ID #867 Targeting lactate production pathways as a novel therapy against DIPG

Abstract

Lactate overproduction in cancer is associated with aggressive tumour cell phenotype and treatment-resistance. Furthermore, it causes direct post-translational modifications (lactylation of lysines), altering activity of proteins and epigenetic patterns. Recent investigations into diffuse intrinsic pontine glioma (DIPG) have demonstrated that lactic acid was three times higher in the H3K27M mutated DIPG cell line compared to wild-type line, it remains unreported if lactylation signalling is induced in the DIPG context and if targeting lactylation signalling could be exploited against the disease.

We found that expression of KAT2A, LDHA and other transcripts in a custom lactylation gene signature was significantly higher in DIPG patient tumours (n = 27), compared to brainstem low-grade gliomas (n = 6, p = 5.84e-04, R2 Paugh data set GSE19578). Both intracellular lactic acid and total lactylation (by western blot) were higher in two different H3K27M DIPG cell lines compared to their isogenic wild-type line. Despite this, expanded comparisons utilizing several patient-derived DIPG lines comparing H3K27M and wild-type lines did not hold this trend, indicating that high lactylation abundance is widespread and impacted by elusive factors. Supplementation with lactate and or serum also increased total lactylation. Interestingly, supplementing standard DIPG growth media with normal physiological lactate levels led to some DIPG cell lines having increased proliferation. Conversely inhibition of lactate production with oxamate significantly reduced DIPG (and other high-grade glioma) adherent cell confluence and spheroid growth. Ongoing studies are analysing the proteomic and transcriptional impact of inducing or inhibiting lactylation signalling, in vitro, as well as evaluating the efficacy of oxamate, a blood-brain barrier penetrant agent in a DIPG orthotopic model.

In summary, oxamate and lactate treatments can be used to manipulate lactylation abundance and growth of DIPG cells. The Lactate-lactylation pathway presents as a novel strategy to target DIPG and potentially other paediatric high-grade gliomas, beyond those harbouring H3K27M mutations.