Neuroblastoma (NB) is a common childhood cancer that accounts for approximately 40% of cancer diagnoses in infants under one year of age. Despite its prevalence, the exact origin of NB remains incompletely understood, however, it is believed to arise from the aberrant differentiation of neural crest (NC) cells, a multipotent, stem-cell-like population which migrate and give rise to various cell types during development. To do so, NCCs respond to precise developmental cues, navigate specific developmental trajectories and ultimately commit to defined cell fates. This process is tightly regulated by transcription factors (TFs), with microRNAs (miRNAs) acting as essential post-transcriptional regulators that modulate TF expression. In turn, TFs often control the transcription of miRNAs, creating intricate feedback loops that fine-tune gene expression programs essential for cellular development and differentiation.
In NB, however, this regulatory balance is disrupted, with aberrant miRNA expression likely leading to the loss of normal TF mediated control over NCC maturation. Using extensive single cell RNA sequencing data from an in vitro differentiation model, our lab has identified a critical developmental "bottleneck" in the differentiation of NCCs to mature sympathetic neurons. We have pinpointed a series of candidate TFs and miRNAs that are dynamically regulated across this stage, including HMGA1, a chromatin-associated architectural TF.
To test HMGA1 function, we performed gain- and loss-of-function experiments across two complementary systems. In BE(2)-C NB cells, stable HMGA1 overexpression impairs ATRA-induced differentiation, while CRISPR-mediated HMGA1 knockout leads to morphological and transcriptional features suggestive of partial differentiation. Additionally, we used an optimised iPSC-to-sympathetic neuron differentiation protocol (developed in our lab) and generated stable, inducible HMGA1-expressing iPSCs, allowing temporal control over HMGA1 activation. Early results show that HMGA1 induction at critical differentiation windows disrupts neuronal maturation, indicating a context-specific block in fate commitment.
We are currently optimising ChIP and ATAC seq protocols in both BE(2)-C and iPSC-derived sympathetic lineage cells to identify HMGA1-bound genomic targets and define its role in maintaining an undifferentiated cellular state.
Overall, this work seeks to combine cancer biology and stem cell approaches to show that HMGA1 may function as a molecular barrier to sympathetic neuronal differentiation and assess its potential as a biomarker or therapeutic agent in NB.