Expression and activity of Fyn mediate proliferation and blastic features of chronic myelogenous leukemia

Selective translational control by PABPC1 phase separation regulates blast crisis and therapy resistance in chronic myeloid leukaemia

Tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL1 fusion tyrosine kinase have revolutionized the treatment of chronic myeloid leukaemia (CML). However, the development of TKI resistance and the subsequent transition from the chronic phase (CP) to blast crisis (BC) threaten patients with CML. Accumulating evidence suggests that translational control is crucial for cancer progression. Our high-throughput CRISPR-Cas9 screening identified poly(A) binding protein cytoplasmic 1 (PABPC1) as a driver for CML progression in the BC stage. PABPC1 preferentially improved the translation efficiency of multiple leukaemogenic mRNAs with long and highly structured 5' untranslated regions by forming biomolecular condensates. Inhibiting PABPC1 significantly suppressed CML cell proliferation and attenuated disease progression, with minimal effects on normal haematopoiesis. Moreover, we identified two PABPC1 inhibitors that inhibited BC progression and overcame TKI resistance in murine and human CML. Overall, our work identifies PABPC1 as a selective translation enhancing factor in CML-BC, with its genetic or pharmacological inhibition overcoming TKI resistance and suppressed BC progression.

Fyn, an important molecule in the brain, is a potential therapeutic target for brain tumours

Under normal physiological conditions, Fyn, a nonreceptor tyrosine kinase, is involved in signal transduction pathways in the nervous system and in the formation and activation of T lymphocytes. Fyn is a member of the Src family of kinases (SFKs) and plays a role in cell morphogenic transformation, motility, proliferation, and death, which in turn influences the development and progression of various cancer types. SFKs are overexpressed or hyperactive in tumours, and they are engaged in several signalling pathways that lead to tumour development. Inhibition of Fyn can enhance patient outcomes and prolong survival. Thus, Fyn is a desirable therapeutic target in a variety of tumour types. To lay the groundwork for further investigation and targeted therapy in tumours, in this article, we review the most recent findings on the function of Fyn in tumours, with an emphasis on its role in gliomas. Understanding the function of Fyn during tumourigenesis and development and in resistance to anticancer therapeutic agents can aid in the development and application of innovative medicines that specifically target this kinase, thus improving the management of cancers.

Expression of genes potentially involved in loss of response in patients with chronic myeloid leukemia

Chronic Myeloid Leukemia (CML) is a hematological malignancy characterized by the presence of the BCR::ABL1 fusion gene, which leads to uncontrolled cell growth and survival. Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of CML, but a significant proportion of patients develop resistance or lose response to these drugs. Understanding the molecular mechanisms underlying treatment response and resistance is crucial for improving patient outcomes. This study aimed to analyze the expression patterns of genes involved in treatment response and resistance in CML patients receiving TKI therapy. The expression levels of MET, FOXO3, p15, p16, HCK, and FYN genes were examined in CML patients and compared to healthy donors. Gene expression levels were compared between optimal responders (OR) and resistant patients (R) vs. healthy donors (HD). The MET and FOXO3 OR group showed significant differences compared with the HD, (p < 0.0001) and (p = 0.0003), respectively. p15 expression showed significant differences between OR and HD groups (p = 0.0078), while no significant differences were found in p16 expression between the HD groups. FYN showed a statistically significant difference between R vs. HD (p = 0.0157). The results of HCK expression analysis revealed significant differences between OR and HD (p = 0.0041) and between R and HD (p = 0.0026). When we analyzed OR patients with undetectable BCR::ABL1 transcripts, a greater expression of HCK was observed in the R group. These findings suggest that monitoring the expression levels of MET and FOXO3 genes could be valuable in predicting treatment response and relapse in CML patients. Our study provides important insights into the potential use of gene expression analysis as a tool for predicting treatment response and guiding treatment decisions in CML patients. This knowledge may ultimately contribute to the development of personalized treatment strategies to improve patient outcomes in CML.

Death by a thousand cuts through kinase inhibitor combinations that maximize selectivity and enable rational multitargeting

Kinase inhibitors are successful therapeutics in the treatment of cancers and autoimmune diseases and are useful tools in biomedical research. However, the high sequence and structural conservation of the catalytic kinase domain complicate the development of selective kinase inhibitors. Inhibition of off-target kinases makes it difficult to study the mechanism of inhibitors in biological systems. Current efforts focus on the development of inhibitors with improved selectivity. Here, we present an alternative solution to this problem by combining inhibitors with divergent off-target effects. We develop a multicompound-multitarget scoring (MMS) method that combines inhibitors to maximize target inhibition and to minimize off-target inhibition. Additionally, this framework enables optimization of inhibitor combinations for multiple on-targets. Using MMS with published kinase inhibitor datasets we determine potent inhibitor combinations for target kinases with better selectivity than the most selective single inhibitor and validate the predicted effect and selectivity of inhibitor combinations using in vitro and in cellulo techniques. MMS greatly enhances selectivity in rational multitargeting applications. The MMS framework is generalizable to other non-kinase biological targets where compound selectivity is a challenge and diverse compound libraries are available.

Investigating the effect of Icaritin on hepatocellular carcinoma based on network pharmacology

Hepatocellular carcinoma is one of the cancers that kill people in the global population. Icaritin, a small molecule drug approved by NMPA, has demonstrated potential anti-HCC effects. However, its underlying molecular mechanisms remain unclear. We employed a multi-omics approach in this study, including pharmaco-omics and proteomics, to look into the Icaritin's possible molecular targets and workings in the therapy of HCC. Through pharmaco-omics analysis, we identified ten putative target genes of Icaritin, including FYN. The relationship between Icaritin and these target genes, particularly FYN, was further validated through in vitro and in vivo experiments. The outcomes revealed that Icaritin may exert its anti-HCC effects through modulating the FYN gene, highlighting the importance of multi-omics approaches in drug discovery research. This research gives valuable insights regarding the therapeutic potential of Icaritin against HCC and its possible molecular mechanisms.

FYN: emerging biological roles and potential therapeutic targets in cancer

Src family protein kinases (SFKs) play a key role in cell adhesion, invasion, proliferation, survival, apoptosis, and angiogenesis during tumor development. In humans, SFKs consists of eight family members with similar structure and function. There is a high level of overexpression or hyperactivity of SFKs in tumor, and they play an important role in multiple signaling pathways involved in tumorigenesis. FYN is a member of the SFKs that regulate normal cellular processes. Additionally, FYN is highly expressed in many cancers and promotes cancer growth and metastasis through diverse biological functions such as cell growth, apoptosis, and motility migration, as well as the development of drug resistance in many tumors. Moreover, FYN is involved in the regulation of multiple cancer-related signaling pathways, including interactions with ERK, COX-2, STAT5, MET and AKT. FYN is therefore an attractive therapeutic target for various tumor types, and suppressing FYN can improve the prognosis and prolong the life of patients. The purpose of this review is to provide an overview of FYN's structure, expression, upstream regulators, downstream substrate molecules, and biological functions in tumors.

Nrf2/p‑Fyn/ABCB1 axis accompanied by p‑Fyn nuclear accumulation plays pivotal roles in vinorelbine resistance in non‑small cell lung cancer

Adjuvant cisplatin‑vinorelbine is a standard therapy for stage II/III lung cancer. However, a poor survival rate of patients with lung cancer is attributed to vinorelbine resistance arising from ATP‑binding cassette (ABC) sub‑family B member 1 (ABCB1) and phosphorylated Fyn (p‑Fyn) overexpression. However, the underlying mechanisms remain unclear. NF‑E2‑related factor 2 (Nrf2) regulates the ABC family and activates the nuclear transport of Fyn. The present study evaluated the roles of the Nrf2/p‑Fyn/ABCB1 axis in vinorelbine‑resistant (VR) cells and clinical samples. To establish VR cells, H1299 cells were exposed to vinorelbine, and the intracellular reactive oxygen species (ROS) level in the H1299 cells was determined using a DCFH‑DA assay. The total and subcellular expression of Nrf2, ABCB1 and p‑Fyn in VR cells was evaluated. Immunofluorescence was used to detect the subcellular localization of p‑Fyn in VR cells. A cell viability assay was used to examine whether the sensitivity of VR cells to vinorelbine is dependent on Nrf2 activity. Immunohistochemistry was performed on 104 tissue samples from patients with lung cancer who underwent surgery followed by cisplatin‑vinorelbine treatment. The results revealed that persistent exposure to vinorelbine induced intracellular ROS formation in H1299 cells. p‑Fyn was localized in the nucleus, and ABCB1 and Nrf2 were overexpressed in VR cells. ABCB1 expression was dependent on Nrf2 downstream activation. The decreased expression of Nrf2 restored the sensitivity of VR cells to vinorelbine. In the surgical samples, Nrf2 and ABCB1 were associated with disease‑free survival, and p‑Fyn was associated with overall survival (P<0.05). On the whole, the present study demonstrates that Nrf2 upregulates ABCB1 and, accompanied by the nuclear accumulation of p‑Fyn, induces vinorelbine resistance. These findings may facilitate the development of drug resistance prevention strategies or new drug targets against non‑small cell lung cancer.

MicroRNA-200c Prevents Progress of Cutaneous Squamous Cell Carcinoma by Targeting Tyrosine-Protein Kinase Fyn (FYN)

Cutaneous squamous cell carcinoma (cSCC), a malignant skin tumor, begins in the epidermis and the keratinocytes of the skin appendages. However, the cause remains unclear. MicroRNA-200c (miR-200c), a key modulator of epithelial-to-mesenchymal transition (EMT), has been reported to act as an anticancer gene in a variety of cancers. However, its role and partial mechanism in cSCC remain undetermined. The results of this study showed depleted levels of miR-200c in cSCC tissues. Its suppressive effects on cell proliferation, and motility, as well as its apoptosis-promoting effect, were observed in the A-431 cells. Additionally, immunofluorescence and qRT-PCR assays revealed that FYN acted as a direct target of miR-200c, and FYN knockdown exerted had similar impact as that of miR-200c overexpression, including increased cellular apoptosis and decreased cellular growth. These results emphasized the onco-suppressive nature of miR-200c, which was evident based on its interaction with FYN in cSCC. This finding could have potential benefits in developing cSCC therapy.

Recent advances in understanding chronic myeloid leukemia: where do we stand?

While the need for complete eradication of leukemic stem cells (LSCs) in chronic myeloid leukemia may be controversial, it is agreed that remaining LSCs are the cause of relapse and disease progression. Current efforts are focused on the understanding of the persistence of immunophenotypically defined LSCs, which feature abnormalities in signaling pathways relating to autophagy, metabolism, epigenetics, and others and are influenced by leukemia cell-extrinsic factors such as the immune and bone marrow microenvironments. In sum, these elements modulate response and resistance to therapies and the clinical condition of treatment-free remission (TFR), the newly established goal in CML treatment, once the patient has achieved a durable molecular remission after treatment with tyrosine kinase inhibitors. Novel combination therapies based on these identified vulnerabilities of LSCs, aimed at the induction or maintenance of TFR, are being developed, while other research is directed at the elucidation of factors mediating progression to blast crisis.

Integrin α6 mediates the drug resistance of acute lymphoblastic B-cell leukemia

Resistance to multimodal chemotherapy continues to limit the prognosis of acute lymphoblastic leukemia (ALL). This occurs in part through a process called adhesion-mediated drug resistance, which depends on ALL cell adhesion to the stroma through adhesion molecules, including integrins. Integrin α6 has been implicated in minimal residual disease in ALL and in the migration of ALL cells to the central nervous system. However, it has not been evaluated in the context of chemotherapeutic resistance. Here, we show that the anti-human α6-blocking Ab P5G10 induces apoptosis in primary ALL cells in vitro and sensitizes primary ALL cells to chemotherapy or tyrosine kinase inhibition in vitro and in vivo. We further analyzed the underlying mechanism of α6-associated apoptosis using a conditional knockout model of α6 in murine BCR-ABL1+ B-cell ALL cells and showed that α6-deficient ALL cells underwent apoptosis. In vivo deletion of α6 in combination with tyrosine kinase inhibitor (TKI) treatment was more effective in eradicating ALL than treatment with a TKI (nilotinib) alone. Proteomic analysis revealed that α6 deletion in murine ALL was associated with changes in Src signaling, including the upregulation of phosphorylated Lyn (pTyr507) and Fyn (pTyr530). Thus, our data support α6 as a novel therapeutic target for ALL.

Chronic Myeloid Leukemia: A Model Disease of the Past, Present and Future

Chronic myeloid leukemia (CML) has been a "model disease" with a long history. Beginning with the first discovery of leukemia and the description of the Philadelphia Chromosome and ending with the current goal of achieving treatment-free remission after targeted therapies, we describe here the journey of CML, focusing on molecular pathways relating to signaling, metabolism and the bone marrow microenvironment. We highlight current strategies for combination therapies aimed at eradicating the CML stem cell; hopefully the final destination of this long voyage.

Emerging Kinase Therapeutic Targets in Pancreatic Ductal Adenocarcinoma and Pancreatic Cancer Desmoplasia

Kinase drug discovery represents an active area of therapeutic research, with previous pharmaceutical success improving patient outcomes across a wide variety of human diseases. In pancreatic ductal adenocarcinoma (PDAC), innovative pharmaceutical strategies such as kinase targeting have been unable to appreciably increase patient survival. This may be due, in part, to unchecked desmoplastic reactions to pancreatic tumors. Desmoplastic stroma enhances tumor development and progression while simultaneously restricting drug delivery to the tumor cells it protects. Emerging evidence indicates that many of the pathologic fibrotic processes directly or indirectly supporting desmoplasia may be driven by targetable protein tyrosine kinases such as Fyn-related kinase (FRK); B lymphoid kinase (BLK); hemopoietic cell kinase (HCK); ABL proto-oncogene 2 kinase (ABL2); discoidin domain receptor 1 kinase (DDR1); Lck/Yes-related novel kinase (LYN); ephrin receptor A8 kinase (EPHA8); FYN proto-oncogene kinase (FYN); lymphocyte cell-specific kinase (LCK); tec protein kinase (TEC). Herein, we review literature related to these kinases and posit signaling networks, mechanisms, and biochemical relationships by which this group may contribute to PDAC tumor growth and desmoplasia.

Expression Analysis of Fyn and Bat3 Signal Transduction Molecules in Patients with Chronic Lymphocytic Leukemia

BACKGROUND

Chronic lymphocytic leukemia (CLL) is correlated with defects in T-cell function resulting imparity in antitumor immune responses. Tim-3 is a co-inhibitory immune checkpoint receptor expressed on exhausted T-cells during tumor progression. Fyn and Bat3 are two important adaptor molecules involved in inhibition and activation of Tim-3 downstream signaling, respectively. In this study, the expression of Tim-3, Fyn, and Bat3 mRNA was evaluated in CLL patients.

METHODS

Peripheral blood mononuclear cells (PBMCs) were isolated from 54 patients with CLL and 34 healthy controls. Total RNA was extracted from all samples and applied for cDNA synthesis. The relative expression of Tim-3, Fyn, and Bat3 mRNA was determined by TaqMan Real-Time PCR using GAPDH as an internal control.

RESULTS

Tim-3 mRNA expression was not significantly different between CLL patients and healthy controls. Fyn mRNA expression was significantly lower in CLL patients and conversely, Bat3 mRNA expression was higher in CLL patients compared to healthy controls. Interestingly, the mRNA expression of Fyn inhibitory adaptor molecule was remarkably associated with expression of Tim-3 in CLL patients.

CONCLUSION

We have highlighted for the first time the expression of Fyn and Bat3 adaptor molecules in CLL patients. Our data demonstrated the strong correlation between the expression of Tim-3 and Fyn inhibitory molecules in CLL implying an important role for Tim-3-Fyn cooperation in induction of T-cell exhaustion.

Fusion of the COL1A1 and FYN Genes in Epithelioid Osteoblastoma

BACKGROUND/AIM

Epithelioid osteoblastoma is a rare benign tumor of the bone. Its pathogenesis is unknown and little is known regarding its genetic features.

MATERIALS AND METHODS

Cytogenetic, RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), genomic PCR, and Sanger sequencing analyses were performed on an epithelioid osteoblastoma.

RESULTS

G-banding analysis of short-term cultured tumor cells yielded a normal male karyotype in all examined metaphases. RNA sequencing detected a fusion of COL1A1 from 17q21 with FYN from 6q21. Both RT-PCR and genomic PCR together with Sanger sequencing verified the presence of a COL1A1-FYN fusion gene. In the COL1A1-FYN chimeric transcript, exon 43 of COL1A1 was fused to exon 2 of FYN. The genomic junction occurred in introns 43 and 1 of COL1A1 and FYN, respectively.

CONCLUSION

A COL1A1-FYN fusion gene was found in an epithelioid osteoblastoma resulting in deregulation of FYN. Whether COL1A1-FYN represents a consistent genetic feature of epithelioid osteoblastomas, remains to be seen.

Beyond TCR Signaling: Emerging Functions of Lck in Cancer and Immunotherapy

In recent years, the lymphocyte-specific protein tyrosine kinase (Lck) has emerged as one of the key molecules regulating T-cell functions. Studies using Lck knock-out mice or Lck-deficient T-cell lines have shown that Lck regulates the initiation of TCR signaling, T-cell development, and T-cell homeostasis. Because of the crucial role of Lck in T-cell responses, strategies have been employed to redirect Lck activity to improve the efficacy of chimeric antigen receptors (CARs) and to potentiate T-cell responses in cancer immunotherapy. In addition to the well-studied role of Lck in T cells, evidence has been accumulated suggesting that Lck is also expressed in the brain and in tumor cells, where it actively takes part in signaling processes regulating cellular functions like proliferation, survival and memory. Therefore, Lck has emerged as a novel druggable target molecule for the treatment of cancer and neuronal diseases. In this review, we will focus on these new functions of Lck.

Binding investigation and preliminary optimisation of the 3-amino-1,2,4-triazin-5(2H)-one core for the development of new Fyn inhibitors

Fyn tyrosine kinase inhibitors are considered potential therapeutic agents for a variety of human cancers. Furthermore, the involvement of Fyn kinase in signalling pathways that lead to severe pathologies, such as Alzheimer's and Parkinson's diseases, has also been demonstrated. In this study, starting from 3-(benzo[d][1,3]dioxol-5-ylamino)-6-methyl-1,2,4-triazin-5(2H)-one (VS6), a hit compound that showed a micromolar inhibition of Fyn (IC₅₀ = 4.8 μM), we computationally investigated the binding interactions of the 3-amino-1,2,4-triazin-5(2H)-one scaffold and started a preliminary hit to lead optimisation. This analysis led us to confirm the hypothesised binding mode of VS6 and to identify a new derivative that is about 6-fold more active than VS6 (compound 3, IC₅₀ = 0.76 μM).

A Pyrazolo[3,4-d]pyrimidine compound inhibits Fyn phosphorylation and induces apoptosis in natural killer cell leukemia

Natural killer (NK) cell neoplasms are characterized by clonal proliferation of cytotoxic NK cells. Since there is no standard treatment to date, new therapeutic options are needed, especially for NK aggressive tumors. Fyn tyrosine kinase has a key role in different biological processes, such as cell growth and differentiation, being also involved in the pathogenesis of hematologic malignancies. Our previous studies led us to identify 4c pyrazolo[3,4-d]pyrimidine compound capable of inhibiting Fyn activation and inducing apoptosis in different cancer cell lines. Here we investigated the presence of Fyn and the effect of its inhibitor in NK malignant cells. Firstly, we showed Fyn over-expression in NK leukemic cells compared to peripheral blood mononuclear cells from healthy donors. Subsequently, we demonstrated that 4c treatment reduced cell viability, induced caspase 3-mediate apoptosis and cell cycle arrest in NK cells. Moreover, by inhibiting Fyn phosphorylation, 4c compound reduced Akt and P70 S6 kinase activation and changed the expression of genes involved in cell death and survival in NK cells. Our study demonstrated that Fyn is involved in the pathogenesis of NK leukemia and that it could represent a potential target for this neoplasm. Moreover, we proved that Fyn inhibitor pyrazolo[3,4-d]pyrimidine compound, could be a started point to develop new therapeutic agents.

Role of Non Receptor Tyrosine Kinases in Hematological Malignances and its Targeting by Natural Products

Tyrosine kinases belong to a family of enzymes that mediate the movement of the phosphate group to tyrosine residues of target protein, thus transmitting signals from the cell surface to cytoplasmic proteins and the nucleus to regulate physiological processes. Non-receptor tyrosine kinases (NRTK) are a sub-group of tyrosine kinases, which can relay intracellular signals originating from extracellular receptor. NRTKs can regulate a huge array of cellular functions such as cell survival, division/propagation and adhesion, gene expression, immune response, etc. NRTKs exhibit considerable variability in their structural make up, having a shared kinase domain and commonly possessing many other domains such as SH2, SH3 which are protein-protein interacting domains. Recent studies show that NRTKs are mutated in several hematological malignancies, including lymphomas, leukemias and myelomas, leading to aberrant activation. It can be due to point mutations which are intragenic changes or by fusion of genes leading to chromosome translocation. Mutations that lead to constitutive kinase activity result in the formation of oncogenes, such as Abl, Fes, Src, etc. Therefore, specific kinase inhibitors have been sought after to target mutated kinases. A number of compounds have since been discovered, which have shown to inhibit the activity of NRTKs, which are remarkably well tolerated. This review covers the role of various NRTKs in the development of hematological cancers, including their deregulation, genetic alterations, aberrant activation and associated mutations. In addition, it also looks at the recent advances in the development of novel natural compounds that can target NRTKs and perhaps in combination with other forms of therapy can show great promise for the treatment of hematological malignancies.

Fyn kinase mediates cortical actin ring depolymerization required for mast cell migration in response to TGF-β in mice

Transforming growth factor-β (TGF-β) is a potent mast cell (MC) chemoattractant able to modulate local inflammatory reactions. The molecular mechanism leading to TGF-β-directed MC migration is not fully described. Here we analyzed the role of the Src family protein kinase Fyn on the main TGF-β-induced cytoskeletal changes leading to MC migration. Utilizing bone marrow-derived mast cells (BMMCs) from WT and Fyn-deficient mice we found that BMMC migration to TGF-β was impaired in the absence of the kinase. TGF-β caused depolymerization of the cortical actin ring and changes on the phosphorylation of cofilin, LIMK and CAMKII only in WT cells. Defective cofilin activation and phosphorylation of regulatory proteins was detected in Fyn-deficient BMMCs and this finding correlated with a lower activity of the catalytic subunit of the phosphatase PP2A. Diminished TGF-β-induced chemotaxis of Fyn-deficient cells was also observed in an in vivo model of MC migration (bleomycin-induced scleroderma). Our results show that Fyn kinase is an important positive effector of TGF-β-induced chemotaxis through the control of PP2A activity and this is relevant to pathological processes that are related to TGF-β-dependent mast cell migration.

Dynamically Coupled Residues within the SH2 Domain of FYN Are Key to Unlocking Its Activity

Src kinase activity is controlled by various mechanisms involving a coordinated movement of kinase and regulatory domains. Notwithstanding the extensive knowledge related to the backbone dynamics, little is known about the more subtle side-chain dynamics within the regulatory domains and their role in the activation process. Here, we show through experimental methyl dynamic results and predicted changes in side-chain conformational couplings that the SH2 structure of Fyn contains a dynamic network capable of propagating binding information. We reveal that binding the phosphorylated tail of Fyn perturbs a residue cluster near the linker connecting the SH2 and SH3 domains of Fyn, which is known to be relevant in the regulation of the activity of Fyn. Biochemical perturbation experiments validate that those residues are essential for inhibition of Fyn, leading to a gain of function upon mutation. These findings reveal how side-chain dynamics may facilitate the allosteric regulation of the different members of the Src kinase family.

Normal ABL1 is a tumor suppressor and therapeutic target in human and mouse leukemias expressing oncogenic ABL1 kinases

Leukemias expressing constitutively activated mutants of ABL1 tyrosine kinase (BCR-ABL1, TEL-ABL1, NUP214-ABL1) usually contain at least 1 normal ABL1 allele. Because oncogenic and normal ABL1 kinases may exert opposite effects on cell behavior, we examined the role of normal ABL1 in leukemias induced by oncogenic ABL1 kinases. BCR-ABL1-Abl1(-/-) cells generated highly aggressive chronic myeloid leukemia (CML)-blast phase-like disease in mice compared with less malignant CML-chronic phase-like disease from BCR-ABL1-Abl1(+/+) cells. Additionally, loss of ABL1 stimulated proliferation and expansion of BCR-ABL1 murine leukemia stem cells, arrested myeloid differentiation, inhibited genotoxic stress-induced apoptosis, and facilitated accumulation of chromosomal aberrations. Conversely, allosteric stimulation of ABL1 kinase activity enhanced the antileukemia effect of ABL1 tyrosine kinase inhibitors (imatinib and ponatinib) in human and murine leukemias expressing BCR-ABL1, TEL-ABL1, and NUP214-ABL1. Therefore, we postulate that normal ABL1 kinase behaves like a tumor suppressor and therapeutic target in leukemias expressing oncogenic forms of the kinase.

Interactome analysis of myeloid-derived suppressor cells in murine models of colon and breast cancer

In solid cancers, myeloid derived suppressor cells (MDSC) infiltrate (peri)tumoral tissues to induce immune tolerance and hence to establish a microenvironment permissive to tumor growth. Importantly, the mechanisms that facilitate such infiltration or a subsequent immune suppression are not fully understood. Hence, in this study, we aimed to delineate disparate molecular pathways which MDSC utilize in murine models of colon or breast cancer. Using pathways enrichment analysis, we completed interactome maps of multiple signaling pathways in CD11b+/Gr1(high/low) MDSC from spleens and tumor infiltrates of mice with c26GM colon cancer and tumor infiltrates of MDSC in 4T1 breast cancer. In both cancer models, infiltrating MDSC, but not CD11b+ splenic cells, have been found to be enriched in multiple signaling molecules suggestive of their enhanced proliferative and invasive phenotypes. The interactome data has been subsequently used to reconstruct a previously unexplored regulation of MDSC cell cycle by the c-myc transcription factor which was predicted by the analysis. Thus, this study represents a first interactome mapping of distinct multiple molecular pathways whereby MDSC sustain cancer progression.

Studies on the ATP Binding Site of Fyn Kinase for the Identification of New Inhibitors and Their Evaluation as Potential Agents against Tauopathies and Tumors

Fyn is a member of the Src-family of nonreceptor protein-tyrosine kinases. Its abnormal activity has been shown to be related to various human cancers as well as to severe pathologies, such as Alzheimer's and Parkinson's diseases. Herein, a structure-based drug design protocol was employed aimed at identifying novel Fyn inhibitors. Two hits from commercial sources (1, 2) were found active against Fyn with K(i) of about 2 μM, while derivative 4a, derived from our internal library, showed a K(i) of 0.9 μM. A hit-to-lead optimization effort was then initiated on derivative 4a to improve its potency. Slightly modifications rapidly determine an increase in the binding affinity, with the best inhibitors 4c and 4d having K(i)s of 70 and 95 nM, respectively. Both compounds were found able to inhibit the phosphorylation of the protein Tau in an Alzheimer's model cell line and showed antiproliferative activities against different cancer cell lines.