Transmembrane Tyrosine Kinase Receptor Research Articles

122 (PB112) - Establishment of RET inhibitor-induced resistant patient-derived colorectal cancer xenograft models

Background: Rearranged during transfection (RET), a transmembrane receptor tyrosine kinase, is involved in multi-system tissue development which includes nervous, hematopoietic, and gastrointestinal systems. Activating RET alteration, induced by gene fusions or point mutations, has been discovered in several different solid tumor types including thyroid cancer, non-small cell lung cancer (NSCLC), breast cancer, and colorectal cancer. Recently, two RET-specific tyrosine kinase inhibitors (TKIs), selpercatinib (LOXO-292) and pralsetinib (BLU-667), were approved by the FDA for the treatment of thyroid cancer and NSCLC.

118P In-silico analysis of fibroblast growth factor receptors (FGFRs) as potential biomarkers for esophageal carcinoma

Expression studies are directed to detect and quantify a specific gene's messenger RNA (mRNA) levels. Fibroblast growth factor receptors (FGFRs) are a family of five highly conserved transmembrane tyrosine kinase receptors (RTKs), which regulate a variety of cellular functions, such as proliferation, and migration, differentiation, and survival. Distorted expression of FGFRs is commonly detected in cancer patients. Various enrichment analysis has investigated the association of FGFR(s) expression with tumorigenicity.

New era for emerging therapeutic targeting human epidermal growth factor receptor 3 (HER 3) in advanced nonsmall cell lung cancer and metastatic breast cancer

AbstractHuman epidermal growth factor receptor 3 (HER3) is a member of the transmembrane receptor tyrosine kinase family. Upregulation of HER3 pathway has been implicated as a mechanism of resistance in solid tumors, particularly in estrogen receptor positive, HER2 positive breast cancer and epidermal growth factor (EGFR) mutant nonsmall cell lung cancer. Several studies suggest that HER3 overexpression represents a negative prognostic biomarker associated with poor survival. Preclinical and clinical studies of anti‐HER3 investigational therapies suggest that expression of the HER3 ligand, neuregulin, may predict response to treatment. Despite its emergence as a key cancer therapeutic target, HER3 cannot be targeted with traditional tyrosine kinase inhibitors therapy due to its weak kinase activity. Monoclonal and bispecific antibodies targeting HER3 have been developed and tested in early phase trials. Objective responses were limited when first‐generation HER3‐specific monoclonal antibodies were investigated as monotherapies in phase 1 and 2 clinical trials for nonsmall cell lung cancer (NSCLC) and metastatic breast cancer (MBC). MBC and NSCLC HER3 specific antibody‐drug conjugates have shown encouraging results in resistance in cancer cells, particularly in those that overexpress HER3. These agents have shown some promise in early phase trials in both NSCLC and MBC setting in heavily pretreated patients with varying degrees of response. It is unclear which subgroup of patients will truly benefit from targeting HER3 as these therapies are under investigation.

The regulation of proliferation and apoptosis in hepatocellular carcinoma via insulin-like growth factor 1 receptor

ObjectivesInsulin-like growth factor 1 receptor (IGF-1R) is a transmembrane tyrosine kinase receptor of the insulin receptor family. Its expression is consistently increased in hepatocellular carcinoma (HCC) tissue, and it participates in hepatic carcinogenesis. Targeting IGF-1R may be a potential therapeutic approach against hepatocellular carcinoma. This study therefore aimed to explore the effect of IGF-1R on hepatocellular carcinoma cells. MethodsIGF-1R silencing cell lines were established by small-interfering RNAs in hepatocellular carcinoma cell line SMMC7721, after which the proliferation, invasion, and apoptosis of SMMC7721 was evaluated. The activation of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT) signaling pathway and the expression of bone morphogenetic protein (BMP)-2 and BMP-7 were measured using Western blot analysis. ResultsThe results indicated that the knockdown of IGF-1R can inhibit the proliferation and invasion of HCC and promote the apoptosis of SMMC7721 by inhibiting the PI3K/AKT signaling pathway. Furthermore, depletion of IGF-1R was found to suppress the expression of BMP-2 and BMP-7. ConclusionsThe findings suggest that IGF-1R plays an important role in the progression of HCC. Therefore, IGF-1R is a potential target for the treatment of HCC in clinic.

Guidelines for HTRF technology in EGFR kinase assay

AbstractEpidermal growth factor receptor (EGFR) is among the first discovered transmembrane receptor tyrosine kinases. Ligand binding to the extracellular domain of EGFR results in the formation of homo‐dimeric or hetero‐dimeric complexes, activation, and auto‐phosphorylation in the intracellular tyrosine kinase domain, then regulates the cell's proliferation, differentiation, migration, and invasion. It has been reported that EGFR is overexpressed, amplified, or mutated in several epithelial tumors. EGFR tyrosine kinase inhibitors (EGFR‐TKIs) specifically bind to the tyrosine kinase domain of EGFR. Homogeneous time‐resolved fluorescence (HTRF) assay is successfully used in kinase assays and is a crucial tool in the drug discovery of various kinases. Moreover, the HTRF assay has been determined to exhibit many advantages, such as being easy to miniaturize, simple to read, and excellent to repeat. In these guidelines, the theory, materials, and reagent preparation of HTRF kinase assay are described and emphasized. Furthermore, the protocol and optimization of the assay are determined to establish an HTRF screening platform, then an optimized HTRF kinase assay is performed to test the compounds for screening potential EGFR‐TKIs. In addition, these guidelines can contribute to verifying the high‐throughput screening results of HTRF and help to reveal the underlying mechanism of the EGFR kinase and tested compounds.

Abstract 848: Inhibition of RTK fusion condensates enhances signal perception and promotes drug tolerance

Abstract Drug resistance remains a significant obstacle in the successful treatment of cancer, highlighting the critical need to understand how oncogenes and cancer drugs impact cell physiology and resistance development. EML4-ALK is a receptor tyrosine kinase (RTK) fusion oncogene that drives 3-7% of lung cancer. Despite potent ALK inhibitors, EML4-ALK+ cancers frequently develop resistance during therapy. Recently, it was discovered that EML4-ALK and other RTK fusions form cytoplasmic protein condensates, and that condensate formation was required for oncogenic signaling. However, whether oncogenic condensates play a role in drug responses is unclear. In this study, we applied an optogenetic technique called ‘functional profiling’ to understand how EML4-ALK condensates impact cell signal transmission and drug response. Using light-stimulated RTKs, we found that EML4-ALK condensates strongly suppress signaling through transmembrane RTKs, including through EGFR, a central receptor in resistance development. Strikingly, treatment with ALK inhibitors (ALKi) rapidly restored and hypersensitized RTK signaling. We found that EML4-ALK condensates suppress RTK signals through sequestration of the downstream adapter Grb2, which is essential for signaling through EGFR and other RTKs. The release of Grb2 from condensates resensitized RTKs within 10s of minutes of ALKi addition. Resensitized RTKs, in turn, caused sporadic RTK activation pulses throughout the cell population, and pulses originated from paracrine RTK signals released by apoptotic neighbors. We found that these paracrine signals counteracted ALK inhibitor therapy and promoted survival and drug tolerance. Blocking paracrine signals through co-treatment of ALKi with inhibitors of either EGFR or matrix metalloproteases enhanced cell killing and minimized long-term drug tolerance. Our study uncovers a role for oncogenic condensates in drug resistance signaling, reveals a novel mechanism for oncogene-induced suppression of RTK signaling, and suggests novel co-therapies to more effectively treat cancers driven by EML4-ALK and possibly other RTK fusions. Our work also demonstrates the potential of functional optogenetic profiling for drug discovery to promote cancer therapy. Citation Format: David Gonzalez-Martinez, Lee Roth, Thomas Mumford, Yael Mosse, Asmin Tulpule, Trever Bivona, Lukasz Jan Bugaj. Inhibition of RTK fusion condensates enhances signal perception and promotes drug tolerance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 848.

Phase 1 dose escalation and expansion study of bemcentinib (BGB324), a first-in-class, selective AXL inhibitor, with docetaxel in patients with previously treated advanced NSCLC.

9081 Background: AXL, a transmembrane receptor tyrosine kinase, is overexpressed and associated with poor prognosis and treatment resistance in non-small cell lung cancer (NSCLC). Bemcentinib (BGB324) is a selective orally bioavailable small molecule inhibitor of AXL, currently in phase 2 clinical development, that has demonstrated synergistic activity with docetaxel in in vivo models of NSCLC. This phase I dose escalation and expansion trial assessed the safety, tolerability, and preliminary efficacy of bemcentinib in combination with docetaxel in previously treated advanced NSCLC. Methods: Dose escalation of daily bemcentinib in combination with docetaxel (60 or 75 mg/m2 every 3 weeks) followed a standard 3+3 design. Bemcentinib monotherapy was administered for one week prior to docetaxel initiation to assess pharmacodynamic effects alone and in combination. Plasma protein biomarker levels were measured using the DiscoveryMap v3.3 panel (Myriad RBM) pre-dose (C1D-7), C1D1, and C2D1. Results: A total of 21 patients (pts) were enrolled with median age 62 (range 39-84) and 67% male. A median of 3 (range 1-13) cycles of therapy were administered. Principal treatment-related adverse events were neutropenia (86%, 76% ≥G3), diarrhea (57%, 0% ≥G3), fatigue (52%, 5% ≥G3), and nausea (52%, 0% ≥G3). Neutropenic fever ≥G3 occurred in 7 (33%) pts. The maximum tolerated dose was 60 mg/m2 docetaxel plus 200 mg bemcentinib daily with prophylactic G-CSF support. Pharmacokinetics of bemcentinib alone and in combination with docetaxel were highly similar. Among 15 evaluable pts, 4 (27%) pts had partial response and 9 (60%) pts had stable disease as the best radiographic response. Bemcentinib treatment resulted in changes in plasma levels of proteins associated with regulation of sterol synthesis and AKT signaling. Conclusions: Bemcentinib in combination with docetaxel and prophylactic G-CSF support has a manageable safety profile, leads to decreases in systemic factors associated with tumor growth and metastasis, and demonstrates evidence of anti-tumor activity in previously treated, advanced NSCLC. Further studies to identify the patient population most likely to benefit from this regimen are warranted. Clinical trial information: NCT02922777.

The landscape of EGFR mutation in Chinese patients with glioma.

e14028 Background: Epidermal growth factor receptor (EGFR), a trans-membrane receptor tyrosine kinase, consists of an extracellular ligand-binding domain (ECD), a single transmembrane domain (STMD) and an intracellular kinase domain (ICD). Glioma is the most common primary brain tumor, and variations of EGFR are frequently reported in glioma patients. This study aimed to analysis the landscape of EGFR mutation subtype in Chinese patients with glioma. Methods: We retrospectively collected 1779 patients with glioma. In all patients enrolled, the comprehensive genomic profiling containing EGFR gene was detected using tumor tissue, including WES, 539 tumor related-gene panel or 131+4 gene panel (Simceredx). And the somatic mutations including SNV, INDEL, CNV, fusion were analyzed correspondingly. Results: Among 1779 patients with glioma, EGFR mutations were identified in 392 (22.03%) patients. The age was significantly higher in patients with EGFR-mutant group than in patients without EGFR-mutant group, with median age 54 vs. 45 (p = 4.81e-19). The sex didn’t reach statistical significance in two group. The incidence rate of different EGFR mutation types among all patients with EGFR-mutant were amplification (314,80.10%), SNV(198,50.51%), Indel(24,6.12%) and fusion(44,11.22%) respectively. 162 (46.69%) had two or more mutation types simultaneously. The main partner gene of EGFR fusion was LOC100996654, followed by ELDR and SEC61G, and the main EGFR breakpoints were in intron24, intron7, exon7. Within 347 SNV and Indel mutations, exon7, 15, 20, 6 and 8 were detected in 103(29.68%), 50(14.41%), 28 (8.07%), 25(7.20%) and 18 (5.19%) respectively. The top three mutaton subtypes within exon7 were account for 19.31%, which included p.A289V,p.A289T,p.T263P. Meanwhile, the mutation frequency within ICD encoded by exons 18-24 was 17.00%, in which exon20 mostly distributed (8%). In exon20, the most common mutation subtypes were p.V774M,p.H773dup,p.T790M, while in the second proportion exon18 (3.46%), the main subtype were p.G719A/D. Conclusions: EGFR amplification was the most common mutation type. There were 122 SNV and Indel subtypes altogether and occurred throughout almost the entire exon region, in which exon7 contained maximum 21 different subtypes and the p.A289V was the main type. The distribution of subtypes in ECD were much more than in ICD. The relationship between subtypes occurrence and cancer will be further studied in the future.

Comprehensive analysis of FGFR mutations in Chinese cancer patients.

e15117 Background: Fibroblast growth factor receptors (FGFRs) are highly conserved transmembrane tyrosine kinase receptors (RTKS) that regulating several cellular processes such as proliferation, differentiation, migration and survival. In recent years, some studies have documented that signaling through FGFRs impact progression of cancer and the survival of patients with cancer. As a potential therapeutic target, exploring the mutation frequency of FGFRs in more different cancers are necessary. Here we performed a comprehensive analysis of the frequency and types of FGFRs mutations in Chinese cancer patients and provided reference for targeted therapy development. Methods: From January 2020 to December 2021, a total of 4,102 patients with nine common cancers were included in the study. The next-generation sequencing was utilized for detecting genetic mutations. Results: A total 328 patients (7.9%) with FGFR mutation were identified. The FGFR 3 was the most frequently gene in our cohort. Among all the cancer patients, the highest frequency of FGFR mutations was observed in bladder cancer (32.5%) and the percentages in FGFR1, FGFR2 and, FGFR3 were 2.7%, 1.35%, and 6.76% respectively. Furthermore, the proportion of FGFR mutation in lung carcinoma, cholangiocarcinoma, colorectal carcinoma, melanoma, breast carcinoma and ovarian carcinoma was 8.64%, 11.58%, 13%, 16.7%, 9.62% and 10.81% respectively. Additionally, FGFR mutation have been detected in other tumor types, including renal cell carcinoma (5.63%), prostate cancer (5.45%), and gastric carcinoma (13.72%). Conclusions: The present study provided the comprehensive FGFR mutation data of Chinese cancer patients. A high frequency mutation in FGFR have been found in Chinese patients with different cancers, which mean that patients with multiple cancer types might benefit from development of efficient EGFR inhibitors.

The EPH/Ephrin System in Bone and Soft Tissue Sarcomas' Pathogenesis and Therapy: New Advancements and a Literature Review.

Musculoskeletal sarcomas represent rare heterogenous malignancies of mesenchymal origin that can be divided in two distinct subtypes, bone and soft tissue sarcomas. Current treatment options combine the surgical excision of local tumors and multidrug chemotherapy to prevent metastatic widespread disease. Due to the grim prognosis that usually accompanies such tumors, researchers have attempted to shed light on the molecular pathways implicated in their pathogenesis in order to develop novel, innovative, personalized therapeutic strategies. Erythropoietin-producing human hepatocellular receptors (EPHs) are tyrosine-kinase transmembrane receptors that, along with their ligands, ephrins, participate in both tumor-suppressive or tumor-promoting signaling pathways in bone and soft tissue sarcomas. The EPH/ephrin axis orchestrates cancerous processes such as cell–cell and cell–substrate adhesion and enhances the remodeling of the intracellular cytoskeleton to stimulate the motility and invasiveness of sarcoma cells. The purpose of our study was to review published PubMed literature to extract results from in vitro, in vivo and clinical trials indicative of the role of EPH/ephrin signaling in bone and soft tissue sarcomas. Based on these reports, significant interactions between the EPH/ephrin signaling pathway and a plethora of normal and abnormal cascades contribute to molecular mechanisms enhancing malignancy during sarcoma progression. In addition, EPHs and ephrins are prospective candidates for diagnostic, monitoring and therapeutic purposes in the clinical setting against bone and soft tissue sarcomas.

High Expression of CSF-1R Predicts Poor Prognosis and CSF-1Rhigh Tumor-Associated Macrophages Inhibit Anti-Tumor Immunity in Colon Adenocarcinoma

BackgroundColony stimulating factor 1 receptor (CSF-1R) is a single channel III transmembrane receptor tyrosine kinase (RTK) and plays an important role in immune regulation and the development of various cancer types. The expression of CSF-1R in colon adenocarcinoma (COAD) and its prognostic value remain incompletely understood. Therefore, we aim to explore the prognostic value of CSF-1R in COAD and its relationship with tumor immunity.MethodsCSF-1R expression in a COAD cohort containing 103 patients was examined using immunohistochemistry (IHC). The relationship between CSF-1R expression and clinicopathological parameters and prognosis was evaluated. Dual immunofluorescence staining was conducted to determine the localization of CSF-1R in COAD tissues. Univariate and multivariate Cox regression analysis were performed to evaluate independent prognostic factors. Transcriptomic profiles of CSF-1Rhigh and CSF-1Rlow tumor-associated macrophages (TAMs) were investigated. Gene enrichment analysis was used to explore the signal pathways related to CSF-1R. In addition, the relationship between CSF-1R in tumor microenvironment (TME) and tumor immunity was also studied.ResultsIHC analysis showed that CSF-1R was overexpressed in COAD, and higher expression was associated with shorter overall survival (OS). Immunofluorescence staining showed that CSF-1R was co-localized with macrophage marker CD68. Univariate and multivariate Cox regression analysis showed that CSF-1R was an independent prognostic factor for COAD. The results of gene enrichment analysis showed that CSF-1R was involved in tumor immune response and regulation of TME. In addition, CSF-1R was significantly correlated with TME, immune cell infiltration, TMB, MSI, Neoantigen, and immune checkpoint molecules.ConclusionCSF-1R can serve as an independent prognostic factor of COAD and promising immunotherapeutic target of COAD.

NRG1/ERBB3/ERBB2 Axis Triggers Anchorage-Independent Growth of Basal-like/Triple-Negative Breast Cancer Cells.

Simple SummaryBreast cancer is a heterogeneous disease, categorized into distinct subgroups with different clinical prognoses and treatment strategies. This study aimed to evaluate the role of ERBB3 in different molecular subtypes of breast cancers. Despite ERBB3/HER3 and its partner ERBB2/HER2 showing low expression levels in basal-like/triple-negative breast cancers, stratification of basal-like patients according to ERBB3 mRNA expression levels highlighted a correlation between higher ERBB3 levels and shorter relapse-free patients’ survival. In vitro analyses unveiled that the activation of the NRG1/ERBB3/ERBB2 axis robustly induces anchorage-independent growth of basal-like/triple-negative breast cancer cellular models, without significant effects on cell proliferation, differentiation, and migration in adhesion. Overall, our data suggest that ERBB2/ERBB3 plays an oncogenic role in basal-like/triple-negative breast cancer patients, suggesting its neutralization as a therapeutic strategy for these breast cancer subtypes, which today have very limited treatment opportunities.ERBB3, also known as HER3, is a tyrosine kinase transmembrane receptor of the ERBB family. Upon binding to neuregulin 1 (NRG1), ERBB3 preferentially dimerizes with HER2 (ERBB2), in turn inducing aggressive features in several cancer types. The analysis of a dataset of breast cancer patients unveiled that higher ERBB3 mRNA expression correlates with shorter relapse-free survival in basal-like breast cancers, despite low ERBB3 expression in this breast cancer subtype. Administration of neuregulin 1 beta (NRG1β) significantly affected neither cellular proliferation nor the basal migratory ability of basal-like/triple-negative quasi-normal MCF10A breast cells, cultured in mono-layer conditions. Furthermore, no significant regulation in cell morphology or in the expression of basal/myoepithelial and luminal markers was observed upon stimulation with NRG1β. In non-adherent conditions, NRG1β administration to MCF10A cells did not significantly influence cell survival; however, it robustly induced cell growth as spheroids (3D growth). Intriguingly, a remarkable upregulation of ERBB3 and ERBB2 protein abundance was observed in 3D compared to 2D cell cultures, and NRG1β-induced 3D cell growth was efficiently prevented by the anti-HER2 monoclonal antibody pertuzumab. Similar results were obtained by the analysis of basal-like/triple-negative breast cancer cellular models, MDA-MB-468 and MDA-MB-231 cells, in which NRG1β induced anchorage-independent cell growth that in turn was prevented or reduced by the simultaneous administration of anti-HER2 neutralizing antibodies. Finally, the ability of pertuzumab in suppressing NRG1β-induced 3D growth was also evaluated and confirmed in MCF10A engineered with HER2-overexpression. We suggest that the NRG1/ERBB3/ERBB2 pathway promotes the anchorage-independent growth of basal-like breast cancer cells. Importantly, we provide evidence that ERBB2 neutralization, in particular by pertuzumab, robustly inhibits this process. Our results pave the way towards the development of novel anticancer strategies for basal-like breast cancer patients based on the interception of the NRG1/ERBB3/ERBB2 signaling axis.

Design and development of photoswitchable DFG-Out RET kinase inhibitors

REarranged during Transfection (RET) is a transmembrane receptor tyrosine kinase that is required for development of multiple human tissues, but which is also an important contributor to human cancers. RET activation through rearrangement or point mutations occurs in thyroid and lung cancers. Furthermore, activation of wild type RET is an increasingly recognized mechanism promoting tumor growth and dissemination of a much broader group of cancers. RET is therefore an attractive therapeutic target for small-molecule kinase inhibitors. Non-invasive control of RET signaling with light offers the promise of unveiling its complex spatiotemporal dynamics in vivo. In this work, photoswitchable DFG-out RET kinase inhibitors based on heterocycle-derived azobenzenes were developed, enabling photonic control of RET activity. Based on the binding mode of DFG-out kinase inhibitors and using RET kinase as the test model, we developed a photoswitchable inhibitor with a quinoline “head” constituting the azoheteroarene. This azo compound was further modified by three different strategies to increase the difference in biological activity between the E-isomer and the light enriched Z-isomer. Stilbene-based derivatives were used as model compounds to guide in the selection of substituents that could eventually be introduced to the corresponding azo compounds. The most promising quinoline-based compound showed more than a 15-fold difference in bioactivity between the two isomers in a biochemical assay. However, the same compound showed a decreased Z/E (IC50) ratio in the cellular assay, tentatively assigned to stability issues. The corresponding stilbene compound gave a Z/E (IC50) ratio well above 100, consistent with that measured in the biochemical assay. Ultimately, a 7-azaindole based photoswitchable DFG-out kinase inhibitor was shown to display more than a 10-fold difference in bioactivity between the two isomers, in both a biochemical and a cell-based assay, as well as excellent stability even under reducing conditions.

Abstract P4-01-12: Short-term trastuzumab treatment increases oncogenic fitness in HER2 overexpressing breast cancer models

Abstract Overexpression of Human EGF Receptor 2 (HER2) is found in up to 20% of primary invasive breast cancers and is a marker of aggressive metastatic disease and poor prognosis. HER2 is a member of the transmembrane tyrosine kinase receptors family which includes EGFR (HER1), HER3 and HER4. Phosphorylation of tyrosine residues in the cytoplasmic domain upon homo- or heterodimerization results in stimulation of cellular proliferation, migration, angiogenesis, and inhibition of apoptosis. HER2 is deemed a preferred heterodimer partner and presents an excellent target for personalized medicine. Anti-HER2 monoclonal antibody trastuzumab (TZM) has been used in the clinic over the last decades and it is considered as one of the most successful targeted anti-cancer therapies. However, a large fraction of eligible patients displays either primary or acquired resistance to TZM treatment. In this study, we report that even relatively short 24h TZM exposure (TZM-priming) of AU565 HER2-overexpressing breast cancer cells results in rapid and profound alterations in HER receptors’ expression level and signaling, as well as upregulation of markers associated with drug resistance. We provide several lines of evidence to support this claim: Firstly, Western blot analysis of both monolayer AU565 cells incubated in the presence or absence of 20 μg/mL TZM (TZM priming) or human IgG (control), as well as of liquid overlay AU565 spheroids generated from TZM-primed or control cells, consistently shows significant increase of HER3 and pHER2 levels in the TZM-primed samples. Secondly, immunofluorescent analysis strongly indicates that TZM priming substantially upregulates HER3 and pHER2 levels both in 2D and 3D (spheroids) models. Importantly, this process is accompanied by rearrangement of endocytic markers Rab4, CD63, Sorl1 as well as Extra domain B fibronectin, found at the cells’ surface together with HER2 and HER3 upon TZM priming. A similar trend was also found in HER2-overexpressing ovarian cancer cells SKOV-3 subjected to short-term TZM treatment. Furthermore, spheroids made with TZM-primed AU565 cells display significantly faster cell proliferation compared to IgG-primed or untreated control counterparts, as measured via optical coherent tomography imaging and Imaris 3D rendering software. Finally, tumor xenografts implanted in athymic nude mice using TZM-primed AU565 cells display continuous growth in contrast to those generated from untreated cells. These results suggest that short-term TZM treatment may inadvertently increase oncogenic fitness via adaptation to TZM-HER2 cellular binding and subsequent disruption of dimerization and signaling. These results are consistent with reports indicating that regional HER2 expression heterogeneity appears to increase with TZM treatment. Moreover, these observations are especially concerning because radiolabeled TZM probes have been employed in PET imaging in HER2+ cancer patients. In summary, our results suggest that short-term TZM treatment may result in priming and selection for more aggressive cancer phenotype. Citation Format: Alena Rudkouskaya, Cassandra L Roberge, Lauren Elder, Kailie Matteson, David T Corr, Margarida Barroso. Short-term trastuzumab treatment increases oncogenic fitness in HER2 overexpressing breast cancer models [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr P4-01-12.

Discoidin Domain Receptor 1, a Potential Biomarker and Therapeutic Target in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is still one of the most lethal human cancers in the world due to its high degree of malignancy, easy invasion and metastasis, poor therapeutic effect and poor prognosis. Nowadays, there is no very effective diagnosis and treatment method. It is crucial to elucidate the underlying pathogenesis and mechanisms of HCC for developing new and effective diagnostic/prognostic biomarkers and therapies. Discoidin domain receptors (DDRs) belong to the family of transmembrane receptor tyrosine kinases (RTKs) and are recognized as playing central regulatory roles in a variety of high incidence human diseases, including tumors. DDRs have two members, DDR1 and DDR2. The role of DDR1 in several tumors has been extensively studied, and many researchers have identified it as a powerful candidate target for the development of functional and effective tumor treatment inhibitors. However, its role and mechanism in HCC are ill defined. In this article, we review the advanced insights into the progression of DDR1 in HCC, particularly the ligands and mechanisms in invasion and metastasis, which may open new avenues for the therapeutic utility of HCC.

Mechanistic insights into the recruitment of RAF kinase to the plasma membrane by KRAS

KRAS is a small GTPase that is frequently mutated in human cancers, particularly pancreatic, colorectal and lung cancer. Engagement of mitogens with transmembrane receptor tyrosine kinases result in the activation of KRAS from an inactive GDP to active GTP bound state. Localized on the inner leaflet of the plasma membrane, active KRAS-GTP serves to recruit RAF kinase to the membrane where it undergoes activation. Oncogenic mutations lock KRAS in the active GTP state resulting in dysregulated cellular growth and proliferation.

Fluorescence Imaging of Epidermal Growth Factor Receptor Tyrosine Kinase Inhibitor Resistance in Non-Small Cell Lung Cancer.

Simple SummaryLung cancer is the leading cause of cancer-related deaths, with a low (<21%) 5-year survival rate. Lung cancer is often driven by the misfunction of molecules on the surface of cells of the epithelium, which orchestrate mechanisms by which these cells grow and proliferate. Beyond common non-specific treatments, such as chemotherapy or radiotherapy, among molecular-specific treatments, a number of small-molecule drugs that block cancer-driven molecular activity have been developed. These drugs initially have significant success in a subset of patients, but these patients systematically develop resistance within approximately one year of therapy. Substantial efforts towards understanding the mechanisms of resistance have focused on the genomics of cancer progression, the response of cells to the drugs, and the cellular changes that allow resistance to develop. Fluorescence microscopy of many flavours has significantly contributed to the last two areas, and is the subject of this review. Non-small cell lung cancer (NSCLC) is a complex disease often driven by activating mutations or amplification of the epidermal growth factor receptor (EGFR) gene, which expresses a transmembrane receptor tyrosine kinase. Targeted anti-EGFR treatments include small-molecule tyrosine kinase inhibitors (TKIs), among which gefitinib and erlotinib are the best studied, and their function more often imaged. TKIs block EGFR activation, inducing apoptosis in cancer cells addicted to EGFR signals. It is not understood why TKIs do not work in tumours driven by EGFR overexpression but do so in tumours bearing classical activating EGFR mutations, although the latter develop resistance in about one year. Fluorescence imaging played a crucial part in research efforts to understand pro-survival mechanisms, including the dysregulation of autophagy and endocytosis, by which cells overcome the intendedly lethal TKI-induced EGFR signalling block. At their core, pro-survival mechanisms are facilitated by TKI-induced changes in the function and conformation of EGFR and its interactors. This review brings together some of the main advances from fluorescence imaging in investigating TKI function and places them in the broader context of the TKI resistance field, highlighting some paradoxes and suggesting some areas where super-resolution and other emerging methods could make a further contribution.

Discoidin domain receptor 1 promotes hepatocellular carcinoma progression through modulation of SLC1A5 and the mTORC1 signaling pathway.

Hepatocellular carcinoma (HCC) is one of the most common cancers in the world with a high mortality rate. Receptor tyrosine kinases play important roles in the occurrence and development of various cancers. Discoid protein domain receptor 1 (DDR1) is a special type of transmembrane receptor tyrosine kinase. Here, we show that the expression of DDR1 is significantly increased in HCC and is related to a poor clinical prognosis. The expression of DDR1 in HCC cell lines and primary HCC specimens was evaluated using Western blotting and immunohistochemistry. A correlation between DDR1 and SLC1A5 expression was also investigated in primary HCC specimens. Cell proliferation was evaluated using in vitro CCK8 and colony formation assays. Gene knock-down and overexpression assays, CHX, NH4CL and Mg132 interference tests and immunoprecipitation, as well as nude mouse xenograft models were used to assess the mechanism by which DDR1 promotes tumorigenesis in vitro and in vivo. We found that DDR1 promotes the proliferation of HCC cells and accelerates the growth of HCC tumor xenografts, while DDR1 downregulation had the opposite effect. We also found that loss or gain of DDR1 expression affected HCC cell cycle progression. Mechanistically, we found that DDR1 interacts with SLC1A5, which belongs to the solute carrier (SLC) family of transporters, and regulates its stability, thereby affecting the mTORC1 signaling pathway. In addition, we found that SLC1A5 regulation by DDR1 can be restored by lysosome inhibitors. We also found that DDR1 is highly expressed in HCC tissues and that increased DDR1 expression predicts a shorter overall survival (OS) time. We additionally found that the expression of SLC1A5 was positively correlated with that of DDR1. Together, our data indicate that DDR1 acts as a tumor-promoting factor that can control HCC cell proliferation and cell cycle progression by stabilizing SLC1A5 in a lysosome-dependent way. Our study reveals a new mechanism by which DDR1 plays a liver cancer-promoting role. We also found that DDR1 expression serves as an independent prognostic marker, and that DDR1 and SLC1A5 expression levels are positively correlated in clinical samples. Our findings provide a new perspective for understanding HCC development and offers new targets for the treatment and management of HCC.

Putative dual inhibitors of mTOR and RET kinase from natural products: Pharmacophore-based hierarchical virtual screening

Protein kinases play quintessential roles in regulating various cellular processes. Aberrant activation of their signal transduction modules contribute to diverse ailments including cancer. Kinases, therefore, have become attractive drug targets for therapeutic intervention. Majority of kinases are classified into the two most widely acknowledged families encompassing serine/threonine and tyrosine kinases. The mTOR (mammalian Target of Rapamycin) is a serine/threonine kinase that regulates fundamental processes including protein synthesis, growth, metabolism, aging, regeneration, and autophagy. RET (REarranged during Transfection) is a transmembrane receptor tyrosine kinase required to maintain the neuronal populations of peripheral, sympathetic, parasympathetic, and enteric nervous systems. The molecules targeting both serine/threonine and tyrosine kinases possess potent antitumor activity and have demonstrated clinical efficacy. The clinical success of PP121, a dual inhibitor of mTOR and RET kinase, therefore, was explored in the present investigation. Correspondingly, an auto-pharmacophore model was generated and employed to screen four databases of natural molecules, which map the features observed for PP121. Within this framework, multiple computational approaches were integrated including homology modeling, molecular docking, molecular dynamics (MD) simulations, and binding free energy calculations. The hierarchical strategy led to identification of two compounds- STOCK1N-98911 and STOCK1N-84953, which bind to ATP-binding sites as well as allosteric sites, of mTOR and RET kinase. Free energy calculations highlighted the role of vital residues contributing to favorable interactions in binding of hits with mTOR and RET kinase. The pharmacokinetic properties of hits were also evaluated in silico to ensure their bioavailability, providing a rationale for their development as leads against both kinases. Altogether, this investigation provides a preliminary platform for future experimental research, towards the development of dual inhibitors of serine/threonine and tyrosine kinases, a persuasive strategy for intersecting two families of oncogenes.

Predictors of pathologic complete response to neoadjuvant treatment in HER2-overexpressing breast cancer: a retrospective analysis using real-world data

The human epidermal growth factor receptor 2 (ERBB2, HER2 or HER2/neu) is a transmembrane tyrosine kinase receptor that is overexpressed in approximately 20% of breast cancers. The use of the anti-HER2 monoclonal antibodies Pertuzumab and Trastuzumab in association with chemotherapy has achieved a higher percentage of pathologic complete response (pCR) than conventional chemotherapy. The purpose of our study was to identify factors that could affect the therapeutic response of patients with breast cancer and HER2 overexpression treated with cytotoxic chemotherapy plus double HER2 blockade in neoadjuvant setting at Fundación Arturo López Pérez (FALP). A case–control study was designed to evaluate the effect of clinical and histopathological variables on the response to neoadjuvant therapy. Ninety-four women with non-metastatic breast cancer and HER2 overexpression received neoadjuvant combination chemotherapy with Trastuzumab and Pertuzumab at FALP during the period 2017–2020. Seventy percent of patients achieved pCR, and in the group of hormone receptor negative patients, 89% of patients achieved pCR. Different variables were analysed trying to look for clinicopathological predictors of complete response. This study provides us with real-world data on the efficacy of using this treatment combination in our population of HER2-overexpressing breast cancer patients.