Littérature scientifique sur le sujet « P65BTK »

Background: Bruton’s tyrosine kinase (BTK) is involved in the immune response and its deficiency impairs B cell maturation. We evaluated the expression of a novel BTK isoform, p65BTK, in colorectal cancer (CRC), to identify its impact on survival. Materials and Methods: This retrospective study evaluated 87 consecutive stage III CRC patients treated at the National Cancer Institute of Aviano (1999–2017). Multiple specimens were collected and analyzed for staining intensity and percentage of tumor cells positive for p65BTK. Prognostic impact was tested by univariate Cox regression analysis. Results: After a median follow-up of 82.59 months, median disease-free survival (DFS) and overall survival (OS) were 11.67 months and 31.33 months, respectively. Interestingly, 10% of patients did not express p65BTK. For the immunohistochemistry IHC intensity 1, the best cutoff point was 1% of p65BTK positivity; for IHC intensity 2, it was 50%; and for IHC intensity 3, it was 80%. Through univariate analysis, patients with highly expressed p65BTK (IHC intensity 3 and ≥80%) were shown to have the worst prognosis in terms of DFS (HR: 6.23; p = 0.005; 95% C.I. 1.75–22.79) and OS (HR: 2.54; p = 0.025; 95% C.I. 1.12–5.76). Conclusions: p65BTK is frequently expressed in CRC and, if highly expressed, is an unfavourable prognostic factor. However, further confirmation is needed and its potential targeting needs to be studied.

ABSTRACT Mycobacterium avium causes disseminated disease in humans with AIDS, paratuberculosis in ruminants, lymphadenopathy in swine, and tuberculosis in birds. We constructed DNA vaccines expressing mycobacterial antigens as fusion proteins with enhanced green fluorescent protein (EGFP). Plasmids p65K-EGFP, p85A-EGFP, and p85B-EGFP expressed the M. avium 65-kDa antigen, theMycobacterium bovis BCG 85A antigen, and the M. avium 85B antigen, respectively, as EGFP fusion proteins. We visualized protein expression directly in cultured murine fibroblasts and intact muscle. p65K-EGFP expressed fusion protein in a diffuse cytoplasmic pattern, and p85A-EGFP and p85B-EGFP produced a speckled pattern. We vaccinated C57BL/6 mice with three doses of plasmid DNA and then challenged them intraperitoneally with M. avium. Negative controls received saline, and positive controls received one dose of BCG vaccine. Mice in all groups developed disseminated infection with a high burden of organisms. Compared to negative controls, mice vaccinated with p85A-EGFP had an eightfold reduction in spleen M. avium CFU at 4 weeks after infection and a fourfold reduction at 8 weeks, reductions similar to those generated by BCG vaccine. Mice vaccinated with p65K-EGFP had a fourfold CFU reduction at 4 weeks and no effect at 8 weeks. This is the first report of DNA vaccines expressing foreign antigens as fusion proteins with EGFP and the first report of successful DNA vaccination againstM. avium.

Notch and NFκB pathways are key regulators of numerous cellular events such as proliferation, differentiation, or apoptosis. In both pathways, association of effector proteins with nuclear corepressors is responsible for their negative regulation. We have previously described that expression of a p65-NFκB mutant that lacks the transactivation domain (p65ΔTA) induces cytoplasmic translocation of N-CoR leading to a positive regulation of different promoters. Now, we show that cytoplasmic sequestration of p65 by IκBα is sufficient to both translocate nuclear corepressors SMRT/N-CoR to the cytoplasm and upregulate transcription of Notch-dependent genes. Moreover, p65 and IκBα are able to directly bind SMRT, and this interaction can be inhibited in a dose-dependent manner by the CREB binding protein (CBP) coactivator and after TNF-α treatment, suggesting that p65 acetylation is modulating this interaction. In agreement with this, TNF-α treatment results in downregulation of the Hes1 gene. Finally, we present evidence on how this mechanism may influence cell differentiation in the 32D myeloid progenitor system.

Among the mechanisms by which the Ras oncogene induces cellular transformation, Ras activates the mitogen-activated protein kinase (MAPK or ERK) cascade and a related cascade leading to activation of Jun kinase (JNK or SAPK). JNK is additionally regulated by the Ras-related G proteins Rac and Cdc42. Ras also regulates the actin cytoskeleton through an incompletely elucidated Rac-dependent mechanism. A candidate for the physiological effector for both JNK and actin regulation by Rac and Cdc42 is the serine/threonine kinase Pak (p65pak). We show here that expression of a catalytically inactive mutant Pak, Pak1(R299), inhibits Ras transformation of Rat-1 fibroblasts but not of NIH 3T3 cells. Typically, 90 to 95% fewer transformed colonies were observed in cotransfection assays with Rat-1 cells. Pak1(R299) did not inhibit transformation by the Raf oncogene, indicating that inhibition was specific for Ras. Furthermore, Rat-1 cell lines expressing Pak1(R299) were highly resistant to Ras transformation, while cells expressing wild-type Pak1 were efficiently transformed by Ras. Pak1(L83,L86,R299), a mutant that fails to bind either Rac or Cdc42, also inhibited Ras transformation. Rac and Ras activation of JNK was inhibited by Pak1(R299) but not by Pak1(L83,L86,R299). Ras activation of ERK was inhibited by both Pak1(R299) and Pak1(L83,L86,R299), while neither mutant inhibited Raf activation of ERK. These results suggest that Pak1 interacts with components essential for Ras transformation and that inhibition can be uncoupled from JNK but not ERK signaling.

Il tumore al polmone è la principale causa di morte per tumore al mondo sia negli uomini che nelle donne. Il tumore polmonare non a piccole cellule (NSCLC) è il più frequente ed è relativamente insensibile a chemioterapia e radioterapia. Nonostante lo sviluppo di terapie molecolari personalizzate contro specifiche “mutazioni driver” e la combinazione di chemioterapia e terapie a bersaglio molecolare, la mortalità per tumore al polmone rimane molto alta a causa dello sviluppo di resistenza alle diverse terapie. Pertanto, rimane particolarmente urgente ricercare nuove terapie per NSCLC. Recentemente nel nostro laboratorio abbiamo scoperto p65BTK, una nuova isoforma della tirosina chinasi di bruton (BTK), la quale è risultata essere un nuovo oncogene a valle del pathway di RAS. Abbiamo dimostrato che la sua inibizione diminuisce la crescita e la sopravvivenza delle cellule di cancro del colon e ri-sensibilizza cellule tumorali resistenti ai trattamenti. Gli obiettivi di questo progetto sono: studiare il ruolo di p65BTK nel NSCLC e verificare se p65BTK può essere un nuovo target teranostico nel NSCLC. Studiando una coorte di 382 pazienti abbiamo dimostrato che p65BTK è espresso nel 50% dei tumori di pazienti con NSCLC e la sua espressione correla con l'istotipo, l’abitudine al fumo e lo stato mutazionale di EGFR. In particolare, abbiamo trovato una maggiore espressione di p65BTK in pazienti con adenocarcinoma, non fumatori e con EGFR non mutato. Generalmente questi pazienti non sono eleggibili per la terapia con inibitori di EGFR a causa della mancanza di EGFR mutato. Tramite western blot, abbiamo confermato l’over-espressione di p65BTK sia in linee cellulari umane di NSCLC mutate per RAS o per uno dei geni del pathway di RAS, che in cellule primarie derivate da tumori di topi Kras/Trp53 null, suggerendo una correlazione tra l’aumentata espressione di p65BTK e la iper-attivazione del pathway di RAS nel NSCLC. In seguito, abbiamo dimostrato che l'inibizione di p65BTK tramite diversi inibitori di BTK (Ibrutinib, AVL-292, RN486) riduce efficacemente la proliferazione e la clonogenicità di linee di NSCLC con differenti background genetici. Per determinare se p65BTK può essere considerato un nuovo bersaglio terapeutico nel NSCLC, abbiamo trattato linee resistenti di NSCLC con chemioterapia (Cisplatino, Gemcitabina, Pemetrexed) o inibitori di EGFR (Gefitinib, Erlotinib) in singolo, o in combinazione con concentrazioni non tossiche degli inibitori di BTK, valutandone l’effetto sulla vitalità cellulare. Gli inibitori di BTK usati in combinazione con gli inibitori di EGFR o con la chemioterapia sono risultati più efficaci nel ri-sensibilizzare le linee di NSCLC scarsamente responsive ai trattamenti standard e le diverse combinazioni hanno mostrato diversi gradi di sinergia. In conclusione, abbiamo dimostrato che p65BTK è over-espressa nei tumori di pazienti con NSCLC e in linee cellulari umane e murine di NSCLC. Pertanto, i nostri dati indicano p65BTK come un emergente target nel NSCLC e suggeriscono che la combinazione di inibitori di BTK e chemioterapia o terapia a bersaglio molecolare potrebbe rappresentare un nuovo approccio per superare la resistenza alle terapie nel NSCLC. I prossimi passi saranno volti a validare gli effetti dell'inibizione di p65BTK in modelli ex vivo (sferoidi derivati da cellule di NSCLC) e in vivo in modelli murini di NSCLC.
Lung cancer is the leading cause of cancer-related death worldwide both in men and women. In particular, Non-Small Cell Lung Cancer (NSCLC) is the most common subtype and is relatively insensitive to chemotherapy and radiation therapy. Despite the development of personalized molecular targeted therapies against specific driver mutations and the combination of chemotherapy with targeted therapy, lung cancer mortality remains very high because of intrinsic and acquired resistance. Thus, new strategies to overcome these limitations are needed. Recently, we discovered a new isoform of the Bruton Tyrosine Kinase (BTK), referred as p65BTK. We characterized p65BTK as a novel oncogene and a pivotal downstream effector of RAS. Moreover, we showed that its inhibition affected growth and survival of colon cancer cells and reverted resistance to chemotherapy. The aims of this project were: study the role of p65BTK in NSCLC cell biology and verify whether p65BTK may be a novel theranostic target in NSCLC. Studying a cohort of 382 patients, we observed that p65BTK was expressed in 50% of NSCLC patients’ tumors and its expression correlated with histotype, smoke habit and EGFR mutational status. In particular, we found p65BTK significantly more expressed in adenocarcinoma than in squamous carcinoma histotype and in non-smoker as compared to smoker patients. Moreover, its expression was significantly higher in non-smoker patients bearing wild type EGFR. Notably, these patients are not eligible for treatments with EGFR inhibitors due to a lack of EGFR mutation. By western blot analysis we confirmed p65BTK overexpression both in vitro, in NSCLC human cell lines with mutations in RAS or in one of the components of the RAS/MAPK pathway, and ex vivo, in tumor-derived primary cells from Kras/Trp53 null mice, suggesting that p65BTK overexpression correlate with a hyper-activated RAS/MAPK pathway also in NSCLC. Then, we showed that p65BTK inhibition by different BTK inhibitors (Ibrutinib, AVL-292, RN486) strongly impaired proliferation and clonogenicity of NSCLC cell lines with different genetic backgrounds. To determine if p65BTK could be a new theranostic target in NSCLC, representative resistant cell lines were treated with chemotherapy (Cisplatin, Gemcitabine, Pemetrexed) or EGFR-targeted therapy (Gefitinib, Erlotinib) alone or in combination with non-toxic concentrations of BTK inhibitors and then their viability was assessed. We found that BTK inhibitors were effective in re-sensitizing NSCLC cells scarcely responsive to the current treatments when used in combination with EGFR-targeted therapy or chemotherapy. However, the different BTK inhibitors’ combinations showed a better or worse synergy depending on which EGFR inhibitor or chemotherapeutic drug they were combined with. Thus, we demonstrate that p65BTK is overexpressed in NSCLC patients’ tumors and in human and murine NSCLC cells. Moreover, our data indicate p65BTK as an emerging actionable target in NSCLC and suggest that the combination of BTK inhibitors with chemotherapy or targeted therapy may represent a novel therapeutic approach to overcome drug resistance in NSCLC. As future perspectives, we will validate the effects of p65BTK inhibition in ex-vivo (spheroids derived from NSCLC cells) models and in in vivo mouse model of NSCLC.