A Conformation Selective Mode of Inhibiting SRC Improves Drug Efficacy and Tolerability

A Fast Method to Monitor Tyrosine Kinase Inhibitor Mechanisms

Methionine residues within the kinase domain of Src serve as unique NMR probes capable of distinguishing between distinct conformational states of full-length Src, including alternative drug-inhibited forms. This approach offers a rapid method to differentiate between various inhibition mechanisms at any stage of drug development, eliminating the need to resolve the structure of Src-drug complexes. Using selectively 13C-methyl-enriched methionine, spectra can be acquired in under an hour, while natural abundance spectra with comparable information are achievable within a few hours.

Feed-forward stimulation of CAMK2 by the oncogenic pseudokinase PEAK1 generates a therapeutically "actionable" signalling axis in triple negative breast cancer

The PEAK family of pseudokinases, comprising PEAK1-3, are signalling scaffolds that play oncogenic roles in several poor prognosis human cancers, including triple negative breast cancer (TNBC). However, therapeutic targeting of pseudokinases is challenging due to their lack of catalytic activity. To address this, we screened for PEAK1 effectors by affinity purification and mass spectrometry, identifying calcium/calmodulin-dependent protein kinase 2 (CAMK2)D and CAMK2G. PEAK1 promoted CAMK2D/G activation in TNBC cells via a novel feed-forward mechanism involving PEAK1/PLCg1/Ca2+ signalling and direct binding via a consensus CAMK2 interaction motif in the PEAK1 N-terminus. In turn, CAMK2 phosphorylated PEAK1 to enhance association with PEAK2, which is critical for PEAK1 oncogenic signalling. To achieve pharmacologic targeting of PEAK1/CAMK2, we repurposed RA306, a second generation CAMK2 inhibitor under pre-clinical development for treatment of cardiovascular disease. RA306 demonstrated on-target activity against CAMK2 in TNBC cells and inhibited PEAK1-enhanced migration and invasion in vitro. Moreover, RA306 significantly attenuated TNBC xenograft growth and blocked metastasis in a manner mirrored by CRISPR-mediated PEAK1 ablation. Overall, these studies establish PEAK1 as a critical cell signalling nexus, identify a novel mechanism for regulation of Ca2+ signalling and its integration with tyrosine kinase signals, and identify CAMK2 as a therapeutically "actionable" target downstream of PEAK1.

Targeting YES1 Disrupts Mitotic Fidelity and Potentiates the Response to Taxanes in Triple-Negative Breast Cancer

Clinical trials examining broad-spectrum Src family kinase (SFK) inhibitors revealed significant dose-limiting toxicities, preventing advancement for solid tumors. SFKs are functionally heterogeneous, thus targeting individual members is a potential strategy to elicit antitumor efficacy while avoiding toxicity. Here, we identified that YES1 is the most highly overexpressed SFK in triple-negative breast cancer (TNBC) and is associated with poor patient outcomes. Disrupting YES1, genetically or pharmacologically, induced aberrant mitosis, centrosome amplification, multipolar spindles, and chromosomal instability. Mechanistically, YES1 sustained FOXM1 protein levels and elevated expression of FOXM1 target genes that control centrosome function and are essential for effective and accurate mitotic progression. In both in vitro and in vivo TNBC models, YES1 suppression potentiated the efficacy of taxanes, cornerstone drugs for TNBC that require elevated chromosomal instability for efficacy. Clinically, elevated expression of YES1 was associated with worse overall survival of patients with TNBC treated with taxane and anthracycline combination regimens. Together, this study demonstrates that YES1 is an essential regulator of genome stability in TNBC that can be leveraged to improve taxane efficacy.  Significance: YES1 is a sentinel regulator of genomic maintenance that controls centrosome homeostasis and chromosome stability through FOXM1, revealing this pathway as a therapeutic vulnerability for enhancing taxane efficacy in triple-negative breast cancer.

The SRC-family serves as a therapeutic target in triple negative breast cancer with acquired resistance to chemotherapy

BACKGROUND

Resistance to chemotherapy, combined with heterogeneity among resistant tumors, represents a significant challenge in the clinical management of triple negative breast cancer (TNBC). By dissecting molecular pathways associated with treatment resistance, we sought to define patient sub-groups and actionable targets for next-line treatment.

METHODS

Bulk RNA sequencing and reverse phase protein array profiling were performed on isogenic patient-derived xenografts (PDX) representing paclitaxel-sensitive and -resistant tumors. Pathways identified as upregulated in the resistant model were further explored as targets in PDX explants. Their clinical relevance was assessed in two distinct patient cohorts (NeoAva and MET500).

RESULTS

Increased activity in signaling pathways involving SRC-family kinases (SFKs)- and MAPK/ERK was found in treatment resistant PDX, with targeted inhibitors being significantly more potent in resistant tumors. Up-regulation of SFKs- and MAPK/ERK-pathways was also detected in a sub-group of chemoresistant patients after neoadjuvant treatment. Furthermore, High SFK expression (of either SRC, FYN and/or YES1) was detected in metastatic lesions of TNBC patients with fast progressing disease (median disease-free interval 27 vs 105 months).

CONCLUSIONS

Upregulation of SFK-signaling is found in a subset of chemoresistant tumors and is persistent in metastatic lesions. Based on pre-clinical results, these patients may respond favorably to treatment targeting SFKs.

Ligand-centred phenotype-driven development of potent kinase inhibitors against oesophageal cancer

Oesophageal cancer (OC) is one of the leading causes of cancer-related deaths worldwide. Due in part to its high heterogeneity, OC prognosis remains poor despite the introduction of targeted and immunotherapy drugs. Although numerous kinases play a significant role in the oncogenesis and progression of OC, targeting kinases have shown so far limited therapeutic success. Based on our understanding of the pharmacological properties of the pyrazolo[3,4-d]pyrimidine scaffold and the complex biology of OC, we implemented a ligand-centred strategy combined with phenotypic screening to develop novel antiproliferative inhibitors against OC. This approach is specifically designed to accelerate the discovery of lead compounds in cancers of high molecular heterogeneity such as OC. In an iterative process driven by structure-antiproliferative activity relationships (SAARs), we synthesised and tested 54 novel pyrazolo[3,4-d]pyrimidine derivatives against OC cell lines. The lead compound 2D7 (a.k.a. eCCA352) induces pan-OC activity and cell cycle arrest in the submicromolar range and was determined to inhibit Aurora kinase A, providing a new starting point to develop anticancer targeted agents against OC.

The SRC family kinase inhibitor NXP900 demonstrates potent antitumor activity in squamous cell carcinomas

NXP900 is a selective and potent SRC family kinase (SFK) inhibitor, currently being dosed in a phase 1 clinical trial, that locks SRC in the "closed" conformation, thereby inhibiting both kinase-dependent catalytic activity and kinase-independent functions. In contrast, several multi-targeted kinase inhibitors that inhibit SRC, including dasatinib and bosutinib, bind their target in the active "open" conformation, allowing SRC and other SFKs to act as a scaffold to promote tumorigenesis through non-catalytic functions. NXP900 exhibits a unique target selectivity profile with sub-nanomolar activity against SFK members over other kinases. This results in highly potent and specific SFK pathway inhibition. Here, we demonstrate that esophageal squamous cell carcinomas and head and neck squamous cell carcinomas are exquisitely sensitive to NXP900 treatment in cell culture and in vivo, and we identify a patient population that could benefit from treatment with NXP900.

High throughput screening identifies dasatinib as synergistic with trametinib in low grade serous ovarian carcinoma

BACKGROUND

Low grade serous ovarian carcinoma (LGSOC) is a distinct histotype of ovarian cancer characterised high levels of intrinsic chemoresistance, highlighting the urgent need for new treatments. High throughput screening in clinically-informative cell-based models represents an attractive strategy for identifying candidate treatment options for prioritisation in clinical studies.

METHODS

We performed a high throughput drug screen of 1610 agents across a panel of 6 LGSOC cell lines (3 RAS/RAF-mutant, 3 RAS/RAF-wildtype) to identify novel candidate therapeutic approaches. Validation comprised dose-response analysis across 9 LGSOC models and 5 high grade serous comparator lines.

RESULTS

16 hits of 1610 screened compounds were prioritised for validation based on >50% reduction in nuclei counts in over half of screened cell lines at 1000 nM concentration. 11 compounds passed validation, and the four agents of greatest interest (dasatinib, tyrosine kinase inhibitor; disulfiram, aldehyde dehydrogenase inhibitor; carfilzomib, proteasome inhibitor; romidepsin, histone deacetylase inhibitor) underwent synergy profiling with the recently approved MEK inhibitor trametinib. Disulfiram demonstrated excellent selectivity for LGSOC versus high grade serous ovarian carcinoma comparator lines (P = 0.003 for IC50 comparison), while the tyrosine kinase inhibitor dasatinib demonstrated favourable synergy with trametinib across multiple LGSOC models (maximum zero interaction potency synergy score 46.9). The novel, highly selective Src family kinase (SFK) inhibitor NXP900 demonstrated a similar trametinib synergy profile to dasatinib, suggesting that SFK inhibition is the likely driver of synergy.

CONCLUSION

Dasatinib and other SFK inhibitors represent novel candidate treatments for LGSOC and demonstrate synergy with trametinib. Disulfiram represents an additional treatment strategy worthy of investigation.

Proteome-based molecular subtyping and therapeutic target prediction in gastric cancer

Different molecular classifications for gastric cancer (GC) have been proposed based on multi-omics platforms with the long-term goal of improved precision treatment. However, the GC (phospho)proteome remains incompletely characterized, particularly at the level of tyrosine phosphorylation. In addition, previous multiomics-based stratification of patient cohorts has lacked identification of corresponding cell line models and comprehensive validation of broad or subgroup-selective therapeutic targets. To address these knowledge gaps, we applied a reverse approach, undertaking the most comprehensive (phospho)proteomic analysis of GC cell lines to date and cross-validating this using publicly available data. Mass spectrometry (MS)-based (phospho)proteomic and tyrosine phosphorylation datasets were subjected to individual or integrated clustering to identify subgroups that were subsequently characterized in terms of enriched molecular processes and pathways. Significant congruence was detected between cell line proteomic and specific patient-derived transcriptomic subclassifications. Many protein kinases exhibiting 'outlier' expression or phosphorylation in the cell line dataset exhibited genomic aberrations in patient samples and association with poor prognosis, with casein kinase I isoform delta/epsilon (CSNK1D/E) being experimentally validated as potential therapeutic targets. Src family kinases were predicted to be commonly hyperactivated in GC cell lines, consistent with broad sensitivity to the next-generation Src inhibitor eCF506. In addition, phosphoproteomic and integrative clustering segregated the cell lines into two subtypes, with epithelial-mesenchyme transition (EMT) and proliferation-associated processes enriched in one, designated the EMT subtype, and metabolic pathways, cell-cell junctions, and the immune response dominating the features of the other, designated the metabolism subtype. Application of kinase activity prediction algorithms and interrogation of gene dependency and drug sensitivity databases predicted that the mechanistic target of rapamycin kinase (mTOR) and dual specificity mitogen-activated protein kinase kinase 2 (MAP2K2) represented potential therapeutic targets for the EMT and metabolism subtypes, respectively, and this was confirmed using selective inhibitors. Overall, our study provides novel, in-depth insights into GC proteomics, kinomics, and molecular taxonomy and reveals potential therapeutic targets that could provide the basis for precision treatments.

Discovery of pyrazolopyrimidines that selectively inhibit CSF-1R kinase by iterative design, synthesis and screening against glioblastoma cells

Glioblastoma multiforme (GBM) is the most aggressive type of brain cancer in adults, with an average life expectancy under treatment of approx. 15 months. GBM is characterised by a complex set of genetic alterations that results in significant disruption of receptor tyrosine kinase (RTK) signaling. We report here an exploration of the pyrazolo[3,4-d]pyrimidine scaffold in search for antiproliferative compounds directed to GBM treatment. Small compound libraries were synthesised and screened against GBM cells to build up structure-antiproliferative activity-relationships (SAARs) and inform further rounds of design, synthesis and screening. 76 novel compounds were generated through this iterative process that found low micromolar potencies against selected GBM lines, including patient-derived stem cells. Phenomics analysis demonstrated preferential activity against glioma cells of the mesenchymal subtype, whereas kinome screening identified colony stimulating factor-1 receptor (CSF-1R) as the lead's target, a RTK implicated in the tumourigenesis and progression of different cancers and the immunoregulation of the GBM microenvironment.

A renaissance for YES in cancer

Most of our understanding regarding the involvement of SRC-family tyrosine kinases in cancer has stemmed from studies focused on the prototypical SRC oncogene. However, emerging research has shed light on the important role of YES signaling in oncogenic transformation, tumor growth, metastatic progression, and resistance to various cancer therapies. Clinical evidence indicates that dysregulated expression or activity of YES is a frequent occurrence in human cancers and is associated with unfavorable outcomes. These findings provide a compelling rationale for specifically targeting YES in certain cancer subtypes. Here, we review the crucial role of YES in cancer and discuss the challenges associated with translating preclinical observations into effective YES-targeted therapies.

Recent advances of small-molecule c-Src inhibitors for potential therapeutic utilities

Proto-oncogene tyrosine-protein kinase Src, also known as c-Src, belongs to the family of non-receptor tyrosine protein kinases (TKs) called Src kinases. It plays a crucial role in cell division, motility, adhesion, and survival in both normal cells and cancer cells by activating various signaling pathways mediated by multiple cytokines. Additionally, c-Src kinase has been implicated in osteoclasts and bone loss diseases mediated by inflammation and osteoporosis. In recent years, remarkable advancements have been achieved in the development of c-Src inhibitors, with several candidates progressing to the clinical stage. This review focuses on the research progress in several areas, including the mechanism of action, drug discovery, combination therapy, and clinical research. By presenting this information, we aim to provide researchers with convenient access to valuable insights and inspire new ideas to expedite future drug discovery programs.

Anti-cervical cancer mechanism of bioactive compounds from Alangium platanifolium based on the 'compound-target-disease' network

In this study, we analyzed the chemical compositions of Alangium platanifolium (Sieb. et Zucc.) Harms (AP) using ultraperformance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS) non-targeted plant metabolomics integration MolNetEnhancer strategy. A total of 75 compounds, including flavonoids, alkaloids, terpenes, C21 steroids, among others, were identified by comparing accurate mass-to-charge ratios, MS2 cleavage fragments, retention times, and MolNetenhancer-integrated analytical data, and the cleavage rules of the characteristic compounds were analyzed. A total of 125 potential cervical cancer (CC) therapeutic targets were obtained through Gene Expression Omnibus (GEO) data mining, differential analysis, and database screening. Hub targets were obtained by constructing protein-protein interaction (PPI) networks and CytoNCA topology analysis, including SRC, STAT3, TP53, PIK3R1, MAPK3, and PIK3CA. According to Gene ontology (GO) analysis, AP was primarily against CC by influencing gland development, oxidative stress processes, serine/threonine kinase, and tyrosine kinase activity. Enrichment analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) indicated that the PI3K/AKT and MAPK signaling pathways play a crucial role in AP treatment for CC. The compound-target-pathway (C-T-P) network revealed that quercetin, methylprednisolone, and caudatin may play key roles in the treatment of CC. The results of molecular docking revealed that the core compound could bind significantly to the core target. In this study, the compounds in AP were systematically analyzed qualitatively, and the core components, core targets, and mechanisms of action of AP in the treatment of CC were screened through a combination of network pharmacology tools. Providing a scientific reference for the therapeutic material basis and quality control of AP.

Macrophages promote anti-androgen resistance in prostate cancer bone disease

Metastatic castration-resistant prostate cancer (PC) is the final stage of PC that acquires resistance to androgen deprivation therapies (ADT). Despite progresses in understanding of disease mechanisms, the specific contribution of the metastatic microenvironment to ADT resistance remains largely unknown. The current study identified that the macrophage is the major microenvironmental component of bone-metastatic PC in patients. Using a novel in vivo model, we demonstrated that macrophages were critical for enzalutamide resistance through induction of a wound-healing-like response of ECM-receptor gene expression. Mechanistically, macrophages drove resistance through cytokine activin A that induced fibronectin (FN1)-integrin alpha 5 (ITGA5)-tyrosine kinase Src (SRC) signaling cascade in PC cells. This novel mechanism was strongly supported by bioinformatics analysis of patient transcriptomics datasets. Furthermore, macrophage depletion or SRC inhibition using a novel specific inhibitor significantly inhibited resistant growth. Together, our findings elucidated a novel mechanism of macrophage-induced anti-androgen resistance of metastatic PC and a promising therapeutic approach to treat this deadly disease.

Aromatase inhibition plus/minus Src inhibitor saracatinib (AZD0530) in advanced breast cancer therapy (ARISTACAT): a randomised phase II study

PURPOSE

The development of oestrogen resistance is a major challenge in managing hormone-sensitive metastatic breast cancer. Saracatinib (AZD0530), an oral Src kinase inhibitor, prevents oestrogen resistance in animal models and reduces osteoclast activity. We aimed to evaluate the efficacy of saracatinib addition to aromatase inhibitors (AI) in patients with hormone receptor-positive metastatic breast cancer.

METHODS

This phase II multicentre double-blinded randomised trial allocated post-menopausal women to AI with either saracatinib or placebo (1:1 ratio). Patients were stratified into an "AI-sensitive/naïve" group who received anastrozole and "prior-AI" group who received exemestane. Primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR) and toxicity.

RESULTS

140 patients were randomised from 20 UK centres to saracatinib/AI (n = 69) or placebo/AI (n = 71). Saracatinib was not associated with an improved PFS (3.7 months v. 5.6 months placebo/AI) and did not reduce likelihood of bony progression. There was no benefit in OS or ORR. Effects were consistent in "AI-sensitive/naive" and "prior-AI" sub-groups. Saracatinib was well tolerated with dose reductions in 16% and the main side effects were gastrointestinal, hypophosphatemia and rash.

CONCLUSION

Saracatinib did not improve outcomes in post-menopausal women with metastatic breast cancer. There was no observed beneficial effect on bone metastases. CRUKE/11/023, ISRCTN23804370.

Proteomic time course of breast cancer cells highlights enhanced sensitivity to Stat3 and Src inhibitors prior to endocrine resistance development

To prevent the development of endocrine-resistant breast cancer, additional targeted therapies are increasingly being trialled in combination with endocrine therapy. The molecular mechanisms facilitating cancer cell survival during endocrine treatment remain unknown but could help direct selection of additional targeted therapies. We present a novel proteomic timecourse dataset, profiling potential drug targets in a population of MCF7 cells during 1 year of tamoxifen treatment. Reverse phase protein arrays profiled >70 proteins across 30 timepoints. A biphasic response to tamoxifen was evident, which coincided with changes in growth rate. Tamoxifen strongly impeded cell growth for the first 160 days, followed by gradual growth recovery and eventual resistance development. The growth-impeded phase was distinguished by the phosphorylation of Stat3 (y705) and Src (y527). Tumour tissue from patients treated with neo-adjuvant endocrine therapy (<4 months) also displayed increased Stat3 and Src signalling. Inhibitors of Stat3 (napabucasin) and Src (dasatinib), were effective at killing tamoxifen-treated MCF7 and T47D cells. Sensitivity to both drugs was significantly enhanced once tamoxifen had induced the growth-impeded phase. This novel proteomic resource identifies key mechanisms enabling cell survival during tamoxifen treatment. It provides valuable insight into potential drug combinations and timing that may prevent the development of endocrine resistance.

Tyrosine kinase SRC-induced YAP1-KLF5 module regulates cancer stemness and metastasis in triple-negative breast cancer

SRC is the first identified oncogene, and its aberrant activation has been implicated as a driving event in tumor initiation and progression. However, its role in cancer stemness regulation and the underlying regulatory mechanism are still elusive. Here, we identified a YAP1 tyrosine phosphorylation-dependent YAP1-KLF5 oncogenic module, as the key downstream mediator of SRC kinase regulating cancer stemness and metastasis in triple-negative breast cancer (TNBC). SRC was overexpressed in TNBC patient tissues and its expression level was highly correlated with the tumor malignancy. SRC activation induced, while inhibition of SRC kinase reduced the cancer stemness, tumor cell growth and metastasis in vitro and in vivo. Transcriptomic and proteomic analysis revealed that SRC-mediated YAP1 tyrosine phosphorylation induced its interaction with Kruppel-like factor 5 (KLF5) to form a YAP1/TEAD-KLF5 complex in TNBC cells. YAP1-KLF5 association further promoted TEAD-mediated transcriptional program independently of canonical Hippo kinases, which eventually gave rise to the enhanced cancer stemness and metastasis. Disruption of YAP1-KLF5 module in TNBC cells dramatically attenuated the SRC-induced cancer stemness and metastasis in vitro and in vivo. Accordingly, co-upregulations of SRC and YAP1-KLF5 module in TNBC tissues were significantly positively correlated with the tumor malignance. Altogether, our work presents a novel tyrosine phosphorylation-dependent YAP1-KLF5 oncogenic module governing SRC-induced cancer stemness and metastasis in TNBC. Therefore, targeting YAP1/KLF5-mediated transcription may provide a promising strategy for TNBC treatment with SRC aberrantly activation.

Synthesis and biological activity evaluation of 3-(hetero) arylideneindolin-2-ones as potential c-Src inhibitors

Inhibition of c-Src is considered one of the most studied approaches to cancer treatment, with several heterocyclic compounds approved during the last 15 years as chemotherapeutic agents. Starting from the biological evaluation of an in-house collection of small molecules, indolinone was selected as the most promising scaffold. In this work, several functionalised indolinones were synthesised and their inhibitory potency and cytotoxic activity were assayed. The pharmacological profile of the most active compounds, supported by molecular modelling studies, revealed that the presence of an amino group increased the affinity towards the ATP-binding site of c-Src. At the same time, bulkier derivatizations seemed to improve the interactions within the enzymatic pocket. Overall, these data represent an early stage towards the optimisation of new, easy-to-be functionalised indolinones as potential c-Src inhibitors.

Src: coordinating metabolism in cancer

Metabolism must be tightly regulated to fulfil the dynamic requirements of cancer cells during proliferation, migration, stemness and differentiation. Src is a node of several signals involved in many of these biological processes, and it is also an important regulator of cell metabolism. Glucose uptake, glycolysis, the pentose-phosphate pathway and oxidative phosphorylation are among the metabolic pathways that can be regulated by Src. Therefore, this oncoprotein is in an excellent position to coordinate and finely tune cell metabolism to fuel the different cancer cell activities. Here, we provide an up-to-date summary of recent progress made in determining the role of Src in glucose metabolism as well as the link of this role with cancer cell metabolic plasticity and tumour progression. We also discuss the opportunities and challenges facing this field.

New insights into FAK structure and function in focal adhesions

Focal adhesion kinase (FAK; also known as PTK2) was discovered three decades ago and is now recognised as a key player in the regulation of cell-matrix adhesion and mesenchymal cell migration. Although it is essential during development, FAK also drives invasive cancer progression and metastasis. On a structural level, the basic building blocks of FAK have been described for some time. However, a picture of how FAK integrates into larger assemblies in various cellular environments, including one of its main cellular locations, the focal adhesion (FA) complex, is only beginning to emerge. Nano-resolution data from cellular studies, as well as atomic structures from reconstituted systems, have provided first insights, but also point to challenges that remain for obtaining a full structural understanding of how FAK is integrated in the FA complex and the structural changes occurring at different stages of FA maturation. In this Review, we discuss the known structural features of FAK, the interactions with its partners within the FA environment on the cell membrane and propose how its initial assembly in nascent FAs might change during FA maturation under force.

In silico analysis and experimental validation to exhibit anti-nasopharyngeal carcinoma effects of plumbagin, an anti-cancer compound

BACKGROUND

Nasopharyngeal carcinoma (NPC) is publicly known as a malignant tumor. Our previous study reported that plumbagin exhibits potent anti-cancer actions. Nevertheless, more mechanical details of plumbagin against NPC remain unknown. The present study aimed to unmask the core targets/genes and anti-NPC mechanisms involved in the signaling pathways of plumbagin prior to biochemical validation.

METHODS

A network pharmacology approach was employed to respective identification of mutual and core targets/genes in plumbagin and/treating NPC. Molecular docking determination was used to identify core target proteins for biochemical validation using human and cell line samples.

RESULTS

In total, 60 anti-NPC genes of plumbagin were screened out, and then nine core target genes of plumbagin against NPC were identified accordingly. The enrichment findings revealed detailed biological functions and pharmacological pathways of plumbagin against NPC. Moreover, in silico analysis using molecular docking had determined the core targets for further experimental validation, comprising protein kinase B (AKT1) and sarcoma gene (SRC). In human sample validation, clinical NPC sections showed increased positive expression of AKT1 and SRC. Additionally, plumbagin-treated NPC cells resulted in inactivated protein expression of AKT1 and SRC.

CONCLUSION

The re-identified core targets/genes in the molecular docking report may function as plumbagin-related pharmacological targets for treating NPC via experimental validation. Furthermore, additional anti-NPC molecular mechanisms of plumbagin action were disclosed on the basis of enrichment findings. © 2022 Society of Chemical Industry.

Pathway profiling of a novel SRC inhibitor, AZD0424, in combination with MEK inhibitors for cancer treatment

A more comprehensive understanding of how cells respond to drug intervention, the likely immediate signalling responses and how resistance may develop within different microenvironments will help inform treatment regimes. The nonreceptor tyrosine kinase SRC regulates many cellular signalling processes, and pharmacological inhibition has long been a target of cancer drug discovery projects. Here, we describe the in vitro and in vivo characterisation of the small-molecule SRC inhibitor AZD0424. We show that AZD0424 potently inhibits the phosphorylation of tyrosine-419 of SRC (IC50 ~ 100 nm) in many cancer cell lines; however, inhibition of cell viability, via a G1 cell cycle arrest, was observed only in a subset of cancer cell lines in the low (on target) micromolar range. We profiled the changes in intracellular pathway signalling in cancer cells following exposure to AZD0424 and other targeted therapies using reverse-phase protein array (RPPA) analysis. We demonstrate that SRC is activated in response to treatment of KRAS-mutant colorectal cell lines with MEK inhibitors (trametinib or AZD6244) and that AZD0424 abrogates this. Cell lines treated with trametinib or AZD6244 in combination with AZD0424 had reduced EGFR, FAK and SRC compensatory activation, and cell viability was synergistically inhibited. In vivo, trametinib treatment of mice-bearing HCT116 tumours increased phosphorylation of SRC on Tyr419, and, when combined with AZD0424, inhibition of tumour growth was greater than with trametinib alone. We also demonstrate that drug-induced resistance to trametinib is not re-sensitised by AZD0424 treatment in vitro, likely as a result of multiple compensatory signalling mechanisms; however, inhibition of SRC remains an effective way to block invasion of trametinib-resistant tumour cells. These data imply that SRC inhibition may offer a useful addition to MEK inhibitor combination strategies.

Loss of Integrin-Linked Kinase Sensitizes Breast Cancer to SRC Inhibitors

SRC is a nonreceptor tyrosine kinase with key roles in breast cancer development and progression. Despite this, SRC tyrosine kinase inhibitors have so far failed to live up to their promise in clinical trials, with poor overall response rates. We aimed to identify possible synergistic gene-drug interactions to discover new rational combination therapies for SRC inhibitors. An unbiased genome-wide CRISPR-Cas9 knockout screen in a model of triple-negative breast cancer revealed that loss of integrin-linked kinase (ILK) and its binding partners α-Parvin and PINCH-1 sensitizes cells to bosutinib, a clinically approved SRC/ABL kinase inhibitor. Sensitivity to bosutinib did not correlate with ABL dependency; instead, bosutinib likely induces these effects by acting as a SRC tyrosine kinase inhibitor. Furthermore, in vitro and in vivo models showed that loss of ILK enhanced sensitivity to eCF506, a novel and highly selective inhibitor of SRC with a unique mode of action. Whole-genome RNA sequencing following bosutinib treatment in ILK knockout cells identified broad changes in the expression of genes regulating cell adhesion and cell-extracellular matrix. Increased sensitivity to SRC inhibition in ILK knockout cells was associated with defective adhesion, resulting in reduced cell number as well as increased G1 arrest and apoptosis. These findings support the potential of ILK loss as an exploitable therapeutic vulnerability in breast cancer, enhancing the effectiveness of clinical SRC inhibitors.

SIGNIFICANCE

A CRISPR-Cas9 screen reveals that loss of integrin-linked kinase synergizes with SRC inhibition, providing a new opportunity for enhancing the clinical effectiveness of SRC inhibitors in breast cancer.

SRC kinase-mediated signaling pathways and targeted therapies in breast cancer

Breast cancer (BC) has been ranked the most common malignant tumor throughout the world and is also a leading cause of cancer-related deaths among women. SRC family kinases (SFKs) belong to the non-receptor tyrosine kinase (nRTK) family, which has eleven members sharing similar structure and function. Among them, SRC is the first identified proto-oncogene in mammalian cells. Oncogenic overexpression or activation of SRC has been revealed to play essential roles in multiple events of BC progression, including tumor initiation, growth, metastasis, drug resistance and stemness regulations. In this review, we will first give an overview of SRC kinase and SRC-relevant functions in various subtypes of BC and then systematically summarize SRC-mediated signaling transductions, with particular emphasis on SRC-mediated substrate phosphorylation in BC. Furthermore, we will discuss the progress of SRC-based targeted therapies in BC and the potential future direction.

Small Molecule Kinase Inhibitor Drugs (1995-2021): Medical Indication, Pharmacology, and Synthesis

The central role of dysregulated kinase activity in the etiology of progressive disorders, including cancer, has fostered incremental efforts on drug discovery programs over the past 40 years. As a result, kinase inhibitors are today one of the most important classes of drugs. The FDA approved 73 small molecule kinase inhibitor drugs until September 2021, and additional inhibitors were approved by other regulatory agencies during that time. To complement the published literature on clinical kinase inhibitors, we have prepared a review that recaps this large data set into an accessible format for the medicinal chemistry community. Along with the therapeutic and pharmacological properties of each kinase inhibitor approved across the world until 2020, we provide the synthesis routes originally used during the discovery phase, many of which were only available in patent applications. In the last section, we also provide an update on kinase inhibitor drugs approved in 2021.