Receptor Tyrosine Kinase Signaling Research Articles

Aberrant MET Receptor Tyrosine Kinase Signaling in Glioblastoma: Targeted Therapy and Future Directions.

Brain tumors represent a heterogeneous group of neoplasms characterized by a high degree of aggressiveness and a poor prognosis. Despite recent therapeutic advances, the treatment of brain tumors, including glioblastoma (GBM), an aggressive primary brain tumor associated with poor prognosis and resistance to therapy, remains a significant challenge. Receptor tyrosine kinases (RTKs) are critical during development and in adulthood. Dysregulation of RTKs through activating mutations and gene amplification contributes to many human cancers and provides attractive therapeutic targets for treatment. Under physiological conditions, the Met RTK, the hepatocyte growth factor/scatter factor (HGF/SF) receptor, promotes fundamental signaling cascades that modulate epithelial-to-mesenchymal transition (EMT) involved in tissue repair and embryogenesis. In cancer, increased Met activity promotes tumor growth and metastasis by providing signals for proliferation, survival, and migration/invasion. Recent clinical genomic studies have unveiled multiple mechanisms by which MET is genetically altered in GBM, including focal amplification, chromosomal rearrangements generating gene fusions, and a splicing variant mutation (exon 14 skipping, METex14del). Notably, MET overexpression contributes to chemotherapy resistance in GBM by promoting the survival of cancer stem-like cells. This is linked to distinctive Met-induced pathways, such as the upregulation of DNA repair mechanisms, which can protect tumor cells from the cytotoxic effects of chemotherapy. The development of MET-targeted therapies represents a major step forward in the treatment of brain tumours. Preclinical studies have shown that MET-targeted therapies (monoclonal antibodies or small molecule inhibitors) can suppress growth and invasion, enhancing the efficacy of conventional therapies. Early-phase clinical trials have demonstrated promising results with MET-targeted therapies in improving overall survival for patients with recurrent GBM. However, challenges remain, including the need for patient stratification, the optimization of treatment regimens, and the identification of mechanisms of resistance. This review aims to highlight the current understanding of mechanisms underlying MET dysregulation in GBM. In addition, it will focus on the ongoing preclinical and clinical assessment of therapies targeting MET dysregulation in GBM.

SOS2 modulates the threshold of EGFR signaling to regulate osimertinib efficacy and resistance in lung adenocarcinoma.

Son of sevenless 1 and 2 (SOS1 and SOS2) are RAS guanine nucleotide exchange factors (RasGEFs) that mediate physiologic and pathologic receptor tyrosine kinase (RTK)-dependent RAS activation. Here, we show that SOS2 modulates the threshold of epidermal growth factor receptor (EGFR) signaling to regulate the efficacy of and resistance to the EGFR tyrosine kinase inhibitor (EGFR-TKI) osimertinib in lung adenocarcinoma (LUAD). SOS2 deletion (SOS2KO ) sensitized EGFR-mutated cells to perturbations in EGFR signaling caused by reduced serum and/or osimertinib treatment to inhibit phosphatidylinositol 3-kinase (PI3K)/AKT pathway activation, oncogenic transformation, and survival. Bypassing RTK reactivation of PI3K/AKT signaling represents a common resistance mechanism to EGFR-TKIs; SOS2KO reduced PI3K/AKT reactivation to limit osimertinib resistance. In a forced HGF/MET-driven bypass model, SOS2KO inhibited hepatocyte growth factor (HGF)-stimulated PI3K signaling to block HGF-driven osimertinib resistance. Using a long-term in situ resistance assay, most osimertinib-resistant cultures exhibited a hybrid epithelial/mesenchymal phenotype associated with reactivated RTK/AKT signaling. In contrast, RTK/AKT-dependent osimertinib resistance was markedly reduced by SOS2 deletion; the few SOS2KO cultures that became osimertinib resistant primarily underwent non-RTK-dependent epithelial-mesenchymal transition (EMT). Since bypassing RTK reactivation and/or tertiary EGFR mutations represent most osimertinib-resistant cancers, these data suggest that targeting proximal RTK signaling, here exemplified by SOS2 deletion, has the potential to delay the development osimertinib resistance and enhance overall clinical responses for patients with EGFR-mutated LUAD.

Functional selectivity of Receptor Tyrosine Kinases regulates distinct cellular outputs.

Functional selectivity refers to the activation of differential signalling and cellular outputs downstream of the same membrane-bound receptor when activated by two or more different ligands. Functional selectivity has been described and extensively studied for G-protein Coupled Receptors (GPCRs), leading to specific therapeutic options for dysregulated GPCRs functions. However, studies regarding the functional selectivity of Receptor Tyrosine Kinases (RTKs) remain sparse. Here, we will summarize recent data about RTK functional selectivity focusing on how the nature and the amount of RTK ligands and the crosstalk of RTKs with other membrane proteins regulate the specificity of RTK signalling. In addition, we will discuss how structural changes in RTKs upon ligand binding affects selective signalling pathways. Much remains to be known about the integration of different signals affecting RTK signalling specificity to orchestrate long-term cellular outcomes. Recent advancements in omics, specifically quantitative phosphoproteomics, and in systems biology methods to study, model and integrate different types of large-scale omics data have increased our ability to compare several signals affecting RTK functional selectivity in a global, system-wide fashion. We will discuss how such methods facilitate the exploration of important signalling hubs and enable data-driven predictions aiming at improving the efficacy of therapeutics for diseases like cancer, where redundant RTK signalling pathways often compromise treatment efficacy.

SUMOylation Fine-Tunes Endothelial HEY1 in the Regulation of Angiogenesis.

Angiogenesis, which plays a critical role in embryonic development and tissue repair, is controlled by a set of angiogenic signaling pathways. As a TF (transcription factor) belonging to the basic helix-loop-helix family, HEY (hairy/enhancer of split related with YRPW motif)-1 (YRPW motif, abbreviation of 4 highly conserved amino acids in the motif) has been identified as a key player in developmental angiogenesis. However, the precise mechanisms underlying HEY1's actions in angiogenesis remain largely unknown. Our previous studies have suggested a potential role for posttranslational SUMOylation in the dynamic regulation of vascular development and organization. Immunoprecipitation, mass spectrometry, and bioinformatics analysis were used to determine the biochemical characteristics of HEY1 SUMOylation. The promoter-binding capability of HEY1 was determined by chromatin immunoprecipitation, dual luciferase, and electrophoretic mobility shift assays. The dimerization pattern of HEY1 was determined by coimmunoprecipitation. The angiogenic capabilities of endothelial cells were assessed by CCK-8 (cell counting kit-8), 5-ethynyl-2-deoxyuridine staining, wound healing, transwell, and sprouting assays. Embryonic and postnatal vascular growth in mouse tissues, matrigel plug assay, cutaneous wound healing model, oxygen-induced retinopathy model, and tumor angiogenesis model were used to investigate the angiogenesis in vivo. We identified intrinsic endothelial HEY1 SUMOylation at conserved lysines by TRIM28 (tripartite motif containing 28) as the unique E3 ligase. Functionally, SUMOylation facilitated HEY1-mediated suppression of angiogenic RTK (receptor tyrosine kinase) signaling and angiogenesis in primary human endothelial cells and mice with endothelial cell-specific expression of wild-type HEY1 or a SUMOylation-deficient HEY1 mutant. Mechanistically, SUMOylation facilitates HEY1 homodimer formation, which in turn preserves HEY1's DNA-binding capability via recognition of E-box promoter elements. Therefore, SUMOylation maintains HEY1's function as a repressive TF controlling numerous angiogenic genes, including RTKs and Notch pathway components. Proangiogenic stimuli induce HEY1 deSUMOylation, leading to heterodimerization of HEY1 with HES (hairy and enhancer of split)-1, which results in ineffective DNA binding and loss of HEY1's angiogenesis-suppressive activity. Our findings demonstrate that reversible HEY1 SUMOylation is a molecular mechanism that coordinates endothelial angiogenic signaling and angiogenesis, both in physiological and pathological milieus, by fine-tuning the transcriptional activity of HEY1. Specifically, SUMOylation facilitates the formation of the HEY1 transcriptional complex and enhances its DNA-binding capability in endothelial cells.

Characterization of gastric cancer-stimulated signaling pathways and function of CTGF in cancer-associated fibroblasts

BackgroundCancer-associated fibroblasts (CAFs) are key components of the tumor microenvironment (TME) that play an important role in cancer progression. Although the mechanism by which CAFs promote tumorigenesis has been well investigated, the underlying mechanism of CAFs activation by neighboring cancer cells remains elusive. In this study, we aim to investigate the signaling pathways involved in CAFs activation by gastric cancer cells (GC) and to provide insights into the therapeutic targeting of CAFs for overcoming GC.MethodsAlteration of receptor tyrosine kinase (RTK) activity in CAFs was analyzed using phospho-RTK array. The expression of CAFs effector genes was determined by RT-qPCR or ELISA. The migration and invasion of GC cells co-cultured with CAFs were examined by transwell migration/invasion assay.ResultsWe found that conditioned media (CM) from GC cells could activate multiple receptor tyrosine kinase signaling pathways, including ERK, AKT, and STAT3. Phospho-RTK array analysis showed that CM from GC cells activated PDGFR tyrosine phosphorylation, but only AKT activation was PDGFR-dependent. Furthermore, we found that connective tissue growth factor (CTGF), a member of the CCN family, was the most pronouncedly induced CAFs effector gene by GC cells. Knockdown of CTGF impaired the ability of CAFs to promote GC cell migration and invasion. Although the PDGFR-AKT pathway was pronouncedly activated in CAFs stimulated by GC cells, its pharmacological inhibition affected neither CTGF induction nor CAFs-induced GC cell migration. Unexpectedly, the knockdown of SRC and SRC-family kinase inhibitors, dasatinib and saracatinib, significantly impaired CTGF induction in activated CAFs and the migration of GC cells co-cultured with CAFs. SRC inhibitors restored the reduced expression of epithelial markers, E-cadherin and Zonula Occludens-1 (ZO-1), in GC cells co-cultured with CAFs, as well as CAFs-induced aggregate formation in a 3D tumor spheroid model.ConclusionsThis study provides a characterization of the signaling pathways and effector genes involved in CAFs activation, and strategies that could effectively inhibit it in the context of GC.DC5ErEG73tsyg3F8WfE1xiVideo

Combining EGFR and KRAS G12C Inhibitors for KRAS G12C Mutated Advanced Colorectal Cancer

KRAS is a commonly mutated gene in advanced colorectal cancer (CRC). Recently, inhibitors of KRAS G12C were developed and have shown promising efficacy for KRAS G12C mutated non-small cell lung cancer. However, KRAS G12C inhibitor monotherapy has not demonstrated excellent efficacy for KRAS G12C mutated advanced CRC due to multiple resistance mechanisms, especially receptor tyrosine kinase (RTK) signaling activation. To overcome this resistance mechanism, various combinations of epithelial growth factor receptor (EGFR) and KRAS G12C inhibitors, including panitumumab plus sotorasib, have been investigated in clinical trials. The combination of EGFR and KRAS G12C inhibitors for KRAS G12C mutated CRC demonstrated overall response rates ranging from 26% to 62.5% in seven clinical trials of phase I to III, whose data are available so far. The median progression-free survival in these trials ranged from 3.9 to 8.1 months. These efficacy data suggest that KRAS G12C inhibitor combination with EGFR inhibitors is more effective for KRAS G12C mutated advanced CRC than KRAS G12C inhibitor monotherapy. They also showed reasonable safety of the combination regimen. Based on these results, phase III clinical trials are being conducted to investigate EGFR and KRAS G12C inhibitor combinations as a first or second-line treatment for KRAS G12C mutated advanced CRC. Furthermore, other KRAS G12C inhibitors, KRAS G12D inhibitors, and pan-RAS inhibitors are being developed, which could make more patients with advanced CRC eligible for KRAS inhibition.

Dissecting phospho-motif-dependent Shc1 interactome using long synthetic protein fragments.

Activated receptor tyrosine kinases (RTKs) rely on the assembly of signaling proteins into high-dimensional protein complexes for signal transduction. Shc1, a prototypical scaffold protein, plays a pivotal role in directing phosphotyrosine (pY)-dependent protein complex formation for numerous RTKs typically through its two pY-binding domains. The three conserved pY sites within its CH1 region (Shc1CH1) hold particular significance due to their substantial contribution to its functions. However, how Shc1 differentially utilizes these sites to precisely coordinate protein complex assembly remains unclear. Here, we employed multiple peptide ligation techniques to synthesize an array of long protein fragments (107 amino acids) covering a significant portion of the Shc1CH1 region with varying phosphorylation states at residues Y239, 240, 313, and S335. By combining these phospho-Shc1CH1 fragments with integrated proteomics sample preparation and quantitative proteomic analysis, we were able to comprehensively resolve the site-specific interactomes of Shc1 with single amino acid resolution. By applying this approach to different cancer cell lines, we demonstrated that these phospho-Shc1CH1 fragments can be effectively used as a diagnostic tool to assess cell type-specific RTK signaling networks. Collectively, these biochemical conclusions help to better understand the sophisticated organization of pY-dependent Shc1 adaptor protein complexes and their functional roles in cancer.

Integration of Multi-Omics Data for the Classification of Glioma Types and Identification of Novel Biomarkers

Glioma is currently one of the most prevalent types of primary brain cancer. Given its high level of heterogeneity along with the complex biological molecular markers, many efforts have been made to accurately classify the type of glioma in each patient, which, in turn, is critical to improve early diagnosis and increase survival. Nonetheless, as a result of the fast-growing technological advances in high-throughput sequencing and evolving molecular understanding of glioma biology, its classification has been recently subject to significant alterations. In this study, we integrate multiple glioma omics modalities (including mRNA, DNA methylation, and miRNA) from The Cancer Genome Atlas (TCGA), while using the revised glioma reclassified labels, with a supervised method based on sparse canonical correlation analysis (DIABLO) to discriminate between glioma types. We were able to find a set of highly correlated features distinguishing glioblastoma from lower-grade gliomas (LGGs) that were mainly associated with the disruption of receptor tyrosine kinases signaling pathways and extracellular matrix organization and remodeling. Concurrently, the discrimination of the LGG types was characterized primarily by features involved in ubiquitination and DNA transcription processes. Furthermore, we could identify several novel glioma biomarkers likely helpful in both diagnosis and prognosis of the patients, including the genes PPP1R8, GPBP1L1, KIAA1614, C14orf23, CCDC77, BVES, EXD3, CD300A, and HEPN1. Collectively, this comprehensive approach not only allowed a highly accurate discrimination of the different TCGA glioma patients but also presented a step forward in advancing our comprehension of the underlying molecular mechanisms driving glioma heterogeneity. Ultimately, our study also revealed novel candidate biomarkers that might constitute potential therapeutic targets, marking a significant stride toward personalized and more effective treatment strategies for patients with glioma.

Targeted Mass Spectrometry for Quantification of Receptor Tyrosine Kinase Signaling.

Targeted proteomics enables sensitive and specific quantification of proteins and post-translational modifications. By coupling peptide immunoaffinity enrichment with targeted mass spectrometry, we have developed the methodology for multiplexed quantification of proteins and phosphosites involved in the RAS/MAPK signaling network. The method uses anti-peptide antibodies to enrich analytes and heavy stable isotope-labeled internal standards, spiked in at known concentrations. The enriched peptides are directly measured by multiple-reaction monitoring (MRM), a well-characterized quantitative mass spectrometry-based method. The analyte (light) peptide response is measured relative to the heavy standard. The method described provides quantitative measurements of phospho-signaling and is generally applicable to other phosphopeptides and sample types.

Cell Membrane-Anchored DNA Nanoinhibitor for Inhibition of Receptor Tyrosine Kinase Signaling Pathways via Steric Hindrance and Lysosome-Induced Protein Degradation.

Receptor tyrosine kinase (RTK) plays a crucial role in cancer progression, and it has been identified as a key drug target for cancer targeted therapy. Although traditional RTK-targeting drugs are effective, there are some limitations that potentially hinder the further development of RTK-targeting drugs. Therefore, it is urgently needed to develop novel, simple, and general RTK-targeting inhibitors with a new mechanism of action for cancer targeted therapy. Here, a cell membrane-anchored RTK-targeting DNA nanoinhibitor is developed to inhibit RTK function. By using a DNA tetrahedron as a framework, RTK-specific aptamers as the recognition elements, and cholesterol as anchoring molecules, this DNA nanoinhibitor could rapidly anchor on the cell membrane and specifically bind to RTK. Compared with traditional RTK-targeting inhibitors, this DNA nanoinhibitor does not need to bind at a limited domain on RTK, which increases the possibilities of developing RTK inhibitors. With the cellular-mesenchymal to epithelial transition factor (c-Met) as a target RTK, the DNA nanoinhibitor can not only induce steric hindrance effects to inhibit c-Met activation but also reduce the c-Met level via lysosome-mediated protein degradation and thus inhibition of c-Met signaling pathways and related cell behaviors. Moreover, the DNA nanoinhibitor is feasible for other RTKs by just replacing aptamers. This work may provide a novel, simple, and general RTK-targeting nanoinhibitor and possess great value in RTK-targeted cancer therapy.

Abstract B093: Treating KRAS(G12D) inhibitor resistance using a KRAS- and HSP90 chaperone-targeted hetero-bispecific small molecule agent

Abstract KRAS is the most frequently mutated oncoprotein in human cancers. Although long considered “undruggable”, recent breakthroughs in medicinal chemistry have led to FDA-approval of the KRAS(G12C) mutation-specific inhibitors sotorasib and adagrasib for the treatment of KRAS(G12C)-positive non-small cell lung cancer. However, illustrating the need to develop additional novel agents targeting mutated KRAS, the 5-year relative survival rate for pancreatic cancer, which is commonly associated with a variety of different KRAS mutations, is only 12% (all SEER stages) due to poor early detection and a lack of effective treatments. In particular, KRAS(G12D) is the most common KRAS mutation, being found in 37% of pancreatic ductal adenocarcinomas (PDACs), as well as in 12.5% of colorectal cancer and 4.9% of lung adenocarcinoma (LUAD) patients. MRTX1133 is a highly-selective, non-covalent KRAS(G12D) inhibitor that has recently entered a phase 1 clinical trial. However, here we show that exposure of KRAS(G12D)-mutated PDAC (PANC-1 and AsPC-1) and LUAD (SK-LU-1) cell lines and a patient-derived organoid (PDO) PDAC model (RPAN001) to MRTX1133 resulted in varying degrees of in vitro efficacy. Decreased downstream KRAS signaling in the form of reduced phospho-ERK1/2 levels was observed to rapidly recover within 24 hours of treatment with 500 nM MRTX1133. Moreover, this rebound coincided with increased expression of KRAS, NRAS andHRAS mRNAs. Concurrently, activation of the receptor tyrosine kinases (RTKs) EGFR and MET was observed in PANC-1 and SK-LU-1 cells that displayed innate resistance to MRTX1133, while the sensitive AsPC-1 cells showed no such RTK activation. These results suggest that targeting of both KRAS(G12D) and RTKs may be needed to treat KRAS(G12D) inhibitor-resistant cancers. To address this, we employed a novel hetero-bispecific CHAMP molecule, RNK08179, that simultaneously targets both KRAS(G12D) and HSP90, an RTK-regulating chaperone protein. RNK08179 treatment demonstrated a striking reduction in phospho-ERK1/2 levels, RTK activation and cell viability in MRTX1133-resistant PANC-1 and SK-LU-1 cells. Furthermore, similar efficacy was observed in the MRTX1133-resistant RPAN001 PDO model. In summary, RNK08179 displayed promising efficacy in cancer models harboring KRAS(G12D) by suppressing both mutated KRAS and HSP90-supported RTK signaling. Citation Format: Ines Pulido, Qiyue Luan, Chenghao Yin, Zimo Yang, Jinhua Lin, Yaya Wang, Yuetong Sun, Chuche Liu, Haoxin Zhou, Marek Massad, Ian Papautsky, Thomas L. Prince, Guoqiang Wang, Kevin P. Foley, Weiwen Ying, Takeshi Shimamura. Treating KRAS(G12D) inhibitor resistance using a KRAS- and HSP90 chaperone-targeted hetero-bispecific small molecule agent [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B093.

Integrative Multi-Omic Analysis for Prognosis Stratification in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) is a heterogeneous hematopoietic malignancy with a dismal prognosis. European LeukemiaNet (ELN) is crucial for tailoring AML treatment individually. Various AML models correlated survival and clinical drug response with immune cell differentiation state by deconvoluting transcriptomics. However, few comprehensive molecular subtyping models integrate multi-omic profiles for prognostic and drug response prediction. Thus, this study aimed to integrate DNA methylation, genomics, transcriptomics and ex vivo drug sensitivity screening of AML patients and explore their roles in facilitating AML molecular stratification and redefining prognosis. Firstly，data on 90 patients with AML(non-promyelocytic leukemia) were retrieved from The Cancer Genome Atlas (TCGA) for consensus clustering by 10 advanced consensus clustering algorithms. The optimal three distinct subtypes, UAMOCS1, UAMOCS2, and UAMCOS3, were identified to achieve the best clustering effect. Multi-omics were orchestrated together for UAMOCS shaping. The UAMOCS can significantly distinguish overall survival (median 18 vs. 27 vs. 45 months, P= 0.0048) among the three instinct subtypes with the integrated contribution of transcriptomic profiles and DNA methylation and mutation data. Also, the activity of AML-specific transcription factors and chromatin remodeling makers showed a diverse pattern among the three subtypes, epigenetically contributing to UAMOCS shaping. Next, the nearest template prediction, a model-free method, was applied to further validate this predictive model. Similar subtyping under this model is generated robustly by imitating 50 subtype-specific genes and capable of identifying survival in both the “ihCAMs-AML” (Figure 1) and GSE37642. The main validation cohort was a real-world de novo AML cohort (acute promyelocytic leukemia excluded), “ihCAMs-AML”（N=98）, aged 14-70 years, with a median follow-up of 28 (1-55) months. The samples were simultaneously available for methylome (N=31, 850K Methylation Chip), DNA mutation (N=96, targeted deep sequencing), transcriptome (N=98, bulk RNA-seq), and ex vivo drug screening (N=66, 17 drugs under 100% peak plasma concentration) profiling analysis. Clinical relevance showed that traditional cytogenetic stratification was strongly correlated with our system. UAMOCS1, acting as an “immune activator”, is characterized by enriching of AML myelodysplasia-related (AML-MR) gene mutations (especially RUNX1 mutation, P = 0.00839), unstable chromosome (deletions on 7q), increased abundance of immune cells with immune escaping marker and poor risk. UAMOCS2 was defined as an intermediate immune burden and a “monocytic-like” phenotype with intermediate survival, corresponding to its inclining result toward M4/M5. UAMOCS3 was an “immune desert” group supposed to be the most favorable subset among the three groups. The ex vivo drug screening result implied that UAMOCS also provide values in distinguishing drug response. UAMOCS1 hardly benefited from commonly used chemotherapeutic drugs compared with the other two distinct subtypes. Pharmacogenomics database GDSC (the Genomics of Drug Sensitivity in Cancer) among AML cell lines was used to evaluate potential drug targets for overcoming drug resistance. Receptor tyrosine kinase signaling inhibitors (SB505124 and EphB4) might be sensitive to UAMOCS1. Taken together, UAMOCS model was generated that can classify AML patients independently and help develop precise chemotherapeutic strategy for patients with AML in the future.

Semaphorin 6 Family—An Important Yet Overlooked Group of Signaling Proteins Involved in Cancerogenesis

According to recent evidence, some groups of semaphorins (SEMAs) have been associated with cancer progression. These proteins are able to modulate the cellular signaling of particular receptor tyrosine kinases (RTKs) via the stimulation of SEMA-specific coreceptors, namely plexins (plexin-A, -B, -C, -D) and neuropilins (Np1, Np2), which share common domains with RTKs, leading to the coactivation of the latter receptors. MET, ERBB2, VEGFR2, PFGFR, and EGFR, among others, represent acknowledged targets of semaphorins that are often associated with tumor progression or poor prognosis. In particular, higher expression of SEMA6 family proteins in cancer cells and stromal cells of the cancer niche is often associated with enhanced tumor angiogenesis, metastasis, and resistance to anticancer therapy. Notably, high SEMA6 expression in malignant tumor cells such as melanoma, pleural mesothelioma, gastric cancer, lung adenocarcinoma, and glioblastoma may serve as a prognostic biomarker of tumor progression. To date, very few studies have focused on the mechanisms of transmembrane SEMA6-driven tumor progression and its underlying interplay with RTKs within the tumor microenvironment. This review presents the growing evidence in the literature on the complex and shaping role of SEMA6 family proteins in cancer responsiveness to environmental stimuli.

Effects of SU5416 on angiogenesis and the ERK-VEGF/MMP-9 pathway in rat endometriosis.

SU5416 is a small molecule vascular endothelial growth factor (VEGF) receptor signal transduction inhibitor, which can block the VEGF re-ceptor autophosphorylation and inhibit receptor tyrosine kinase signal trans-duction, thereby reducing VEGF activity. However, there are few reports about the correlation of SU5416 to the occurrence and angiogenesis in endometrio-sis. In this study, we observed the effects of VEGF receptor inhibitor SU5416 on angiogenesis in endometriosis in rats. Thirty femalespecific-pathogen-free Sprague-Dawley rats were randomly divided into sham operation group (SOG), model group (MG), and SU5416 group (n=10 for each group). In the SOG, only the uterus was cut and sutured, and endometriosis models were established in the MG and SU5416 group by autologous transplantation. The SU5416 group was injected with 15 mg/kg SU5416 intraperitoneally, and the SOG and MG were intraperitoneally injected with an equal volume of normal saline for 6 weeks. The volume of ectopic lesions was lower in the SU5416 group at 42 d postoperatively thanin the MG (p<0.05). The proportion of CD31-positive cells in the endometrial tissue of the SU5416 group was lower than that of the MG (p<0.05); angiopoietin-1 (Ang-1), angiopoietin-2 (Ang-2), laminin-5γ2 (LN-5γ2) and phosphorylation of ERK (P-ERK), VEGF, matrix metalloproteinase (MMP)-2, and MMP-9 protein expressions were lower in the SU5416 groupthan in the MG (p<0.05).VEGFreceptor inhibitor SU5416 can inhibit endometrio-sis angiogenesis and reduce inflammatory response in rats, and its mechanism of action may be related to the down-regulation of the ERK-VEGF/MMP-9 path-way expression.

EGFR signaling controls directionality of epithelial multilayer formation upon loss of cell polarity.

Apical-basal polarity is maintained by distinct protein complexes that reside in membrane junctions, and polarity loss in monolayered epithelial cells can lead to formation of multilayers, cell extrusion, and/or malignant overgrowth. Yet, how polarity loss cooperates with intrinsic signals to control directional invasion toward neighboring epithelial cells remains elusive. Using the Drosophila ovarian follicular epithelium as a model, we found that posterior follicle cells with loss of lethal giant larvae (lgl) or Discs large (Dlg) accumulate apically toward germline cells, whereas cells with loss of Bazooka (Baz) or atypical protein kinase C (aPKC) expand toward the basal side of wildtype neighbors. Further studies revealed that these distinct multilayering patterns in the follicular epithelium were determined by epidermal growth factor receptor (EGFR) signaling and its downstream target Pointed, a zinc-finger transcription factor. Additionally, we identified Rho kinase as a Pointed target that regulates formation of distinct multilayering patterns. These findings provide insight into how cell polarity genes and receptor tyrosine kinase signaling interact to govern epithelial cell organization and directional growth that contribute to epithelial tumor formation.

A human mucosal melanoma organoid platform for modeling tumor heterogeneity and exploring immunotherapy combination options.

Mucosal melanoma (MM), an aggressive rare subtype of melanoma, is distinct from cutaneous melanoma and has poor prognoses. We addressed the lack of cell models for MM by establishing 30 organoids of human oral MM (OMM), which retained major histopathological and functional features of parental tumors. Organoid groups derived from chronologically or intratumorally distinct lesions within the same individual displayed heterogeneous genetics, expression profiles, and drug responses, indicating rapid tumor evolution and poor clinical response. Furthermore, transcriptome analysis revealed receptor tyrosine kinases (RTKs) signaling, particularly NGFR, a nerve growth factor receptor, was significantly up-regulated in OMMs and organoids from patients resistant to anti-programmed cell death protein 1 (anti-PD-1) therapy. Combining anti-PD-1 with anlotinib (a phase 2 multitarget RTK inhibitor for OMM) or NGFR knockdown enhanced the effective activity of immune cells in organoid-immune cell coculture systems. Together, our study suggested that OMM organoids serve as faithful models for exploring tumor evolution and immunotherapy combination strategies.

NRF2 connects Src tyrosine kinase to ferroptosis resistance in glioblastoma.

Glioblastoma is a severe brain tumor characterized by an extremely poor survival rate of patients. Glioblastoma cancer cells escape to standard therapeutic protocols consisting of a combination of ionizing radiation and temozolomide alkylating drugs that trigger DNA damage by rewiring of signaling pathways. In recent years, the up-regulation of factors that counteract ferroptosis has been highlighted as a major driver of cancer resistance to ionizing radiation, although the molecular connection between the activation of oncogenic signaling and the modulation of ferroptosis has not been clarified yet. Here, we provide the first evidence for a molecular connection between the constitutive activation of tyrosine kinases and resistance to ferroptosis. Src tyrosine kinase, a central hub on which deregulated receptor tyrosine kinase signaling converge in cancer, leads to the stabilization and activation of NRF2 pathway, thus promoting resistance to ionizing radiation-induced ferroptosis. These data suggest that the up-regulation of the Src-NRF2 axis may represent a vulnerability for combined strategies that, by targeting ferroptosis resistance, enhance radiation sensitivity in glioblastoma.

C-Cbl Regulates Murine Subventricular Zone-Derived Neural Progenitor Cells in Dependence of the Epidermal Growth Factor Receptor.

The localization, expression, and physiological role of regulatory proteins in the neurogenic niches of the brain is fundamental to our understanding of adult neurogenesis. This study explores the expression and role of the E3-ubiquitin ligase, c-Cbl, in neurogenesis within the subventricular zone (SVZ) of mice. In vitro neurosphere assays and in vivo analyses were performed in specific c-Cbl knock-out lines to unravel c-Cbl's role in receptor tyrosine kinase signaling, including the epidermal growth factor receptor (EGFR) pathway. Our findings suggest that c-Cbl is significantly expressed within EGFR-expressing cells, playing a pivotal role in neural stem cell proliferation and differentiation. However, c-Cbl's function extends beyond EGFR signaling, as its loss upon knock-out stimulated progenitor cell proliferation in neurosphere cultures. Yet, this effect was not detected in hippocampal progenitor cells, reflecting the lack of the EGFR in the hippocampus. In vivo, c-Cbl exerted only a minor proneurogenic influence with no measurable impact on the formation of adult-born neurons. In conclusion, c-Cbl regulates neural stem cells in the subventricular zone via the EGFR pathway but, likely, its loss is compensated by other signaling modules in vivo.

Prognostic model construction and target identification of Si-Wu-Tang against breast cancer

The targets and mechanisms of Si-Wu-Tang (SWT) against (Breast cancer) BRCA were identified and a survival model and nomogram was construted by network pharmacology, bioinformatic analysis and in vitro experiments. A total of 72 anti-breast cancer SWT targets were selected, among which eleven genes (MAOA、SQLE、CACNA2D1、GLI1、RORB、ITGB3、TACR1、NR3C2、CA3、RBP4 and PTK6) were used to construct a novel prognostic model of breast cancer. The anti-breast cancer activity of SWT was related to the modulation of the receptor tyrosine kinases signaling pathways. Moreover, two compounds, mairin and senkyunone were found to bind directly to ITGB3 and RORB proteins. Finally, mRNA and protein expression of ITGB3 and RORB was observed to be significantly down-regulated after incubation of MCF-7 cells with SWT. Overall, our results indicated that mairin and senkyunone were the key ingredients present in SWT, and ITGB3 as well as RORB proteins were the major targets affected by SWT. The prognostic model can be used to predict the outcome of BRCA patients.

Targeting collagen XVIII improves the efficiency of ErbB inhibitors in breast cancer models.

The tumor extracellular matrix (ECM) critically regulates cancer progression and treatment response. Expression of the basement membrane component collagen XVIII (ColXVIII) is induced in solid tumors, but its involvement in tumorigenesis has remained elusive. We show here that ColXVIII was markedly upregulated in human breast cancer (BC) and was closely associated with a poor prognosis in high-grade BCs. We discovered a role for ColXVIII as a modulator of epidermal growth factor receptor tyrosine kinase (ErbB) signaling and show that it forms a complex with ErbB1 and -2 (also known as EGFR and human epidermal growth factor receptor 2 [HER2]) and α6-integrin to promote cancer cell proliferation in a pathway involving its N-terminal portion and the MAPK/ERK1/2 and PI3K/AKT cascades. Studies using Col18a1 mouse models crossed with the mouse mammary tumor virus-polyoma virus middle T antigen (MMTV-PyMT) mammary carcinogenesis model showed that ColXVIII promoted BC growth and metastasis in a tumor cell-autonomous manner. Moreover, the number of mammary cancer stem cells was significantly reduced in the MMTV-PyMT and human cell models upon ColXVIII inhibition. Finally, ablation of ColXVIII substantially improved the efficacy of ErbB-targeting therapies in both preclinical models. In summary, ColXVIII was found to sustain the stemness properties of BC cells and tumor progression and metastasis through ErbB signaling, suggesting that targeting ColXVIII in the tumor milieu may have important therapeutic potential.