A renaissance for SRC

Oxidation-Dependent Activation of Src Kinase Mediates Epithelial IL-33 Production and Signaling during Acute Airway Allergen Challenge

The respiratory epithelium forms the first line of defense against inhaled pathogens and acts as an important source of innate cytokine responses to environmental insults. One critical mediator of these responses is the IL-1 family cytokine IL-33, which is rapidly secreted upon acute epithelial injury as an alarmin and induces type 2 immune responses. Our recent work highlighted the importance of the NADPH oxidase dual oxidase 1 (DUOX1) in acute airway epithelial IL-33 secretion by various airborne allergens associated with H2O2 production and reduction-oxidation-dependent activation of Src kinases and epidermal growth factor receptor (EGFR) signaling. In this study, we show that IL-33 secretion in response to acute airway challenge with house dust mite (HDM) allergen critically depends on the activation of Src by a DUOX1-dependent oxidative mechanism. Intriguingly, HDM-induced epithelial IL-33 secretion was dramatically attenuated by small interfering RNA- or Ab-based approaches to block IL-33 signaling through its receptor IL1RL1 (ST2), indicating that HDM-induced IL-33 secretion includes a positive feed-forward mechanism involving ST2-dependent IL-33 signaling. Moreover, activation of type 2 cytokine responses by direct airway IL-33 administration was associated with ST2-dependent activation of DUOX1-mediated H2O2 production and reduction-oxidation-based activation of Src and EGFR and was attenuated in Duox1 -/- and Src +/- mice, indicating that IL-33-induced epithelial signaling and subsequent airway responses involve DUOX1/Src-dependent pathways. Collectively, our findings suggest an intricate relationship between DUOX1, Src, and IL-33 signaling in the activation of innate type 2 immune responses to allergens, involving DUOX1-dependent epithelial Src/EGFR activation in initial IL-33 secretion and in subsequent IL-33 signaling through ST2 activation.

Recent advances in pharmacological diversification of Src family kinase inhibitors

Background

Src kinase, a nonreceptor protein-tyrosine kinase is composed of 11 members (in human) and is involved in a wide variety of essential functions required to sustain cellular homeostasis and survival.

Main body of the abstract

Deregulated activity of Src family kinase is related to malignant transformation. In 2001, Food and Drug Administration approved imatinib for the treatment of chronic myeloid leukemia followed by approval of various other inhibitors from this category as effective therapeutics for cancer patients. In the past decade, Src family kinase has been investigated for the treatment of diverse pathologies in addition to cancer. In this regard, we provide a systematic evaluation of Src kinase regarding its mechanistic role in cancer and other diseases. Here we comment on preclinical and clinical success of Src kinase inhibitors in cancer followed by diabetes, hypertension, tuberculosis, and inflammation.

Short conclusion

Studies focusing on the diversified role of Src kinase as potential therapeutical target for the development of medicinally active agents might produce significant advances in the management of not only various types of cancer but also other diseases which are in demand for potent and safe therapeutics.

Cabozantinib and dasatinib synergize to induce tumor regression in non-clear cell renal cell carcinoma

The lack of effective treatment options for advanced non-clear cell renal cell carcinoma (NCCRCC) is a critical unmet clinical need. Applying a high-throughput drug screen to multiple human kidney cancer cells, we identify the combination of the VEGFR-MET inhibitor cabozantinib and the SRC inhibitor dasatinib acts synergistically in cells to markedly reduce cell viability. Importantly, the combination is well tolerated and causes tumor regression in vivo. Transcriptional and phosphoproteomic profiling reveals that the combination converges to downregulate the MAPK-ERK signaling pathway, a result not predicted by single-agent analysis alone. Correspondingly, the addition of a MEK inhibitor synergizes with either dasatinib or cabozantinib to increase its efficacy. This study, by using approved, clinically relevant drugs, provides the rationale for the design of effective combination treatments in NCCRCC that can be rapidly translated to the clinic.

Therapeutic targeting of Lyn kinase to treat chorea-acanthocytosis

Chorea-Acanthocytosis (ChAc) is a devastating, little understood, and currently untreatable neurodegenerative disease caused by VPS13A mutations. Based on our recent demonstration that accumulation of activated Lyn tyrosine kinase is a key pathophysiological event in human ChAc cells, we took advantage of Vps13a^−/− mice, which phenocopied human ChAc. Using proteomic approach, we found accumulation of active Lyn, γ-synuclein and phospho-tau proteins in Vps13a^−/− basal ganglia secondary to impaired autophagy leading to neuroinflammation. Mice double knockout Vps13a^−/− Lyn^−/− showed normalization of red cell morphology and improvement of autophagy in basal ganglia. We then in vivo tested pharmacologic inhibitors of Lyn: dasatinib and nilotinib. Dasatinib failed to cross the mouse brain blood barrier (BBB), but the more specific Lyn kinase inhibitor nilotinib, crosses the BBB. Nilotinib ameliorates both Vps13a^−/− hematological and neurological phenotypes, improving autophagy and preventing neuroinflammation. Our data support the proposal to repurpose nilotinib as new therapeutic option for ChAc patients.

Methionine restriction breaks obligatory coupling of cell proliferation and death by an oncogene Src in Drosophila

Oncogenes often promote cell death as well as proliferation. How oncogenes drive these diametrically opposed phenomena remains to be solved. A key question is whether cell death occurs as a response to aberrant proliferation signals or through a proliferation-independent mechanism. Here, we reveal that Src, the first identified oncogene, simultaneously drives cell proliferation and death in an obligatorily coupled manner through parallel MAPK pathways. The two MAPK pathways diverge from a lynchpin protein Slpr. A MAPK p38 drives proliferation whereas another MAPK JNK drives apoptosis independently of proliferation signals. Src-p38-induced proliferation is regulated by methionine-mediated Tor signaling. Reduction of dietary methionine uncouples the obligatory coupling of cell proliferation and death, suppressing tumorigenesis and tumor-induced lethality. Our findings provide an insight into how cells evolved to have a fail-safe mechanism that thwarts tumorigenesis by the oncogene Src. We also exemplify a diet-based approach to circumvent oncogenesis by exploiting the fail-safe mechanism.

c-Src Promotes Tumorigenesis and Tumor Progression by Activating PFKFB3

Reprogramming of glucose metabolism is a key event in tumorigenesis and progression. Here, we show that active c-Src stimulates glycolysis by phosphorylating (Tyr194) and activating PFKFB3, a key enzyme that boosts glycolysis by producing fructose-2,6-bisphosphate and activating PFK1. Increased glycolysis intermediates replenish non-oxidative pentose phosphate pathway (PPP) and serine pathway for biosynthesis of cancer cells. PFKFB3 knockout (KO) cells and their counterpart reconstituted with PFKFB3-Y194F show comparably impaired abilities for proliferation, migration, and xenograft formation. Furthermore, PFKFB3-Y194F knockin mice show impaired glycolysis and, mating of these mice with APC^min/+ mice attenuates spontaneous colon cancer formation in APC^min/+ mice. In summary, we identify a specific mechanism by which c-Src mediates glucose metabolism to meet cancer cells' requirements for maximal biosynthesis and proliferation. The PFKFB3-Tyr194 phosphorylation level highly correlates with c-Src activity in clinical tumor samples, indicating its potential as an evaluation for tumor prognosis.

Screening for Combination Cancer Therapies With Dynamic Fuzzy Modeling and Multi-Objective Optimization

Combination therapies proved to be a valuable strategy in the fight against cancer, thanks to their increased efficacy in inducing tumor cell death and in reducing tumor growth, metastatic potential, and the risk of developing drug resistance. The identification of effective combinations of drug targets generally relies on costly and time consuming processes based on in vitro experiments. Here, we present a novel computational approach that, by integrating dynamic fuzzy modeling with multi-objective optimization, allows to efficiently identify novel combination cancer therapies, with a relevant saving in working time and costs. We tested this approach on a model of oncogenic K-ras cancer cells characterized by a marked Warburg effect. The computational approach was validated by its capability in finding out therapies already known in the literature for this type of cancer cell. More importantly, our results show that this method can suggest potential therapies consisting in a small number of molecular targets. In the model of oncogenic K-ras cancer cells, for instance, we identified combination of up to three targets, which affect different cellular pathways that are crucial for cancer proliferation and survival.

Paradoxical activation of c-Src as a drug-resistant mechanism

ATP-competitive inhibitors have been developed as promising anti-cancer agents. However, drug-resistance frequently occurs, and the underlying mechanisms are not fully understood. Here, we show that the activation of c-Src and its downstream phosphorylation cascade can be paradoxically induced by Src-targeted and RTK-targeted kinase inhibitors. We reveal that inhibitor binding induces a conformational change in c-Src, leading to the association of the active form c-Src with focal adhesion kinase (FAK). Reduction of the inhibitor concentration results in the dissociation of inhibitors from the c-Src-FAK complex, which allows c-Src to phosphorylate FAK and initiate FAK-Grb2-mediated Erk signaling. Furthermore, a drug-resistant mutation in c-Src, which reduces the affinity of inhibitors for c-Src, converts Src inhibitors into facilitators of cell proliferation by enhancing the phosphorylation of FAK and Erk in c-Src-mutated cells. Our data thus reveal paradoxical enhancement of cell growth evoked by target-based kinase inhibitors, providing potentially important clues for the future development of effective and safe cancer treatment.

The tyrosine kinase v-Src modifies cytotoxicities of anticancer drugs targeting cell division

v-Src oncogene causes cell transformation through its strong tyrosine kinase activity. We have revealed that v-Src-mediated cell transformation occurs at a low frequency and it is attributed to mitotic abnormalities-mediated chromosome instability. v-Src directly phosphorylates Tyr-15 of cyclin-dependent kinase 1 (CDK1), thereby causing mitotic slippage and reduction in Eg5 inhibitor cytotoxicity. However, it is not clear whether v-Src modifies cytotoxicities of the other anticancer drugs targeting cell division. In this study, we found that v-Src restores cancer cell viability reduced by various microtubule-targeting agents (MTAs), although v-Src does not alter cytotoxicity of DNA-damaging anticancer drugs. v-Src causes mitotic slippage of MTAs-treated cells, consequently generating proliferating tetraploid cells. We further demonstrate that v-Src also restores cell viability reduced by a polo-like kinase 1 (PLK1) inhibitor. Interestingly, treatment with Aurora kinase inhibitor strongly induces cell death when cells express v-Src. These results suggest that the v-Src modifies cytotoxicities of anticancer drugs targeting cell division. Highly activated Src-induced resistance to MTAs through mitotic slippage might have a risk to enhance the malignancy of cancer cells through the increase in chromosome instability upon chemotherapy using MTAs.

Novel Tyrosine Kinase Targets in Urothelial Carcinoma

Urothelial carcinoma represents one of the most prevalent types of cancer worldwide, and its incidence is expected to grow. Although the treatment of the advanced disease was based on chemotherapy for decades, the developments of different therapies, such as immune checkpoint inhibitors, antibody drug conjugates and tyrosine kinase inhibitors, are revolutionizing the therapeutic landscape of this tumor. This development coincides with the increasing knowledge of the pathogenesis and genetic alterations in urothelial carcinoma, from the non-muscle invasive setting to the metastatic one. The purpose of this article is to provide a comprehensive review of the different tyrosine kinase targets and their roles in the therapeutic scene of urothelial carcinoma.

Characterization of the interactome of c-Src within the mitochondrial matrix by proximity-dependent biotin identification

C-Src kinase is localized in several subcellular compartments, including mitochondria where it is involved in the regulation of organelle functions and overall metabolism. Surprisingly, the characterization of the intramitochondrial Src interactome has never been fully determined. Using in vitro proximity-dependent biotin identification (BioID) coupled to mass spectrometry, we identified 51 candidate proteins that may interact directly or indirectly with c-Src within the mitochondrial matrix. Pathway analysis suggests that these proteins are involved in a large array of mitochondrial functions such as protein folding and import, mitochondrial organization and transport, oxidative phosphorylation, tricarboxylic acid cycle and metabolism of amino and fatty acids. Among these proteins, we identified 24 tyrosine phosphorylation sites in 17 mitochondrial proteins (AKAP1, VDAC1, VDAC2, VDAC3, LonP1, Hsp90, SLP2, PHB2, MIC60, UBA1, EF-Tu, LRPPRC, ACO2, OAT, ACAT1, ETFβ and ATP5β) as potential substrates for intramitochondrial Src using in silico prediction of tyrosine phospho-sites. Interaction of c-Src with SLP2 and ATP5β was confirmed using coimmunoprecipitation. This study suggests that the intramitochondrial Src could target several proteins and regulate different mitochondrial functions.

The tyrosine kinase SRC of grass carp (Ctenopharyngodon idellus) up-regulates the expression of IFN I by activating TANK binding kinase 1

In response to viral infections, various pattern recognition receptors (PRRs) are activated for the production of type I interferon (IFN I). As a center of these receptor responses, TANK binding kinase-1 (TBK1) activates interferon regulatory factor 3 (IRF3). SRC is a member of Src family kinases (SFK) which participates in TBK1-mediated IFN I signaling pathway. In mammals, the immunological function of SRC is depended on its interaction with TBK1. To date, SRC has not been studied in fish. In this paper, we cloned the ORF of grass carp (Ctenopharyngodon idellus) SRC (CiSRC). CiSRC has a closer relationship with Sinocyclocheilus rhinocerous SRC (SrSRC). The expression level of CiSRC was significantly up-regulated following poly (I:C) stimulation in grass carp tissues and cells. Subcellular localization results showed that CiSRC is located both in the cytoplasm and nucleus, while CiTBK1 is only located in the cytoplasm of CIK cells. When GFP-CiSRC and FLAG-CiTBK1 were co-transfected into CIK cells, we found that they were co-localized in the cytoplasm. GST-pulldown and Co-immunoprecipitation analysis revealed that CiSRC and CiSRC tyrosine kinase domain deletion mutant (SRC-ΔTyrkc) can interact with CiTBK1, respectively. CiSRC promotes the phosphorylation of CiTBK1. Furthermore, the phosphorylation of TBK1 is more strongly under poly (I:C) stimulation. We also demonstrated that SRC can up-regulate IFN I expression. These results above unraveled that CiSRC initiates innate immune response by binding to and then up-regulating the phosphorylation of TBK1.

Intracellular Progesterone Receptor and cSrc Protein Working Together to Regulate the Activity of Proteins Involved in Migration and Invasion of Human Glioblastoma Cells

Glioblastomas are the most common and aggressive primary brain tumors in adults, and patients with glioblastoma have a median survival of 15 months. Some alternative therapies, such as Src family kinase inhibitors, have failed presumably because other signaling pathways compensate for their effects. In the last ten years, it has been proven that sex hormones such as progesterone (P4) can induce growth, migration, and invasion of glioblastoma cells through its intracellular progesterone receptor (PR), which is mostly known for its role as a transcription factor, but it can also induce non-genomic actions. These non-classic actions are, in part, a consequence of its interaction with cSrc, which plays a significant role in the progression of glioblastomas. We studied the relation between PR and cSrc, and its effects in human glioblastoma cells. Our results showed that P4 and R5020 (specific PR agonist) activated cSrc protein since both progestins increased the p-cSrc (Y416)/cSrc ratio in U251 and U87 human glioblastoma derived cell lines. When siRNA against the PR gene was used, the activation of cSrc by P4 was abolished. The co-immunoprecipitation assay showed that cSrc and PR interact in U251 cells. P4 treatment also promoted the increase in the p-Fak (Y397) (Y576/577)/Fak and the decrease in p-Paxillin (Y118)/Paxillin ratio, which are significant components of the focal adhesion complex and essential for migration and invasion processes. A siRNA against cSrc gene blocked the increase in the p-Fak (Y576/Y577)/Fak ratio and the migration induced by P4, but not the decrease in p-Paxillin (Y118)/Paxillin ratio. We analyzed the potential role of cSrc over PR phosphorylation in three databases, and one putative tyrosine residue in the amino acid 87 of PR was found. Our results showed that P4 induces the activation of cSrc protein through its PR. The latter and cSrc could interact in a bidirectional mode for regulating the activity of proteins involved in migration and invasion of glioblastomas.

SRC Signaling in Cancer and Tumor Microenvironment

Pioneering experiments performed by Harold Varmus and Mike Bishop in 1976 led to one of the most influential discoveries in cancer research and identified the first cancer-causing oncogene called Src. Later experimental and clinical evidence suggested that Src kinase plays a significant role in promoting tumor growth and progression and its activity is associated with poor patient survival. Thus, several Src inhibitors were developed and approved by FDA for treatment of cancer patients. Tumor microenvironment (TME) is a highly complex and dynamic milieu where significant cross-talk occurs between cancer cells and TME components, which consist of tumor-associated macrophages, fibroblasts, and other immune and vascular cells. Growth factors and chemokines activate multiple signaling cascades in TME and induce multiple kinases and pathways, including Src, leading to tumor growth, invasion/metastasis, angiogenesis, drug resistance, and progression. Here, we will systemically evaluate recent findings regarding regulation of Src and significance of targeting Src in cancer therapy.

COVID-19 and Cell Stress

The present century will undoubtedly be marked with the COVID-19 global health crisis. It is not time yet to talk about the total number of deaths and hospitalizations, as they are enormously growing daily. Understanding the nature of COVID-19-induced pneumonia is vital in order to deal with the associated health complications. Cell stress is an established mechanism known to be associated with infection and cancer. Different proteins crucial for cellular response to stress are reported to be a possible target to stop the infection and to reduce the chemo-resistance in cancer. Heat shock protein (HSP) families of chaperones play an essential role in cells both in normal state and under stress. The upregulation of HSP5A, also termed GRP78 or Bip, is reported in different viral infections. This chapter introduces the current knowledge about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which has caused the COVID-19 pandemic, and cell stress aimed at defining possible strategies to combat the COVID-19 pandemic.

α-Linolenic acid attenuates pseudo-allergic reactions by inhibiting Lyn kinase activity

BACKGROUND

Pseudo-allergic reactions are potentially fatal hypersensitivity responses caused by mast cell activation. α-linolenic acid (ALA) is known for its anti-allergic properties. However, its potential anti-pseudo-allergic effects were not much investigated.

PURPOSE

To investigate the inhibitory effects of ALA on IgE-independent allergy in vitro, and in vivo, as well as the mechanism underlying its effects.

METHODS/STUDY DESIGNS

The anti-anaphylactoid activity of ALA was evaluated in passive cutaneous anaphylaxis reaction (PCA) and systemic anaphylaxis models. Calcium imaging was used to assess intracellular Ca2+ mobilization. The release of cytokines and chemokines was measured using enzyme immunoassay kits. Western blot analysis was conducted to investigate the molecules of Lyn-PLCγ-IP3R-Ca2+ and Lyn-p38/NF-κB signaling pathway.

RESULTS

ALA (0, 1.0, 2.0, and 4.0 mg/kg) dose-dependently reduced serum histamine, chemokine release, vasodilation, eosinophil infiltration, and the percentage of degranulated mast cells in C57BL/6 mice. In addition, ALA (0, 50, 100, and 200 μM) reduced Compound 48/80 (C48/80) (30 μg/ml)-or Substance P (SP) (4 μg/ml)-induced calcium influx, mast cell degranulation and cytokines and chemokine release in Laboratory of Allergic Disease 2 (LAD2) cells via Lyn-PLCγ-IP3R-Ca2+ and Lyn-p38/NF-κB signaling pathway. Moreover, ALA (0, 50, 100, and 200 μM) inhibited C48/80 (30 μg/ml)- and SP (4 μg/ml)-induced calcium influx in Mas-related G-protein coupled receptor member X2 (MrgX2)-HEK293 cells and in vitro kinase assays confirmed that ALA inhibited the activity of Lyn kinase. In response to 200 μM of ALA, the activity of Lyn kinase by (7.296 ± 0.03751) × 10-5 units/μl and decreased compared with C48/80 (30 μg/ml) by (8.572 ± 0.1365) ×10-5 units/μl.

CONCLUSION

Our results demonstrate that ALA might be a potential Lyn kinase inhibitor, which could be used to treat pseudo-allergic reaction-related diseases such as urticaria.

Recurrent Glioblastoma: From Molecular Landscape to New Treatment Perspectives

Glioblastoma is the most frequent and aggressive form among malignant central nervous system primary tumors in adults. Standard treatment for newly diagnosed glioblastoma consists in maximal safe resection, if feasible, followed by radiochemotherapy and adjuvant chemotherapy with temozolomide; despite this multimodal treatment, virtually all glioblastomas relapse. Once tumors progress after first-line therapy, treatment options are limited and management of recurrent glioblastoma remains challenging. Loco-regional therapy with re-surgery or re-irradiation may be evaluated in selected cases, while traditional systemic therapy with nitrosoureas and temozolomide rechallenge showed limited efficacy. In recent years, new clinical trials using, for example, regorafenib or a combination of tyrosine kinase inhibitors and immunotherapy were performed with promising results. In particular, molecular targeted therapy could show efficacy in selected patients with specific gene mutations. Nonetheless, some molecular characteristics and genetic alterations could change during tumor progression, thus affecting the efficacy of precision medicine. We therefore reviewed the molecular and genomic landscape of recurrent glioblastoma, the strategy for clinical management and the major phase I-III clinical trials analyzing recent drugs and combination regimens in these patients.

Dasatinib and PD-L1 inhibitors provoke toxicity and inhibit angiogenesis in the embryo

Dasatinib is a targeted cancer therapy, while programmed death ligand 1 (PD-L1) inhibitors are a form of immune checkpoint therapy used to treat various types of cancers. Several studies showed the potential efficacy of these drugs in the management of triple-negative breast cancer- an aggressive subtype of breast cancer, which can develop during pregnancy. Nevertheless, side effects of Dasatinib (DA) and PD-L1 drugs during pregnancy, especially in the early stages of embryogenesis are not explored yet. The aim of this study is to assess the individual and combined toxicity of DA and PD-L1 inhibitors during the early stages of embryogenesis and to evaluate their effect(s) on angiogenesis using the chorioallantoic membrane (CAM) model of the embryo. Our results show that embryos die at greater rates after exposure to DA and PD-L1 inhibitors as compared to their matched controls. Moreover, treatment with these drugs significantly inhibits angiogenesis of the CAM. To further elucidate key regulator genes of embryotoxicity induced by the actions of PD-L1 and DA, an RT-PCR analysis was performed for seven target genes that regulate cell proliferation, angiogenesis, and survival (ATF3, FOXA2, MAPRE2, RIPK1, INHBA, SERPINA4, and VEGFC). Our data revealed that these genes are significantly deregulated in the brain, heart, and liver tissues of exposed embryos, compared to matched control tissues. Nevertheless, further studies are necessary to evaluate the effects of these anti breast cancer drugs and elucidate their role during pregnancy.

Novel Targeted Photosensitizer as an Immunomodulator for Highly Efficient Therapy of T-Cell Acute Lymphoblastic Leukemia

Dasatinib is a kinase-targeted drug used in the treatment of leukemia. Regrettably, it remains far from optimal medicine due to insurmountable drug resistance and side effects. Photodynamic therapy (PDT) has proven that it can induce systemic immune responses. However, conventional photosensitizers as immunomodulators produce anticancer immunities, which are inadequate to eliminate residual cancer cells. Herein, a novel compound 4 was synthesized and investigated, which introduces dasatinib and zinc(II) phthalocyanine as the targeting and photodynamic moiety, respectively. Compound 4 exhibits a high affinity to CCRF-CEM cells/tumor tissues, which overexpress lymphocyte-specific protein tyrosine kinase (LCK), and preferential elimination from the body. Meanwhile, compound 4 shows excellent photocytotoxicity and tumor regression. Significantly, compound 4-induced PDT can obviously enhance immune responses, resulting in the production of more immune cells. We believe that the proposed manner is a potential strategy for the treatment of T-cell acute lymphoblastic leukemia.

Proto-oncogene Src links lipogenesis via lipin-1 to breast cancer malignancy

Increased lipogenesis has been linked to an increased cancer risk and poor prognosis; however, the underlying mechanisms remain obscure. Here we show that phosphatidic acid phosphatase (PAP) lipin-1, which generates diglyceride precursors necessary for the synthesis of glycerolipids, interacts with and is a direct substrate of the Src proto-oncogenic tyrosine kinase. Obesity-associated microenvironmental factors and other Src-activating growth factors, including the epidermal growth factor, activate Src and promote Src-mediated lipin-1 phosphorylation on Tyr398, Tyr413 and Tyr795 residues. The tyrosine phosphorylation of lipin-1 markedly increases its PAP activity, accelerating the synthesis of glycerophospholipids and triglyceride. Alteration of the three tyrosine residues to phenylalanine (3YF-lipin-1) disables lipin-1 from mediating Src-enhanced glycerolipid synthesis, cell proliferation and xenograft growth. Re-expression of 3YF-lipin-1 in PyVT;Lpin1-/- mice fails to promote progression and metastasis of mammary tumours. Human breast tumours exhibit increased p-Tyr-lipin-1 levels compared to the adjacent tissues. Importantly, statistical analyses show that levels of p-Tyr-lipin-1 correlate with tumour sizes, lymph node metastasis, time to recurrence and survival of the patients. These results illustrate a direct lipogenesis-promoting role of the pro-oncogenic Src, providing a mechanistic link between obesity-associated mitogenic signaling and breast cancer malignancy.

Downregulation of miR-654-3p in Colorectal Cancer Indicates Poor Prognosis and Promotes Cell Proliferation and Invasion by Targeting SRC

Background

MicroRNAs (miRNAs), such as miR-654-3p, regulate gene expression at the post-transcriptional level affecting malignant tumor behavior. However, the expression levels, function, and mechanism of miR-654-3p in colorectal cancer (CRC) are unknown.

Methods

The expression levels of miR-654-3p and SRC in 103 CRC tissues and matched normal colorectal tissues were detected by a quantitative real-time polymerase chain reaction (qRT-PCR). miR-654-3p was overexpressed by RNA mimics and SRC knockdown by siRNA. Function-based experiments were carried out to detect the proliferation and migration abilities in CRC cell lines. Flow cytometry assay was performed to evaluate the effect of miR-654-3p on cell apoptosis and cycle distribution. Xenograft tumor models in nude mice were utilized to evaluate miR-654-3p functions in vivo. Dual-fluorescence reporter assay was used to verify the direct binding between miR-654-3p and SRC.

Results

miR-654-3p was downregulated in CRC tissues as compared to matched normal colorectal tissues. The expression levels of miR-654-3p were closely associated with distant metastasis. In addition, elevated expression of miR-654-3p in CRC patients prolonged the overall survival. Upregulated miR-654-3p significantly suppressed the proliferation and migration capacity of CRC cells by enhancing apoptosis and promoting G0/G1 phase arrest. The direct binding between miR-654-3p and SRC was verified by the dual-luciferase reporter gene. Furthermore, the suppression of proliferation and migration capacity by elevated miR-654-3p level could be reversed by overexpressing SRC.

Conclusion

miR-654-3p acts as a tumor suppressor through regulating SRC. It might also serve as a diagnostic and prognostic indicator and a novel molecular target for CRC therapy.

Transcriptomics-Based Drug Repurposing Approach Identifies Novel Drugs against Sorafenib-Resistant Hepatocellular Carcinoma

Simple Summary

Hepatocellular carcinoma (HCC), a type of liver cancer, remains a treatment challenge due to late detection and resistance to currently approved drugs. It takes 15–20 years for a single new drug to become FDA approved. The purpose of this study was to expedite identification of novel drugs against drug-resistant HCC. For this, we matched gene expression alterations in resistant HCC with gene expression changes caused by treatment of cancer cells with drugs already FDA approved for other diseases to find the drug that can reverse the resistance-related changes. Among the identified drugs, we validated the growth inhibitory effect of two drugs, identified their mechanism in HCC and, thus, provided proof of concept evidence for validity of this drug repurposing approach with potential for use in personalized medicine.

Abstract

Objective: Hepatocellular carcinoma (HCC) is frequently diagnosed in patients with late-stage disease who are ineligible for curative surgical therapies. The majority of patients become resistant to sorafenib, the only approved first-line therapy for advanced cancer, underscoring the need for newer, more effective drugs. The purpose of this study is to expedite identification of novel drugs against sorafenib resistant (SR)-HCC. Methods: We employed a transcriptomics-based drug repurposing method termed connectivity mapping using gene signatures from in vitro-derived SR Huh7 HCC cells. For proof of concept validation, we focused on drugs that were FDA-approved or under clinical investigation and prioritized two anti-neoplastic agents (dasatinib and fostamatinib) with targets associated with HCC. We also prospectively validated predicted gene expression changes in drug-treated SR Huh7 cells as well as identified and validated the targets of Fostamatinib in HCC. Results: Dasatinib specifically reduced the viability of SR-HCC cells that correlated with up-regulated activity of SRC family kinases, its targets, in our SR-HCC model. However, fostamatinib was able to inhibit both parental and SR HCC cells in vitro and in xenograft models. Ingenuity pathway analysis of fostamatinib gene expression signature from LINCS predicted JAK/STAT, PI3K/AKT, ERK/MAPK pathways as potential targets of fostamatinib that were validated by Western blot analysis. Fostamatinib treatment reversed the expression of genes that were deregulated in SR HCC. Conclusion: We provide proof of concept evidence for the validity of this drug repurposing approach for SR-HCC with implications for personalized medicine.

Systematic Elucidation of the Mechanism of Quercetin against Gastric Cancer via Network Pharmacology Approach

This study was aimed at elucidating the potential mechanisms of quercetin in the treatment of gastric cancer (GC). A network pharmacology approach was used to analyze the targets and pathways of quercetin in treating GC. The predicted targets of quercetin against GC were obtained through database mining, and the correlation of these targets with GC was analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Next, the protein-protein interaction (PPI) network was constructed, and overall survival (OS) analysis of hub targets was performed using the Kaplan–Meier Plotter online tool. Finally, the mechanism was further analyzed via molecular docking of quercetin with the hub targets. Thirty-six quercetin-related genes were identified, 15 of which overlapped with GC-related targets. These targets were further mapped to 319 GO biological process terms and 10 remarkable pathways. In the PPI network analysis, six hub targets were identified, including AKT1, EGFR, SRC, IGF1R, PTK2, and KDR. The high expression of these targets was related to poor OS in GC patients. Molecular docking analysis confirmed that quercetin can bind to these hub targets. In conclusion, this study provided a novel approach to reveal the therapeutic mechanisms of quercetin on GC, which will ease the future clinical application of quercetin in the treatment of GC.

IGF2BP1 is a targetable SRC/MAPK-dependent driver of invasive growth in ovarian cancer

Epithelial-to-mesenchymal transition (EMT) is a hallmark of aggressive, mesenchymal-like high-grade serous ovarian carcinoma (HGSOC). The SRC kinase is a key driver of cancer-associated EMT promoting adherens junction (AJ) disassembly by phosphorylation-driven internalization and degradation of AJ proteins. Here, we show that the IGF2 mRNA-binding protein 1 (IGF2BP1) is up-regulated in mesenchymal-like HGSOC and promotes SRC activation by a previously unknown protein-ligand-induced, but RNA-independent mechanism. IGF2BP1-driven invasive growth of ovarian cancer cells essentially relies on the SRC-dependent disassembly of AJs. Concomitantly, IGF2BP1 enhances ERK2 expression in an RNA-binding dependent manner. Together this reveals a post-transcriptional mechanism of interconnected stimulation of SRC/ERK signalling in ovarian cancer cells. The IGF2BP1-SRC/ERK2 axis is targetable by the SRC-inhibitor saracatinib and MEK-inhibitor selumetinib. However, due to IGF2BP1-directed stimulation, only combinatorial treatment effectively overcomes the IGF2BP1-promoted invasive growth in 3D culture conditions as well as intraperitoneal mouse models. In conclusion, we reveal an unexpected role of IGF2BP1 in enhancing SRC/MAPK-driven invasive growth of ovarian cancer cells. This provides a rationale for the therapeutic benefit of combinatorial SRC/MEK inhibition in mesenchymal-like HGSOC.

PRMT5 promotes DNA repair through methylation of 53BP1 and is regulated by Src-mediated phosphorylation

PRMT5 participates in various cellular processes, including transcription regulation, signal transduction, mRNA splicing, and DNA repair; however, its mechanism of regulation is poorly understood. Here, we demonstrate that PRMT5 is phosphorylated at residue Y324 by Src kinase, a negative regulator of its activity. Either phosphorylation or substitution of the Y324 residue suppresses PRMT5 activity by preventing its binding with the methyl donor S-adenosyl-L-methionine. Additionally, we show that PRMT5 activity is associated with non-homologous end joining (NHEJ) repair by methylating and stabilizing p53-binding protein 1 (53BP1), which promotes cellular survival after DNA damage. Src-mediated phosphorylation of PRMT5 and the subsequent inhibition of its activity during the DNA damage process blocks NHEJ repair, leading to apoptotic cell death. Altogether, our findings suggest that PRMT5 regulates DNA repair through Src-mediated Y324 phosphorylation in response to DNA damage.

Hwang et al. show that the activity of PRMT5 methyltransferase is regulated by Src kinase-mediated phosphorylation at Y324 in response to DNA damage. They also show that PRMT5 participates in NHEJ repair by regulating 53BP1 protein levels and is critical for cellular survival after DNA damage.

Targeted therapies in gynecological cancers: a comprehensive review of clinical evidence

Advanced and recurrent gynecological cancers are associated with poor prognosis and lack of effective treatment. The developments of the molecular mechanisms on cancer progression provide insight into novel targeted therapies, which are emerging as groundbreaking and promising cancer treatment strategies. In gynecologic malignancies, potential therapeutic targeted agents include antiangiogenic agents, poly (ADP-ribose) polymerase (PARP) inhibitors, tumor-intrinsic signaling pathway inhibitors, selective estrogen receptor downregulators, and immune checkpoint inhibitors. In this article, we provide a comprehensive review of the clinical evidence of targeted agents in gynecological cancers and discuss the future implication.

Src Family Tyrosine Kinases in Intestinal Homeostasis, Regeneration and Tumorigenesis

Src, originally identified as an oncogene, is a membrane-anchored tyrosine kinase and the Src family kinase (SFK) prototype. SFKs regulate the signalling induced by a wide range of cell surface receptors leading to epithelial cell growth and adhesion. In the intestine, the SFK members Src, Fyn and Yes regulate epithelial cell proliferation and migration during tissue regeneration and transformation, thus implicating conserved and specific functions. In patients with colon cancer, SFK activity is a marker of poor clinical prognosis and a potent driver of metastasis formation. These tumorigenic activities are linked to SFK capacity to promote the dissemination and tumour-initiating capacities of epithelial tumour cells. However, it is unclear how SFKs promote colon tumour formation and metastatic progression because SFK-encoding genes are unfrequently mutated in human cancer. Here, we review recent findings on SFK signalling during intestinal homeostasis, regeneration and tumorigenesis. We also describe the key nongenetic mechanisms underlying SFK tumour activities in colorectal cancer, and discuss how these mechanisms could be exploited in therapeutic strategies to target SFK signalling in metastatic colon cancer.

Historical retrospective of the oncogene and new perspectives (Review)

Since its first discovery as part of the Rous sarcoma virus (RSV) genome, the c-SRC (SRC) proto-oncogene has been proved a key regulator of cancer development and progression, and thus it has been highlighted as an attractive target for anti-cancer therapeutic strategies. Though the exact mechanisms of its action are still not fully understood, SRC protein mediates crucial normal cell functions, such as cell development, proliferation and survival, and its dysregulation is considered as an oncogenic signature and a driving force for cancer initiation. In the present review, we present a flashback to the history of the Src research, while focusing on the most important milestones in the field. Moreover, we investigate the proposed regulatory mechanisms and molecules that mediate its action in order to designate putative therapeutic targets and useful prognostic and/or diagnostic tools. Furthermore, we present and discuss existing therapeutic approaches that are explored in clinical settings.

Targeting SRC Family Kinases in Mesothelioma: Time to Upgrade

Malignant mesothelioma (MM) is a deadly tumor mainly caused by exposure to asbestos. Unfortunately, no current treatment is able to change significantly the natural history of the disease, which has a poor prognosis in the majority of patients. The non-receptor tyrosine kinase SRC and other SRC family kinase (SFK) members are frequently hyperactivated in many cancer types, including MM. Several works have indeed suggested that SFKs underlie MM cell proliferation, survival, motility, and invasion, overall affecting multiple oncogenic pathways. Consistently, SFK inhibitors effectively counteracted MM cancerous features at the preclinical level. Dasatinib, a multi-kinase inhibitor targeting SFKs, was also assessed in clinical trials either as second-line treatment for patients with unresectable MM or, more recently, as a neoadjuvant agent in patients with resectable MM. Here, we provide an overview of the molecular mechanisms implicating SFKs in MM progression and discuss possible strategies for a more successful clinical application of SFK inhibitors. Our aim is to stimulate discussion and further consideration of these agents in better designed preclinical and clinical studies to make the most of another class of powerful antitumoral drugs, which too often are lost in translation when applied to MM.

The retinal tyrosine kinome of diabetic Akimba mice highlights potential for specific Src family kinase inhibition in retinal vascular disease

Although anti-VEGF therapies have radically changed clinical practice, there is still an urgent demand for novel, integrative approaches for sight-threatening retinal vascular diseases. As we hypothesize that protein tyrosine kinases are key signaling mediators in retinal vascular disease, we performed a comprehensive activity-based tyrosine kinome profiling on retinal tissue of 12-week-old Akimba mice, a translational model displaying hallmarks of early and advanced diabetic retinopathy. Western blotting was used to confirm retinal tyrosine kinase activity in Akimba mice. HUVEC tube formation and murine organotypic choroidal sprouting assays were applied to compare tyrosine kinase inhibitors with different specificity profiles. HUVEC toxicity and proliferation were evaluated using the CellTox™ Green Cytotoxicity and PrestoBlue™ Assays. Our results indicate a shift of the Akimba retinal tyrosine kinome towards a hyperactive state. Functional network analysis of significantly hyperphosphorylated peptides and upstream kinase prediction revealed a central role for Src-FAK family kinases. Western blotting confirmed hyperactivity of this signaling node in the retina of Akimba mice. We demonstrated that not only Src but also FAK family kinase inhibitors with different selectivity profiles were able to suppress angiogenesis in vitro and ex vivo. In the latter model, the novel selective Src family kinase inhibitor eCF506 was able to achieve potent reduction of angiogenesis, comparable to the less specific inhibitor Dasatinib. None of the tested compounds demonstrated acute endothelial cell toxicity. Overall, the collected findings provide the first comprehensive overview of retinal tyrosine kinome changes in the Akimba model of diabetic retinopathy and for the first time highlight Src family kinase inhibition using highly specific inhibitors as an attractive therapeutic intervention for retinal vascular pathology.

Src Inhibitors Pyrazolo[3,4-d]pyrimidines, Si306 and Pro-Si306, Inhibit Focal Adhesion Kinase and Suppress Human Glioblastoma Invasion In Vitro and In Vivo

Glioblastoma (GBM), as the most aggressive brain tumor, displays a high expression of Src tyrosine kinase, which is involved in the survival, migration, and invasiveness of tumor cells. Thus, Src emerged as a potential target for GBM therapy. The effects of Src inhibitors pyrazolo[3,4-d]pyrimidines, Si306 and its prodrug pro-Si306 were investigated in human GBM cell lines (U87 and U87-TxR) and three primary GBM cell cultures. Primary GBM cells were more resistant to Si306 and pro-Si306 according to the 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. However, the ability of all GBM cells to degrade the extracellular matrix was considerably compromised after Si306 and pro-Si306 applications. Besides reducing the phosphorylation of Src and its downstream signaling pathway components, both compounds decreased the phosphorylated form of focal adhesion kinase (FAK) and epidermal growth factor receptor (EGFR) expression, showing the potential to suppress the aggressiveness of GBM. In vivo, Si306 and pro-Si306 displayed an anti-invasive effect against U87 xenografts in the zebrafish embryo model. Considering that Si306 and pro-Si306 are able to cross the blood–brain barrier and suppress the spread of GBM cells, we anticipate their clinical testing in the near future. Moreover, the prodrug showed similar efficacy to the drug, implying the rationality of its use in clinical settings.

c-Src and EGFR Inhibition in Molecular Cancer Therapy: What Else Can We Improve?

The proto-oncogene c-Src is a non-receptor tyrosine kinase playing a key role in many cellular pathways, including cell survival, migration and proliferation. c-Src de-regulation has been observed in several cancer types, making it an appealing target for drug discovery efforts. Recent evidence emphasizes its crucial role not only in promoting oncogenic traits, but also in the acquisition and maintenance of cancer resistance to various chemotherapeutic or molecular target drugs. c-Src modulates epidermal growth factor receptor (EGFR) activation and amplifies its downstream oncogenic signals. In this review, we report several studies supporting c-Src kinase role in the intricate mechanisms of resistance to EGFR tyrosine kinase inhibitors (TKIs). We further highlighted pre- and clinical progresses of combined treatment strategies made in recent years. Several pre-clinical data have encouraged the use of c-Src inhibitors in combination with EGFR inhibitors. However, clinical trials provided controversial outcomes in some cancer types. Despite c-Src inhibitors showed good tolerability in cancer patients, no incontrovertible and consistent clinical responses were recorded, supporting the idea that a better selection of patients is needed to improve clinical outcome. Currently, the identification of biological markers predictive of therapy response and the accurate molecular screening of cancer patients aimed to gain most clinical benefits become decisive and mandatory.

Src couples estrogen receptor to the anticipatory unfolded protein response and regulates cancer cell fate under stress

Accumulation of unfolded protein, or other stresses, activates the classical reactive unfolded protein response (UPR). In the recently characterized anticipatory UPR, receptor-bound estrogen, progesterone and other mitogenic hormones rapidly elicit phosphorylation of phospholipase C γ (PLCγ), activating the anticipatory UPR. How estrogen and progesterone activating their receptors couples to PLCγ phosphorylation and anticipatory UPR activation was unknown. We show that the oncogene c-Src is a rate-limiting regulator whose tyrosine kinase activity links estrogen and progesterone activating their receptors to anticipatory UPR activation. Supporting Src coupling estrogen and progesterone to anticipatory UPR activation, we identified extranuclear complexes of estrogen receptor α (ERα):Src:PLCγ and progesterone receptor:Src:PLCγ. Moreover, Src inhibition protected cancer cells against cell death. To probe Src's role, we used the preclinical ERα biomodulator, BHPI, which kills cancer cells by inducing lethal anticipatory UPR hyperactivation. Notably, Src inhibition blocked BHPI-mediated anticipatory UPR activation and the resulting rapid increase in intracellular calcium. After unbiased long-term selection for BHPI-resistant human breast cancer cells, 4/11 BHPI-resistant T47D clones, and nearly all MCF-7 clones, exhibited reduced levels of normally growth-stimulating Src. Notably, Src overexpression by virus transduction restored sensitivity to BHPI. Furthermore, in wild type cells, several-fold knockdown of Src, but not of ERα, strongly blocked BHPI-mediated UPR activation and subsequent HMGB1 release and necrotic cell death. Thus, Src plays a previously undescribed pivotal role in activation of the tumor-protective anticipatory UPR, thereby increasing the resilience of breast cancer cells. This is a new role for Src and the anticipatory UPR in breast cancer.

Regulation of Src Family Kinases during Colorectal Cancer Development and Its Clinical Implications

Src family kinases (SFKs) are non-receptor kinases that play a critical role in the pathogenesis of colorectal cancer (CRC). The expression and activity of SFKs are upregulated in patients with CRC. Activation of SFKs promotes CRC cell proliferation, metastases to other organs and chemoresistance, as well as the formation of cancer stem cells (CSCs). The enhanced expression level of Src is associated with decreased survival in patients with CRC. Src-mediated regulation of CRC progression involves various membrane receptors, modulators, and suppressors, which regulate Src activation and its downstream targets through various mechanisms. This review provides an overview of the current understanding of the correlations between Src and CRC progression, with a special focus on cancer cell proliferation, invasion, metastasis and chemoresistance, and formation of CSCs. Additionally, this review discusses preclinical and clinical strategies to improve the therapeutic efficacy of drugs targeting Src for treating patients with CRC.

APE1 Promotes Pancreatic Cancer Proliferation through GFRα1/Src/ERK Axis-Cascade Signaling in Response to GDNF

Pancreatic cancer is the worst exocrine gastrointestinal cancer leading to the highest mortality. Recent studies reported that aberrant expression of apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) is involved in uncontrolled cell growth. However, the molecular mechanism of APE1 biological role remains unrevealed in pancreatic cancer progression. Here, we demonstrate that APE1 accelerates pancreatic cancer cell proliferation through glial cell line-derived neurotrophic factor (GDNF)/glial factor receptor α1 (GFRα1)/Src/ERK axis-cascade signaling. The proliferation of endogenous APE1 expressed-MIA PaCa-2, a human pancreatic carcinoma cell line, was increased by treatment with GDNF, a ligand of GFRα1. Either of downregulated APE1 or GFRα1 expression using small interference RNA (siRNA) inhibited GDNF-induced cancer cell proliferation. The MEK-1 inhibitor PD98059 decreased GDNF-induced MIA PaCa-2 cell proliferation. Src inactivation by either its siRNA or Src inhibitor decreased ERK-phosphorylation in response to GDNF in MIA PaCa-2 cells. Overexpression of GFRα1 in APE1-deficient MIA PaCa-2 cells activated the phosphorylation of Src and ERK. The expression of both APE1 and GFRα1 was gradually increased as progressing pancreatic cancer grades. Our results highlight a critical role for APE1 in GDNF-induced pancreatic cancer cell proliferation through APE1/GFRα1/Src/ERK axis-cascade signaling and provide evidence for future potential therapeutic drug targets for the treatment of pancreatic cancer.

Development of Pyrazolo[3,4-d]pyrimidine Kinase Inhibitors as Potential Clinical Candidates for Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most aggressive primary brain tumor. Residual cells at the tumor margin are responsible for up to 85% of GBM recurrences after standard treatment. Despite this evidence, the identification of compounds active on this cell population is still an underexplored field. Herein, starting from the knowledge that kinases are implicated in GBM, we evaluated three in-house pyrazolo[3,4-d]pyrimidines active as Src, Fyn, and SGK1 kinase inhibitors against patient derived cell lines from either the invasive region or contrast-enhanced core of GBM. We identified our Src inhibitor, SI306, as a promising lead compound for eradicating invasive GBM cells. Furthermore, aiming at the development of a feasible oral treatment for GBM, we performed a formulation study using 2D inkjet printing to generate soluble polymer-drug dispersions. Overall, this study led to the identification of a set of polymer-formulated pyrazolo[3,4-d]pyrimidine kinase inhibitors as promising candidates for GBM preclinical efficacy studies.

Jeans N, Mandal D, Tiwari RK, Ul-Haq Z, Parang K. Phenylpyrazalopyrimidines as Tyrosine Kinase Inhibitors: Synthesis, Antiproliferative Activity, and Molecular Simulations

N1-(α,β-Alkene)-substituted phenylpyrazolopyrimidine derivatives with acetyl and functionalized phenyl groups at α- and β-positions, respectively, were synthesized by the reaction of 3-phenylpyrazolopyrimidine (PhPP) with bromoacetone, followed by a chalcone reaction with differently substituted aromatic aldehydes. The Src kinase enzyme assay revealed modest inhibitory activity (half maximal inhibitory concentration, IC₅₀ = 21.7–192.1 µM) by a number of PhPP derivatives. Antiproliferative activity of the compounds was evaluated on human leukemia (CCRF-CEM), human ovarian adenocarcinoma (SK-OV-3), breast carcinoma (MDA-MB-231), and colon adenocarcinoma (HT-29) cells in vitro. 4-Chlorophenyl carbo-enyl substituted 3-phenylpyrazolopyrimidine (10) inhibited the cell proliferation of HT-29 and SK-OV-3 by 90% and 79%, respectively, at a concentration of 50 µM after 96 h incubation. The compound showed modest inhibitory activity against c-Src (IC₅₀ = 60.4 µM), Btk (IC₅₀ = 90.5 µM), and Lck (IC₅₀ = 110 µM), while it showed no activity against Abl1, Akt1, Alk, Braf, Cdk2, and PKCa. In combination with target selection and kinase profiling assay, extensive theoretical studies were carried out to explore the selectivity behavior of compound 10. Specific interactions were also explored by examining the changing trends of interactions of tyrosine kinases with the phenylpyrazolopyrimidine derivative. The results showed good agreement with the experimental selectivity pattern among c-Src, Btk, and Lck.

Results of a Randomized, Double-Blinded, Placebo-Controlled, Phase 2.5 Study of Saracatinib (AZD0530), in Patients with Recurrent Osteosarcoma Localized to the Lung

Purpose

Osteosarcoma is a rare cancer and a third of patients who have completed primary treatment will develop osteosarcoma recurrence. The Src pathway has been implicated in the metastatic behavior of osteosarcoma; about 95% of samples examined express Src or have evidence of downstream activation of this pathway. Saracatinib (AZD0530) is a potent and selective Src kinase inhibitor that was evaluated in adults in Phase 1 studies. The primary goal of this study was to determine if treatment with saracatinib could increase progression-free survival (PFS) for patients who have undergone complete resection of osteosarcoma lung metastases in a double-blinded, placebo-controlled trial. Patients and Methods. Subjects with recurrent osteosarcoma localized to lung and who had complete surgical removal of all lung nodules were randomized within six weeks after complete surgical resection. Saracatinib, or placebo, was administered at a dose of 175 mg orally, once daily, for up to thirteen 28-day cycles.

Results

Thirty-seven subjects were included in the analyses; 18 subjects were randomized to receive saracatinib and 19 to receive placebo. Intent-to-treat analysis demonstrated a median PFS of 19.4 months in the saracatinib treatment group and 8.6 months in the placebo treatment group (p=0.47). Median OS was not reached in either arm.

Conclusions

Although saracatinib was well tolerated in this patient population, there was no apparent impact of the drug in this double-blinded, placebo-controlled trial on OS, and Src inhibition alone may not be sufficient to suppress metastatic progression in osteosarcoma. There is a suggestion of potential clinical benefit as evidenced by longer PFS in patients randomized to saracatinib based on limited numbers of patients treated.

Design, Synthesis, and Biological Evaluation of Proteolysis Targeting Chimeras (PROTACs) for the Dual Degradation of IGF-1R and Src

A focused PROTAC library was developed to degrade both IGF-1R and Src proteins, which are associated with various cancers. PROTACs with IGF-1R and Src degradation potentials were synthesized by tethering different inhibitor warhead units and the E3 ligase (CRBN) recruiting-pomalidomide with various linkers. The designed PROTACs 12a-b inhibited the proliferation and migration of MCF7 and A549 cancer cells with low micromolar potency (1-5 μM) in various cellular assays.

c-Src kinase impairs the expression of mitochondrial OXPHOS complexes in liver cancer

Src family kinases (SFKs) play a crucial role in the regulation of multiple cellular pathways, including mitochondrial oxidative phosphorylation (OXPHOS). Aberrant activities of one of the most predominant SFKs, c-Src, was identified as a fundamental cause for dysfunctional cell signaling and implicated in cancer development and metastasis, especially in human hepatocellular carcinoma (HCC). Recent work in our laboratory revealed that c-Src is implicated in the regulation of mitochondrial energy metabolism in cancer. In this study, we investigated the effect of c-Src expression on mitochondrial energy metabolism by examining changes in the expression and activities of OXPHOS complexes in liver cancer biopsies and cell lines. An increased expression of c-Src was correlated with an impaired expression of nuclear- and mitochondrial-encoded subunits of OXPHOS complexes I and IV, respectively, in metastatic biopsies and cell lines. Additionally, we observed a similar association between high c-Src and reduced OXPHOS complex expression and activity in mouse embryonic fibroblast (MEF) cell lines. Interestingly, the inhibition of c-Src kinase activity with the SFK inhibitor PP2 and c-Src siRNA stimulated the expression of complex I and IV subunits and increased their enzymatic activities in both cancer and normal cells. Evidence provided in this study reveals that c-Src impairs the expression and function of mitochondrial OXPHOS complexes, resulting in a significant defect in mitochondrial energy metabolism, which can be a contributing factor to the development and progression of liver cancer. Furthermore, our findings strongly suggest that SFK inhibitors should be used in the treatment of HCC and other cancers with aberrant c-Src kinase activity to improve mitochondrial energy metabolism.

Feedback analysis identifies a combination target for overcoming adaptive resistance to targeted cancer therapy

Targeted drugs aim to treat cancer by directly inhibiting oncogene activity or oncogenic pathways, but drug resistance frequently emerges. Due to the intricate dynamics of cancer signaling networks, which contain complex feedback regulations, cancer cells can rewire these networks to adapt to and counter the cytotoxic effects of a drug, thereby limiting the efficacy of targeted therapies. To identify a combinatorial drug target that can overcome such a limitation, we developed a Boolean network simulation and analysis framework and applied this approach to a large-scale signaling network of colorectal cancer with integrated genomic information. We discovered Src as a critical combination drug target that can overcome the adaptive resistance to the targeted inhibition of mitogen-activated protein kinase pathway by blocking the essential feedback regulation responsible for resistance. The proposed framework is generic and can be widely used to identify drug targets that can overcome adaptive resistance to targeted therapies.

Ubiquitination of Src promotes its secretion via small extracellular vesicles

Upregulation of the Src tyrosine kinase is implicated in the progression of cancer. The oncogenic potential of Src is suppressed via several negative regulation systems including degradation via the ubiquitin-proteasome pathway. Here, we show that ubiquitination of Src promotes its secretion via small extracellular vesicles (sEVs) to suppress its oncogenic potential. In MDCK cells expressing a modified Src that can be activated by hydroxytamoxifen, activated Src was transported to late endosomes/lysosomes and secreted via sEVs. The secretion of Src was suppressed by ablation of Cbl E3-ligase, suggesting the contribution of ubiquitination to this process. Activated Src was ubiquitinated at multiple sites, and Lys429 was identified as a critical site for sEV-mediated secretion. Mutation of Src at Lys429 (R429) caused resistance to ubiquitination and decreased its secretion via sEVs. The activated R429 mutant was also transported to late endosomes/lysosomes, whereas its incorporation into intraluminal vesicles was reduced. Activation of the R429 mutant induced a greater FAK activation than that of wild-type Src, thereby potentiating Src-induced invasive phenotypes, such as invadopodia formation and invasive activity. These findings demonstrate that ubiquitination of activated Src at Lys429 promotes its secretion via sEVs, suggesting a potential strategy to suppress the oncogenic function of upregulated Src.

The Role of Kinase Signaling in Resistance to Bevacizumab Therapy for Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most malignant primary brain tumor and is characterized by vascular hyperplasia, necrosis, and high cell proliferation. Despite current standard therapies, including surgical resection and chemoradiotherapy, GBM patients survive for only about 15 months after diagnosis. Recently, the U.S. Food and Drug Administration (FDA) has approved an antiangiogenesis medication for recurrent GBM-bevacizumab-which has improved progression-free survival in GBM patients. Although bevacizumab has resulted in significant early clinical benefit, it inescapably predisposes tumor to relapse that can be represented as an infiltrative phenotype. Fundamentally, bevacizumab antagonizes the vascular endothelial growth factor A (VEGF_A), which is consistently released on both endothelial cells (ECs) and GBM cells. Actually, VEGF_A inhibition on the ECs leads to the suppression of vascular progression, permeability, and the vasogenic edema. However, the consequence of the VEGF_A pathway blockage on the GBM cells remains controversial. Nevertheless, a piece of evidence supports the relationship between bevacizumab application and compensatory activation of kinase signaling within GBM cells, leading to a tumor cell invasion known as the main mechanism of bevacizumab-induced tumor resistance. A complete understanding of kinase responses associated with tumor invasion in bevacizumab-resistant GBMs offers new therapeutic opportunities. Thus, this study aimed at presenting a brief overview of preclinical and clinical data of the tumor invasion and resistance induced by bevacizumab administration in GBMs, with a focus on the kinase responses during treatment. The novel therapeutic strategies to overcome this resistance by targeting protein kinases have also been summarized.

c-Src promotes tumor progression through downregulation of microRNA-129-1-3p

MicroRNAs (miRNAs) fine‐tune cellular signaling by regulating expression of signaling proteins, and aberrant expression of miRNAs is observed in many cancers. The tyrosine kinase c‐Src is upregulated in various human cancers, but the molecular mechanisms underlying c‐Src‐mediated tumor progression remain unclear. In previous investigations of miRNA‐mediated control of c‐Src‐related oncogenic pathways, we identified miRNAs that were downregulated in association with c‐Src transformation and uncovered the signaling networks by predicting their target genes, which might act cooperatively to control tumor progression. Here, to further elucidate the process of cell transformation driven by c‐Src, we analyzed the expression profiles of miRNAs in a doxycycline‐inducible Src expression system. We found that miRNA (miR)‐129‐1‐3p was downregulated in the early phase of c‐Src‐induced cell transformation, and that reexpression of miR‐129‐1‐3p disrupted c‐Src‐induced cell transformation. In addition, miR‐129‐1‐3p downregulation was tightly associated with tumor progression in human colon cancer cells/tissues. Expression of miR‐129‐1‐3p in human colon cancer cells caused morphological changes and suppressed tumor growth, cell adhesion, and invasion. We also identified c‐Src and its critical substrate Fer, and c‐Yes, a member of the Src family of kinases, as novel targets of miR‐129‐1‐3p. Furthermore, we found that miR‐129‐1‐3p‐mediated regulation of c‐Src/Fer and c‐Yes is important for controlling cell adhesion and invasion. Downregulation of miR‐129‐1‐3p by early activation of c‐Src increases expression of these target genes and synergistically promotes c‐Src‐related oncogenic signaling. Thus, c‐Src‐miR‐129‐1‐3p circuits serve as critical triggers for tumor progression in many human cancers that harbor upregulation of c‐Src.

Rho GTPases and related signaling complexes in cell migration and invasion

Cell migration and invasion play an important role in the development of cancer. Cell migration is associated with several specific actin filament-based structures, including lamellipodia, filopodia, invadopodia and blebs, and with cell-cell adhesion, cell-extracellular matrix adhesion. Migration occurs via different modes, human epithelial cancer cells mainly migrate collectively, while in vivo imaging studies in laboratory animals have found that most cells migrate as single cells. Rho GTPases play an important role in the process of cell migration, and several Rho GTPase-related signaling complexes are also involved. However, the exact mechanism by which these signaling complexes act remains unclear. This paper reviews how Rho GTPases and related signaling complexes interact with other proteins, how their expression is regulated, how tumor microenvironment-related factors play a role in invasion and metastasis, and the mechanism of these complex signaling networks in cell migration and invasion.

TWEAK promotes hepatic stellate cell migration through activating EGFR/Src and PI3K/AKT pathways

Activated human hepatic stellate cells (HSCs) showed enhanced ability of migration compared with quiescent HSCs, which is pivotal in liver fibrogenesis. The aim of the present study was to investigate the effects of tumor necrosis factor-like weak inducer of apoptosis (TWEAK) on the migration of activated HSCs and to explore the relevant potential mechanisms. Human HSCs LX-2 cells were cultured with TWEAK. TNFRSF12A-downexpressing lentiviruses were used to infect LX-2 cells. The specific matrix metalloproteinases inhibitor BB94, the Src family kinase inhibitor, Dasatinib, and the specific inhibitor of phosphoinositide 3-kinase (PI3K), LY294002 were used to treat LX-2 cells combined with TWEAK. Cell migration and invasion was tested by the transwell assay. The expression of EGFR/Src, PI3K/AKT, and matrix metallopeptidase 9 (MMP9) was identified by real-time polymerase chain reaction or western blotting. The result showed TWEAK promoted HSC migration and collagen production. BB94 significantly attenuated the migration of LX-2 induced by TWEAK. Dasatinib inhibited the ability of cell migration stimulated by TWEAK. TWEAK upregulated the phosphorylation of epidermal growth factor receptor (EGFR) and Src. The phosphorylation of PI3K and AKT was significantly activated by TWEAK stimulation. Inhibition of PI3K/AKT reduced the expression of MMP9 induced by TWEAK. The present study, for the first time, demonstrated that TWEAK promoted HSC migration through the activation of EGFR/Src and PI3K/AKT pathways, and showed a novel potential mechanism of HSC migration regulated by TWEAK.

MicroRNA-144-3p suppressed TGF-β1-induced lung cancer cell invasion and adhesion by regulating the Src-Akt-Erk pathway

Lung cancer remains a leading cause to cancer-related death worldwide. The anti-cancer ability of microRNA-144-3p has been reported in many cancer types. This study focused on the mechanisms underlying miR-144-3p in inhibiting lung cancer. The expression levels of miR-144-3p and steroid receptor coactivator (Src) in different lung cancer cell lines and those in bronchial epithelial cells (16HBE) were compared. miR-144-3p mimic and siSrc were transfected into A549 cells. Under the conditions of transforming growth factor-β1 (TGF-β1). Small interfering transfection or TGF-β1 treatment, cell invasive and adhesive abilities were analyzed by Transwell and cell adhesion assays. miR-144-3p inhibitor and siSrc were co-transfected into A549 cells and the changes in cell invasion and adhesion were detected. The activation of Src-protein kinase B-extracellular-regulated protein kinases (Src-Akt-Erk) pathway was determined using Western blot. The downregulated miR-144-3p and upregulated Src were generally detected in lung cancer cell lines and were the most significant genes in A549 cells. Both miR-144-3p overexpression and Src inhibition could obviously inhibit the invasion and adhesion abilities of A549 cells in the presence or absence of the effects of TGF-β1. The inhibition of Src could block the promotive effects of miR-144-3p inhibitor and TGF-β1 on cell invasion and adhesion. Furthermore, we found that miR-144-3p could negatively regulate the phosphorylation levels of Akt and Erk. Our data indicated the essential role of Src in the mechanisms underlying TGF-β1-induced cell invasion and adhesion of lung cancer, and that miR-144-3p could effectively suppress TGF-β1-induced aggressive lung cancer cells by regulating Src expression.

Src Kinase Is Biphosphorylated at Y416/Y527 and Activates the CUB-Domain Containing Protein 1/Protein Kinase C δ Pathway in a Subset of Triple-Negative Breast Cancers

Targeted therapeutics are needed for triple-negative breast cancer (TNBC). In this study, we investigated the activation of Src family of cytoplasmic tyrosine kinases (SFKs) and two SFK substrates-CUB-domain containing protein 1 (CDCP1) and protein kinase C δ (PKCδ)-in 56 formalin-fixed, paraffin-embedded (FFPE) TNBCs. Expression of SFK phosphorylated at Y416 (SFK_pY416⁺) in tumor cells was strongly associated with phosphorylation of CDCP1 and PKCδ (CDCP1_ pY743⁺ and PKCδ_pY311⁺), as assessed by immunohistochemistry, indicating increased SFK activity in situ. To enable biochemical analysis, protein extraction from FFPE tissue was optimized. Cleaved CDCP1 isoform (70 kDa) was expressed to a varying degree in all samples but only phosphorylated in TNBC tumor cells that expressed SFK_pY416. Interestingly, active SFK was found to be biphosphorylated (SFK_pY416⁺/pY527⁺). Biphosphorylated active SFK was observed more frequently in forkhead box protein A1 (FOXA1)^- TNBCs. In addition, in SFK_pY416^- samples, FOXA1⁺ TNBC tended to be SFK_pY527⁺ (classic inactive SFK), and FOXA1^- TNBC tended to be SFK_pY527^- (SFK poised for activation). Strong SFK_pY416 staining was also observed in tumor-infiltrating lymphocytes in a subset of TNBCs with high tumor-infiltrating lymphocyte content. This report will facilitate protein biochemical analysis of FFPE tumor samples and justifies the development of therapies targeting the SFK/CDCP1/PKCδ pathway for TNBC treatment.

Proliferative signaling by ERBB proteins and RAF/MEK/ERK effectors in polycystic kidney disease

A primary pathological feature of polycystic kidney disease (PKD) is the hyperproliferation of epithelial cells in renal tubules, resulting in formation of fluid-filled cysts. The proliferative aspects of the two major forms of PKD-autosomal dominant PKD (ADPKD), which arises from mutations in the polycystins PKD1 and PKD2, and autosomal recessive PKD (ARPKD), which arises from mutations in PKHD1-has encouraged investigation into protein components of the core cell proliferative machinery as potential drivers of PKD pathogenesis. In this review, we examine the role of signaling by ERBB proteins and their effectors, with a primary focus on ADPKD. The ERBB family of receptor tyrosine kinases (EGFR/ERBB1, HER2/ERBB2, ERBB3, and ERBB4) are activated by extracellular ligands, inducing multiple pro-growth signaling cascades; among these, activation of signaling through the RAS GTPase, and the RAF, MEK1/2, and ERK1/2 kinases enhance cell proliferation and restrict apoptosis during renal tubuloepithelial cyst formation. Characteristics of PKD include overexpression and mislocalization of the ERBB receptors and ligands, leading to enhanced activation and increased activity of downstream signaling proteins. The altered regulation of ERBBs and their effectors in PKD is influenced by enhanced activity of SRC kinase, which is promoted by the loss of cytoplasmic Ca²⁺ and an increase in cAMP-dependent PKA kinase activity that stimulates CFTR, driving the secretory phenotype of ADPKD. We discuss the interplay between ERBB/SRC signaling, and polycystins and their depending signaling, with emphasis on thes changes that affect cell proliferation in cyst expansion, as well as the inflammation-associated fibrogenesis, which characterizes progressive disease. We summarize the current progress of preclinical and clinical trials directed at inhibiting this signaling axis, and discuss potential future strategies that may be productive for controlling PKD.