The human immune system plays a vital role in the combat against neoplastic cell development. Cancer cells can thrive and metastasise when the defence system fails to do its job. Scientists found a connection between the expression of fragile X mental retardation protein (FMRP) and cancer cell development. It was discovered that cancer cells with elevated FMRP expression tend to have a low number of cytotoxic T cells due to the production of IL-33, PROS1 ligands and M2 macrophages that inhibit the activities of T cells. To investigate the opposite effect, investigators remove the FMR1 gene through CRISPR-Cas9 in mice, thus knocking out the FMRP. Subsequently, the immunosuppressive effect of tumours was reduced, while the secretion of a T cell attracting factor, C-C motif chemokine ligand 7 (CCL7), was activated. However, FMRP does not serve as a prognostic biomarker, as the correlation between FMRP expression and survival rate was not established in the study, while that between depletion of CD8/ CD4 T cells and survival rate was. With further investigation, the discoveries from this study are hoped to provide diagnostic and therapeutic benefits to cancer patients in the future.

Reference:

Zeng Q, et al. Science. 2022 Nov 18;378(6621):eabl7207.