Abstract
Disclosure: R. Fang: None. Background and Objective: Kisspeptin (Kiss1) neurons play a crucial role in regulating puberty and reproductive function in both males and females. Stress, hormones, under and over nutrition, and others, are thought to influence Kiss1 neuron function and reproduction, yet the specific signaling pathways, transcription factors, and epigenetic modulators remain largely unknown. In the absence of proper cell models, there is a lack of effective methods for identifying novel Kiss1 regulators, posing a significant challenge to the field. Though Kiss1 expression is highly restricted in the brain, a subset of glioblastomas (GBM) express Kiss1. Malignant transformation and mutation selections provide a unique opportunity to examine the evolution of Kiss1 transcription activation. We hypothesize that uncovering the mechanisms underlying Kiss1 activation in glioblastoma may provide insights into its activation during puberty. Methods: 172 GBM in TCGA were categorized into 4 groups based on Kiss1 gene expression: high, medium, low, and very low expression. Differentially expressed genes (DEGs) in pair-wise comparisons were identified using EdgeR. ChEA (ChIP Enrichment Analysis) was used to identify transcription factors that enriched at DEGs and are potential regulators of Kiss1 gene expression. Results: The pseudo evolution tree built upon DEG similarities indicated that Kiss1 activation in GBM followed sequential steps, evolving from very low expression (TPM 0.2-0.6) to low expression (TPM 0.6-1), and subsequently diverging along different paths to intermedium (TPM 1.6-6) and high expression (TPM >20). GBM is primarily originated from astrocytes. However, DEGs in the Kiss1 high group were enriched in the Neuroactive ligand-receptor interaction pathway and GABAgenic synapse pathways, indicating similarity to Kiss1 neurons (50% of ARC Kiss1 neurons and 75% of AVPV Kiss1 neurons are GABAgenic). ChEA analysis identified known Kiss1 regulators, including ESR1 (encoding ERa), NR3C1 (encoding GR), as well as RING1B and RNF2, which are components of the Polycomb Repressive Complex 1 (PRC1). Among the most notable novel candidates were EZH2, EED2, SUZ12 and JARID2, the core components of PRC2. Supporting their role in prepubertal Kiss1 suppression in vivo, we observed downregulation of these genes in the ARC in diestrus adult females compared to day 21 mice. Moreover, EZH2 inhibitor potently reactivated Kiss1 gene expression in the immortalized Kiss1 neuron cell line KaVR, in which Kiss1 expression was turned off after passage. Reactivated Kiss1 was downregulate by E2, indicating a preserved negative feedback loop. Conclusion: Our study identifies PRC2 as a novel Kiss1 regulator that may play an important role in pubertal development. Our discovery also opens new avenues for developing ex vivo Kiss1 neuron models with stable Kiss1 expression and provides a valuable tool for future research. Presentation: Saturday, July 12, 2025