4/15/2016
Patrick Frost is at the Department of Hematology-Oncology at the VA Hospital in Los Angeles. He has been using an H35 HypOxystation for almost 3 years, and just in March published his most recent findings on multiple myeloma cells cultured in the HypOxystation. At lower than 1% oxygen, the atmosphere inside the chamber mimics the hypoxic niche in the bone marrow microenvironment. Patrick Frost’s group investigated the effects of a polyamide capable of binding to the hypoxia response element HRE of genes such as VEGF that are up-regulated under low oxygen conditions. They found a significant cytotoxic effect of the polyamide against MM tumor cells which they traced to an inhibition of HIF-mediated gene transcription and decreased resistance to hypoxia-induced apoptosis. These results are described in “A DNA-binding Molecule Targeting the Adaptive Hypoxic Response in Multiple Myeloma Has Potent Antitumor Activity” (Mysore et al., 2016, Mol Cancer Res; 14(3); 253-66.)
The focus of our lab’s research is multiple myeloma, specifically with the aim of targeting the adaptive hypoxic response in myeloma cells. We have a number of interesting compounds, and we are studying HIF regulation to understand the mechanisms of what happens in these cells treated with the compounds. We have a polyamide, a synthetic molecule that recognizes the hypoxia response element HRE and binds to the minor groove of the DNA. We have to use relatively high concentrations of this compound but it is a good model to block the hypoxic response. In order to characterize the effect of the molecule, we used it in some reporter assays, in reporter cells, then we tested it to see whether it could overcome their resistance to hypoxia-mediated killing. There is some thought that hypoxia confers resistance to drugs, which we did not find in our particular experiments. We found that the drugs and the hypoxia actually synergize. I think there is a need to differentiate more between resistance and cell cycle arrest in this regard, as opposed to killing the cells. The HypOxystation is very good for placing the cells at hypoxic conditions, at different levels, and sampling at different time points. The time points especially are very useful with this chamber, because with other systems such as boxes, once the cells are inside and you start doing anything with them, you’ve re-set the system; it doesn’t take very long for those media to get re-oxygenated. So we can set up to do a 24 hour assay, using the interlock to get in and out, and take a sample of the growing cells every 24 hours. That really helps to get a nice time course. Once we have the cells inside the chamber, we can assay apoptosis, gene expression, protein expression, anything. The in vitro models are really very useful, we can cover a lot of ground quickly.
Read more: Targeting the adaptive hypoxic response in multiple myeloma
2/18/2015
Dr. Houda Benlhabib is in the Department of Biochemistry at UT Southwestern in Dallas, working on the role of genetic and epigenetic mechanisms in the regulation of fetal lung development as well as in reproductive and perinatal biology.
- “Estrogen-Related Receptor γ (ERRγ) Regulates Oxygen-Dependent Expression of Voltage-gated Potassium (K+) Channels and Tissue Kallikrein during Human Trophoblast Differentiation” (2013) Yanmin Luo, Premlata Kumar, and Carole R. Mendelson; Mol Endocrinol, Jun; 27(6): 940–952.
Placental development during pregnancy is accompanied by increasing tissue oxygen levels, while persisting hypoxia contributes to the pathogenesis of pre-eclampsia and IUGR. HypOxystation user Carole Mendelson describes studies examining the expression patterns of genes for potassium channels and tissue kallikrein under hypoxic (2% O2) conditions. She found a novel role for estrogen-related receptor ϒ (ERRϒ) as an oxygen-responsive transcription factor during trophoblast differentiation.
- “The c-Myc-Regulated MicroRNA-17∼92 (miR-17∼92) and miR-106a∼363 Clusters Target hCYP19A1 and hGCM1 To Inhibit Human Trophoblast Differentiation” (2013) Premlata Kumar, Yanmin Luo, Carmen Tudela, James M. Alexander, and Carole R. Mendelson; Mol Cell Biol. 2013 May; 33(9): 1782–1796.
Mendelson’s group investigated the role of miRNA’s in regulating expression of genes involved in trophoblast differentiation. Oxygen tension and vascularization play a significant role in pre-eclampsia, one of the leading causes of fetal and maternal death. C-Myc expression was elevated at hypoxia, and translation of miR-17∼92 and miR-106a∼363 clusters was found to be increased, also. Together, these factors seem to promote stemness in the proliferating cytotrophoblasts and inhibit differentiation. Interesting commonalities with tumor cells with regard to proliferation and miRNA expression are discussed in this paper.
The lab has been using an HypOxystation for about 4 years now. HypOxygen asked how the lab uses the workstation for hypoxic cell culture.
Read more: UT Southwestern explores the role of genetic and epigenetic mechanisms in the regulation of fetal...
