Yes and Lyn play a role in nuclear translocation of the epidermal growth factor receptor

Network-based elucidation of colon cancer drug resistance mechanisms by phosphoproteomic time-series analysis

Aberrant signaling pathway activity is a hallmark of tumorigenesis and progression, which has guided targeted inhibitor design for over 30 years. Yet, adaptive resistance mechanisms, induced by rapid, context-specific signaling network rewiring, continue to challenge therapeutic efficacy. Leveraging progress in proteomic technologies and network-based methodologies, we introduce Virtual Enrichment-based Signaling Protein-activity Analysis (VESPA)-an algorithm designed to elucidate mechanisms of cell response and adaptation to drug perturbations-and use it to analyze 7-point phosphoproteomic time series from colorectal cancer cells treated with clinically-relevant inhibitors and control media. Interrogating tumor-specific enzyme/substrate interactions accurately infers kinase and phosphatase activity, based on their substrate phosphorylation state, effectively accounting for signal crosstalk and sparse phosphoproteome coverage. The analysis elucidates time-dependent signaling pathway response to each drug perturbation and, more importantly, cell adaptive response and rewiring, experimentally confirmed by CRISPR knock-out assays, suggesting broad applicability to cancer and other diseases.

YES1 as a potential target to overcome drug resistance in EGFR-deregulated non-small cell lung cancer

Epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) such as gefitinib and osimertinib have primarily been used as first-line treatments for patients with EGFR-activating mutations in non-small cell lung cancer (NSCLC). Novel biomarkers are required to distinguish patients with lung cancer who are resistant to EGFR-TKIs. The aim of the study is to investigate the expression and functional role of YES1, one of the Src-family kinases, in EGFR-TKI-resistant NSCLC. YES1 expression was elevated in gefitinib-resistant HCC827 (HCC827/GR) cells, harboring EGFR mutations. Moreover, HCC827/GR cells exhibited increased reactive oxygen species (ROS) levels compared to those of the parent cells, resulting in the phosphorylation/activation of YES1 due to oxidation of the cysteine residue. HCC827/GR cells showed elevated expression levels of YES1-associated protein 1 (YAP1), NF-E2-related factor 2 (Nrf2), cancer stemness-related markers, and antioxidant proteins compared to those of the parent cells. Knockdown of YES1 in HCC827/GR cells suppressed YAP1 phosphorylation, leading to the inhibition of Bcl-2, Bcl-xL, and Cyclin D1 expression. Silencing YES1 markedly attenuated the proliferation, migration, and tumorigenicity of HCC827/GR cells. Dasatinib inhibited the proliferation of HCC827/GR cells by targeting YES1-mediated signaling pathways. Furthermore, the combination of gefitinib and dasatinib demonstrated a synergistic effect in suppressing the proliferation of HCC827/GR cells. Notably, YES1- and Nrf2-regulated genes showed a positive regulatory relationship in patients with lung cancer and in TKI-resistant NSCLC cell lines. Taken together, these findings suggest that modulation of YES1 expression and activity may be an attractive therapeutic strategy for the treatment of drug-resistant NSCLC.

Emerging role of MYB transcription factors in cancer drug resistance

Decades ago, the viral myeloblastosis oncogene v-myb was identified as a gene responsible for the development of avian leukemia. However, the relevance of MYB proteins for human cancer diseases, in particular for solid tumors, remained basically unrecognized for a very long time. The human family of MYB transcription factors comprises MYB (c-MYB), MYBL2 (b-MYB), and MYBL1 (a-MYB), which are overexpressed in several cancers and are associated with cancer progression and resistance to anticancer drugs. In addition to overexpression, the presence of activated MYB-fusion proteins as tumor drivers was described in certain cancers. The identification of anticancer drug resistance mediated by MYB proteins and their underlying mechanisms are of great importance in understanding failures of current therapies and establishing new and more efficient therapy regimens. In addition, new drug candidates targeting MYB transcription factor activity and signaling have emerged as a promising class of potential anticancer therapeutics that could tackle MYB-dependent drug-resistant cancers in a more selective way. This review describes the correlation of MYB transcription factors with the formation and persistence of cancer resistance to various approved and investigational anticancer drugs.

Network-based elucidation of colon cancer drug resistance by phosphoproteomic time-series analysis

Aberrant signaling pathway activity is a hallmark of tumorigenesis and progression, which has guided targeted inhibitor design for over 30 years. Yet, adaptive resistance mechanisms, induced by rapid, context-specific signaling network rewiring, continue to challenge therapeutic efficacy. By leveraging progress in proteomic technologies and network-based methodologies, over the past decade, we developed VESPA-an algorithm designed to elucidate mechanisms of cell response and adaptation to drug perturbations-and used it to analyze 7-point phosphoproteomic time series from colorectal cancer cells treated with clinically-relevant inhibitors and control media. Interrogation of tumor-specific enzyme/substrate interactions accurately inferred kinase and phosphatase activity, based on their inferred substrate phosphorylation state, effectively accounting for signal cross-talk and sparse phosphoproteome coverage. The analysis elucidated time-dependent signaling pathway response to each drug perturbation and, more importantly, cell adaptive response and rewiring that was experimentally confirmed by CRISPRko assays, suggesting broad applicability to cancer and other diseases.

EGFR pathway targeting drugs in head and neck cancer in the era of immunotherapy

Receptor tyrosine kinases (RTKs) are cell surface receptors that bind growth factor ligands and initiate cellular signaling. Of the 20 classes of RTKs, 7 classes, I-V, VIII, and X, are linked to head and neck cancers (HNCs). We focus on the first class of RTK, epidermal growth factor receptor (EGFR), as it is the most thoroughly studied class. EGFR overexpression is observed in 20% of tumors, and expression of EGFR variant III is seen in 15% of aggressive chemoradiotherapy resistant HNCs. Currently, the EGFR monoclonal antibody (mAb) cetuximab is the only FDA approved RTK-targeting drug for the treatment of HNCs. Clinical trials have also included EGFR mAbs, with tyrosine kinase inhibitors, and small molecule inhibitors targeting the EGFR, MAPK, and mTOR pathways. Additionally, Immunotherapy has been found to be effective in 15 to 20% of patients with recurrent or metastatic HNC as a monotherapy. Thus, attempts are underway for the combinatorial treatment of immunotherapy and EGFR mAbs to determine if the recruitment of immune cells in the tumor microenvironment can overcome EGFR resistance.

Targeting HER3-dependent activation of nuclear AKT improves radiotherapy of non-small cell lung cancer

BACKGROUND

AKT1 must be present and activated in the nucleus immediately after irradiation to stimulate AKT1-dependent double-strand breaks (DSB) repair through the fast non-homologous end-joining (NHEJ) repair process. We investigated the subcellular distribution of AKT1 and the role of HER family receptor members on the phosphorylation of nuclear AKT and radiation response.

MATERIALS AND METHODS

Using genetic approaches and pharmacological inhibitors, we investigated the subcellular distribution of AKT1 and the role of HER family receptor members on the activation of nuclear AKT in non-small cell lung cancer (NSCLC) cells in vitro. ɤH2AX foci assay was applied to investigate the role of AKT activating signaling pathway on DSB repair. A mouse tumor xenograft model was used to study the impact of discovered signaling pathway activating nuclear AKT on the radiation response of tumors in vivo.

RESULTS

Our data suggests that neither ionizing radiation (IR) nor stimulation with HER family receptor ligands induced rapid nuclear translocation of endogenous AKT1. GFP-tagged exogenous AKT1 translocated to the nucleus under un-irradiated conditions and IR did not stimulate this translocation. Nuclear translocation of GFP-AKT1 was impaired by the AKT inhibitor MK2206 as shown by its accumulation in the cytoplasmic fraction. IR-induced phosphorylation of nuclear AKT was primarily dependent on HER3 expression and tyrosine kinase activation of epidermal growth factor receptor. In line with the role of AKT1 in DSB repair, the HER3 neutralizing antibody patritumab as well as HER3-siRNA diminished DSB repair in vitro. Combination of patritumab with radiotherapy improved the effect of radiotherapy on tumor growth delay in a xenograft model.

CONCLUSION

IR-induced activation of nuclear AKT occurs inside the nucleus that is mainly dependent on HER3 expression in NSCLC. These findings suggest that targeting HER3 in combination with radiotherapy may provide a logical treatment option for investigation in selected NSCLC patients.

Fisetin induces DNA double-strand break and interferes with the repair of radiation-induced damage to radiosensitize triple negative breast cancer cells

Background

Triple-negative breast cancer (TNBC) is associated with aggressiveness and a poor prognosis. Besides surgery, radiotherapy serves as the major treatment modality for TNBC. However, response to radiotherapy is limited in many patients, most likely because of DNA damage response (DDR) signaling mediated radioresistance. Y-box binding protein-1 (YB-1) is a multifunctional protein that regulates the cancer hallmarks among them resisting to radiotherapy-induced cell death. Fisetin, is a plant flavonol of the flavonoid family of plant polyphenols that has anticancer properties, partially through inhibition of p90 ribosomal S6 kinase (RSK)-mediated YB-1 phosphorylation. The combination of fisetin with radiotherapy has not yet been investigated.

Methods

Activation status of the RSK signaling pathway in total cell lysate and in the subcellular fractions was analyzed by Western blotting. Standard clonogenic assay was applied to test post-irradiation cell survival. γH2AX foci assay and 3 color fluorescence in situ hybridization analyses were performed to study frequency of double-strand breaks (DSB) and chromosomal aberrations, respectively. The underlying repair pathways targeted by fisetin were studied in cells expressing genomically integrated reporter constructs for the DSB repair pathways via quantifying the expression of green fluorescence protein by flow cytometry. Flow cytometric quantification of sub-G1 cells and the protein expression of LC3-II were employed to measure apoptosis and autophagy, respectively. Kinase array and phosphoproteomics were performed to study the effect of fisetin on DDR response signaling.

Results

We showed that the effect of fisetin on YB-1 phosphorylation in TNBC cells is comparable to the effect of the RSK pharmacological inhibitors. Similar to ionizing radiation (IR), fisetin induces DSB. Additionally, fisetin impairs repair of IR-induced DSB through suppressing the classical non-homologous end-joining and homologous recombination repair pathways, leading to chromosomal aberration as tested by metaphase analysis. Effect of fisetin on DSB repair was partially dependent on YB-1 expression. Phosphoproteomic analysis revealed that fisetin inhibits DDR signaling, which leads to radiosensitization in TNBC cells, as shown in combination with single dose or fractionated doses irradiation.

Conclusion

Fisetin acts as a DSB-inducing agent and simultaneously inhibits repair of IR-induced DSB. Thus, fisetin may serve as an effective therapeutic strategy to improve TNBC radiotherapy outcome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13046-022-02442-x.

YES1: a novel therapeutic target and biomarker in cancer

YES1 is a non-receptor tyrosine kinase that belongs to the SRC family of kinases (SFKs) and controls multiple cancer signaling pathways. YES1 is amplified and overexpressed in many tumor types, where it promotes cell proliferation, survival and invasiveness. Therefore, YES1 has been proposed as an emerging target in solid tumors. In addition, studies have shown that YES1 is a prognostic biomarker and a predictor of dasatinib activity. Several SFKs-targeting drugs have been developed and some of them have reached clinical trials. However, these drugs have encountered challenges to their utilization in the clinical practice in unselected patients due to toxicity and lack of efficacy. In the case of YES1, novel specific inhibitors have been developed and tested in preclinical models, with impressive antitumor effects. In this review, we summarize the structure and activation of YES1 and describe its role in cancer as a target and prognostic and companion biomarker. We also address the efficacy of SFKs inhibitors that are currently in clinical trials, highlighting the main hindrances for their clinical use. Current available information strongly suggests that inhibiting YES1 in tumors with high expression of this protein is a promising strategy against cancer.

Identification and robust estimation of swapped direct and indirect effects: Mediation analysis with unmeasured mediator-outcome confounding and intermediate confounding

Counterfactual-model-based mediation analysis can yield substantial insight into the causal mechanism through the assessment of natural direct effects (NDEs) and natural indirect effects (NIEs). However, the assumptions regarding unmeasured mediator-outcome confounding and intermediate mediator-outcome confounding that are required for the determination of NDEs and NIEs present practical challenges. To address this problem, we introduce an instrumental blocker, a novel quasi-instrumental variable, to relax both of these assumptions, and we define a swapped direct effect (SDE) and a swapped indirect effect (SIE) to assess the mediation. We show that the SDE and SIE are identical to the NDE and NIE, respectively, based on a causal interpretation. Moreover, the empirical expressions of the SDE and SIE are derived with and without an intermediate mediator-outcome confounder. Then, a multiply robust estimation method is derived to mitigate the model misspecification problem. We prove that the proposed estimator is consistent, asymptotically normal, and achieves the semiparametric efficiency bound. As an illustration, we apply the proposed method to genomic datasets of lung cancer to investigate the potential role of the epidermal growth factor receptor in the treatment of lung cancer.

Primaquine Inhibits the Endosomal Trafficking and Nuclear Localization of EGFR and Induces the Apoptosis of Breast Cancer Cells by Nuclear EGFR/Stat3-Mediated c-Myc Downregulation

Triple-negative breast cancer (TNBC) cells overexpress the epidermal growth factor receptor (EGFR). Nuclear EGFR (nEGFR) drives resistance to anti-EGFR therapy and is correlated with poor survival in breast cancer. Inhibition of EGFR nuclear translocation may be a reasonable approach for the treatment of TNBC. The anti-malarial drugs chloroquine and primaquine have been shown to promote an anticancer effect. The aim of the present study was to investigate the effect and mechanism of chloroquine- and primaquine-induced apoptosis of breast cancer cells. We showed that primaquine, a malaria drug, inhibits the growth, migration, and colony formation of breast cancer cells in vitro, and inhibits tumor growth in vivo. Primaquine induces damage to early endosomes and inhibits the nuclear translocation of EGFR. Primaquine inhibits the interaction of Stat3 and nEGFR and reduces the transcript and protein levels of c-Myc. Moreover, primaquine and chloroquine induce the apoptosis of breast cancer cells through c-Myc/Bcl-2 downregulation, induce early endosome damage and reduce nEGFR levels, and induce apoptosis in breast cancer through nEGFR/Stat3-dependent c-Myc downregulation. Our study of primaquine and chloroquine provides a rationale for targeting EGFR signaling components in the treatment of breast cancer.

Evidence for 2-Methoxyestradiol-Mediated Inhibition of Receptor Tyrosine Kinase RON in the Management of Prostate Cancer

2-Methoxyestradiol (2-ME₂) possesses anti-tumorigenic activities in multiple tumor models with acceptable tolerability profile in humans. Incomplete understanding of the mechanism has hindered its development as an anti-tumorigenic compound. We have identified for the first-time macrophage stimulatory protein 1 receptor (MST1R) as a potential target of 2-ME₂ in prostate cancer cells. Human tissue validation studies show that MST1R (a.k.a RON) protein levels are significantly elevated in prostate cancer tissues compared to adjacent normal/benign glands. Serum levels of macrophage stimulatory protein (MSP), a ligand for RON, is not only associated with the risk of disease recurrence, but also significantly elevated in samples from African American patients. 2-ME₂ treatment inhibited mechanical properties such as adhesion and elasticity that are associated with epithelial mesenchymal transition by downregulating mRNA expression and protein levels of MST1R in prostate cancer cell lines. Intervention with 2-ME₂ significantly reduced tumor burden in mice. Notably, global metabolomic profiling studies identified significantly higher circulating levels of bile acids in castrated animals that were decreased with 2-ME₂ intervention. In summary, findings presented in this manuscript identified MSP as a potential marker for predicting biochemical recurrence and suggest repurposing 2-ME₂ to target RON signaling may be a potential therapeutic modality for prostate cancer.

Profiling and Functional Analysis of Long Noncoding RNAs and mRNAs during Porcine Skeletal Muscle Development

Gene transcripts or mRNAs and long noncoding RNAs (lncRNAs) are differentially expressed during porcine skeletal muscle development. However, only a few studies have been conducted on skeletal muscle transcriptome in pigs based on timepoints according to the growth curve for porcine. Here, we investigated gene expression in Qingyu pigs at three different growth stages: the inflection point with the maximum growth rate (MGI), the inflection point of the gradually increasing stage to the rapidly increasing stage (GRI), and the inflection point of the rapidly increasing stage to the slowly increasing stage (RSI). Subsequently, we explored gene expression profiles during muscle development at the MGI, GRI and RSI stages by Ribo-Zero RNA sequencing. Qingyu pigs reached the MGI, GRI and RSI stages at 156.40, 23.82 and 288.97 days of age with 51.73, 3.14 and 107.03 kg body weight, respectively. A total of 14,530 mRNAs and 11,970 lncRNAs were identified at the three stages, and 645, 323 differentially expressed genes (DEGs) and 696, 760 differentially expressed lncRNAs (DELs) were identified in the GRI vs. MGI, and RSI vs. MGI, comparisons. Functional enrichment analysis revealed that genes involved in immune system development and energy metabolism (mainly relate to amino acid, carbohydrate and lipid) were enriched at the GRI and MGI stages, respectively, whereas genes involved in lipid metabolism were enriched at the RSI stage. We further characterized G1430, an abundant lncRNA. The full-length sequence (316 nt) of lncRNA G1430 was determined by rapid amplification of cDNA ends (RACE). Subcellular distribution analysis by quantitative real-time PCR (qRT-PCR) revealed that G1430 is a cytoplasmic lncRNA. Binding site prediction and dual luciferase assay showed that lncRNA G1430 directly binds to microRNA 133a (miR-133a). Our findings provide the basis for further investigation of the regulatory mechanisms and molecular genetics of muscle development in pigs.

Association between B-Myb proto-oncogene and the development of malignant tumors

B-Myb is a critical transcription factor in regulating cell cycle. Dysregulated expression of B-Myb promotes tumor formation and development. B-Myb is a proto-oncogene ubiquitously expressed in proliferating cells, which maintains normal cell cycle progression. It participates in cell apoptosis, tumorigenesis and aging. In addition, B-Myb is overexpressed in several malignant tumors, including breast cancer, lung cancer and hepatocellular carcinoma, and is associated with tumor development. B-Myb expression is also associated with the prognosis of patients with malignant tumors. Both microRNAs and E2F family of transcription factors (E2Fs) contribute to the function of B-Myb. The present review highlights the association between B-Myb and malignant tumors, and offers a theoretical reference for the diagnosis and treatment of malignant tumors.

Recent Advances of Functional Proteomics in Gastrointestinal Cancers- a Path towards the Identification of Candidate Diagnostic, Prognostic, and Therapeutic Molecular Biomarkers

Gastrointestinal (GI) cancer remains one of the common causes of morbidity and mortality. A high number of cases are diagnosed at an advanced stage, leading to a poor survival rate. This is primarily attributed to the lack of reliable diagnostic biomarkers and limited treatment options. Therefore, more sensitive, specific biomarkers and curative treatments are desirable. Functional proteomics as a research area in the proteomic field aims to elucidate the biological function of unknown proteins and unravel the cellular mechanisms at the molecular level. Phosphoproteomic and glycoproteomic studies have emerged as two efficient functional proteomics approaches used to identify diagnostic biomarkers, therapeutic targets, the molecular basis of disease and mechanisms underlying drug resistance in GI cancers. In this review, we present an overview on how functional proteomics may contribute to the understanding of GI cancers, namely colorectal, gastric, hepatocellular carcinoma and pancreatic cancers. Moreover, we have summarized recent methodological developments in phosphoproteomics and glycoproteomics for GI cancer studies.

Role of YES1 amplification in EGFR mutation-positive non-small cell lung cancer: Primary resistance to afatinib in a patient

Epidermal growth factor receptor (EGFR) mutation-positive non-small cell lung cancer (NSCLC) patients benefit from EGFR tyrosine kinase inhibitors (TKIs), while some patients demonstrate a resistance to EGFR-TKIs. In the case reported here, the NSCLC patient harboring an EGFR-sensitive mutation and YES1 amplification was treated with afatinib as first-line therapy, but was found to have progressive disease four weeks later. During subsequent chemotherapy, this patient's disease progressed rapidly. Mechanisms of primary resistance to EGFR-TKIs remain unclear. This case suggested that YES1 amplification might be associated with primary resistance to EGFR-TKIs and YES1 amplification might be a negative predictor of EGFR-TKI treatment in NSCLC patients harboring EGFR sensitive mutations.

Erlotinib is effective against FLT3-ITD mutant AML and helps to overcome intratumoral heterogeneity via targeting FLT3 and Lyn

Erlotinib has potential therapeutic effect on acute myeloid leukemia (AML) in patients, but the mechanism is not clear. Effective tumor biomarkers for erlotinib in the treatment of AML remain poorly defined. Here, we demonstrate that erlotinib in vitro significantly inhibits the growth of the FLT3-ITD mutant AML cell MV4-11 and Ba/F3-FLT3-ITD cell via targeting FLT3, a certified valid target for the effective treatment of AML. In vivo, oral administration of erlotinib at 100 mg/kg/day induced rapid MV4-11 tumor regression and significantly prolonged the survival time of bone marrow engraftment AML mice via inhibiting the FLT3 signal. Thus, the therapeutic benefits of erlotinib on AML are due to its ability to target FLT3. FLT3-ITD mutation is an effective biomarker for erlotinib during AML treatment. In addition, we also demonstrate that erlotinib inhibits the activity of AML cell KG-1 (no FLT3 expression) by targeting Lyn. Recently, single cell analysis demonstrated that intratumoral heterogeneity are one of the contributors in the relapse and FLT3 inhibitor resistance. Erlotinib could effectively inhibit the MV4-11 cells via targeting FLT3, and inhibit KG-1 cells via targeting Lyn. Therefore, Erlotinib also has the potential to overcome intratumoral heterogeneity via targeting FLT3 and Lyn.

Discovery of Cell-Surface Vimentin (CSV) as a Sarcoma Target and Development of CSV-Targeted IL12 Immune Therapy

This chapter discusses a novel target of osteosarcoma (OS), cell-surface vimentin (CSV), and a novel generation of interleukin-12 (IL12), CSV-targeted IL12, for treating OS tumor metastasis. Vimentin is a known intracellular structural protein for mesenchymal cells but is also documented in tumor cells. Our recent study definitively revealed that vimentin can be translocated to the surface of very aggressive tumor cells, such as metastatic cells. This CSV property allows investigators to capture circulating tumor cells (CTCs) across any type of tumor, including OS. CTCs are known as the seeds of metastasis; therefore, targeting these cells using CSV is a logical approach for use in a metastatic OS setting. Interestingly, we found that the peptide VNTANST can bind to CSV when fused to the p40 subunit encoding the DNA of IL12. Systemic delivery of this CSV-targeted IL12 immune therapy inhibited OS metastasis and relapse in a mouse tumor model as detailed in this chapter. This CSV-targeted delivery of IL12 also reduced toxicity of IL12. In summary, this chapter details a novel approach for safe IL12 immune therapy via targeting CSV.

YES1 Drives Lung Cancer Growth and Progression and Predicts Sensitivity to Dasatinib

Rationale: The characterization of new genetic alterations is essential to assign effective personalized therapies in non-small cell lung cancer (NSCLC). Furthermore, finding stratification biomarkers is essential for successful personalized therapies. Molecular alterations of YES1, a member of the SRC (proto-oncogene tyrosine-protein kinase Src) family kinases (SFKs), can be found in a significant subset of patients with lung cancer.Objectives: To evaluate YES1 (v-YES-1 Yamaguchi sarcoma viral oncogene homolog 1) genetic alteration as a therapeutic target and predictive biomarker of response to dasatinib in NSCLC.Methods: Functional significance was evaluated by in vivo models of NSCLC and metastasis and patient-derived xenografts. The efficacy of pharmacological and genetic (CRISPR [clustered regularly interspaced short palindromic repeats]/Cas9 [CRISPR-associated protein 9]) YES1 abrogation was also evaluated. In vitro functional assays for signaling, survival, and invasion were also performed. The association between YES1 alterations and prognosis was evaluated in clinical samples.Measurements and Main Results: We demonstrated that YES1 is essential for NSCLC carcinogenesis. Furthermore, YES1 overexpression induced metastatic spread in preclinical in vivo models. YES1 genetic depletion by CRISPR/Cas9 technology significantly reduced tumor growth and metastasis. YES1 effects were mainly driven by mTOR (mammalian target of rapamycin) signaling. Interestingly, cell lines and patient-derived xenograft models with YES1 gene amplifications presented a high sensitivity to dasatinib, an SFK inhibitor, pointing out YES1 status as a stratification biomarker for dasatinib response. Moreover, high YES1 protein expression was an independent predictor for poor prognosis in patients with lung cancer.Conclusions: YES1 is a promising therapeutic target in lung cancer. Our results provide support for the clinical evaluation of dasatinib treatment in a selected subset of patients using YES1 status as predictive biomarker for therapy.

MicroRNA-133a inhibits the proliferation of non-small cell lung cancer by targeting YES1

Previous studies have reported that microRNA-133a (miR-133a) is involved in the pathogenesis of human cancers. This study investigated the effect of miR-133a on cell proliferation in non-small cell lung cancer (NSCLC). The expression of miR-133a and YES proto-oncogene 1 (YES1) was detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) assay. The CCK-8 assay was used to measure cell proliferation. The relationship between miR-133a and YES1 was confirmed by dual luciferase assay. Downregulation of miR-133a was identified in NSCLC and correlated with poor prognosis in NSCLC patients. Moreover, the overexpression of miR-133a inhibited proliferation of NSCLC cells. YES1 was also confirmed as a direct target of miR-133a. Downregulation of YES1 was found to inhibit cell proliferation in NSCLC. By contrast, the upregulation of YES1 abolished the inhibitory effect of miR-133a on cell proliferation in NSCLC. miR-133a inhibited cell proliferation in NSCLC by targeting YES1, indicating that miR-133a can be used as an indicator of prognosis in NSCLC patients.

Dysregulated Redox Regulation Contributes to Nuclear EGFR Localization and Pathogenicity in Lung Cancer

Lung cancers are frequently characterized by inappropriate activation of epidermal growth factor receptor (EGFR)-dependent signaling and epigenetic silencing of the NADPH oxidase (NOX) enzyme DUOX1, both potentially contributing to worse prognosis. Based on previous findings linking DUOX1 with redox-dependent EGFR activation, the present studies were designed to evaluate whether DUOX1 silencing in lung cancers may be responsible for altered EGFR regulation. In contrast to normal epithelial cells, EGF stimulation of lung cancer cell lines that lack DUOX1 promotes EGF-induced EGFR internalization and nuclear localization, associated with induction of EGFR-regulated genes and related tumorigenic outcomes. Each of these outcomes could be reversed by overexpression of DUOX1 or enhanced by shRNA-dependent DUOX1 silencing. EGF-induced nuclear EGFR localization in DUOX1-deficient lung cancer cells was associated with altered dynamics of cysteine oxidation of EGFR, and an overall reduction of EGFR cysteines. These various outcomes could also be attenuated by silencing of glutathione S-transferase P1 (GSTP1), a mediator of metabolic alterations and drug resistance in various cancers, and a regulator of cysteine oxidation. Collectively, our findings indicate DUOX1 deficiency in lung cancers promotes dysregulated EGFR signaling and enhanced GSTP1-mediated turnover of EGFR cysteine oxidation, which result in enhanced nuclear EGFR localization and tumorigenic properties.

Prognostic implications of MYBL2 in resected Chinese gastric adenocarcinoma patients

Background and aim

Gastric cancer (GC), a malignant tumor worldwide, is mostly diagnosed at an advanced stage. We selected the oncogene encoding transcription factors MYBL2 to investigate the connection between MYBL2 expression and GC prognosis.

Materials and methods

MYBL2 mRNA and protein expression were measured by real-time PCR and immunohistochemistry, respectively. The relationship between MYBL2 protein expression and survival time was estimated by the Kaplan-Meier analysis. Cox proportional hazards model was used to evaluate the prognostic impact of MYBL2 expression.

Results

The overexpression of MYBL2 was related to tumor cell differentiation, Lauren type, and metastasis of lymph nodes (P<0.05). In the MYBL2 overexpression group, the median disease free survival was even poorer (P=0.000) and it comes to median overall survival (P=0.000). The study showed that MYBL2 expression was an independent hazard for disease free survival (P=0.004).

Conclusion

The results of this study suggest that MYBL2 could indicate a promisingly prognostic biomarker for GC patients.

[Nuclear EGFR: a new mode of oncogenic signalling in cancer]

EGFR (Epidermal Growth Factor Receptor) is one of the most studied molecules in biology. From its early identification and cloning to the discovery of its role in cancer, it has been at the forefront of our understanding of Receptor Tyrosine Kinase (RTK) and cell signals that induce homeostasis, but when overexpressed, facilitate tumorigenesis. While the biological functions of EGFR traditionally involve the activation of a signaling network from the plasma membrane that includes activation of the RAS/MAPK/ERK, PI3K/AKT and STATS pathways, a new mode of EGFR signaling has been progressively decoded in which membrane-associated EGFR is transported after endocytosis from cell surface to the nucleus through endocytosis, retrograde trafficking to the Golgi, the endoplasmic reticulum and the inner nuclear membrane through a series of proteic interactions. In the nucleus, EGFR acts as a transcriptional regulator, a kinase and a physical interactor, transmits signals and is involved in multiple biological functions, including cell proliferation, tumor progression, DNA repair and replication, and resistance to cancer therapies. In this review, we will summarize current knowledge of the EGFR nuclear signaling network, including how it is delivered to the nucleus, the functions it serves in the nucleus and how these functions affect cancer progression, survival and the response to treatment.

The Drosophila Epidermal Growth Factor Receptor does not act in the nucleus

Mammalian members of the ErbB family, including the epidermal growth factor receptor (EGFR), can regulate transcription, DNA replication and repair through nuclear entry of either the full-length proteins or their cleaved cytoplasmic domains. In cancer cells, these nuclear functions contribute to tumor progression and drug resistance. Here, we examined whether the single Drosophila EGFR can also localize to the nucleus. A chimeric EGFR protein fused at its cytoplasmic C-terminus to DNA-binding and transcriptional activation domains strongly activated transcriptional reporters when overexpressed in cultured cells or in vivo However, this activity was independent of cleavage and endocytosis. Without an exogenous activation domain, EGFR fused to a DNA-binding domain did not activate or repress transcription. Addition of the same DNA-binding and transcriptional activation domains to the endogenous Egfr locus through genome editing led to no detectable reporter expression in wild-type or oncogenic contexts. These results show that, when expressed at physiological levels, the cytoplasmic domain of the Drosophila EGFR does not have access to the nucleus. Therefore, nuclear EGFR functions are likely to have evolved after vertebrates and invertebrates diverged.

The tyrosine phosphorylated pro-survival form of Fas intensifies the EGF-induced signal in colorectal cancer cells through the nuclear EGFR/STAT3-mediated pathway

Tyrosine phosphorylation of Fas (TNFRSF6/CD95) in its death domain turns off Fas-mediated apoptosis, turns on the pro-survival signal, and has implications in different cancers types. We show here that Fas in its pro-survival state, phosphorylated at Y291 (pY291-Fas), functionally interacts with the epidermal growth factor receptor (EGFR), a key cancer-driving protein and major therapeutic target. Using an evolution-guided pY291-Fas proxy, RNA interference, and site-specific phospho-protein detection, we show that pY291-Fas significantly intensifies EGFR signaling in anti-EGFR-resistant colorectal cancer cells via the Yes-1/STAT3-mediated pathway. The pY291-Fas is essential for the EGF-induced formation of the Fas-mediated nuclear EGFR/STAT3 signaling complex consisting of Fas, EGFR, Yes-1, Src, and STAT3. The pY291-Fas accumulates in the nucleus upon EGF treatment and promotes the nuclear localization of phospho-EGFR and phospho-STAT3, the expression of cyclin D1, the activation of STAT3-mediated Akt and MAPK pathways, and cell proliferation and migration. This novel cancer-promoting function of phosphorylated Fas in the nuclear EGFR signaling constitutes the foundation for developing pro-survival-Fas targeted anti-cancer therapies to overcome disease recurrence in patients with anti-EGFR resistant cancer.

Stress-Induced Phosphorylation of Nuclear YB-1 Depends on Nuclear Trafficking of p90 Ribosomal S6 Kinase

Ionizing radiation (IR) and epidermal growth factor (EGF) stimulate Y-box binding protein-1 (YB-1) phosphorylation at Ser-102 in KRAS wild-type (KRASwt) cells, whereas in KRAS mutated (KRASmut) cells, YB-1 is constitutively phosphorylated, independent of IR or EGF. YB-1 activity stimulates the repair of IR-induced DNA double-strand breaks (DSBs) in the nucleus. Thus far, the YB-1 nuclear translocation pattern after cell exposure to various cellular stressors is not clear. In the present study, we investigated the pattern of YB-1 phosphorylation and its possible translocation to the nucleus in KRASwt cells after exposure to IR, EGF treatment, and conditional expression of mutated KRAS(G12V). IR, EGF, and conditional KRAS(G12V) expression induced YB-1 phosphorylation in both the cytoplasmic and nuclear fractions of KRASwt cells. None of the stimuli induced YB-1 nuclear translocation, while p90 ribosomal s6 kinase (RSK) translocation was enhanced in KRASwt cells after any of the stimuli. EGF-induced RSK translocation to the nucleus and nuclear YB-1 phosphorylation were completely blocked by the EGF receptor kinase inhibitor erlotinib. Likewise, RSK inhibition blocked RSK nuclear translocation and nuclear YB-1 phosphorylation after irradiation and KRAS(G12V) overexpression. In summary, acute stimulation of YB-1 phosphorylation does not lead to YB-1 translocation from the cytoplasm to the nucleus. Rather, irradiation, EGF treatment, or KRAS(G12V) overexpression induces RSK activation, leading to its translocation to the nucleus, where it activates already-existing nuclear YB-1. Our novel finding illuminates the signaling pathways involved in nuclear YB-1 phosphorylation and provides a rationale for designing appropriate targeting strategies to block YB-1 in oncology as well as in radiation oncology.

Honokiol Inhibits Proliferation, Invasion and Induces Apoptosis Through Targeting Lyn Kinase in Human Lung Adenocarcinoma Cells

Honokiol is a natural compound with small molecular structure and extracted from bark of magnolia trees. The biological activities of honokiol include anti-oxidation, anti-inflammation as well as anti-tumor. However, their mechanism remains unknown. In this study, A549 cell line and EGFR-mutant cell line PC-9 with higher expression level of Lyn than A549 cells were used to assess the anti-tumor effects of honokiol. As shown in this study, honokiol is an effective drug on inhibiting proliferation and inducing apoptosis depended on Lyn and EGFR signal pathway regulated by Lyn, and its efficacy is stronger in PC-9 cells than A549 cells. In addition, this anti-tumor effect in PC-9 cells was weakened by Lyn-knockdown. Taken together, this study indicated the mechanism of honokiol on lung adenocarcinoma and provides a possibility of honokiol as an effective anti-tumor medicine.

LYN expression predicts the response to dasatinib in a subpopulation of lung adenocarcinoma patients

Therapies targeting SRC family kinases (SFKs) have shown efficacy in treating non-small cell lung cancer (NSCLC). However, recent clinical trials have found that the SFK inhibitor dasatinib is ineffective in some patient cohorts. Regardless, dasatinib treatment may benefit some NSCLC patient subgroups. Here, we investigated whether expression of LYN, a member of the SFK family, is associated with patient survival, the efficacy of dasatinib, and/or NSCLC cell viability. LYN expression was associated with poor overall survival in a multivariate analysis, and this association was strongest in non-smoker female patients with adenocarcinoma (ADC). In lung ADC cells, LYN expression enhanced cell proliferation, migration, and invasion. Dasatinib inhibited LYN activity and decreased cell viability in LYN-positive ADC cell lines and xenografts. Additionally, we identified the SFKs SRC and YES as candidate dasatinib targets in LYN-negative ADC cell lines. Our findings suggest that LYN is a useful prognostic marker and a selective target of dasatinib therapy in the lung ADC subpopulation especially in female non-smokers with lung ADC.

Inhibition of SLC1A5 sensitizes colorectal cancer to cetuximab

Cetuximab resistance is a key barrier in treating metastatic colorectal cancer (mCRC). Targeting of metabolic resources import could resensitize drug-resistant cancer cells to anticancer treatments. Here we showed that the expression of the glutamine transporter solute carrier 1 family member 5 (SLC1A5) in clinical CRC samples of patients resisted to cetuximab was significantly higher than in those of patients responded to cetuximab. Inhibition of SLC1A5 by shRNA-mediated gene silencing or pharmacological inhibitor significantly suppressed the growth of CRC. Moreover, inhibition of SLC1A5 significantly enhanced the inhibitory efficacy of cetuximab on CRC proliferation both in vitro and in vivo. Mechanistically, SLC1A5 inhibition facilitated EGFR degradation through the ubiquitin-proteasome pathway, and decreased the expression of nuclear EGFR, both of which might have contribution to the improved response to cetuximab. This study provides the metabolic molecule SLC1A5 as a potential therapeutic target to increase the efficacy of cetuximab on CRC.

A Small Organic Molecule Blocks EGFR Transport into the Nucleus by the Nonclassical Pathway Resulting in Repression of Cancer Invasion

In addition to the traditional epidermal growth factor receptor (EGFR) signaling pathways, nuclear EGFR has been shown to control multiple cellular functions, including cell proliferation and invasion. It has been reported that EGFR is transported into the nucleus after forming a complex with KPNA/KPNB1 or KPNB1. Herein, it is shown that EGFR can interact with both KP and KPNA, but EGF-activated EGFR mostly binds with KPNB1 through the pull-down assay. Also, a small organic molecule (1), an effective binder of KPNB1, inhibits the interaction between EGFR and KPNB1 in the nonclassical transport pathway, but not KPNA. Furthermore, treatment of cancer cells with 1 noticeably blocks the nuclear entry of EGFR, which results in significant suppression of invasion by lung cancer H1299 cells. These findings show that 1 is an effective inhibitor of EGFR/KPNB1 interactions in vitro, it may be used in cellular studies as a tool to determine the role of nuclear EGFR, and it is a drug candidate.

A small molecule induces integrin β4 nuclear translocation and apoptosis selectively in cancer cells with high expression of integrin β4

Increased integrin β4 (ITGB4) level is accompanied by malignant progression of multiple carcinomas. However, selective therapeutic strategies against cancer cells expressing a high level of ITGB4 have not been reported. Here, for the first time, we report that a chiral small molecule, SEC, selectively promotes apoptosis in cancer cells expressing a high level of ITGB4 by inducing ITGB4 nuclear translocation. Nuclear ITGB4 can bind to the ATF3 promoter region and activate the expression of ATF3, then upregulate the downstream pro-apoptosis genes. Furthermore, SEC promoted the binding of annexin A7 (ANXA7) to ITGB4 and increased ANXA7 GTPase activity. Activated ANXA7 promoted ITGB4 nuclear translocation by triggering ITGB4 phosphorylation at Y1494. SEC also inhibited the growth of xenograft tumors in the avian embryo model. We identified a small molecule, SEC, with selective pro-apoptosis effects on cancer cells with high expression of ITGB4, both in vitro and in vivo, by triggering the binding of ITGB4 and ANXA7, ITGB4 nuclear trafficking, and pro-apoptosis gene expression.

Epigenetic silencing of tumor suppressor candidate 3 confers adverse prognosis in early colorectal cancer

Colorectal cancer (CRC) is a biologically and clinically heterogeneous disease. Even though many recurrent genomic alterations have been identified that may characterize distinct subgroups, their biological impact and clinical significance as prognostic indicators remain to be defined. The tumor suppressor candidate-3 (TUSC3/N33) locates to a genomic region frequently deleted or silenced in cancers. TUSC3 is a subunit of the oligosaccharyltransferase (OST) complex at the endoplasmic reticulum (ER) which catalyzes bulk N-glycosylation of membrane and secretory proteins. However, the consequences of TUSC3 loss are largely unknown. Thus, the aim of the study was to characterize the functional and clinical relevance of TUSC3 expression in CRC patients' tissues (n=306 cases) and cell lines. TUSC3 mRNA expression was silenced by promoter methylation in 85 % of benign adenomas (n=46 cases) and 35 % of CRCs (n =74 cases). Epidermal growth factor receptor (EGFR) was selected as one exemplary ER-derived target protein of TUSC3-mediated posttranslational modification. We found that TUSC3 inhibited EGFR-signaling and promoted apoptosis in human CRC cells, whereas TUSC3 siRNA knock-down increased EGFR-signaling. Accordingly, in stage I/II node negative CRC patients (n=156 cases) loss of TUSC3 protein expression was associated with poor overall survival. In sum, our data suggested that epigenetic silencing of TUSC3 may be useful as a molecular marker for progression of early CRC.

Deep Phospho- and Phosphotyrosine Proteomics Identified Active Kinases and Phosphorylation Networks in Colorectal Cancer Cell Lines Resistant to Cetuximab

Abnormality in cellular phosphorylation is closely related to oncogenesis. Thus, kinase inhibitors, especially tyrosine kinase inhibitors (TKIs), have been developed as anti-cancer drugs. Genomic analyses have been used in research on TKI sensitivity, but some types of TKI resistance have been unclassifiable by genomic data. Therefore, global proteomic analysis, especially phosphotyrosine (pY) proteomic analysis, could contribute to predict TKI sensitivity and overcome TKI-resistant cancer. In this study, we conducted deep phosphoproteomic analysis to select active kinase candidates in colorectal cancer intrinsically resistant to Cetuximab. The deep phosphoproteomic data were obtained by performing immobilized metal-ion affinity chromatography-based phosphoproteomic and highly sensitive pY proteomic analyses. Comparison between sensitive (LIM1215 and DLD1) and resistant cell lines (HCT116 and HT29) revealed active kinase candidates in the latter, most of which were identified by pY proteomic analysis. Remarkably, genomic mutations were not assigned in most of these kinases. Phosphorylation-based signaling network analysis of the active kinase candidates indicated that SRC-PRKCD cascade was constitutively activated in HCT116 cells. Treatment with an SRC inhibitor significantly inhibited proliferation of HCT116 cells. In summary, our results based on deep phosphoproteomic data led us to propose novel therapeutic targets against cetuximab resistance and showed the potential for anti-cancer therapy.

miR-140-5p suppresses the proliferation, migration and invasion of gastric cancer by regulating YES1

BACKGROUND

The aberrant expression of microRNA-140-5p (miR-140-5p) has been described in gastric cancer (GC). However, the role of miR-140-5p in GC remains unclear. In this study, the prognostic relevance of miR-140-5p in GC was investigated and YES1 was identified as a novel target of miR-140-5p in regulating tumor progression.

METHODS

miR-140-5p level was determined in 20 paired frozen specimens through quantitative real-time PCR, and analyzed in tissue microarrays through in situ hybridization. The target of miR-140-5p was verified through a dual luciferase reporter assay, and the effects of miR-140-5p on phenotypic changes in GC cells were investigated in vitro and in vivo.

RESULTS

Compared with that in adjacent normal tissues, miR-140-5p expression decreased in cancerous tissues. The downregulated miR-140-5p in 144 patients with GC was significantly correlated with the reduced overall survival of these patients. miR-140-5p could inhibit GC cell proliferation, migration and invasion by directly targeting 3'-untranlated region of YES1. miR-140-5p could also remarkably reduce the tumor size in GC xenograft mice.

CONCLUSIONS

miR-140-5p serves as a potential prognostic factor in patients with GC, and miR-140-5p mediated YES1 inhibition is a novel mechanism behind the suppressive effects of miR-140-5p in GC.

Identification of transcription factors that may reprogram lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma is one of most threatening disease to human health. Although many efforts have been devoted to its genetic study, few researches have been focused on the transcription factors which regulate tumor initiation and progression by affecting multiple downstream gene transcription. It is proved that proper transcription factors may mediate the direct reprogramming of cancer cells, and reverse the tumorigenesis on the epigenetic and transcription levels.

METHODS

In this paper, a computational method is proposed to identify the core transcription factors that can regulate as many as possible lung adenocarcinoma associated genes with as little as possible redundancy. A greedy strategy is applied to find the smallest collection of transcription factors that can cover the differentially expressed genes by its downstream targets. The optimal subset which is mostly enriched in the differentially expressed genes is then selected.

RESULTS

Seven core transcription factors (MCM4, VWF, ECT2, RBMS3, LIMCH1, MYBL2 and FBXL7) are detected, and have been reported to contribute to tumorigenesis of lung adenocarcinoma. The identification of the transcription factors provides a new insight into its oncogenic role in tumor initiation and progression, and benefits the discovery of functional core set that may reverse malignant transformation and reprogram cancer cells.

RETRACTED: The receptor tyrosine kinase AXL mediates nuclear translocation of the epidermal growth factor receptor

The epidermal growth factor receptor (EGFR) is a therapeutic target in patients with various cancers. Unfortunately, resistance to EGFR-targeted therapeutics is common. Previous studies identified two mechanisms of resistance to the EGFR monoclonal antibody cetuximab. Nuclear translocation of EGFR bypasses the inhibitory effects of cetuximab, and the receptor tyrosine kinase AXL mediates cetuximab resistance by maintaining EGFR activation and downstream signaling. Thus, we hypothesized that AXL mediated the nuclear translocation of EGFR in the setting of cetuximab resistance. Cetuximab-resistant clones of non-small cell lung cancer in culture and patient-derived xenografts in mice had increased abundance of AXL and nuclear EGFR (nEGFR). Cellular fractionation analysis, super-resolution microscopy, and electron microscopy revealed that genetic loss of AXL reduced the accumulation of nEGFR. SRC family kinases (SFKs) and HER family ligands promote the nuclear translocation of EGFR. We found that AXL knockdown reduced the expression of the genes encoding the SFK family members YES and LYN and the ligand neuregulin-1 (NRG1). AXL knockdown also decreased the interaction between EGFR and the related receptor HER3 and accumulation of HER3 in the nucleus. Overexpression of LYN and NRG1 in cells depleted of AXL resulted in accumulation of nEGFR, rescuing the deficit induced by lack of AXL. Collectively, these data uncover a previously unrecognized role for AXL in regulating the nuclear translocation of EGFR and suggest that AXL-mediated SFK and NRG1 expression promote this process.

Intra-tumor AvidinOX allows efficacy of low dose systemic biotinylated Cetuximab in a model of head and neck cancer

For locally advanced and metastatic head and neck squamous cell carcinoma (HNSCC), the current clinical use of Cetuximab in chemo/radiotherapy protocols is often associated to severe systemic toxicity. Here we report in vitro data in human FaDu pharynx SCC cells, showing that inactive concentrations of biotinylated Cetuximab (bCet) become active upon anchorage to AvidinOX on the surface of tumor cells. AvidinOX-anchored bCet induces apoptosis and DNA damage as well as specific inhibition of signaling, degradation and abrogation of nuclear translocation of EGFR. In the mouse model of FaDu cancer, we show that intra-tumor injection of AvidinOX allows anti-tumor activity of an otherwise inactive, intraperitoneally delivered, low dose bCet. Consistently with in vitro data, in vivo tumor inhibition is associated to induction of apoptosis, DNA damage and reduced angiogenesis. AvidinOX is under clinical investigation for delivering radioactive biotin to inoperable tumors (ClinicalTrials.gov NCT02053324) and present data support its use for the local treatment of HNSCC in combination with systemic administration of low dose bCet.

Co-targeting of EGF receptor and neuropilin-1 overcomes cetuximab resistance in pancreatic ductal adenocarcinoma with integrin β1-driven Src-Akt bypass signaling

Pancreatic ductal adenocarcinoma (PDAC) cells usually overexpress the epidermal growth factor receptor (EGFR); however, most are resistant to the anti-EGFR monoclonal antibody, cetuximab. In this study, we report that the molecular mechanism of resistance to cetuximab in PDAC cells is mediated by the overexpression of active integrin β1 with downstream Src-Akt activation; this triggers an EGFR ligand-independent proliferation signaling, bypassing EGFR-blocking effect. Knockdown of integrin β1 or inhibition of Src or Akt sensitized cetuximab-resistant (Ctx^R) PDAC cells to cetuximab. We found that neuropilin-1 (NRP1) physically interacts with active integrin β1, but not inactive one, on the cell surface. To inhibit active integrin β1-driven signaling by targeting NRP1, while suppressing EGFR signaling, we generated an EGFR and NRP1 dual targeting antibody, Ctx-TPP11, by genetic fusion of the NRP1-targeting peptide, TPP11, to the C terminus of the cetuximab heavy chain (Ctx-TPP11). We demonstrate that Ctx-TPP11 efficiently inhibited the growth of Ctx^R PDAC cells, in vitro and in vivo. The sensitization mechanism involved downregulating active integrin β1 levels through NRP1-coupled internalization mediated by the TPP11 moiety, leading to the inhibition of active integrin β1-driven bypass signaling. Our findings identify aberrant active integrin β1-driven Src-Akt hyperactivation as a primary resistance mechanism to cetuximab in PDAC cells and offer an effective therapeutic strategy to overcome this resistance using an EGFR and NRP1 dual targeting antibody.

LYN Kinase in the Tumor Microenvironment Is Essential for the Progression of Chronic Lymphocytic Leukemia

Survival of chronic lymphocytic leukemia (CLL) cells strictly depends on the support of an appropriate tumor microenvironment. Here, we demonstrate that LYN kinase is essential for CLL progression. Lyn deficiency results in a significantly reduced CLL burden in vivo. Loss of Lyn within leukemic cells reduces B cell receptor (BCR) signaling including BTK phosphorylation, but surprisingly does not affect leukemic cell expansion. Instead, syngeneic CLL transplantation of CLL cells into Lyn- or Btk-deficient recipients results in a strongly delayed leukemic progression and prolonged survival. Moreover, Lyn deficiency in macrophages hinders nursing functions for CLL cells, which is mediated by direct contact rather than secretion of soluble factors. Taken together, LYN and BTK seem essential for the formation of a microenvironment supporting leukemic growth.

Nuclear expression of Lyn, a Src family kinase member, is associated with poor prognosis in renal cancer patients

Background

8000 cases of renal cancer are diagnosed each year in the UK, with a five-year survival rate of 50 %. Treatment options are limited; a potential therapeutic target is the Src family kinases (SFKs). SFKs have roles in multiple oncogenic processes and promote metastases in solid tumours. The aim of this study was to investigate SFKs as potential therapeutic targets for clear cell renal cell carcinoma (ccRCC).

Methods

SFKs expression was assessed in a tissue microarray consisting of 192 ccRCC patients with full clinical follow-up. SFK inhibitors, dasatinib and saracatinib, were assessed in early ccRCC cell lines, 786-O and 769-P and a metastatic ccRCC cell line, ACHN (± Src) for effects on protein expression, apoptosis, proliferation and wound healing.

Results

High nuclear expression of Lyn and the downstream marker of activation, paxillin, were associated with decreased patient survival. Conversely, high cytoplasmic expression of other SFK members and downstream marker of activation, focal adhesion kinase (FAK) were associated with increased patient survival. Treatment of non-metastatic 786-O and 769-P cells with dasatinib, dose dependently reduced SFK activation, shown via SFK (Y⁴¹⁹) and FAK (Y⁸⁶¹) phosphorylation, with no effect in metastatic ACHN cells. Dasatinib also increased apoptosis, while decreasing proliferation and migration in 786-O and 769-P cell lines, both in the presence and absence of Src protein.

Conclusions

Our data suggests that nuclear Lyn is a potential therapeutic target for ccRCC and dasatinib affects cellular functions associated with cancer progression via a Src kinase independent mechanism.

Use of mechanistic models to integrate and analyze multiple proteomic datasets

Proteins in cell signaling networks tend to interact promiscuously through low-affinity interactions. Consequently, evaluating the physiological importance of mapped interactions can be difficult. Attempts to do so have tended to focus on single, measurable physicochemical factors, such as affinity or abundance. For example, interaction importance has been assessed on the basis of the relative affinities of binding partners for a protein of interest, such as a receptor. However, multiple factors can be expected to simultaneously influence the recruitment of proteins to a receptor (and the potential of these proteins to contribute to receptor signaling), including affinity, abundance, and competition, which is a network property. Here, we demonstrate that measurements of protein copy numbers and binding affinities can be integrated within the framework of a mechanistic, computational model that accounts for mass action and competition. We use cell line-specific models to rank the relative importance of protein-protein interactions in the epidermal growth factor receptor (EGFR) signaling network for 11 different cell lines. Each model accounts for experimentally characterized interactions of six autophosphorylation sites in EGFR with proteins containing a Src homology 2 and/or phosphotyrosine-binding domain. We measure importance as the predicted maximal extent of recruitment of a protein to EGFR following ligand-stimulated activation of EGFR signaling. We find that interactions ranked highly by this metric include experimentally detected interactions. Proteins with high importance rank in multiple cell lines include proteins with recognized, well-characterized roles in EGFR signaling, such as GRB2 and SHC1, as well as a protein with a less well-defined role, YES1. Our results reveal potential cell line-specific differences in recruitment.

Non-canonical signaling mode of the epidermal growth factor receptor family

Epidermal growth factor receptor (EGFR) and its family members are key players in both physiological and pathological settings for which they are well recognized as models for investigating the functions and regulations of other membrane receptor tyrosine kinases (RTKs) and serve as therapeutic targets critical to clinical need and fundamental research. The canonical view of the pivotal functions in the EGFR family has been well documented as being an initiator of signaling amplification cascades from the plasma membrane to different subcellular compartments via receptor endocytic trafficking, intermolecular interaction, and kinase-substrate reaction in a temporalspatial manner. However, several lines of evidence have identified non-canonical roles of the EGFR family, acting as a transcriptional factor and a chromatin regulator in the nucleus to regulate gene expression, DNA replication, and DNA damage repair. Moreover, the EGFR family can even exert its impact outside the host cell through exosomal vesicle secretion. The emerging concept of the non-canonical roles of the EGFR family reveals an astonishing and elaborate scheme on the molecular functions of membrane RTKs, offering new insights into the receptor biology as well as the development of comprehensive therapeutic strategies in the future.

Phosphotyrosine profiling identifies ephrin receptor A2 as a potential therapeutic target in esophageal squamous-cell carcinoma

Esophageal squamous‐cell carcinoma (ESCC) is one of the most common malignancies in Asia. Currently, surgical resection of early‐stage tumor is the best available treatment. However, most patients present late when surgery is not an option. Data suggest that chemotherapy regimens are inadequate for clinical management of advanced cancer. Targeted therapy has emerged as one of the most promising approaches to treat several malignancies. A prerequisite for developing targeted therapy is prior knowledge of proteins and pathways that drive proliferation in malignancies. We carried out phosphotyrosine profiling across four different ESCC cell lines and compared it to non‐neoplastic Het‐1A cell line to identify activated tyrosine kinase signaling pathways in ESCC. A total of 278 unique phosphopeptides were identified across these cell lines. This included several tyrosine kinases and their substrates that were hyperphosphorylated in ESCC. Ephrin receptor A2 (EPHA2), a receptor tyrosine kinase, was hyperphosphorylated in all the ESCC cell lines used in the study. EPHA2 is reported to be oncogenic in several cancers and is also known to promote metastasis. Immunohistochemistry‐based studies have revealed EPHA2 is overexpressed in nearly 50% of ESCC. We demonstrated EPHA2 as a potential therapeutic target in ESCC by carrying out siRNA‐based knockdown studies. Knockdown of EPHA2 in ESCC cell line TE8 resulted in significant decrease in cell proliferation and invasion, suggesting it is a promising therapeutic target in ESCC that warrants further evaluation.

PML represses lung cancer metastasis by suppressing the nuclear EGFR-mediated transcriptional activation of MMP2

Promyelocytic leukemia protein (PML) is emerging as an important tumor suppressor. Its expression is lost during the progression of several types of cancer, including lung cancer. The EGF receptor (EGFR), a membrane-bound receptor tyrosine kinase, transduces intracellular signals responsible for cell proliferation, differentiation and migration. EGFR activity is frequently abnormally upregulated in lung adenocarcinoma (LAC) and thus is considered to be a driving oncogene for LAC. EGFR translocates into the nucleus and transcriptionally activates genes, such as CCND1, that promote cell growth. Recently, we demonstrated that PML interacted with nuclear EGFR (nEGFR) and suppressed the nEGFR-mediated transcriptional activation of CCND1 in lung cancer cells, thereby restraining cell growth. When we further investigated the interplay between PML and EGFR in lung cancer metastasis, we found that the matrix metalloprotease-2 gene (MMP2) was a novel nEGFR target gene and was repressed by PML. We provide evidence that nEGFR bound to the AT-rich sequence (ATRS) in the MMP2 promoter and enhanced its transcriptional activity. In addition, we demonstrated that PML repressed nEGFR-induced MMP2 transcription and reduced cell invasion. PML was recruited by nEGFR to the MMP2 promoter where it reduced histone acetylation, leading to the transcriptional repression of MMP2. Finally, we demonstrated that PML upregulation by interferon-β (IFNβ) in lung cancer cells decreased MMP2 expression and cell invasion. Together, our results suggested that IFNβ induced PML to inhibit lung cancer metastasis by repressing the nEGFR-mediated transcriptional activation of MMP2.

Efficacy of aerosol therapy of lung cancer correlates with EGFR paralysis induced by AvidinOX-anchored biotinylated Cetuximab

Lung cancer, as well as lung metastases from distal primary tumors, could benefit from aerosol treatment. Unfortunately, because of lung physiology, clearance of nebulized drugs is fast, paralleled by unwanted systemic exposure. Here we report that nebulized AvidinOX can act as an artificial receptor for biotinylated drugs. In nude and SCID mice with advanced human KRAS-mutated A549 metastatic lung cancer, pre-nebulization with AvidinOX enables biotinylated Cetuximab to control tumor growth at a dose lower than 1/25,000 the intravenous effective dose. This result correlates with a striking, specific and unpredictable effect of AvidinOX-anchored biotinylated Cetuximab, as well as Panitumumab, observed on a panel of tumor cell lines, leading to inhibition of dimerization and signalling, blockade of endocytosis, induction of massive lysosomal degradation and abrogation of nuclear translocation of EGFR. Excellent tolerability, together with availability of pharmaceutical-grade AvidinOX and antibodies, will allow rapid clinical translation of the proposed therapy.

Recepteur d'origine nantais (RON), more than a kinase: Role in castrate-resistant prostate cancer

Prostate cancer (PCA) is the second leading cause of cancer-related deaths in men in the United States. It is natural for a hormone-driven malignancy such as prostate cancer that androgen deprivation therapy (ADT) would be the preferred treatment for clinical disease management. However, after initial treatment response a vast majority of patients develop metastatic castrate-resistant prostate cancer (CRPC), which is fatal. While great headway has been made to understand the possible mechanisms that drive castrate-resistant disease, a bonafide cure remains elusive. Reactivation of androgen receptor (AR) signaling partly contributes to the emergence of CRPC. Here we briefly examine some of the known mechanisms of AR reactivation including intratumoral synthesis of androgens, modulation of AR coregulators, and AR variants with constitutive activity as well as activation of receptor tyrosine kinases. We primarily focus on the emerging dual function of the receptor tyrosine kinase (recepteur d'origine nantais; RON) as a traditional tyrosine kinase and transcription factor. We further discuss activation of RON as an alternate mechanism in the development of CRPC and available therapeutic approaches for clinical management of CRPC by combined inhibition of RON and AR.

Proteolytic cleavage, trafficking, and functions of nuclear receptor tyrosine kinases

Intracellular localization has been reported for over three-quarters of receptor tyrosine kinase (RTK) families in response to environmental stimuli. Internalized RTK may bind to non-canonical substrates and affect various cellular processes. Many of the intracellular RTKs exist as fragmented forms that are generated by γ-secretase cleavage of the full-length receptor, shedding, alternative splicing, or alternative translation initiation. Soluble RTK fragments are stabilized and intracellularly transported into subcellular compartments, such as the nucleus, by binding to chaperone or transcription factors, while membrane-bound RTKs (full-length or truncated) are transported from the plasma membrane to the ER through the well-established Rab- or clathrin adaptor protein-coated vesicle retrograde trafficking pathways. Subsequent nuclear transport of membrane-bound RTK may occur via two pathways, INFS or INTERNET, with the former characterized by release of receptors from the ER into the cytosol and the latter characterized by release of membrane-bound receptor from the ER into the nucleoplasm through the inner nuclear membrane. Although most non-canonical intracellular RTK signaling is related to transcriptional regulation, there may be other functions that have yet to be discovered. In this review, we summarize the proteolytic processing, intracellular trafficking and nuclear functions of RTKs, and discuss how they promote cancer progression, and their clinical implications.

AXL Is a Logical Molecular Target in Head and Neck Squamous Cell Carcinoma

PURPOSE

Head and neck squamous cell carcinoma (HNSCC) represents the eighth most common malignancy worldwide. Standard-of-care treatments for patients with HNSCC include surgery, radiation, and chemotherapy. In addition, the anti-EGFR monoclonal antibody cetuximab is often used in combination with these treatment modalities. Despite clinical success with these therapeutics, HNSCC remains a difficult malignancy to treat. Thus, identification of new molecular targets is critical.

EXPERIMENTAL DESIGN

In the current study, the receptor tyrosine kinase AXL was investigated as a molecular target in HNSCC using established cell lines, HNSCC patient-derived xenografts (PDX), and human tumors. HNSCC dependency on AXL was evaluated with both anti-AXL siRNAs and the small-molecule AXL inhibitor R428. Furthermore, AXL inhibition was evaluated with standard-of-care treatment regimens used in HNSCC.

RESULTS

AXL was found to be highly overexpressed in several models of HNSCC, where AXL was significantly associated with higher pathologic grade, presence of distant metastases, and shorter relapse-free survival in patients with HNSCC. Further investigations indicated that HNSCC cells were reliant on AXL for cellular proliferation, migration, and invasion. In addition, targeting AXL increased HNSCC cell line sensitivity to chemotherapy, cetuximab, and radiation. Moreover, radiation-resistant HNSCC cell line xenografts and PDXs expressed elevated levels of both total and activated AXL, indicating a role for AXL in radiation resistance.

CONCLUSIONS

This study provides evidence for the role of AXL in HNSCC pathogenesis and supports further preclinical and clinical evaluation of anti-AXL therapeutics for the treatment of patients with HNSCC.

YES oncogenic activity is specified by its SH4 domain and regulates RAS/MAPK signaling in colon carcinoma cells

Members of the SRC family of tyrosine kinases (SFK) display important functions in human cancer, but their specific role in tumorigenesis remains unclear. We previously demonstrated that YES regulates a unique oncogenic signaling important for colorectal cancer (CRC) progression that is not shared with SRC. Here, we addressed the underlying mechanism involved in this process. We show that YES oncogenic signaling relies on palmitoylation of its SH4 domain that controls YES localization in cholesterol-enriched membrane micro-domains. Specifically, deletion of the palmitoylation site compromised YES transforming activity, while addition of a palmitoylation site in the SH4 domain of SRC was sufficient for SRC to restore the transforming properties of cells in which YES had been silenced. Subsequently, SILAC phosphoproteomic analysis revealed that micro-domain-associated cell adhesive components and receptor tyrosine kinases are major YES substrates. YES also phosphorylates upstream regulators of RAS/MAPK signaling, including EGFR, SHC and SHP2, which were not targeted by SRC due to the absence of palmitoylation. Accordingly, EGFR-induced MAPK activity was attenuated by YES down-regulation, while increased RAS activity significantly restored cell transformation that was lost upon YES silencing. Collectively, these results uncover a critical role for the SH4 domain in the specification of SFK oncogenic activity and a selective role for YES in the induction of RAS/MAPK signaling in CRC cells.