c-Src activation through a TrkA and c-Src interaction is essential for cell proliferation and hematological malignancies

Regulating Tumorigenicity and Cancer Metastasis through TRKA Signaling

Tropomyosin receptor kinase (TRK) A, TRKA, is a specific binding receptor of nerve growth factor (NGF), which plays an essential role in the occurrence and progression of human cancers. TRKA overexpression has been proven to be a powerful carcinogenic driver and has been verified in many tumors. The TRKA receptor kinase domain is over-activated in an NGF-dependent manner, accompanied by activation of downstream signal pathways, such as RAS-MAPK, PI3K-AKT, JAK2-STAT3 pathway, PLC γ pathway, and Hippo pathway, which participate in tumor cell proliferation, invasion, epithelial-mesenchymal transition (EMT), perineural invasion (PNI), drug resistance, and cancer pain. In addition, chimeric oncogenes produced by the fusion of NTRK1 and other genes are also the direct cause of tumorigenesis and cancer development. The newly developed TRK inhibitors can improve symptoms and tumor regression in cancer patients with overexpression of TRKA or NTRK1 fusion gene. With the emergence of drug resistance, next generation of TRK inhibitors can still maintain strong clinical efficacy in the case of TRK kinase domain mutations, and these inhibitors are in clinical trials. This review summarizes the characteristics and research progress of TRKA, focusing on the regulatory role of the TRKA signal pathway in different tumors. In addition, we have summarized the clinical significance of TRKA and the TRK inhibitors. This review may provide a new reference for the study of the mechanism of TRKA in different tumors, and also provide a new perspective for the in-depth understanding of the role of TRKA as a biomarker and therapeutic target in human cancer.

c-Src promotes the growth and tumorigenesis of hepatocellular carcinoma via the Hippo signaling pathway

We investigated the association between c-Src and the progression of hepatocellular carcinoma (HCC) and its underlying mechanisms. The relationship between c-Src expression and the occurrence and development of HCC was explored using GEPIA and further confirmed by western blotting analysis and real-time quantitative PCR. CCK-8, flow cytometry, Transwell, and wound-healing assays were conducted to analyze the effects of c-Src on the growth, cell cycle, apoptosis, migration, and infiltration of HCC cells. Mouse models of transplanted xenogeneic human tumors were constructed to explore the effects of c-Src on HCC tumor growth. Compared with that in adjacent normal liver tissues, the expression level of c-Src in HCC tissues was significantly increased and was negatively correlated with patient survival. These findings are consistent with those in the GEPIA database. Downregulation of c-Src expression can inhibit the growth, infiltration, and migration of HCC cells. c-Src impeded the translocation of YAP from the nucleus to the cytoplasm and promoted Yes-associated protein transcriptional activity. In vivo experiments showed that c-Src inhibition suppressed tumor growth in mice. We found that c-Src can promote the growth and tumorigenesis of HCC cells by activating the Hippo signaling pathway.

Identification of an Immune-Related Gene Signature Based on Immunogenomic Landscape Analysis to Predict the Prognosis of Adult Acute Myeloid Leukemia Patients

Acute myeloid leukemia (AML) is a hematopoietic malignancy characterized by highly heterogeneous molecular lesions and cytogenetic abnormalities. Immune disorders in AML and impaired immune cell function have been found to be associated with abnormal karyotypes in AML patients. Immunotherapy has become an alternative therapeutic method that can improve the outcomes of AML patients. For solid tumors, the expression patterns of genes associated with the immune microenvironment provide valuable prognostic information. However, the prognostic roles of immune genes in AML have not been studied as yet. In this study, we identified 136 immune-related genes associated with overall survival in AML patients through a univariate Cox regression analysis using data from TCGA-AML and GTEx datasets. Next, we selected 24 hub genes from among the 136 genes based on the PPI network analysis. The 24 immune-related hub genes further underwent multivariate Cox regression analysis and LASSO regression analysis. Finally, a 6 immune-related gene signature was constructed to predict the prognosis of AML patients. The function of the hub IRGs and the relationships between hub IRGs and transcriptional factors were investigated. We found that higher levels of expression of CSK, MMP7, PSMA7, PDCD1, IKBKG, and ISG15 were associated with an unfavorable prognosis of AML patients. Meanwhile, patients in the TCGA-AML datasets were divided into a high risk score group and a low risk score group, based on the median risk score value. Patients in the high risk group tended to show poorer prognosis [P = 0.00019, HR = 1.89 (1.26–2.83)]. The area under the curve (AUC) was 0.6643. Multivariate Cox Regression assay confirmed that the 6 IRG signature was an independent prognostic factor for AML. The prognostic role of the immune related-gene signature was further validated using an independent AML dataset, GSE37642. In addition, patients in the high risk score group in the TCGA dataset were found to be of an advanced age, IDH mutation, and M5 FAB category. These results suggested that the proposed immune related-gene signature may serve as a potential prognostic tool for AML patients.

Novel Quinoline Compounds Active in Cancer Cells through Coupled DNA Methyltransferase Inhibition and Degradation

DNA methyltransferases (DNMTs) play a relevant role in epigenetic control of cancer cell survival and proliferation. Since only two DNMT inhibitors (azacitidine and decitabine) have been approved to date for the treatment of hematological malignancies, the development of novel potent and specific inhibitors is urgent. Here we describe the design, synthesis, and biological evaluation of a new series of compounds acting at the same time as DNMTs (mainly DNMT3A) inhibitors and degraders. Tested against leukemic and solid cancer cell lines, 2a-c and 4a-c (the last only for leukemias) displayed up to submicromolar antiproliferative activities. In HCT116 cells, such compounds induced EGFP gene expression in a promoter demethylation assay, confirming their demethylating activity in cells. In the same cell line, 2b and 4c chosen as representative samples induced DNMT1 and -3A protein degradation, suggesting for these compounds a double mechanism of DNMT3A inhibition and DNMT protein degradation.

MEST induces Twist-1-mediated EMT through STAT3 activation in breast cancers

The loss of imprinting of MEST has been linked to certain types of cancer by promoter switching. However, MEST-mediated regulation of tumorigenicity and metastasis are yet to be understood. Herein, we reported that MEST is a key regulator of IL-6/JAK/STAT3/Twist-1 signal pathway-mediated tumor metastasis. Enhanced MEST expression is significantly associated with pathogenesis of breast cancer patients. Also, MEST induces metastatic potential of breast cancer through induction of the EMT-TFs-mediated EMT program. Moreover, MEST leads to Twist-1 induction by STAT3 activation and subsequently enables the induction of activation of the EMT program via the induction of STAT3 nuclear translocation. Furthermore, the c-terminal region of MEST was essential for STAT3 activation via the induction of JAK2/STAT3 complex formation. Finally, MEST is required for metastasis in an experimental metastasis model. These observations suggest that MEST is a promising target for intervention to prevent tumor metastasis.

Inhibition of Tropomyosin Receptor Kinase A Signaling Negatively Regulates Megakaryopoiesis and induces Thrombopoiesis

Neurotrophin signaling modulates the differentiation and function of mature blood cells. The expression of neurotrophin receptors and ligands by hematopoietic and stromal cells of the bone marrow indicates that neurotrophins have the potential to regulate hematopoietic cell fate decisions. This study investigates the role of neurotrophins and Tropomyosin receptor kinases (Trk) in the development of megakaryocytes (MKs) and their progeny cells, platelets. Results indicate that primary human MKs and MK cells lines, DAMI, Meg-01 and MO7e express TrkA, the primary receptor for Nerve Growth Factor (NGF) signaling. Activation of TrkA by NGF enhances the expansion of human MK progenitors (MKPs) and, to some extent, MKs. Whereas, inhibition of TrkA receptor by K252a leads to a 50% reduction in the number of both MKPs and MKs and is associated with a 3-fold increase in the production of platelets. In order to further confirm the role of TrkA signaling in platelet production, TrkA deficient DAMI cells were generated using CRISPR-Cas9 technology. Comparative analysis of wild-type and TrkA-deficient Dami cells revealed that loss of TrkA signaling induced apoptosis of MKs and increased platelet production. Overall, these findings support a novel role for TrkA signaling in platelet production and highlight its potential as therapeutic target for Thrombocytopenia.

How is the relationship between TWIST-1 and BCR-ABL1 gene expressions in chronic myeloid leukaemia patients?

BACKGROUND

The activation and increased expression of BCR-ABL1 lead to malignant chronic myelogenous leukaemia (CML) cells, as well as the resistance to antitumour agents and apoptosis inducers. Moreover, TWIST-1 protein is a prognostic factor of leukemogenesis, and its level is raised in CML patients with cytogenetic resistance to imatinib. So, there is a likely relationship between BCR-ABL1 and TWIST-1 genes.

OBJECTIVE

The aim of the study was to assess the relationship between TWIST-1 and BCR-ABL1 expressions.

METHODS

Peripheral blood samples were obtained from 44 CML patients under treatment and also from ten healthy subjects as normal controls. The expression of TWIST-1 and BCR-ABL1 genes was measured using real-time PCR, and ABL1 was used as the reference gene. The gene expression was evaluated by REST software.

RESULTS

The expression levels of TWIST-1 and BCR-ABL1 genes in CML patients was changed 40.23 ± 177.75-fold and 6 ± 18-fold, respectively.

DISCUSSION

No significant relationship was observed between the expressions of TWIST-1 and BCR-ABL1 genes. All patients with TWIST-1 expression levels ≥100-fold had failure of response to treatment.

CONCLUSION

The probability of the relationship between BCR-ABL1 and TWIST-1 is still debatable, and the average of TWIST-1 expression has been higher in patients without response to treatment. Definitive conclusion needs further investigations.

TrkA is a binding partner of NPM-ALK that promotes the survival of ALK+ T-cell lymphoma

Nucleophosmin‐anaplastic lymphoma kinase‐expressing (NPM‐ALK⁺) T‐cell lymphoma is an aggressive neoplasm that is more commonly seen in children and young adults. The pathogenesis of NPM‐ALK⁺ T‐cell lymphoma is not completely understood. Wild‐type ALK is a receptor tyrosine kinase that is physiologically expressed in neural tissues during early stages of human development, which suggests that ALK may interact with neurotrophic factors. The aberrant expression of NPM‐ALK results from a translocation between the ALK gene on chromosome 2p23 and the NPM gene on chromosome 5q35. The nerve growth factor (NGF) is the first neurotrophic factor attributed to non‐neural functions including cancer cell survival, proliferation, and metastasis. These functions are primarily mediated through the tropomyosin receptor kinase A (TrkA). The expression and role of NGF/TrkA in NPM‐ALK⁺ T‐cell lymphoma are not known. In this study, we tested the hypothesis that TrkA signaling is upregulated and sustains the survival of this lymphoma. Our data illustrate that TrkA and NGF are expressed in five NPM‐ALK⁺ T‐cell lymphoma cell lines and TrkA is expressed in 11 of 13 primary lymphoma tumors from patients. In addition, we found evidence to support that NPM‐ALK and TrkA functionally interact. A selective TrkA inhibitor induced apoptosis and decreased cell viability, proliferation, and colony formation of NPM‐ALK⁺ T‐cell lymphoma cell lines. These effects were associated with downregulation of cell survival regulatory proteins. Similar results were also observed using specific knockdown of TrkA in NPM‐ALK⁺ T‐cell lymphoma cells by siRNA. Importantly, the inhibition of TrkA signaling was associated with antitumor effects in vivo, because tumor xenografts in mice regressed and the mice exhibited improved survival. In conclusion, TrkA plays an important role in the pathogenesis of NPM‐ALK⁺ T‐cell lymphoma, and therefore, targeting TrkA signaling may represent a novel approach to eradicate this aggressive neoplasm.

Ablation of CD44 induces glycolysis-to-oxidative phosphorylation transition via modulation of the c-Src–Akt–LKB1–AMPKα pathway

Cluster of differentiation 44 (CD44) is a transmembrane glycoprotein that has been identified as a cancer stem cell marker in various cancer cells. Although many studies have focused on CD44 as a cancer stem cell marker, its effect on cancer cell metabolism remains unclear. To investigate the role of CD44 on cancer cell metabolism, we established CD44 knock-down cells via retroviral delivery of shRNA against CD44 in human breast cancer cells. Silencing of CD44 decreased the glycolytic phenotype of cancer cells, affecting glucose uptake, ATP production, and lactate production. We also found that ablation of the CD44-induced lactate dehydrogenase (LDH) isoenzyme results in a shift to LDH1 due to LDHA down-regulation and LDHB up-regulation, implying the importance of LDH isoenzyme modulation on cancer metabolism. The expression of glycolysis-related proteins including hypoxia inducible factor-1α (HIF-1α) and LDHA was decreased by CD44 silencing. These effects were due to the up-regulation of liver kinase B1 (LKB1)/AMP-activated protein kinase (AMPK)α activity by reduction in c-Src and Akt activity in CD44 knock-down cells. Finally, induction of LKB1/AMPKα activity blocked the expression of HIF-1α and its target gene, LDHA. Inversely, LDHB expression was repressed by HIF-1α. Collectively, these results indicate that the CD44 silencing-induced metabolic shift is mediated by the regulation of c-Src/Akt/LKB1/AMPKα/HIF-1α signaling in human breast cancer cells.

Kinase activity profiling reveals active signal transduction pathways in pediatric acute lymphoblastic leukemia: a new approach for target discovery

Still about 20% of patients with acute lymphoblastic leukemia (ALL) struggle with relapse, despite intensive chemotherapy. We and others have shown that kinase activity profiling is able to give more insights in active signal transduction pathways and point out interesting signaling hubs as well as new potential druggable targets. With this technique the gap between newly designed drugs and ALL may be bridged. The aim of this study was to perform kinome profiling on 20 pediatric ALL samples (14 BCP-ALL and six T-ALL) to identify signaling proteins relevant to ALL. We defined 250 peptides commonly activated in both BCP-ALL and T-ALL representing major signal transduction pathways including MAPK, PI3K/Akt, and regulators of the cell cycle/p53 pathway. For 27 peptides, differentially phosphorylation between BCP-ALL and T-ALL was observed. Among these, ten peptides were more highly phosphorylated in BCP-ALL while 17 peptides showed increased phosphorylation in T-ALL. Furthermore we selected one lead of the list of commonly activated peptides (HGFR_Y1235) in order to test its efficacy as a potential target and provide proof of principle for this approach. In conclusion kinome profiling is an elegant approach to study active signaling and identify interesting potential druggable targets.

Pilot study of erlotinib in patients with acute myeloid leukemia

We conducted a pilot study to investigate clinical efficacy of tyrosine kinase inhibitor erlotinib in the treatment of acute myeloid leukemia (AML). A total of 11 patients with de novo AML were treated, including 2 with relapsed and/or refractory disease and 9 older patients with previously untreated AML. Patients with high baseline leukocyte count were excluded. Erlotinib was given orally at 150 mg per day continuously in 28-day cycles. The treatment was tolerated well, and no toxicities were observed. An initial reduction in circulating blasts, followed by disease progression, was observed in 2 patients. Nine other patients did not demonstrate any response in blood or bone marrow. Baseline and post-cycle 1 flow-cytometry were performed on bone marrow blasts to investigate signs of differentiation. No immunophenotypic changes suggestive of differentiation were observed. This pilot study did not demonstrate response to standard doses of erlotinib in patients with AML.