UC San Diego

Epigenetic regulation has recently been at the forefront of cancer therapeutic research. Multiple therapies that target histone modification factors such as histone lysine deacetylases and histone lysine methyltransferases have entered the market with considerable success. Histone lysine demethylases is a third class of histone modification factors that have yet to make significant stride in the market, but still show considerable promise for treating various cancer types, including leukemia, colon cancer, and breast cancer. Thus, it is of interest that ZFP36L2, an mRNA decay activator, has previously been shown to regulate multiple histone lysine demethylases, including KDM4B, KDM4C, and KDM5B. In addition, mutations in the ZFP36L2 gene has been associated with many cancer types, including acute myeloid leukemia and colorectal cancer. Expanding upon these findings, my study herein aims to investigate the relationship between ZFP36L2 and histone lysine demethylases in malignant cells through both experimental and computational analysis. Towards these goals, I generated HeLa cells with stably repressed ZFP36L2 expression using the CRISPR-Cas9 technique. These ZFP36L2- knockdown cells were used to assess changes in the expression levels of histone lysine demethylases and changes in a major cancer hallmark - cell proliferation. My experiments suggested that these ZFP36L2-knockdown cells had decreased cell proliferation, implying that ZFP36L2 is a negative regulator of cell proliferation. This does not appear to be due ZFP36L2’s previously reported ability to destabilize ARE-containing histone lysine demethylases mRNAs, as my ZFP36L2-knockdown cells had downregulated (rather than upregulated) expression of histone lysine demethylases mRNAs. To assess the effect of ZFP36L2 loss in a different type of cancer, I analyzed a previously a published RNA-seq dataset of ZFP36L2-knockout acute myeloid leukemia (AML) cells using a published algorithm to infer mRNA stability. Specifically, I asked if the loss of ZFP36L2 results in an increase of stability in the transcripts of histone lysine demethylases, as this would be consistent with a conserved mechanistic relationship between ZFP36L2 and histone lysine demethylases expression. I identified a small subset of mRNAs that are either significantly stabilized or destabilized. However, no KDM mRNAs were identified. Additional studies will be needed to validate my findings and further investigate the relationship between ZFP36L2 and regulation of KDM expression in cancer.