapamycin (PI3K/mTOR) pathway, the B-cell receptor/spleen tyrosine kinase (BCR/Syk) pathway, and the protein kinase C-beta (PKC-β) pathway, known to be important to lymphoma cells. The mTOR inhibitors temsirolimus and everolimus have demonstrated antitumor activity in all types of lymphoma, the Syk inhibitor fostamatinib has activity in diffuse large B-cell lymphoma and chronic lymphocytic leukemia, and the PKC-β inhibitor enzastaurin is being used as consolidation therapy after remission in diffuse large B-cell lymphoma. This review discusses the biology behind the development of each new agent and the results of initial clinical trials. The goal is to provide the hematologist/oncologist background information on these new agents and understand their current and potential role in the management of patients.

Abstract Abstract SCI-26 We have developed loss-of-function, RNA interference-based screens to reveal genes essential for cancer cell proliferation and survival. In parallel, we are using high-throughput RNA resequencing (RNA-seq) to identify somatic mutations and other structural abnormalities in cancer. The intersection of these two data sets has helped us to discover novel pathogenetic pathways in lymphoma that are amenable to therapeutic attack. The activated B-cell-like (ABC) subtype of diffuse large B-cell lymphoma (DLBCL) has constitutive activation of the NF-κB pathway, which we traced to the signaling adapter CARD11. In some ABC DLBCL biopsies (∼10%), somatic mutations produce CARD11 isoforms that spontaneously activate NF-κB signaling. In ABC DLBCL tumors with wild-type CARD11, we defined a “chronic active” form of B-cell receptor (BCR) signaling that activates NF-κB. Such ABC DLBCLs are killed by knockdown of BCR signaling components, such as Bruton's tyrosine kinase (BTK), or components of the BCR itself. Over one-fifth of ABC DLBCLs have mutations in the CD79B or CD79A subunits of the BCR. In 18 percent of cases, mutations occur in a single tyrosine residue in the critical “ITAM” signaling motif, generating BCRs that avoid negative autoregulation by the LYN tyrosine kinase. Based on these findings, we are conducting clinical trials of ibrutinib in relapsed/refractory DLBCL. Ibrutinib is an irreversible and highly selective small-molecule inhibitor of BTK. Thus far, ibrutinib monotherapy has induced many complete and partial responses in patients with ABC DLBCL, including those with “primary refractory” tumors that had never responded to any prior therapy. One patient has been in a sustained complete response for over 19 months, taking ibrutinib daily with no discernible side effects. Of note, ABC DLBCL tumors with and without CD79B mutations have responded, suggesting that BCR pathway addiction may be a prevalent feature in this lymphoma subtype. More recently, we have uncovered a “tonic” form of BCR signaling in Burkitt lymphoma that engages the prosurvival PI(3) kinase pathway. Two-thirds of Burkitt lymphoma cell lines die upon knockdown of BCR subunits or the proximal kinase SYK, due to loss of PI(3) kinase signaling. Moreover, a gene expression signature of PI(3) kinase activity is more highly expressed in Burkitt lymphoma biopsies than in biopsies of other aggressive lymphomas. Tonic BCR signaling in Burkitt lymphoma is mechanistically distinct from chronic active BCR signaling in ABC DLBCL, since it does not engage BTK, CARD11, or NF-κB. RNA-seq revealed that 70 percent of sporadic Burkitt lymphoma cases harbor somatic mutations that potentiate the action of the transcription factor TCF3 by preventing its inhibitory heterodimerization with the DNA-binding inhibitor ID3. TCF3 promotes tonic BCR signaling and PI(3) kinase activity in Burkitt lymphoma by transactivating the immunoglobulin heavy- and light-chain genes, thereby increasing surface BCR expression, and by repressing the phosphatase SHP-1, a potent negative regulator of BCR signaling. Hence, inhibitors of proximal BCR signaling and the PI(3) kinase pathway should be evaluated in Burkitt lymphoma, especially in patients for whom high-dose chemotherapy is infeasible, such as older individuals and those with the endemic form of this lymphoma. Disclosures: Off Label Use: I will be discussing clinical trials of ibrutinib (PCI-32765) in lymphoma. Ibrutinib is an investigational drug that has not yet received FDA approval for any indication.

AbstractWith the recent success of the Bruton's tyrosine kinase (BTK) inhibitor, ibrutinib, and the phosphoinositide-3-kinase (PI3K) inhibitor, idelalisib, in the treatment of patients with relapsed or refractory non-Hodgkin's lymphoma (NHL), a number of new agents targeting the B-cell receptor (BCR) pathway are in clinical development. In addition, multiple trials combining these agents with conventional cytotoxic chemotherapy, immunomodulatory agents, monoclonal antibodies, or other kinase inhibitors are underway. This review will summarize the current data with the use of single agent and combination therapy with BCR inhibitors in NHL. In addition, commonly encountered as well as serious toxicities and hypothesized resistance mechanisms will be discussed. Lastly, this review will examine the future of these agents and opportunities to maneuver them into the front-line setting in selected NHL subtypes.

Abstract Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin's lymphoma with poor response to therapy and unfavorable prognosis. Here, we show that retinoic acid (RA) isomers significantly inhibit the proliferation of both primary MCL cultures (n = 7) and established cell lines (Granta 519 and SP-53) as shown by [3H]thymidine uptake and carboxyfluorescein diacetate succinimidyl ester labeling coupled with cyclin D1 staining. RA induces cell accumulation in G0-G1 together with a marked up-regulation of p27Kip1 by inhibiting ubiquitination and proteasome-dependent degradation of the protein. The p21Cip1 inhibitor was also up-regulated by RA in Granta 519 cells, whereas the expression of cyclin D1 is unaffected. Most of RA-induced p27Kip1 was bound to cyclin D1/cyclin-dependent kinase 4 complexes, probably contributing to the decreased cyclin-dependent kinase 4 kinase activity and pRb hypophosphorylation observed in RA-treated cells. Experiments with receptor-selective ligands indicate that RA receptor α cooperates with retinoid X receptors in mediating RA-dependent MCL cell growth inhibition. Notably, RA isomers, and particularly 9-cis-RA, also inhibited the growth-promoting effect induced in primary MCL cells by CD40 activation alone or in combination with interleukin-4. Immunohistochemical analysis showed that significant numbers of CD40L-expressing lymphoid cells are present in lymph node biopsies of MCL patients. These results therefore further strengthen the possibility that triggering of CD40 by infiltrating CD40L+ cells may continuously promote the growth of MCL cells in vivo. On these grounds, our findings that RA inhibits basal MCL proliferation as well as MCL growth-promoting effects exerted by microenvironmental factors make these compounds highly attractive in terms of potential clinical efficacy in this setting.

Abstract Oncogenic co-operation between c-Myc and activated phosphoinositide 3-kinase (PI3K) signaling pathways is crucial in lymphomagenesis, providing an opportunity for developing mechanism-based therapy to disrupt this co-operative survival mechanism. Combining constitutive c-Myc expression with constitutive PI3K activity in mouse germinal center B (GCB) cells resulted in Burkitt lymphoma-like tumors. Furthermore, analysis of primary human Burkitt lymphoma (BL) tissue sections revealed that two-thirds of the cases expressed high levels of phosphorylated AKT and S6 proteins, indicative of PI3K and mTORC1 activation. Prior attempts to develop small molecule inhibitors that specifically and directly target c-Myc protein have been unsuccessful. However, c-Myc cellular protein abundance can be decreased by using epigenetic modifying drugs (HDAC inhibitors or bromodomain/BET inhibitors) that are known to inhibit c-Myc transcription. Several investigators attempted disrupting c-Myc and PI3K cooperation by combining HDAC inhibitors and PI3K pathway inhibitors and synergic activity was demonstrated in DLBCL irrespective of subtype. In this study, we assessed the efficacy of CUDC-907, a new rationally designed dual inhibitor of PI3K and HDACs, in a panel of lymphoma cell lines. CUDC-907 treatment resulted in a dose- and time-dependent growth inhibition and cell death of DLBCL cell lines, irrespective of the cell of origin. CUDC-907 treatment down-regulated the phosphorylation of PI3K downstream targets, including AKT, PRAS40, S6, and 4EBP1, increased histone 3 acetylation, and decreased Myc protein levels. SILAC-based quantitative mass spectrometry demonstrated that CUDC-907 treatment decreased the protein levels of several components of the B cell receptor (BCR) and Toll like receptor (TLR) pathways, including BTK, SYK, and MyD88 proteins. These cellular changes were associated with an inhibition of NF-kB activation. CUDC-907 demonstrated in vivo efficacy with no significant toxicity in a human DLBCL xenograft mouse model. Collectively, these data provide a mechanistic rationale for evaluating CUDC-907 for the treatment of patients with c-Myc and PI3K-dependent lymphomas. Disclosures No relevant conflicts of interest to declare.

Abstract Targeting the B-cell receptor and phosphatidylinositol 3-kinase/mTOR signaling pathways has shown meaningful, but incomplete, antitumor activity in lymphoma. Glycogen synthase kinase 3 (GSK3) α and β are 2 homologous and functionally overlapping serine/threonine kinases that phosphorylate multiple protein substrates in several key signaling pathways. To date, no agent targeting GSK3 has been approved for lymphoma therapy. We show that lymphoma cells abundantly express GSK3α and GSK3β compared with normal B and T lymphocytes at the messenger RNA and protein levels. Utilizing a new GSK3 inhibitor 9-ING-41 and by genetic deletion of GSK3α and GSK3β genes using CRISPR/CAS9 knockout, GSK3 was demonstrated to be functionally important to lymphoma cell growth and proliferation. GSK3β binds to centrosomes and microtubules, and lymphoma cells treated with 9-ING-41 become arrested in mitotic prophase, supporting the notion that GSK3β is necessary for the progression of mitosis. By analyzing recently published RNA sequencing data on 234 diffuse large B-cell lymphoma patients, we found that higher expression of GSK3α or GSK3β correlates well with shorter overall survival. These data provide rationale for testing GSK3 inhibitors in lymphoma patient trials.

Abstract Abstract 3667 Cell survival and proliferation of diffuse large B-cell lymphomas (DLBCL) are dependent on the NF-κB signaling pathway. Antigen binding of the B-cell receptor (BCR) leads to phosphorylation of Src tyrosine kinases, resulting in PLCg2 activation, which is important for regulation of NF-κB through the protein kinase C (PKC). The PLC-PKC cascade also activates the Ras signaling pathway. There are several clinical studies showing that inhibition of PKCβ with the specific inhibitor Enzastaurin could be a promising new therapy target for DLBCL. To our knowledge, there are little data about the role of PLCg2 in DLBCL. It has been shown that the activity of Syk and PLCg2 are well correlated with sensitivity of DLBCL to dasatinib. Our study performed immunohistological staining of PLCg2 in 86 primary DLBCL. PLCg2 was strongly expressed in 54 out of 86 cases (63%) and weakly expressed in 28 cases (32%). Only 4 cases (5%) were negative for PLCg2. In three DLBCL cell lines (SuDHL-4, SuDHL-6 and U2932) we could show an inhibitory effect of the PLC-inhibitor U73122 on cell proliferation. Treatment in combination with Enzastaurin or the Src-inhibitor pp2 had an additive effect on cell proliferation compared to U73122 alone. In conclusion, PLCg2 is strongly expressed in a great subset of DLBCL. Inhibition of PLCg2 could be, at least in these cases, a new target for lymphoma treatment. Disclosures: No relevant conflicts of interest to declare.

CK2 is a highly conserved Ser/Thr protein kinase, consisting of two catalytic (a) and two regulatory (b) subunits assembled to form a tetramer. It is involved in a broad variety of cellular processes, among which survival, proliferation, differentiation, DNA damage and other stress responses, leading to the activation of context-specific transcription factors such as c-Myc and NF-kB. This kinase has been found overexpressed in several solid tumors and hematologic malignancies, and its overexpression seems to be an unfavorable prognostic marker. It has been fully demonstrated that CK2 acts as a potent antiapoptotic factor that promotes a “non-oncogene addiction” phenotype in cancer cells. In other words, high CK2 levels and activity contribute to create a cellular environment favorable to the establishment and maintenance of a neoplastic phenotype. In particular, it was recently shown that many B-cell derived tumors, like multiple myeloma, mantle cell lymphoma and chronic lymphocytic leukemia, rely on high CK2 activity and that its downmodulation induces malignant cell death without significantly affecting normal B lymphocytes. Diffuse Large B-Cell Lymphoma (DLBCL) is an aggressive B-cell derived neoplasia that originates from follicles and is the most common type of non-Hodgkin lymphoma, accounting for about 40% of all cases. It is divided into two subtypes: Germinal Center B-cell like (GCB) and Activated B-Cell like (ABC) DLBCL, characterized by different genetic lesions and, therefore, variable response to therapy. Up to one-third of patients does not achieve cure with initial therapy and has refractory disease or relapse. The standard salvage treatment for these patients is autologous stem cell transplantation, but success rates are poor and most of them succumb to the disease. These facts clearly demonstrate the need for new rational combination therapeutics. It is well known that the B-Cell Receptor (BCR) signalling strongly influences B-cell development and is fundamental for peripheral B-cell survival. After BCR ligation by the antigen, the signal is transduced across the plasma membrane and propagated inside the cell through a group of intracellular proteins, which interact to form a complex, called signalosome. Among these proteins there are the tyrosine kinases SYK and BTK, the phospholipase PLCg2 and the adaptor BLNK. Once activated by SYK, BTK phosphorylates PLCg2, which in turn generates IP3 thus causing Ca++ release from the endoplasmic reticulum stores. Ca++ acts in the cytoplasm as a second messenger that binds several Ca++-dependent proteins that are then able to activate transcription factors, like NFAT and NF-kB, modifying gene expression. The result of this process consists in activation, expansion, antigen presentation and B-cell differentiation. For these reasons, it comes as no surprise that inhibitors targeting the BCR signalling have shown promising therapeutic outcomes for patients with B-cell lymphomas. Here we show that a and b subunits of protein kinase CK2 are overexpressed in ABC- and GCB-DLBCL primary patient samples and immortalized cell lines when compared with normal counterparts. Moreover, we demonstrate that CK2 inhibition with CX-4945, an ATP-competitive CK2 inhibitor currently under clinical trials, causes apoptosis of DLBCL cell lines in a dose and time dependent fashion, and that malignant cell death is significative even at low drug doses not toxic to normal counterparts. We also reveal that the downmodulation of CK2 catalytic activity leads to a reduction in Ca++ release from the endoplasmic reticulum stores, and impairs AKT and NF-kB RELA phosphorylation after BCR stimulation. These findings propose a role for CK2 downstream of the BCR engagement, in controlling survival pathways crucial for B-cell endurance. Furthermore, we found out that CX-4945 synergises with inhibitors of kinases, like SYK and BTK, essential in spreading the BCR signal, thus proving that this drug combination enhances DLBCL cell death and could be considered an effective therapeutic strategy.
CK2 è una Ser/Thr chinasi altamente conservata dal punto di vista evolutivo, costituita da due subunità catalitiche (a) e due subunità regolatorie (b) unite a formare un tetramero. Essa è coinvolta in numerosi processi cellulari, tra cui sopravvivenza, proliferazione, differenziamento, risposta al danno al DNA e ad altri stress, portando in definitiva all’attivazione di specifici fattori di trascrizione, come c-Myc ed NF-kB. Questa chinasi è stata trovata sovrespressa in svariati tumori solidi e neoplasie ematologiche, portando ad una correlazione tra alti livelli di CK2 e prognosi sfavorevole. È stato ampiamente dimostrato che CK2 agisce come un potente fattore antiapoptotico nelle cellule tumorali, promuovendo un meccanismo definito “non-oncogene addiction”. In altre parole, l’overespressione e l’aumento dell’attività catalitica dell’enzima contribuiscono notevolmente a creare un ambiente intracellulare favorevole allo sviluppo e al consolidamento di un fenotipo neoplastico. In particolare, è stato recentemente dimostrato che molte neoplasie, derivate dalla trasformazione maligna dei linfociti B, come il mieloma multiplo, il linfoma mantellare e la leucemia linfatica cronica, dipendono da un’aumentata attività di CK2 per il loro mantenimento; infatti, una sua inibizione è in grado di indurre apoptosi cellulare. Il linfoma diffuso a grandi cellule (DLBCL) è una neoplasia di tipo aggressivo derivata dalla trasformazione dei linfociti B nel follicolo ed è il tipo più comune di linfoma non-Hodgkin, rappresentando circa il 40% di tutti i casi. È suddiviso in due sottotipi: uno di derivazione da cellule B del centro germinativo (GCB), l’altro di derivazione da cellule B post centro germinativo (ABC), che sono caratterizzati da differenti alterazioni genetiche e, di conseguenza, da una differente risposta alla terapia. Fino a un terzo dei pazienti non raggiunge la cura con la terapia iniziale e sviluppa una malattia refrattaria o ricade. Il trattamento di salvataggio standard per questi pazienti è il trapianto autologo di cellule staminali, ma il tasso di successo è scarso e la maggior parte di essi non sopravvive alla malattia, dimostrando chiaramente la necessità di nuove terapie di combinazione. È risaputo che il segnale generato dal recettore dell’antigene B (BCR) è in grado di influenzare il differenziamento del linfocita B nella milza e la sua sopravvivenza a livello periferico. In seguito al legame del recettore da parte dell’antigene, il segnale viene trasmesso attraverso la membrana plasmatica e propagato all’interno tramite un gruppo di proteine intracellulari, che si combinano a formare un complesso denominato signalosoma. Tra queste proteine figurano le tirosin chinasi SYK e BTK, la fosfolipasi PLCg2 e l’adattatore BLNK. Una volta attivata da SYK, BTK è in grado di fosforilare PLCg2, che, a sua volta, genera IP3, il quale induce il rilascio di Ca++ dal reticolo endoplasmatico. Il Ca++ agisce nel citoplasma come secondo messaggero, interagendo con varie proteine Ca++-dipendenti, che attivano fattori di trascrizione, come NFAT e NF-kB, modificando, in tal modo, l'espressione genica. Il risultato di questo processo consiste in attivazione, espansione, presentazione dell’antigene e differenziamento del linfocita B. Non sorprende, perciò, che gli inibitori della cascata del segnale del BCR abbiano dimostrato risultati terapeutici promettenti in pazienti con linfomi di tipo B. In questo lavoro di tesi si evidenzia che le subunità a e b di CK2 sono sovrespresse sia in campioni primari, che in linee cellulari immortalizzate di ABC- e GCB-DLBCL, rispetto alle controparti non neoplastiche. Inoltre, si dimostra che l'inibizione di CK2 con CX-4945, un inibitore di CK2 attualmente in trial clinici, provoca l'apoptosi di linee cellulari di DLBCL in maniera dose e tempo dipendente e che l'aumento della morte delle cellule neoplastiche è significativa anche alle dosi di farmaco che non uccidono le cellule normali. Inoltre, l’abbassamento dell’attività catalitica di CK2 porta ad una riduzione del Ca++ rilasciato dal reticolo endoplasmatico, e compromette la fosforilazione di AKT e NF-kB RELA, in seguito a stimolazione del BCR. Questi risultati propongono un ruolo per CK2 a valle del BCR, nel controllo di vie del segnale pro sopravvivenza centrali per il linfocita B. Infine, si evidenzia che il CX-4945 sinergizza con inibitori di chinasi essenziali per la propagazione del segnale del BCR, quali SYK e BTK, provando che questa combinazione di farmaci aumenta la morte delle cellule linfomatose e può considerarsi un’efficace strategia terapeutica.

The PIM family kinases promote growth and survival of tumor cells and are expressed in a wide variety of human cancers. Their potential as therapeutic targets, however, is complicated by overlapping activities with multiple other pathways and remains poorly defined in most clinical scenarios. Here we explore activity of the new pan-PIM inhibitor PIM447 in a variety of lymphoid-derived tumors. We find strong activity in cell lines derived from the activated B-cell subtype of diffuse large B-cell lymphoma (ABC-DLBCL). Sensitive lines show lost activation of the mTORC1 signaling complex and subsequent lost activation of cap-dependent protein translation. In addition, we characterize recurrent PIM1 protein-coding mutations found in DLBCL clinical samples and find most preserve the wild-type protein's ability to protect cells from apoptosis but do not bypass activity of PIM447. Pan-PIM inhibition therefore may have an important role to play in the therapy of selected ABC-DLBCL cases.

Deregulation of a broad range of protein kinases has been linked to the development and growth of cancer cells. Protein kinases are intracellular enzymes that regulate cell growth and proliferation as well as the triggering and regulation of immune responses. Protein kinases are important therapeutic targets in cancer because of their critical role in signalling mechanisms that drive malignant cell characteristics. Intensive efforts in drug research have been made in this area over the last two decades. The current study delves into the catalytic domain of a protein kinase as well as information transfer from the cell’s membrane to internal targets. It also discusses the function of protein kinases in signal transduction and their cellular signalling pathways. Furthermore, it specifically outlines a systematic method to hybrid therapies to solve the issue of protein kinase resistance. The therapeutic use of nitric oxide, as well as other targets such as Phosphoinositide 3-kinases (PI3K), Protein Kinase B (Akt), serine/threonine protein kinase (mTOR), p38 mitogen-activated protein kinases (p38 MAPK), vascular endothelial growth factor receptors (VEGFR), epidermal growth factor receptors (EGFR), and anaplastic lymphoma (ALK) etc., According to the review article, selective therapy has shown high effectiveness in the treatment of advanced cancer, with protein kinase inhibitors being a main focus of the therapy. As a result, the latest review summarized that, the current state of science with the aim of identifying a novel protein kinase inhibitor that may be utilized in the treatment of advanced cancers.