An Ni Zhang

All Publications

• Effects of hyperinsulinemia on pancreatic cancer development and the immune microenvironment revealed through single-cell transcriptomics. Cancer & metabolism Zhang, A. M., Chu, K. H., Daly, B. F., Ruiter, T., Dou, Y., Yang, J. C., de Winter, T. J., Chhuor, J., Wang, S., Flibotte, S., Zhao, Y. B., Hu, X., Li, H., Rideout, E. J., Schaeffer, D. F., Johnson, J. D., Kopp, J. L. 2022; 10 (1): 5

  Abstract

  Hyperinsulinemia is independently associated with increased risk and mortality of pancreatic cancer. We recently reported that genetically reduced insulin production resulted in ~ 50% suppression of pancreatic intraepithelial neoplasia (PanIN) precancerous lesions in mice. However, only female mice remained normoglycemic, and only the gene dosage of the rodent-specific Ins1 alleles was tested in our previous model. Moreover, we did not delve into the molecular and cellular mechanisms associated with modulating hyperinsulinemia.We studied how reduced Ins2 gene dosage affects PanIN lesion development in both male and female Ptf1aCreER;KrasLSL-G12D mice lacking the rodent-specific Ins1 gene (Ins1-/-). We generated control mice having two alleles of the wild-type Ins2 gene (Ptf1aCreER;KrasLSL-G12D;Ins1-/-;Ins2+/+) and experimental mice having one allele of Ins2 gene (Ptf1aCreER;KrasLSL-G12D;Ins1-/-;Ins2+/-). We then performed thorough histopathological analyses and single-cell transcriptomics for both genotypes and sexes.High-fat diet-induced hyperinsulinemia was transiently or modestly reduced in female and male mice, respectively, with only one allele of Ins2. This occurred without dramatically affecting glucose tolerance. Genetic reduction of insulin production resulted in mice with a tendency for less PanIN and acinar-to-ductal metaplasia (ADM) lesions. Using single-cell transcriptomics, we found hyperinsulinemia affected multiple cell types in the pancreas, with the most statistically significant effects on local immune cell types that were highly represented in our sampled cell population. Specifically, hyperinsulinemia modulated pathways associated with protein translation, MAPK-ERK signaling, and PI3K-AKT signaling, which were changed in epithelial cells and subsets of immune cells.These data suggest a potential role for the immune microenvironment in hyperinsulinemia-driven PanIN development. Together with our previous work, we propose that mild suppression of insulin levels may be useful in preventing pancreatic cancer by acting on multiple cell types.

  View details for DOI 10.1186/s40170-022-00282-z

  View details for PubMedID 35189981

  View details for PubMedCentralID PMC8862319

• Breast Cancer Endocrine Therapy Promotes Weight Gain With Distinct Adipose Tissue Effects in Lean and Obese Female Mice. Endocrinology Scalzo, R. L., Foright, R. M., Hull, S. E., Knaub, L. A., Johnson-Murguia, S., Kinanee, F., Kaplan, J., Houck, J. A., Johnson, G., Sharp, R. R., Gillen, A. E., Jones, K. L., Zhang, A. M., Johnson, J. D., MacLean, P. S., Reusch, J. E., Wright-Hobart, S., Wellberg, E. A. 2021; 162 (11)

  Abstract

  Breast cancer survivors treated with tamoxifen and aromatase inhibitors report weight gain and have an elevated risk of type 2 diabetes, especially if they have obesity. These patient experiences are inconsistent with, preclinical studies using high doses of tamoxifen which reported acute weight loss. We investigated the impact of breast cancer endocrine therapies in a preclinical model of obesity and in a small group of breast adipose tissue samples from women taking tamoxifen to understand the clinical findings. Mature female mice were housed at thermoneutrality and fed either a low-fat/low-sucrose (LFLS) or a high-fat/high-sucrose (HFHS) diet. Consistent with the high expression of Esr1 observed in mesenchymal stem cells from adipose tissue, endocrine therapy was associated with adipose accumulation and more preadipocytes compared with estrogen-treated control mice but resulted in fewer adipocyte progenitors only in the context of HFHS. Analysis of subcutaneous adipose stromal cells revealed diet- and treatment-dependent effects of endocrine therapies on various cell types and genes, illustrating the complexity of adipose tissue estrogen receptor signaling. Breast cancer therapies supported adipocyte hypertrophy and associated with hepatic steatosis, hyperinsulinemia, and glucose intolerance, particularly in obese females. Current tamoxifen use associated with larger breast adipocyte diameter only in women with obesity. Our translational studies suggest that endocrine therapies may disrupt adipocyte progenitors and support adipocyte hypertrophy, potentially leading to ectopic lipid deposition that may be linked to a greater type 2 diabetes risk. Monitoring glucose tolerance and potential interventions that target insulin action should be considered for some women receiving life-saving endocrine therapies for breast cancer.

  View details for DOI 10.1210/endocr/bqab174

  View details for PubMedID 34410380

  View details for PubMedCentralID PMC8455348

• Hyperinsulinemia in Obesity, Inflammation, and Cancer. Diabetes & metabolism journal Zhang, A. M., Wellberg, E. A., Kopp, J. L., Johnson, J. D. 2021; 45 (3): 285-311

  Abstract

  The relative insufficiency of insulin secretion and/or insulin action causes diabetes. However, obesity and type 2 diabetes mellitus can be associated with an absolute increase in circulating insulin, a state known as hyperinsulinemia. Studies are beginning to elucidate the cause-effect relationships between hyperinsulinemia and numerous consequences of metabolic dysfunctions. Here, we review recent evidence demonstrating that hyperinsulinemia may play a role in inflammation, aging and development of cancers. In this review, we will focus on the consequences and mechanisms of excess insulin production and action, placing recent findings that have challenged dogma in the context of the existing body of literature. Where relevant, we elaborate on the role of specific signal transduction components in the actions of insulin and consequences of chronic hyperinsulinemia. By discussing the involvement of hyperinsulinemia in various metabolic and other chronic diseases, we may identify more effective therapeutics or lifestyle interventions for preventing or treating obesity, diabetes and cancer. We also seek to identify pertinent questions that are ripe for future investigation.

  View details for DOI 10.4093/dmj.2020.0250

  View details for PubMedID 33775061

  View details for PubMedCentralID PMC8164941

• PRDM3 attenuates pancreatitis and pancreatic tumorigenesis by regulating inflammatory response. Cell death & disease Ye, J., Huang, A., Wang, H., Zhang, A. M., Huang, X., Lan, Q., Sato, T., Goyama, S., Kurokawa, M., Deng, C., Sander, M., Schaeffer, D. F., Li, W., Kopp, J. L., Xie, R. 2020; 11 (3): 187

  Abstract

  Pancreatic ductal adenocarcinoma (PDAC) is associated with metaplastic changes in the pancreas but the transcriptional program underlying these changes is incompletely understood. The zinc finger transcription factor, PRDM3, is lowly expressed in normal pancreatic acini and its expression increases during tumorigenesis. Although PRDM3 promotes proliferation and migration of PDAC cell lines, the role of PRDM3 during tumor initiation from pancreatic acinar cells in vivo is unclear. In this study, we showed that high levels of PRDM3 expression in human pancreas was associated with pancreatitis, and well-differentiated but not poorly differentiated carcinoma. We examined PRDM3 function in pancreatic acinar cells during tumor formation and pancreatitis by inactivating Prdm3 using a conditional allele (Ptf1aCreER;Prdm3flox/flox mice) in the context of oncogenic Kras expression and supraphysiological cerulein injections, respectively. In Prdm3-deficient mice, KrasG12D-driven preneoplastic lesions were more abundant and progressed to high-grade precancerous lesions more rapidly. This is consistent with our observations that low levels of PRDM3 in human PDAC was correlated significantly with poorer survival in patient. Moreover, loss of Prdm3 in acinar cells elevated exocrine injury, enhanced immune cell activation and infiltration, and greatly increased acinar-to-ductal cell reprogramming upon cerulein-induced pancreatitis. Whole transcriptome analyses of Prdm3 knockout acini revealed that pathways involved in inflammatory response and Hif-1 signaling were significantly upregulated in Prdm3-depleted acinar cells. Taken together, our results suggest that Prdm3 favors the maintenance of acinar cell homeostasis through modulation of their response to inflammation and oncogenic Kras activation, and thus plays a previously unexpected suppressive role during PDAC initiation.

  View details for DOI 10.1038/s41419-020-2371-x

  View details for PubMedID 32179733

  View details for PubMedCentralID PMC7075911

• Endogenous Hyperinsulinemia Contributes to Pancreatic Cancer Development. Cell metabolism Zhang, A. M., Magrill, J., de Winter, T. J., Hu, X., Skovsø, S., Schaeffer, D. F., Kopp, J. L., Johnson, J. D. 2019; 30 (3): 403-404

  View details for DOI 10.1016/j.cmet.2019.07.003

  View details for PubMedID 31378465

• Selective defects in gene expression control genome instability in yeast splicing mutants. Molecular biology of the cell Tam, A. S., Sihota, T. S., Milbury, K. L., Zhang, A., Mathew, V., Stirling, P. C. 2019; 30 (2): 191-200

  Abstract

  RNA processing mutants have been broadly implicated in genome stability, but mechanistic links are often unclear. Two predominant models have emerged: one involving changes in gene expression that perturb other genome maintenance factors and another in which genotoxic DNA:RNA hybrids, called R-loops, impair DNA replication. Here we characterize genome instability phenotypes in yeast splicing factor mutants and find that mitotic defects, and in some cases R-loop accumulation, are causes of genome instability. In both cases, alterations in gene expression, rather than direct cis effects, are likely to contribute to instability. Genome instability in splicing mutants is exacerbated by loss of the spindle-assembly checkpoint protein Mad1. Moreover, removal of the intron from the α-tubulin gene TUB1 restores genome integrity. Thus, differing penetrance and selective effects on the transcriptome can lead to a range of phenotypes in conditional mutants of the spliceosome, including multiple routes to genome instability.

  View details for DOI 10.1091/mbc.E18-07-0439

  View details for PubMedID 30462576

  View details for PubMedCentralID PMC6589566

• CX-5461 is a DNA G-quadruplex stabilizer with selective lethality in BRCA1/2 deficient tumours. Nature communications Xu, H., Di Antonio, M., McKinney, S., Mathew, V., Ho, B., O'Neil, N. J., Santos, N. D., Silvester, J., Wei, V., Garcia, J., Kabeer, F., Lai, D., Soriano, P., Banáth, J., Chiu, D. S., Yap, D., Le, D. D., Ye, F. B., Zhang, A., Thu, K., Soong, J., Lin, S. C., Tsai, A. H., Osako, T., Algara, T., Saunders, D. N., Wong, J., Xian, J., Bally, M. B., Brenton, J. D., Brown, G. W., Shah, S. P., Cescon, D., Mak, T. W., Caldas, C., Stirling, P. C., Hieter, P., Balasubramanian, S., Aparicio, S. 2017; 8: 14432

  Abstract

  G-quadruplex DNAs form four-stranded helical structures and are proposed to play key roles in different cellular processes. Targeting G-quadruplex DNAs for cancer treatment is a very promising prospect. Here, we show that CX-5461 is a G-quadruplex stabilizer, with specific toxicity against BRCA deficiencies in cancer cells and polyclonal patient-derived xenograft models, including tumours resistant to PARP inhibition. Exposure to CX-5461, and its related drug CX-3543, blocks replication forks and induces ssDNA gaps or breaks. The BRCA and NHEJ pathways are required for the repair of CX-5461 and CX-3543-induced DNA damage and failure to do so leads to lethality. These data strengthen the concept of G4 targeting as a therapeutic approach, specifically for targeting HR and NHEJ deficient cancers and other tumours deficient for DNA damage repair. CX-5461 is now in advanced phase I clinical trial for patients with BRCA1/2 deficient tumours (Canadian trial, NCT02719977, opened May 2016).

  View details for DOI 10.1038/ncomms14432

  View details for PubMedID 28211448

  View details for PubMedCentralID PMC5321743