Subcellular partitioning of Kaiso (ZBTB33) as a biomarker to predict overall breast cancer survival.

Abstract

3534 Background: The epigenetic transcriptional regulator, Kaiso (ZBTB33) has been identified as a member of the C2H2 zinc finger proteins containing a BTB/POZ -zinc finger family of transcription factors that are implicated in development of cancer. Although, our understanding of clinical relevance of subcellular distribution (cytoplasmic/nuclear) Kaiso in the growth and survival of human Breast cancer (BC) is limited. Methods: We examined a cohort of 555 BC patients who underwent surgery for their primary BC in Greenville, NC using AI and SM approach. Results: The sub-classification BC shows, cytoplasmic Kaiso is differentially enriched in ER- BC (p=0.001) compared nuclear Kaiso (p=0.8) and is significantly enriched in the more aggressive classes LumB (p=0.0017), HER2+ (p=0.05) and TNBC (p=6.1e-07) with respect to LumA BC patients. Additionally, the survival analysis of different compartments of Kaiso demonstrates that high cytoplasmic Kaiso (HR = 16.29 (7.6 – 34.8), p = 5.5e−13) is much more predictive of poor survival compared to nuclear Kaiso (HR = 2.83 (2.02 – 3.8), p = 6.1e−11). At gene expression level, ZBTB33 mRNA levels do not correlate with either nuclear (Spearman correlation: -0.03157, p= 0.7267) or cytoplasmic levels (Spearman correlation: -0.03526, p= 0.6962) of Kaiso. Surprisingly, ZBTB33 mRNA abundance is predictive of poor overall BC survival as demonstrated in two independent publicly available BC cohorts Metabric (HR = 2.14 (1.49 − 3.08), p = 2.7e−05) and Gyorffy B et al. (HR = 1.81 (1.55 − 2.12), p = 2.5e−14). Nuclear and cytoplasmic levels of Kaiso do not show significant differences based on race p=0.27 and p=0.1 respectively. Conclusions: Our data suggest subcellular distribution of high Kaiso is associated with poor prognosis of BC survival and subcellular localizations of Kaiso may play differential biological roles in BC prognosis.