Platelet-derived Growth Factor Receptor Research Articles

Spatiotemporal ATF3 Expression Determines VSMC Fate in Abdominal Aortic Aneurysm.

Abdominal aortic aneurysm (AAA) is a catastrophic disease with little effective therapy, likely due to the limited understanding of the mechanisms underlying AAA development and progression. ATF3 (activating transcription factor 3) has been increasingly recognized as a key regulator of cardiovascular diseases. However, the role of ATF3 in AAA development and progression remains elusive. Genome-wide RNA sequencing analysis was performed on the aorta isolated from saline or Ang II (angiotensin II)-induced AAA mice, and ATF3 was identified as the potential key gene for AAA development. To examine the role of ATF3 in AAA development, vascular smooth muscle cell-specific ATF3 knockdown or overexpressed mice by recombinant adeno-associated virus serotype 9 vectors carrying ATF3, or shRNA-ATF3 with SM22α (smooth muscle protein 22-α) promoter were used in Ang II-induced AAA mice. In human and murine vascular smooth muscle cells, gain or loss of function experiments were performed to investigate the role of ATF3 in vascular smooth muscle cell proliferation and apoptosis. In both Ang II-induced AAA mice and patients with AAA, the expression of ATF3 was reduced in aneurysm tissues but increased in aortic lesion tissues. The deficiency of ATF3 in vascular smooth muscle cell promoted AAA formation in Ang II-induced AAA mice. PDGFRB (platelet-derived growth factor receptor β) was identified as the target of ATF3, which mediated vascular smooth muscle cell proliferation in response to TNF-alpha (tumor necrosis factor-α) at the early stage of AAA. ATF3 suppressed the mitochondria-dependent apoptosis at the advanced stage by upregulating its direct target BCL2. Our chromatin immunoprecipitation results also demonstrated that the recruitment of NFκB1 and P300/BAF/H3K27ac complex to the ATF3 promoter induces ATF3 transcription via enhancer activation. NFKB1 inhibitor (andrographolide) inhibits the expression of ATF3 by blocking the recruiters NFKB1 and ATF3-enhancer to the ATF3-promoter region, ultimately leading to AAA development. Our results demonstrate a previously unrecognized role of ATF3 in AAA development and progression, and ATF3 may serve as a novel therapeutic and prognostic marker for AAA.

Fusion of Platelet Derived Growth Factor Receptor Alpha (PDGFRA) With Ubiquitin Specific Peptidase 8 (USP8) in a Calcified Chondroid Mesenchymal Neoplasm Harboring t(4;15)(q12;q21) as a Sole Aberration.

The term "calcified chondroid mesenchymal neoplasm" was introduced in 2021 to describe a group of tumors characterized by various morphological features, including the formation of cartilage or chondroid matrix. These tumors frequently carry chimeric genes where the 5'-end partner gene is fibronectin 1 and the 3'-end partner gene codes for receptor tyrosine kinase. Our study explores fusion of the genes platelet-derived growth factor receptor alpha (PDGFRA) and ubiquitin-specific peptidase 8 (USP8) in calcified chondroid mesenchymal neoplasm. Genetic investigations were conducted on a tumor located in the leg of a 71-year-old woman. G-banding analysis of short-term cultured tumor cells revealed the karyotype 46,XX,t(4;15)(q12;q21)[6]/46,XX[4]. RNA sequencing detected in-frame PDGFRA::USP8 and USP8::PDGFRA chimeric transcripts, which were validated by RT-PCR/Sanger sequencing. The PDGFRA::USP8 chimeric protein is predicted to have cell membrane location and functions as a chimeric ubiquitinyl hydrolase. The USP8::PDGFRA protein was predicted to be nuclear and function as a positive regulator of cellular metabolic process. We report, for the first time, a calcified chondroid mesenchymal neoplasm carrying a balanced t(4;15)(q12;q21) chromosomal translocation, resulting in the generation of both PDGFRA::USP8 and USP8::PDGFRA chimeras. The PDGFRA::USP8 protein is located on the cell membrane and functions as a chimeric ubiquitinyl hydrolase, activated by PDGFs. Conversely, USP8::PDGFRA is a nuclear protein regulating metabolic processes.

Targeting PDGF signaling of cancer-associated fibroblasts blocks feedback activation of HIF-1α and tumor progression of clear cell ovarian cancer

Ovarian clear cell carcinoma (OCCC) is a gynecological cancer with a dismal prognosis; however, the mechanism underlying OCCC chemoresistance is not well understood. To explore the intracellular networks associated with the chemoresistance, we analyze surgical specimens by performing integrative analyses that combine single-cell analyses and spatial transcriptomics. We find that a chemoresistant OCCC subpopulation with elevated HIF activity localizes mainly in areas populated by cancer-associated fibroblasts (CAFs) with a myofibroblastic phenotype, which is corroborated by quantitative immunostaining. CAF-enhanced chemoresistance and HIF-1α induction are recapitulated in co-culture assays, which show that cancer-derived platelet-derived growth factor (PDGF) contributes to the chemoresistance and HIF-1α induction via PDGF receptor signaling in CAFs. Ripretinib is identified as an effective receptor tyrosine kinase inhibitor against CAF survival. In the co-culture system and xenograft tumors, ripretinib prevents CAF survival and suppresses OCCC proliferation in the presence of carboplatin, indicating that combination of conventional chemotherapy and CAF-targeted agents is effective against OCCC.

Endothelial HIFα/PDGF-B to smooth muscle Beclin1 signaling sustains pathological muscularization in pulmonary hypertension.

Mechanisms underlying maintenance of pathological vascular hypermuscularization are poorly delineated. Herein, we investigated retention of smooth muscle cells (SMCs) coating normally unmuscularized distal pulmonary arterioles in pulmonary hypertension (PH) mediated by chronic hypoxia with or without Sugen 5416, and reversal of this pathology. With hypoxia in mice or culture, lung endothelial cells (ECs) upregulated hypoxia-inducible factor 1α (HIF1-α) and HIF2-α, which induce platelet-derived growth factor B (PDGF-B), and these factors were reduced to normoxic levels with re-normoxia. Re-normoxia reversed hypoxia-induced pulmonary vascular remodeling, but with EC HIFα overexpression during re-normoxia, pathological changes persisted. Conversely, after establishment of distal muscularization and PH, EC-specific deletion of Hif1a, Hif2a, or Pdgfb induced reversal. In human idiopathic pulmonary artery hypertension, HIF1-α, HIF2-α, PDGF-B, and autophagy-mediating gene products, including Beclin1, were upregulated in pulmonary artery SMCs and/or lung lysates. Furthermore, in mice, hypoxia-induced EC-derived PDGF-B upregulated Beclin1 in distal arteriole SMCs, and after distal muscularization was established, re-normoxia, EC Pdgfb deletion, or treatment with STI571 (which inhibits PDGF receptors) downregulated SMC Beclin1 and other autophagy products. Finally, SMC-specific Becn1 deletion induced apoptosis, reversing distal muscularization and PH mediated by hypoxia with or without Sugen 5416. Thus, chronic hypoxia induction of the HIFα/PDGF-B axis in ECs is required for non-cell-autonomous Beclin1-mediated survival of pathological distal arteriole SMCs.

Corosolic acid attenuates platelet-derived growth factor signaling in macrophages and smooth muscle cells of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and life-threatening disease that is characterized by vascular remodeling of the pulmonary artery. Pulmonary vascular remodeling is primarily caused by the excessive proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs), which are facilitated by perivascular inflammatory cells including macrophages. Corosolic acid (CRA) is a natural pentacyclic triterpenoid that exerts anti-inflammatory effects. In the present study, the effects of CRA on the viability of macrophages were examined using monocrotaline (MCT)-induced PAH rats and human monocyte-derived macrophages. Although we previously reported that CRA inhibited signal transducer and activator of transcription 3 (STAT3) signaling and ameliorated pulmonary vascular remodeling in PAH, the inhibitory mechanism remains unclear. Therefore, the underlying mechanisms were investigated using PASMCs from idiopathic PAH (IPAH) patients. In MCT-PAH rats, CRA inhibited the accumulation of macrophages around remodeled pulmonary arteries. CRA reduced the viability of human monocyte-derived macrophages. In IPAH-PASMCs, CRA attenuated cell proliferation and migration facilitated by platelet-derived growth factor (PDGF)-BB released from macrophages and PASMCs. CRA also downregulated the expression of PDGF receptor β and its signaling pathways, STAT3 and nuclear factor-κB (NF-κB). In addition, CRA attenuated the phosphorylation of PDGF receptor β and STAT3 following the PDGF-BB simulation. The expression and phosphorylation levels of PDGF receptor β after the PDGF-BB stimulation were reduced by the small interfering RNA knockdown of NF-κB, but not STAT3, in IPAH-PASMCs. In conclusion, CRA attenuated the PDGF-PDGF receptor β-STAT3 and PDGF-PDGF receptor β-NF-κB signaling axis in macrophages and PASMCs, and thus, ameliorated pulmonary vascular remodeling in PAH.

Shenqi Yizhi prescription prevents AβO-induced memory impairment in mice by regulating the contractility of brain pericytes

BackgroundCerebral microcirculation disturbance manifested by decrease of cerebral blood flow (CBF) is one of early features of Alzheimer's disease (AD). Shenqi Yizhi prescription (SQYZ) is widely used in the treatment of AD. However, the effect of SQYZ on the early feature of AD is not clarified. PurposeTo explore the effect and mechanism of SQYZ on AD-like behavior from the perspective of early pathological features of AD. MethodsThe fingerprint of SQYZ was established by ultra-high-performance liquid chromatograph. The improvement effect of SQYZ on Aβ1–42 Oligomer (AβO)-induced AD-like behavior of mice was evaluated by behavioral test. The changes of CBF were detected by laser doppler meter and laser speckle imaging. The pathological changes of the hippocampus were observed by HE staining and transmission electron microscope. The expressions of intercellular communication molecules were detected by western blotting or immunofluorescence staining. The content of platelet-derived growth factor-BB (PDGF-BB) was detected by ELISA. Finally, the core components of SQYZ were docked with platelet-derived growth factor receptor beta (PDGFRβ) using AutoDock Vina software. ResultsThe similarity of the components in SQYZ extracted from different batches of medicinal materials was higher than 0.9. SQYZ administration could improve AβO-induced memory impairment and CBF reduction. Compared with the sham group, the number of neurons in the hippocampi of AβO group was significantly reduced, and the microvessels were shrunken and deformed. By contrary, SQYZ administration mitigated those pathological changes. Compared with the sham mice, the expressions of CD31, N-cadherin, PDGFRβ, glial fibrillary acidic protein, phosphorylation of focal adhesion kinase, integrin β1, and integrin α5 in the hippocampi of AβO mice were significantly increased. However, SQYZ administration significantly reduced AβO-induced expression of those proteins. Interestingly, the effect of PDGFRβ inhibitor, sunitinib demonstrated a consistent modulating effect as SQYZ. Finally, the brain-entering components of SQYZ, including ginsenoside Rg5, coptisine, cryptotanshinone, dihydrotanshinone IIA, stigmasterol, and tanshinone IIA had high binding force with PDGFRβ, implicating PDGFRβ as a potential target for SQYZ. ConclusionsOur data indicate that SQYZ improves CBF in AβO-triggered AD-like mice through inhibiting brain pericyte contractility, indicating the treatment potential of SQYZ for AD at the early stage.

Commonality and heterogeneity of pacemaker mechanisms in the male reproductive organs.

During emission, the first phase of ejaculation, smooth muscle in organs of the male reproductive tract (MRT) vigorously contract upon sympathetic nerve excitation to expel semen consisting of sperm and seminal plasma. During inter-ejaculation phases, the epididymis, seminal vesicles and prostate undergo spontaneous phasic contractions (SPCs), this transporting and maintaining the quality of sperm and seminal plasma. Recent studies have revealed platelet-derived growth factor receptor α-expressing (PDGFRα+) subepithelial interstitial cells in seminal vesicles subserve the role of pacemaker cells that electrically drive SPCs in this organ. PDGFRα+ smooth muscle cells in the epididymis also appear to function as pacemaker cells implicating PDGFRα as a potential signature molecule in MRT pacemaking. The dominant mechanism driving pacemaking in these organs is the cytosolic Ca2+ oscillator. This operates through entrainment of the release-refill cycle of Ca2+ stores, the released Ca2+ ions opening Ca2+-activated chloride channels, including in some cases ANO1 (TMEM16A), with the resultant pacemaker potential activating L-type voltage-dependent Ca2+ channels in the smooth muscle causing contraction (viz. SPCs). A second pacemaker mechanism, namely the membrane oscillator also has a role in specific cases. Further investigations into the commonality and heterogeneity of MRT pacemakers will open an avenue for understanding the pathogenesis of male infertility associated with deterioration of seminal plasma.

Association between Platelet-Derived Growth Factor Receptor Alpha Gene Polymorphisms and Platelet-Rich Plasma's Efficiency in Treating Lateral Elbow Tendinopathy-A Prospective Cohort Study.

Individual differences in the response to platelet-rich plasma (PRP) therapy can be observed among patients. The genetic background may be the cause of this variability. The current study focused on the impact of genetic variants on the effectiveness of PRP. The aim of the present study was to analyze the impact of single nucleotide polymorphisms (SNP) of the platelet-derived growth factor receptor alpha (PDGFRA) gene on the effectiveness of treating lateral elbow tendinopathy (LET) with PRP. The treatment's efficacy was analyzed over time (2, 4, 8, 12, 24, 52 and 104 weeks after the PRP injection) on 107 patients using patient-reported outcome measures (PROM) and achievement of a minimal clinically important difference (MCID). Four SNPs of the PDGFRA gene (rs7668190, rs6554164, rs869978 and rs1316926) were genotyped using the TaqMan assay method. Patients with the AA genotypes of the rs7668190 and the rs1316926 polymorphisms, as well as carriers of the T allele of rs6554164 showed greater effectiveness of PRP therapy than carriers of other genotypes. Moreover, the studied SNPs influenced the platelets' parameters both in whole blood and in PRP. These results showed that PDGFRA gene polymorphisms affect the effectiveness of PRP treatment. Genotyping the rs6554164 and the rs1316926 SNPs may be considered for use in individualized patient selection for PRP therapy.

Safety and efficacy of anlotinib combined with taxane and lobaplatin in neoadjuvant treatment of clinical stage II/III triple-negative breast cancer in China (the neoALTAL trial): a single-arm, phase 2 trial

Anlotinib is a new type of tyrosine kinase inhibitor that targets vascular endothelial growth factor receptors 1/2/3, platelet-derived growth factor receptors α/β, and fibroblast growth factor receptors 1-4 and c-Kit, with a broad spectrum of inhibitory effects on tumor angiogenesis and growth. It has been proven effective in HER2-negative metastatic breast cancer, but its efficacy in early-stage triple-negative breast cancer (TNBC) is unknown. This phase 2 study aims to evaluate the efficacy and safety of adding anlotinib to neoadjuvant chemotherapy in patients with TNBC. Patients with clinical stage II/III TNBC were treated with 5 cycles of anlotinib (12mg, d1-14, q3w) plus 6 cycles of taxanes (docetaxel 75 mg/m2 ,d1, q3w or nab-paclitaxel 125 mg/m2, d1 and d8, q3w) and lobaplatin (30 mg/m2, d1, q3w), followed by surgery. The primary endpoint was pathological complete response (pCR; ypT0/is ypN0) and the secondary endpoints include breast pCR (bpCR), axillary pCR (apCR), residual cancer burden (RCB), objective response rate (ORR), survival, and safety. Exploratory endpoints were efficacy biomarkers based on Fudan University Shanghai Cancer Center Immunohistochemical (FUSCC IHC) classification for TNBC and next-generation sequencing (NGS) of DNA from tumor tissue and blood samples of patients with 425-gene panel. This trial is registered with www.chictr.org.cn (ChiCTR2100043027). From Jan 2021 to Aug 2022, 48patients were assessed and 45 were enrolled. All patients received at least one dose of study treatment and underwent surgery. The median age was 48.5 years (SD: 8.7), 71% were nodal involved, and 20% had stage III. In the intention-to-treat population, 26 out of 45patients achieved pCR (57.8%; 90% CI, 44.5%-70.3%), and 39 achieved residual cancer burden class 0-I (86.7%; 95% CI, 73.2%-94.9%). The bpCR and apCR rate were 64.4% (29/45) and 71.9% (23/32), respectively. No recurrence or metastasis occurred during the short-term follow-up. Based on the FUSCC IHC-based subtypes, the pCR rates were 68.8% (11/16) for immunomodulatory subtype, 58.3% (7/12) for basal-like immune-suppressed subtype and 33.3% (4/12) for luminal androgen receptor subtype, respectively. NGS revealed that the pCR were 77% (10/13) and 50% (14/28) in MYC-amplified and wild-type patients, respectively, and 78% (7/9) and 53% (17/32) in gBRCA1/2-mutated and wild-type patients, respectively. The median follow-up time of the study was 14.9 months (95% CI: 13.5-16.3 months). There was no disease progression or death during neoadjuvant therapy. No deaths occurred during postoperative follow-up. In the safety population (N=45), Grade 3 or 4 treatment emergent adverse events occurred in 29patients (64%), and the most common events were neutropenia (38%), leukopenia (27%), thrombocytopenia (25%), anemia (13%), and hypertension (13%), respectively. The addition of anlotinib to neoadjuvant chemotherapy showed manageable toxicity and encouraging antitumor activity for patients with clinical stage II/III TNBC. Chongqing Talents Project, Chongqing Key Project of Technology Innovation and Application Development and Chongqing Outstanding Youth Natural Science Foundation.

Insights on Platelet-Derived Growth Factor Receptor α-Positive Interstitial Cells in the Male Reproductive Tract.

Male infertility is a significant factor in approximately half of all infertility cases and is marked by a decreased sperm count and motility. A decreased sperm count is caused by not only a decreased production of sperm but also decreased numbers successfully passing through the male reproductive tract. Smooth muscle movement may play an important role in sperm transport in the male reproductive tract; thus, understanding the mechanism of this movement is necessary to elucidate the cause of sperm transport disorder. Recent studies have highlighted the presence of platelet-derived growth factor receptor α (PDGFRα)-positive interstitial cells (PICs) in various smooth muscle organs. Although research is ongoing, PICs in the male reproductive tract may be involved in the regulation of smooth muscle movement, as they are in other smooth muscle organs. This review summarizes the findings to date on PICs in male reproductive organs. Further exploration of the structural, functional, and molecular characteristics of PICs could provide valuable insights into the pathogenesis of male infertility and potentially lead to new therapeutic approaches.

Involvement of ANO1 currents in pacemaking of PDGFRα-positive specialised smooth muscle cells in rat caudal epididymis.

The epididymal duct exhibits spontaneous phasic contractions (SPCs) to store and transport sperm. Here, we explored molecular identification of pacemaker cells driving SPCs in the caudal epididymal duct and also investigated properties of pacemaker currents underlying SPCs focusing on ANO1 Ca2+-activated Cl- channels (CaCCs). Immunohistochemistry was performed to visualise the distribution of platelet-derived growth factor receptor α (PDGFRα)- or ANO1-positive cells in the rat caudal epididymal duct. Perforated whole-cell patch clamp technique was applied to enzymatically isolated epididymal cells, while SPCs were recorded with video edge-tracking technique. Immunohistochemistry revealed the distribution of α-smooth muscle actin (α-SMA)-positive cells co-expressing both PDGFRα and ANO1 in the innermost smooth muscle layer. Approximately one-third of isolated epididymis cells exhibited spontaneous transient inward currents (STICs) at the holding potential -60 mV. The reversal potential for STICs was close to the calculated chloride equivalent potential depending on intracellular Cl- concentrations. Ani9 (3 µM), the ANO1 specific inhibitor, decreased both amplitude and frequency of STICs, while cyclopiazonic acid (CPA, 30 µM), a sarco-/endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitor, abolished STICs. Ani9 (3 or 10 µM) reduced the frequency of SPCs without changing their amplitude. Thus, PDGFRα+, ANO1+ specialised smooth muscle cells (SMCs) appear to function as pacemaker cells to electrically drive epididymal SPCs by generating ANO1-dependnet STICs. STICs arising from spontaneous Ca2+ release from intracellular Ca2+ store and subsequent opening of ANO1 result in depolarisations that spread into adjacent SMCs where L-type voltage-dependent Ca2+ channels are activated to develop SPCs.

Phylogenetic and transcriptomic characterization of insulin and growth factor receptor tyrosine kinases in crustaceans.

Receptor tyrosine kinases (RTKs) mediate the actions of growth factors in metazoans. In decapod crustaceans, RTKs are implicated in various physiological processes, such molting and growth, limb regeneration, reproduction and sexual differentiation, and innate immunity. RTKs are organized into two main types: insulin receptors (InsRs) and growth factor receptors, which include epidermal growth factor receptor (EGFR), fibroblast growth factor receptor (FGFR), vascular endothelial growth factor receptor (VEGFR), and platelet-derived growth factor receptor (PDGFR). The identities of crustacean RTK genes are incomplete. A phylogenetic analysis of the CrusTome transcriptome database, which included all major crustacean taxa, showed that RTK sequences segregated into receptor clades representing InsR (72 sequences), EGFR (228 sequences), FGFR (129 sequences), and PDGFR/VEGFR (PVR; 235 sequences). These four receptor families were distinguished by the domain organization of the extracellular N-terminal region and motif sequences in the protein kinase catalytic domain in the C-terminus or the ligand-binding domain in the N-terminus. EGFR1 formed a single monophyletic group, while the other RTK sequences were divided into subclades, designated InsR1-3, FGFR1-3, and PVR1-2. In decapods, isoforms within the RTK subclades were common. InsRs were characterized by leucine-rich repeat, furin-like cysteine-rich, and fibronectin type 3 domains in the N-terminus. EGFRs had leucine-rich repeat, furin-like cysteine-rich, and growth factor IV domains. N-terminal regions of FGFR1 had one to three immunoglobulin-like domains, whereas FGFR2 had a cadherin tandem repeat domain. PVRs had between two and five immunoglobulin-like domains. A classification nomenclature of the four RTK classes, based on phylogenetic analysis and multiple sequence alignments, is proposed.

Endocytic vesicles act as vehicles for glucose uptake in response to growth factor stimulation

Glycolysis is a fundamental cellular process, yet its regulatory mechanisms remain incompletely understood. Here, we show that a subset of glucose transporter 1 (GLUT1/SLC2A1) co-endocytoses with platelet-derived growth factor (PDGF) receptor (PDGFR) upon PDGF-stimulation. Furthermore, multiple glycolytic enzymes localize to these endocytosed PDGFR/GLUT1-containing vesicles adjacent to mitochondria. Contrary to current models, which emphasize the importance of glucose transporters on the cell surface, we find that PDGF-stimulated glucose uptake depends on receptor/transporter endocytosis. Our results suggest that growth factors generate glucose-loaded endocytic vesicles that deliver glucose to the glycolytic machinery in proximity to mitochondria, and argue for a new layer of regulation for glycolytic control governed by cellular membrane dynamics.

The Notch-PDGFRβ axis suppresses brown adipocyte progenitor differentiation in early post-natal mice

De novo brown adipogenesis holds potential in combating the epidemics of obesity and diabetes. However, the identity of brown adipocyte progenitor cells (APCs) and their regulation have not been extensively explored. Here, through invivo lineage tracing and mouse modeling, we observed that platelet-derived growth factor receptor beta (PDGFRβ)+ pericytes give rise to developmental brown adipocytes but not to those in adult homeostasis. By contrast, T-box 18 (TBX18)+ pericytes contribute to brown adipogenesis throughout both developmental and adult stages, though in a depot-specific manner. Mechanistically, Notch inhibition in PDGFRβ+ pericytes promotes brown adipogenesis by downregulating PDGFRβ. Furthermore, inhibition of Notch signaling in PDGFRβ+ pericytes mitigates high-fat, high-sucrose (HFHS)-induced glucose and metabolic impairment in mice during their development and juvenile phases. Collectively, these findings show that the Notch/PDGFRβ axis negatively regulates developmental brown adipogenesis, and its repression promotes brown adipose tissue expansion and improves metabolic health.

Molecular diversity in isocitrate dehydrogenase-wild-type glioblastoma.

In the dynamic landscape of glioblastoma, the 2021 World Health Organization Classification of Central Nervous System tumours endeavoured to establish biological homogeneity, yet isocitrate dehydrogenase-wild-type (IDH-wt) glioblastoma persists as a tapestry of clinical and molecular diversity. Intertumoural heterogeneity in IDH-wt glioblastoma presents a formidable challenge in treatment strategies. Recent strides in genetics and molecular biology have enhanced diagnostic precision, revealing distinct subtypes and invasive patterns that influence survival in patients with IDH-wt glioblastoma. Genetic and molecular biomarkers, such as the overexpression of neurofibromin 1, phosphatase and tensin homolog and/or cyclin-dependent kinase inhibitor 2A, along with specific immune cell abundance and neurotransmitters, correlate with favourable outcomes. Conversely, increased expression of epidermal growth factor receptor tyrosine kinase, platelet-derived growth factor receptor alpha and/or vascular endothelial growth factor receptor, coupled with the prevalence of glioma stem cells, tumour-associated myeloid cells, regulatory T cells and exhausted effector cells, signifies an unfavourable prognosis. The methylation status of O6-methylguanine-DNA methyltransferase and the influence of microenvironmental factors and neurotransmitters further shape treatment responses. Understanding intertumoural heterogeneity is complemented by insights into intratumoural dynamics and cellular interactions within the tumour microenvironment. Glioma stem cells and immune cell composition significantly impact progression and outcomes, emphasizing the need for personalized therapies targeting pro-tumoural signalling pathways and resistance mechanisms. A successful glioblastoma management demands biomarker identification, combination therapies and a nuanced approach considering intratumoural variability. These advancements herald a transformative era in glioblastoma comprehension and treatment.

PDGFRA K385 mutants in myxoid glioneuronal tumors promote receptor dimerization and oncogenic signaling

Myxoid glioneuronal tumors (MGNT) are low-grade glioneuronal neoplasms composed of oligodendrocyte-like cells in a mucin-rich stroma. These tumors feature a unique dinucleotide change at codon 385 in the platelet-derived growth factor receptor α (encoded by the PDGFRA gene), resulting in the substitution of lysine 385 into leucine or isoleucine. The functional consequences of these mutations remain largely unexplored. Here, we demonstrated their oncogenic potential in fibroblast and Ba/F3 transformation assays. We showed that the K385I and K385L mutants activate STAT and AKT signaling in the absence of ligand. Co-immunoprecipitations and BRET experiments suggested that the mutations stabilized the active dimeric conformation of the receptor, pointing to a new mechanism of oncogenic PDGF receptor activation. Furthermore, we evaluated the sensitivity of these mutants to three FDA-approved tyrosine kinase inhibitors: imatinib, dasatinib, and avapritinib, which effectively suppressed the constitutive activity of the mutant receptors. Finally, K385 substitution into another hydrophobic amino acid also activated the receptor. Interestingly, K385M was reported in a few cases of brain tumors but not in MGNT. Our results provide valuable insights into the molecular mechanism underlying the activation of PDGFRα by the K385I/L mutations, highlighting their potential as actionable targets in the treatment of myxoid glioneuronal tumors.

Abstract 283: Fibroblast diversity and immune microenvironment in pseudoangiomatous stromal hyperplasia (PASH): Associations with breast cancer risk

Abstract Benign breast disease (BBD) affects over one million women annually in the United States and is diagnosed in nearly half of all women during their lifetime. Pseudoangiomatous stromal hyperplasia (PASH), a common BBD subtype, is characterized by an overaccumulation of tissue fibroblasts. Current research suggests a pivotal role of the immune microenvironment in progression of BBD to breast cancer, suggesting its composition as a determinant of breast cancer risk. Our study evaluates whether fibroblast variations and immune microenvironment differences in BBD biopsies containing PASH lesions are associated with subsequent breast cancer development. We evaluated BBD biopsies from women who subsequently developed breast cancer (cases, N=5) or remained cancer-free (controls, N=5). Using Opal-based multiplex immunofluorescence (mIF) assays, we mapped expression of fibroblast markers linked to breast cancer associated fibroblasts (CAFs), including vimentin (VIM), smooth muscle actin (ACTA2), fibroblast specific protein-1 (S100A4/FSP1), fibroblast associated protein (FAP), integrin beta-1 (CD29/ITGB1), and platelet derived growth factor receptor beta (PDGFRβ) and markers of key immune cells (T cells: CD4, CD8; dendritic cells: CD11c; B cells: CD20; and macrophages: CD68) along with MKI67 as a proliferation marker. Our results revealed marked differences in fibroblast marker expression and immune cell populations between these groups in the normal lobules in the BBD biopsies. PASH cases showed elevated PDGFRβ and CD29/ITGB1 expression in VIM-positive fibroblasts, markers characteristic of CAF subtypes known to accumulate in more aggressive tumor microenvironments. Conversely, a higher percentage of FSP1+/VIM+ cells, similar to that of a different CAF subtype, was noted in the lobules of PASH controls. This difference in biomarker expression, along with corresponding variations in immune cell counts, suggests a complex interplay between fibroblast composition and immune response that ultimately modulate cancer risk in PASH-containing BBD tissues. Additionally, increased MKI67 expression in PASH cases potentially signals the higher likelihood of cancer development. This work advances our understanding of fibroblast heterogeneity in BBD and its implications for breast cancer risk and progression, and paves the way for innovative strategies to improve clinical outcomes for BBD patients to reduce their incidence of breast cancer. Citation Format: Nicole Cruz-Reyes, Matilde Rossi, Melody Stallings Mann, Bryan McCauley, Tanya Hoskin, Robert Vierkant, Stacey Winham, Amy Degnim, Mark E. Sherman, Derek C. Radisky. Fibroblast diversity and immune microenvironment in pseudoangiomatous stromal hyperplasia (PASH): Associations with breast cancer risk [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 283.

Abstract 4736: Evaluate the potential sensitization effect and underlying mechanism of lenvatinib on cisplatin resistance oral squamous cell carcinoma

Abstract Oral squamous cell carcinoma (OSCC) is a prevalent form of cancer that develops in the oral cavity, globally recognized as the eighth most commonly diagnosed cancer. Despite the application of standard surgical techniques or concurrent chemoradiotherapy, the prognosis for OSCC patients remains unsatisfactory. Initially, cisplatin, the primary and most frequently used chemotherapy agent for treating OSCC, demonstrates effectiveness in therapy. Nonetheless, chemoresistance frequently arises, leading to treatment failure, and this is intricately associated with the activation of hypoxia-inducible factor 1α (HIF-1α) signaling. Recent research has brought to light heightened levels of HIF-1α-mediated vascular endothelial growth factor (VEGF) and BCL-2 in OSCC tumor sites, which play crucial roles in regulating angiogenesis and anti-apoptotic processes within cancer cells. Additionally, interventions aimed at targeting anti-apoptotic molecules or augmenting the expression of pro-apoptotic molecules may represent promising strategies to overcome chemoresistance in OSCC. Therefore, HIF-1α/VEGF/BCL-2 axis could be considered a potential target for the development of chemopreventive and chemotherapeutic strategies for OSCC. Lenvatinib is a targeted multi-kinase inhibitor that can inhibit tumor growth and angiogenesis by blocking the activation of vascular endothelial growth factor receptor (VEGFR) 1-3, fibroblast growth factor receptor (FGFR) 1-4, platelet-derived growth factor receptor (PDGFR) α, as well as the proto-oncogenes RET and KIT. However, whether lenvatinib may sensitizes OSCC to cisplatin remains unclear. In our study, we used the MTT assay to prove the cytotoxicity of OSCC cells (SAS and MOC1 cells) was induced by cisplatin and lenvatinib. We employed flow cytometry to verify that the combination of lenvatinib and cisplatin can indeed trigger both extrinsic and intrinsic apoptotic pathways in OSCC cells. Furthermore, our demonstration revealed that the induction of apoptosis pathways by the combination of lenvatinib and cisplatin is associated with mitochondrial-dependent apoptosis and death receptor-dependent apoptosis. Then, transwell invasion and migration assay results proved the inhibition effect of lenvatinib combined with cisplatin in SAS and MOC1 cells. Furthermore, we indicated that the combination of lenvatinib and cisplatin can effectively inhibit angiogenesis and anti-apoptotic mechanisms mediated by the HIF-1α/VEGF/BCL-2 axis in OSCC cells. In summary, our results demonstrate that the combined treatment with lenvatinib and cisplatin enhances the response of OSCC cells under hypoxic conditions. Additionally, it aims to mitigate the negative impact of hypoxia on cisplatin's therapeutic effectiveness and increase the sensitivity of OSCC cells to cisplatin. Citation Format: Ying-Tzu Chen, Yan-Ting Tsai, Fei-Ting Hsu, Hsi-Feng Tu. Evaluate the potential sensitization effect and underlying mechanism of lenvatinib on cisplatin resistance oral squamous cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4736.

Abstract 4131: Combination therapeutic strategy to fight against triple-negative breast cancer

Abstract Triple-negative breast cancers (TNBCs) lack estrogen-and progesteron receptors and human epidermal growth factor receptor-2 (HER2) which limits the therapeutic approaches. The high metastasizing capability of TNBCs is in correlation with the poor oxygenation of the cancerous breast tissue. This leads to the activation of the hypoxia-inducible-factor 1 (HIF-1), which induces multiple target genes that are involved in tumor progression and metastasis formation. This makes HIF-1 an attractive drug target, however, HIF-1 inhibitors failed if applied in monotherapy. Therefore, our aim is to investigate the combined therapeutic effect of HIF-1 inhibitor acriflavine and paclitaxel, a commonly used taxane in TNBC treatment. The synergy assessment of the two drugs was carried out by utilizing Sulforhodamine B assay on TNBC cell lines. The in vivo toxicity and efficacy of the drug combination was tested on NOD SCID mice with orthotopically inoculated MDA-MB-231 cell line. Quantitative and qualitative analysis of multiple genes involved in tumor progression was performed by mRNA and protein expression level assessment with qPCR, western blot and immunohistochemistry methods. HIF-1 stimulation was achieved by either incubating the cells at 1% oxygen level or through CoCl2 treatment. The in vitro mRNA expression studies demonstrated that acriflavin possesses a hypoxic-effect-mitigating property on the expression of metastasis-involved- and HIF-1 target genes. Acriflavine alleviated the epithelial-mesenchymal transition of TNBC cells by increasing the expression of the epithelial marker, E-cadherin. At protein level, we detected decrease in HIF-1alpha and Phospho-Protein kinase B (Akt) and increase in p53 tumor suppressor gene expression in response to acriflavine treatment. We further established MDA-MB-231 xenograft model in mice for investigating in vivo toxicity and efficacy. The drug combination efficiently reduced the tumor size and the macrometastasis formation compared to the control groups. The protein analysis of frozen tumor tissue samples indicated that the combination therapy decreased the HIF-1alpha expression and the amount of Phospho-Akt and Phospho-Mitogen-activated protein kinases (pMAPK/pERK) in CoCl2treated mice. Additionally, expression of epithelial markers increased and that of mesenchymal markers decreased. The combination therapy led to a decrease in the platelet-derived growth factor receptor beta (PDGFRB) as well. To conclude, we identified a novel drug combination which can efficiently combat TNBC by inhibiting HIF-1 signaling, mitigating cell migration and metastasis formation and suppressing the activation of the Phosphoinositide 3-kinase (PI3K) and MAPK pathways. This work was supported by the Hungarian Thematic Excellence Program (TKP2021-EGA-44) and the National Laboratories Program - National Laboratory for Tumor Biology (NLP-17). Citation Format: Laura Svajda, Ivan Ranđelović, Sára Eszter Surguta, Marcell Baranyi, István Kenessey, Mihály Cserepes, József Tóvári. Combination therapeutic strategy to fight against triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4131.

Abstract 716: Depletion of stromal cells remodels tumor microenvironment and potentiates immune checkpoint blockade in pancreatic cancer

Abstract During carcinoma progression, mesenchymal stromal cells (MSCs) become recruited to tumors and contribute to the pool of cancer-associated fibroblasts (CAFs). Sub-populations of CAFs, have diverse and incompletely understood effects on disease progression and resistance to therapy. Adipose stromal cells (ASCs), the MSCs from fat tissue increasingly recruited by carcinomas in the context of obesity, have been shown to support cancer progression. Here, the roles of perivascular CAFs expressing platelet-derived growth factor receptor beta (Pdgfrb) and of CAFs expressing non-glycanated decorin (ngDCN), a marker of ASCs, were analyzed. We used mice orthotopically grafted with pancreatic ductal adenocarcinoma (KPC) cells. Ablation of cells expressing thymidine kinase under the control of Pdgfrb promoter with ganciclovir resulted in suppression of primary pancreatic tumor growth. However, ablation Pdgfrb+ cells induced spontaneous metastases to the liver. For depletion of ngDCN+ cells, we used a hunter-killer peptide D-CAN, which has been previously reported to induce apoptosis of ASCs and CAFs in mouse models. Here, D-CAN also had a negative effect on pancreatic tumor growth, however, there was no significant effect on metastatic dissemination. Single cell RNA sequencing of tumors demonstrated that targeting of Pdgfrb+ and ngDCN+ stromal cells had distinct effects on sub-populations of CAFs. Endothelial cell and cancer cell survival was decreased by depletion of either Pdgfrb+ or ngDCN+ stroma. However, pathway analysis revealed that depletion of Pdgfrb+ and ngDCN+ stromal cells has different effects on the markers of cancer cell aggressiveness. D-CAN treatment, and to a less extent Pdgfrb+ cell ablation, suppressed macrophage M2 polarization and increased infiltration of cytotoxic T-lymphocytes. This observation, confirmed in the MyCap graft model of prostate cancer, suggested that ablation of ngDCN+ stroma should synergize with immune checkpoint inhibitors. We tested the effect of D-CAN on the efficacy of anti-PDL1 antibody in the orthotopic KPC model. Compared to D-CAN and anti-PDL1 antibody alone, combination treatment had a synergistic effect on tumor growth. Importantly, liver metastases were suppressed by the D-CAN/anti-PDL1 antibody combination, but not by individual agents. We conclude that improved approaches to target mesenchymal stroma in tumors may be effective in combination with immunotherapy. Citation Format: Joseph Rupert, Alexes Daquinag, Lingyi Cai, Yulin Dai, Zhongming Zhao, Dimitris Anastassiou, Mikhail Kolonin. Depletion of stromal cells remodels tumor microenvironment and potentiates immune checkpoint blockade in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 716.