- Browse by Author
Browsing by Author "Nabinger, Sarah C."
Now showing 1 - 10 of 10
Results Per Page
Sort Options
Item Author Correction: Mutant p53 drives clonal hematopoiesis through modulating epigenetic pathway(Nature Publishing Group, 2020-07-28) Chen, Sisi; Wang, Qiang; Yu, Hao; Capitano, Maegan L.; Vemula, Sasidhar; Nabinger, Sarah C.; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Geng, Zhuangzhuang; Fahey, Aidan; Henley, Danielle; Liu, Stephen Z.; Barajas, Sergio; Cai, Wenjie; Wolf, Eric R.; Ramdas, Baskar; Cai, Zhigang; Gao, Hongyu; Luo, Na; Sun, Yang; Wong, Terrence N.; Link, Daniel C.; Liu, Yunlong; Boswell, H. Scott; Mayo, Lindsey D.; Huang, Gang; Kapur, Reuben; Yoder, Mervin C.; Broxmeyer, Hal E.; Gao, Zhonghua; Liu, Yan; Biochemistry and Molecular Biology, School of MedicineItem Mutant p53 drives clonal hematopoiesis through modulating epigenetic pathway(Nature Research, 2019-12-11) Chen, Sisi; Wang, Qiang; Yu, Hao; Capitano, Maegan L.; Vemula, Sasidhar; Nabinger, Sarah C.; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Geng, Zhuangzhuang; Fahey, Aidan; Henley, Danielle; Liu, Stephen Z.; Barajas, Sergio; Sergio, Wenjie; Wolf, Eric R.; Ramdas, Baskar; Cai, Zhigang; Gao, Hongyu; Luo, Na; Sun, Yang; Wong, Terrence N.; Link, Daniel C.; Liu, Yunlong; Boswell, H. Scott; Mayo, Lindsey D.; Huang, Gang; Kapur, Reuben; Yoder, Mervin C.; Broxmeyer, Hal E.; Gao, Zhonghua; Liu, Yan; Biochemistry and Molecular Biology, School of MedicineClonal hematopoiesis of indeterminate potential (CHIP) increases with age and is associated with increased risks of hematological malignancies. While TP53 mutations have been identified in CHIP, the molecular mechanisms by which mutant p53 promotes hematopoietic stem and progenitor cell (HSPC) expansion are largely unknown. Here we discover that mutant p53 confers a competitive advantage to HSPCs following transplantation and promotes HSPC expansion after radiation-induced stress. Mechanistically, mutant p53 interacts with EZH2 and enhances its association with the chromatin, thereby increasing the levels of H3K27me3 in genes regulating HSPC self-renewal and differentiation. Furthermore, genetic and pharmacological inhibition of EZH2 decreases the repopulating potential of p53 mutant HSPCs. Thus, we uncover an epigenetic mechanism by which mutant p53 drives clonal hematopoiesis. Our work will likely establish epigenetic regulator EZH2 as a novel therapeutic target for preventing CHIP progression and treating hematological malignancies with TP53 mutations.Item Mutant p53 enhances leukemia-initiating cell self-renewal to promote leukemia development(Nature, 2019-06) Nabinger, Sarah C.; Chen, Sisi; Gao, Rui; Yao, Chonghua; Kobayashi, Michihiro; Vemula, Sasidhar; Fahey, Aidan C.; Wang, Christine; Daniels, Cecil; Boswell, H. Scott; Sandusky, George E.; Mayo, Lindsey D.; Kapur, Reuben; Liu, Yan; Pediatrics, School of MedicineItem Necdin modulates leukemia-initiating cell quiescence and chemotherapy response(Impact Journals, 2017-09-18) Yao, Chonghua; Kobayashi, Michihiro; Chen, Sisi; Nabinger, Sarah C.; Gao, Rui; Liu, Stephen Z.; Asai, Takashi; Liu, Yan; Pediatrics, School of MedicineAcute myeloid leukemia (AML) is a devastating illness which carries a very poor prognosis, with most patients living less than 18 months. Leukemia relapse may occur because current therapies eliminate proliferating leukemia cells but fail to eradicate quiescent leukemia-initiating cells (LICs) that can reinitiate the disease after a period of latency. While we demonstrated that p53 target gene Necdin maintains hematopoietic stem cell (HSC) quiescence, its roles in LIC quiescence and response to chemotherapy are unclear. In this study, we utilized two well-established murine models of human AML induced by MLL-AF9 or AML1-ETO9a to determine the role of Necdin in leukemogenesis. We found that loss of Necdin decreased the number of functional LICs and enhanced myeloid differentiation in vivo, leading to delayed development of leukemia induced by MLL-AF9. Importantly, Necdin null LICs expressing MLL-AF9 were less quiescent than wild-type LICs. Further, loss of Necdin enhanced the response of MLL-AF9+ leukemia cells to chemotherapy treatment, manifested by decreased viability and enhanced apoptosis. We observed decreased expression of Bcl2 and increased expression of p53 and its target gene Bax in Necdin null leukemia cells following chemotherapy treatment, indicating that p53-dependent apoptotic pathways may be activated in the absence of Necdin. In addition, we found that loss of Necdin decreased the engraftment of AML1-ETO9a+ hematopoietic stem and progenitor cells in transplantation assays. However, Necdin-deficiency did not affect the response of AML1-ETO9a+ hematopoietic cells to chemotherapy treatment. Thus, Necdin regulates leukemia-initiating cell quiescence and chemotherapy response in a context-dependent manner. Our findings suggest that pharmacological inhibition of Necdin may hold potential as a novel therapy for leukemia patients with MLL translocations.Item Pathophysiological role of microRNA-29 in pancreatic cancer stroma(Office of the Vice Chancellor for Research, 2015-04-17) Kwon, Jason J.; Nabinger, Sarah C.; Alluri, Ravi K.; Vega, Zachary; Sahu, Smiti S.; Abdul-Sater, Zahi; Yu, Zhangsheng; Gore, A. Jesse; Nalepa, Grzegorz; Saxena, Romil; Korc, Murray; Kota, JanaiahBackground: Dense fibrotic stroma associated with pancreatic ductal adenocarcinoma (PDAC) has been a major obstacle for drug delivery to the tumor bed and may impede attempts to slow down PDAC progression and metastasis. However, current antistromal drugs have not improved tumor response to chemotherapy or patient survival. Thus, a better understanding of the molecular mechanisms associated with tumorstromal interactions is desperately needed to develop novel anti-stromal therapeutic approaches. MicroRNAs (miRNAs) are an abundant class of highly conserved, small non-coding RNAs that function as key regulators of eukaryotic gene expression and cellular homeostasis. miR-29 is known to play a paramount role in the fibrotic process of several organs by providing crucial functions downstream of pro-fibrotic signaling pathways such as TGF-β1 and regulates the expression of extracellular matrix (ECM) proteins, a major component in the PDAC stroma. Upregulation of TGF-β1 is associated with PDAC pathogenesis and is known to activate stromal cells. Furthermore, vascular endothelial growth factor (VEGF) that stimulates tumor angiogenesis is a predicted target of miR-29. We hypothesize that miR-29 may be misregulated in TGF-β1 activated PDAC stromal cells and lead to excessive accumulation of ECM proteins and VEGF. Kwon et al. 2015 Annual AACR Meeting Restored expression of miR-29 could be therapeutically beneficial to modulate tumorstromal interactions. Methods: Northern blot or qPCR techniques were used to assess miR-29 levels in vitro stromal cells, murine PDAC model, and PDAC patient biopsies, and stromal deposition/fibrosis was determined by Sirius red staining. In murine and human PDAC samples, stromal specific miR-29 expression was determined via in situ hybridization by co-staining pancreatic tissues with glial fibrillary acidic protein a marker for stromal cells and miR-29. miR-29 functional studies were conducted by transfection of stroma cells with synthetic miR-29 mimics and locked nucleic acid, a miR-29 inhibitor, and ECM protein/VEGF expression was analyzed by western blot analysis. The effect of miR-29 overexpression in stromal cells on cancer colony growth was evaluated by direct coculture of stromal cells ectopically expressing miR-29 with pancreatic cancer cells, and subsequently, cancer colony number and stromal accumulation was determined by crystal violet and sirius red stains respectively. Results: In both in vitro and in vivo models as well as PDAC patient biopsies, we observed loss of miR-29 is a common phenomenon of activated stromal cells, and is associated with a significant increase in ECM and VEGF accumulation. Restored expression of miR-29 in stromal cells reduced the deposition of matrix proteins, VEGF expression, and cancer colony formation in direct co-culture. Conclusion: These results provide insight into the mechanistic role of miR-29 in PDAC stroma and its potential use as an anti-stromal/angiogenic therapeutic agent.Item Pathophysiological role of microRNA-29 in pancreatic cancer stroma(Nature Publishing Group, 2015-06-22) Kwon, Jason J.; Nabinger, Sarah C.; Vega, Zachary; Snigdha Sahu, Smiti; Alluri, Ravi K.; Abdul-Sater, Zahi; Yu, Zhangsheng; Gore, Jesse; Nalepa, Grzegorz; Saxena, Romil; Korc, Murray; Kota, Janaiah; Department of Medical & Molecular Genetics, IU School of MedicineDense fibrotic stroma associated with pancreatic ductal adenocarcinoma (PDAC) is a major obstacle for drug delivery to the tumor bed and plays a crucial role in pancreatic cancer progression. Current, anti-stromal therapies have failed to improve tumor response to chemotherapy and patient survival. Furthermore, recent studies show that stroma impedes tumor progression, and its complete ablation accelerates PDAC progression. In an effort to understand the molecular mechanisms associated with tumor-stromal interactions, using in vitro and in vivo models and PDAC patient biopsies, we show that the loss of miR-29 is a common phenomenon of activated pancreatic stellate cells (PSCs)/fibroblasts, the major stromal cells responsible for fibrotic stromal reaction. Loss of miR-29 is correlated with a significant increase in extracellular matrix (ECM) deposition, a major component in PDAC stroma. Our in vitro miR-29 gain/loss-of-function studies document the role of miR-29 in PSC-mediated ECM stromal protein accumulation. Overexpression of miR-29 in activated stellate cells reduced stromal deposition, cancer cell viability, and cancer growth in co-culture. Furthermore, the loss of miR-29 in TGF-β1 activated PSCs is SMAD3 dependent. These results provide insights into the mechanistic role of miR-29 in PDAC stroma and its potential use as a therapeutic agent to target PDAC.Item Protein-tyrosine Phosphatase Shp2 Positively Regulates Macrophage Oxidative Burst(2015-02) Li, Xing Jun; Goodwin, Charles B.; Nabinger, Sarah C.; Richine, Briana M.; Yang, Zhenyun; Hanenberg, Helmut; Ohnishi, Hiroshi; Matozaki, Takashi; Feng, Gen-Sheng; Chan, Rebecca J.; Department of Pediatrics, Indiana University School of MedicineMacrophages are vital to innate immunity and express pattern recognition receptors and integrins for the rapid detection of invading pathogens. Stimulation of Dectin-1 and complement receptor 3 (CR3) activates Erk- and Akt-dependent production of reactive oxygen species (ROS). Shp2, a protein-tyrosine phosphatase encoded by Ptpn11, promotes activation of Ras-Erk and PI3K-Akt and is crucial for hematopoietic cell function; however, no studies have examined Shp2 function in particulate-stimulated ROS production. Maximal Dectin-1-stimulated ROS production corresponded kinetically to maximal Shp2 and Erk phosphorylation. Bone marrow-derived macrophages (BMMs) from mice with a conditionally deleted allele of Ptpn11 (Shp2flox/flox;Mx1Cre+) produced significantly lower ROS levels compared with control BMMs. Although YFP-tagged phosphatase dead Shp2-C463A was strongly recruited to the early phagosome, its expression inhibited Dectin-1- and CR3-stimulated phospho-Erk and ROS levels, placing Shp2 phosphatase function and Erk activation upstream of ROS production. Further, BMMs expressing gain of function Shp2-D61Y or Shp2-E76K and peritoneal exudate macrophages from Shp2D61Y/+;Mx1Cre+ mice produced significantly elevated levels of Dectin-1- and CR3-stimulated ROS, which was reduced by pharmacologic inhibition of Erk. SIRPα (signal regulatory protein α) is a myeloid inhibitory immunoreceptor that requires tyrosine phosphorylation to exert its inhibitory effect. YFP-Shp2C463A-expressing cells have elevated phospho-SIRPα levels and an increased Shp2-SIRPα interaction compared with YFP-WT Shp2-expressing cells. Collectively, these findings indicate that Shp2 phosphatase function positively regulates Dectin-1- and CR3-stimulated ROS production in macrophages by dephosphorylating and thus mitigating the inhibitory function of SIRPα and by promoting Erk activation.Item The Role and Therapeutic Potential of miRNAs in Colorectal Liver Metastasis(Office of the Vice Chancellor for Research, 2015-04-17) Bansal, Ruchi; Sahu, Smiti Snigdha; Nabinger, Sarah C.; Guanglong, Jiang; Bates, Alison; Lee, Sangbin; Hiromi, Tanaka; Liu, Yunlong; Kota, JanaiahColorectal cancer (CRC) is the third most common malignancy worldwide. Liver metastasis occurs in 60% of CRC patients and responds poorly to the available treatments making it the major cause of their mortality. MicroRNAs (miRNAs) are highly conserved, endogenously encoded small, non-coding RNA molecules that regulate global gene expression. The role of microRNAs in cancer pathogenesis, including CRC, has been well documented. However, in-depth miRNA expression analysis on a large cohort of CRC tumors is needed to identify the clinically relevant miRNAs and explore their potential to target liver metastases. To this purpose, we analyzed miRNA expression data of 406 CRC tumors from the publicly available colorectal cancer genome sequencing project and identified 58 miRNAs that were significantly downregulated. 10 miRNAs were selected for further analyses that were either known to target genes in cellular pathways or located within the commonly lost chromosomal loci associated with CRC liver metastases. Of these 10 miRNAs, miR-132, miR-378f, miR-605 and miR-1976 showed significant downregulation with >2 fold change (p>0.05) in primary and CRC liver metastasis tissues and in CRC cell lines. To investigate their anti-tumorigenic and metastatic properties, we transfected 3 different CRC cell lines (SW620, HCT-116 and CT-26) with miR-mimics and subjected them to cell proliferation, apoptosis and cell transformation assays. Ectopic expression of miR-378f, -605 and -1976 suppressed CRC cell proliferation, anchorage independent growth, migration and invasion and induced apoptosis. Interestingly, CRC patients with high miR-378f and miR-1976 had better survival compared to low expressing patients (p<0.044). Our in vitro data suggest the anti-tumorigenic/metastatic properties of miR-378f, -605 and -1976 in CRC. Further understanding of their functions and in vivo therapeutic evaluations may help in developing novel therapeutic strategies for this malignancy.Item The Role and Therapeutic Potential of miRNAs in Colorectal Liver Metastasis(Springer Nature, 2019-11) Sahu, Smiti S.; Dey, Shatovisha; Nabinger, Sarah C.; Jiang, Guanglong; Bates, Alison; Tanaka, Hiromi; Liu, Yunlong; Kota, Janaiah; Medical and Molecular Genetics, School of MedicineColorectal cancer (CRC) is the fourth leading cause of cancer-related deaths worldwide. Liver metastasis is the major cause of CRC patient mortality, occurring in 60% patients with no effective therapies. Although studies have indicated the role of miRNAs in CRC, an in-depth miRNA expression analysis is essential to identify clinically relevant miRNAs and understand their potential in targeting liver metastasis. Here we analyzed miRNA expressions in 405 patient tumors from publicly available colorectal cancer genome sequencing project database. Our analyses showed miR-132, miR-378f, miR-605 and miR-1976 to be the most significantly downregulated miRNAs in primary and CRC liver metastatic tissues, and CRC cell lines. Observations in CRC cell lines indicated that ectopic expressions of miR-378f, -605 and -1976 suppress CRC cell proliferation, anchorage independent growth, metastatic potential, and enhance apoptosis. Consistently, CRC patients with higher miR-378f and miR-1976 levels exhibited better survival. Together, our data suggests an anti-tumorigenic role of these miRNAs in CRC and warrant future in vivo evaluation of the molecules for developing biomarkers or novel therapeutic strategies.Item Shp2 function in hematopoietic stem cell biology and leukemogenesis(Ovid Technologies (Wolters Kluwer) - Lippincott Williams & Wilkins, 2012-07) Nabinger, Sarah C.; Chan, Rebecca J.; Department of Pediatrics, IU School of MedicinePURPOSE OF REVIEW: The protein tyrosine phosphatase Shp2 is encoded by PTPN11 and positively regulates physiologic hematopoiesis. Mutations of PTPN11 cause the congenital disorder Noonan syndrome and pathologically promote human leukemias. Given the high frequency of PTPN11 mutations in human disease, several animal models have been generated to investigate Shp2 in hematopoietic stem cell (HSC) function and leukemic transformation. RECENT FINDINGS: Two independent animal models bearing knockout of Shp2 in hematopoietic tissues clearly demonstrate the necessity of Shp2 in HSC repopulating capacity. Reduced HSC quiescence and increased apoptosis accounts for diminished HSC function in the absence of Shp2. The germline mutation Shp2D61G enhances HSC activity and induces myeloproliferative disease (MPD) in vivo by HSC transformation. The somatic mutation Shp2D61Y produces MPD in vivo but fails to induce acute leukemia, whereas somatic Shp2E76K produces MPD in vivo that transforms into full-blown leukemia. HSCs expressing Shp2D61Y do not generate MPD in recipient animals upon transplantation, whereas Shp2E76K-expressing HSCs yield MPD as well as acute leukemia in recipient animals. The mechanisms underlying the unique functions of Shp2D61Y and Shp2E76K in HSC transformation and leukemogenesis continue to be under investigation. SUMMARY: Further understanding of the physiologic and pathologic role of Shp2 in hematopoiesis and leukemogenesis, respectively, will yield information needed to develop therapeutic strategies targeted to Shp2 in human disease.