Abstract RB1 loss-of-function genomic alterations confer resistance to CDK4/6 inhibitors (CDK4/6i) and are enriched post treatment of CDK4/6i in estrogen receptor-positive (ER+) metastatic breast cancer. ER+/Rb-deficient breast cancer is a rising patient population in need of novel therapeutic strategies. Herein, we used a genome-wide CRISPR screen and identified protein arginine methyltransferase 5 (PRMT5) as a molecular vulnerability in this refractory breast cancer subtype. sgRNA-induced depletion of PRMT5 arrested growth of MCF-7 and T47D RB1 knockout (RBKO) cells. PRMT5 catalyzes symmetric dimethylation of arginine (SDMA). In RBKO cells carrying doxycycline-inducible shRNA targeting the 3’UTR of PRMT5, rescue with wild-type but not an enzymatically dead mutant of PRMT5 restored cell growth, supporting that PRMT5 methyltrasferase activity is essential for growth of these cells. Gene set enrichment analysis (GSEA) of RNA-seq data revealed significant downregulation of cell cycle-related Hallmark gene signatures in RBKO cells treated with PRMT5 siRNA versus control siRNA. Both gene silencing and pharmacological blockade of PRMT5 with the small molecule inhibitor pemrametostat impeded G1-to-S cell cycle progression in MCF-7 and T47D RBKO cells and in lung, prostate, and triple-negative breast cancer cells with natural RB1 mutations or deletions, suggesting that PRMT5 inhibition can block the G1-to-S transition even in the absence of Rb. To identify the protein interactome of PRMT5 and the mechanism by which it promotes cell cycle progression in Rb-deficient cells, we performed proteomics analysis of Co-IP mass spectrometry and an SDMA post-translational modification scan and pinpointed FUS (fused in sarcoma) as a putative downstream effector of PRMT5. FUS is known to regulate RNA polymerase II (Pol II)-mediated transcription. Inhibition of PRMT5 with pemrametostat significantly reduced SDMA levels on FUS and dissociated FUS from Pol II as evidenced by FUS Co-IP and immunoblot analysis. ChIP-seq analysis revealed that treatment of RBKO cells with pemrametostat derepressed phosphorylation of Ser2 in the C-terminus of Pol II at transcription start sites (TSS) of genes involved in cell cycle progression. In accordance with the abnormal accumulation of pSer2 Pol II at TSS, pemrametostat treatment also resulted in an increased Pol II pausing index and an enrichment of intron retention splicing variants. Finally, therapeutic inhibition of PRMT5 with pemrametostat synergized with fulvestrant (a selective ER degrader) against growth of ER+/Rb-deficient breast cancer cell line- and patient-derived xenografts in mice, suggesting this combination as a novel therapeutic strategy for ER+/Rb-deficient metastatic breast cancers. Citation Format: Chang-Ching Lin, Tsung-Cheng Chang, Yunguan Wang, Yanfeng Zhang, Andrew Lemoff, Yisheng V. Fang, He Zhang, Dan Ye, Isabel Soria-Bretones, Alberto Servetto, Kyung-min Lee, Xuemei Luo, Joseph J. Otto, Hiroaki Akamatsu, David W. Cescon, Lin Xu, Yang Xie, Joshua T. Mendell, Ariella B. Hanker, Carlos L. Arteaga. PRMT5 is an actionable target in CDK4/6 inhibitor-resistant ER+/Rb-deficient breast cancer. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3934.
Hypoxia induces a vast array of long noncoding RNAs (lncRNA) in breast cancer cells, but their biological functions remain largely unknown. Here, we identified a hitherto uncharacterized hypoxia-induced lncRNA RAB11B-AS1 in breast cancer cells. RAB11B-AS1 is a natural lncRNA upregulated in human breast cancer and its expression is induced by hypoxia-inducible factor 2 (HIF2), but not HIF1, in response to hypoxia. RAB11B-AS1 enhanced the expression of angiogenic factors including VEGFA and ANGPTL4 in hypoxic breast cancer cells by increasing recruitment of RNA polymerase II. In line with increased angiogenic factors, conditioned media from RAB11B-AS1-overexpressing breast cancer cells promoted tube formation of human umbilical vein endothelial cells in vitro. Gain- and loss-of-function studies revealed that RAB11B-AS1 increased breast cancer cell migration and invasion in vitro and promoted tumor angiogenesis and breast cancer distant metastasis without affecting primary tumor growth in mice. Taken together, these findings uncover a fundamental mechanism of hypoxia-induced tumor angiogenesis and breast cancer metastasis. SIGNIFICANCE: This study reveals the molecular mechanism by which the lncRNA RAB11B-AS1 regulates hypoxia-induced angiogenesis and breast cancer metastasis, and provides new insights into the functional interaction between a lncRNA and tumor microenvironment. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/5/964/F1.large.jpg.
Leaf-chewing insects are important pests that cause yield loss and reduce seed quality in soybeans (Glycine max). Breeding soybean varieties that are resistant to leaf-chewing insects can minimize the need for insecticide use and reduce yield loss. The marker gene for QTL-M, Glyma.07g110300 (LOC100775351) that encodes a UDP-glycosyltransferase (UGT) is the major determinant of resistance against leaf-chewing insects in soybean; it exhibits a loss of function in insect-resistant soybean germplasms. In this study, Agrobacterium-mediated transformation introduced the CRISPR/Cas9 expression vector into the soybean cultivar Tianlong No. 1 to generate Glyma.07g110300-gene mutants. We obtained two novel types of mutations, a 33-bp deletion and a single-bp insertion in the GmUGT coding region, which resulted in an enhanced resistance to Helicoverpa armigera and Spodoptera litura. Additionally, overexpressing GmUGT produced soybean varieties that were more sensitive to H. armigera and S. litura. Both mutant and overexpressing lines exhibited no obvious phenotypic changes. The difference in metabolites and gene expression suggested that GmUGT is involved in imparting resistance to leaf-chewing insects by altering the flavonoid content and expression patterns of genes related to flavonoid biosynthesis and defense. Furthermore, ectopic expression of the GmUGT gene in the ugt72b1 mutant of Arabidopsis substantially rescued the phenotype of H. armigera resistance in the atugt72b1 mutant. Our study presents a strategy for increasing resistance against leaf-chewing insects in soybean through CRISPR/Cas9-mediated targeted mutagenesis of the UGT genes.
Abstract Despite major advances in the treatment of estrogen receptor positive (ER+) breast cancer (BC), advanced disease continues to be the main cause of death from this disease. The role of the tumor immune microenvironment (TIME) in the progression of ER+ BC and its response to treatment is not completely understood. The aim of this study was to elucidate the role the TIME in the response of ER+ tumors to estrogen deprivation (ED). We collected samples from 215 postmenopausal patients with stage I-III ER+ BC, treated with letrozole for 2-4 weeks, to induce ED. We used AQUA on pre-treatment biopsies and on-treatment surgical biopsies to assess ER, PR, HER2, and Ki67. Then, we categorized the patients’ response to ED based on the Ki67 score in on-treatment samples: ED-sensitive (ED-S) if natural log (ln) of the Ki67 score ≤1.0 or ≤2.7% Ki67+ cells vs. ED-resistant (ED-R) if ln ≥2.0 or ≥7.4% Ki67+ cells. Firstly, we assessed TIME composition by investigating stromal tumor-infiltrating lymphocytes (sTILs) in H&E-stained FFPE of on-treatment tumor sections. ED-R tumors exhibited a significantly higher stromal TILs score (p=0.0001) relative to ED-S tumors. We next prepared tissue microarrays from 227 (on-treatment) surgical sections and subjected them to cyclic immunofluorescence (CycIF) with 38 antibodies to examine their intra-tumoral immune cell infiltration. From each tumor core, we segmented single cells and labeled them as immune, cancer, or stromal cells based on expression of a set of markers. Briefly, cells that stained strongly for CD45 (leukocyte marker), and/or CD4 (T lymphocyte marker), or CD68 (macrophage marker) were labeled immune cells. CD45/CD4/CD68-negative cells were categorized as tumor if E-cadherin and/or cytokeratin-positive, or stromal cells if -negative. Next, we assessed cell specific spatial enrichment by quantifying the expression of immune markers in the area immediately adjacent to each tumor cell. Immune-suppressive T-reg (FOXP3+) cells were enriched in the ED-S tumors (p=0.0004), as well as PD1+ (exhausted) T cells (p=0.0004), and CD68+ cells (p < 0.0001) compared to ED-R tumors. ED-R tumors exhibited higher CD20+ B cells (p < 0.0001), higher CD8+ T cells (p=0.0329), in addition to higher CD45+ cells (p < 0.0001), compared to ED-S tumors. RNA-sequencing of the same surgical samples showed a higher T cells cytolytic score in ED-R relative to ED-S (p=0.0058), suggesting enhanced CD8+ T cells activity, in addition to their higher infiltration. We are currently analyzing letrozole-induced changes in TIME composition using Geomix digital spatial profiler in paired pre- and on-treatment biopsies from ED-R and ED-S tumors and will be presented at the meeting. Consistent with the CycIF findings, GSEA of hallmark gene signatures from bulk RNA-sequencing of treated tumors revealed that immune-related gene sets, such as “IFN α response”, “IFNɣ response”, and “allograft rejection” were upregulated in ED-R vs. ED-S cancers. ED-R tumors showed enrichment of CXCL9, CXCL10, and CXCL11 chemokines and their receptor, CXCR3. Publicly available datasets of patients with ER+ breast cancers showed that higher expression CXCL9 (HR 1.36; p=0.016), CXCL10 (HR 1.71; p< 0.0001), and CXCL11 (HR 1.5; p=0.0016) are predictive of shorter relapse-free survival on antiestrogen therapy. We are currently investigating whether these chemokines play a causal role in resistance to ED, and if this is phenocopied by co-cultures of ER+ BC cells and CD8+ T-cells. Conclusions ED-resistant tumors are enriched with stromal TILs and exhibit higher immune cell intra-tumoral infiltration and CD8+T cells cytolytic activity compared to ER+ tumors sensitive to estrogen suppression. In contrast, ED-S tumors showed a more immunosuppressed milieu. The role of CXCL9, CXCL10 and CXCL11 in inducing resistance to ED warrants further investigation. Citation Format: Fabiana Napolitano, Yunguan Wang, Dhivya Sudhan, Paula Gonzalez-Ericsson, Luigi Formisano, Lei Guo, M Rosario Chica-Parrado, Chang-Ching Lin, Kyung-Min Lee, Hongli Ma, Nathaniel Evans, Alberto Servetto, Saurabh Mendiratta, Spencer Barnes, Yisheng Fang, Lin Xu, Justin Balko, Gordon Mills, Marilyne Labrie, Ariella Hanker, Carlos Arteaga. Tumor immune microenvironment modulates resistance to estrogen suppression in ER+ breast cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PS03-04.
Primary breast osteosarcoma (PBO) is a rare tumor of the breast, with only case reports and small case series published in the literature. Classic imaging findings of sunburst calcifications, a rim of intermediate density, and intense uptake on bone scintigraphy can help make the correct diagnosis preoperatively, allowing for appropriate surgical and chemotherapeutic management. We present the imaging evaluation, treatment course, and follow-up of a case of PBO diagnosed in a 67-year-old patient.
Breast carcinoma with skin ulceration (SU) is considered a locally advanced disease. The purpose of the study is to investigate if SU is an independent adverse factor. Breast carcinoma patients with SU (n=111) were included in the study. A subset (n=38, study cohort) was matched with cases that had no SU (n=38, matched cohort); the survival analyses were compared between these groups. Then, cases (n=80) were staged independent from SU into stage I, II or III. Disease free survival (DFS) and overall survival (OS) were analyzed. Patients with larger tumors tended to present with distant metastases more often than patients with smaller tumors (P=.004). In the matched cases, the 5-year DFS probability was 53% for the study cohort and 58% for the matched cohort; and for OS 75% for the study cohort and 84% for the matched cohort with no statistical significant difference. However, there was a trend towards worse DFS for the patients whose tumors had SU. When the cases were staged based on tumor size and node status (I, II or III), the OS was statistically significant (P=.047) but not the DFS (P=.195). Relatively small tumors with SU had an extent of disease similar to that observed in patients with early stages disease. The survival analysis suggests that SU may not be an adverse factor. However, more cases are needed to further examine this finding.
Aims Touch preparation (TP) and frozen section (FS) are the two methods routinely used in the intraoperative evaluation (IOE) of sentinel lymph nodes (SLNs) to detect metastases in patients with breast cancer. Both methods are extremely sensitive and specific in the primary surgery (non-neoadjuvant systemic therapy (non-NST)) setting. Since NST introduces unique challenges in the IOE of SLNs, the aim was to determine the accuracy of TP and FS in the IOE of SLNs in the NST setting and compare the results with the non-NST setting and to examine factors that contribute to any differences. Methods We analysed 871 SLNs from 232 patients (615 SLNs from NST and 256 SLNs from non-NST settings) between 2016 through 2019. Results In the NST group, TP alone (n=366) had a sensitivity of 45.7% and specificity of 99.7%; FS alone (n=90) had a sensitivity of 83.3% and specificity of 100%. When both TP and FS (n=135) were used, the sensitivity was 80.3% and the specificity was 98.6%. In the non-NST group, TP alone (n=193) had a sensitivity of 66.7% and specificity of 100%; FS alone (n=22) had a sensitivity and specificity of 100%; and combined TP and FS (n=34) had a sensitivity and specificity of 100% and 96%, respectively. Conclusions Evaluating SLNs intraoperatively in the NST setting can be challenging secondary to therapy-related changes. In the NST setting, FS has higher sensitivity and specificity compared with TP for the IOE of SLNs and should be the preferred method.
Gold nanoparticles (AuNPs) are a promising nanomaterial due to their drug-delivery properties and inherent anti-neoplastic activity. Here, we focused on the anti-neoplastic effects of an improved targeting polymer and folic acid-modified gold nanoparticles (AuNPP-FA) without therapeutic drugs. AuNPP-FA inhibited tumor proliferation both in vitro and in vivo, and tumor metastasis was controlled in vivo. We also found that, in addition to inhibiting tumor angiogenesis, AuNPP-FA normalized tumor vasculature by increasing pericyte coverage and strengthening tight junctions by upregulating VE-cadherin (VE-cad) levels on endothelial cells. This decreased vascular permeability, improved vascular perfusion, and alleviated tissue hypoxia. The immunotherapeutic response was enhanced due to the increased infiltration of CD3+CD8+ T lymphocytes. AuNPP-FA increased the expression and secretion of semaphorin 3A (SEMA3A) in cancer cells to further inhibit Smad2/3 signaling in human umbilical vein endothelial cells (HUVECs). This normalized tumor vasculature and inhibited metastasis. In conclusion, AuNPP-FA normalized tumor vasculature; therefore, AuNPP-FA has great potential for future clinical applications.
Abstract Background Connective tissue diseases (CTDs) are a heterogeneous group of disorders defined by the association of a variety of clinical manifestations with immunologic and other laboratory findings. Overlap of syndromes and aberrant findings appear rather frequently. Methods Sera of eight antinuclear antibody (ANA) negative, cases of subacute cutaneous lupus erythematosus (SCLE) with antibodies to Ro (SS‐A) and a ninth case with clinical and laboratory signs of Sjögren’s syndrome and systemic lupus erythematosus (SLE) were tested for complement (C′) fixing antinuclear antibodies (C‐ANAs). The ninth case was examined in depth by direct immunofluorescence (DIF) and a two‐step “C + DIF” test of biopsies for C′ fixation to in vivo bound ANAs, as well as serum tests for C‐ANA, ANA, and SCLE markers. Results Sera of five of the eight ANA negative, Ro(SS‐A) positive SCLE cases had C‐ANAs. The ninth case, a 50‐year‐old woman with clinical and laboratory signs of Sjögren’s syndrome and SLE, gave a strong positive C + DIF reaction in the skin biopsy for in vivo bound ANAs that fix C′, but negative ANAs and C‐ANAs in routine serum tests; they revealed antimitochondrial antibodies. Serum tests on normal skin, however, revealed weak ANA and strong C‐ANA reactions with in vitro fixed C′. Conclusions ANA negative cases of SCLE or Sjögren’s syndrome may have C‐ANAs. A case with Sjögren’s syndrome and signs of SLE had both in vivo and in vitro C′ fixing ANAs. C‐ANA tests can aid in the identification of such cases.
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