Oral Presentation AUS-oMicS 2025

Surface proteomic analysis reveals the present of non-canonical cell membrane ER chaperone proteins in high-grade gliomas (#23)

Alexis Minchaca 1 , Jean Bertoldo 1 , Philipp Graber 1 , Dong-Hun Bae 1 , Nisitha Jayatilleke 1 , Chelsea Mayoh 1 , Brett Stringer 2 , Louise Ludlow 3 4 5 , Maria Kavallaris 1 , Angelica Merlot 1 6
  1. Children's Cancer Institute, Sydney
  2. Griffith University, Nathan
  3. The Royal Children’s Hospital, Melbourne
  4. University of Melbourne, Melbourne
  5. Murdoch Children’s Research Institute, Melbourne
  6. University of New South Wales, Sydney

Background

High-grade gliomas (HGG) are highly aggressive tumours that are predominately fatal in adult and paediatric patients. Immunotherapies have shifted the paradigm of several cancer types, yet their success in HGG has been hindered by the lack of appropriate selective cancer surface targets.

Method

We implemented a mass spectrometry (MS)-based analysis of the surface proteome (surfaceome) of a comprehensive panel of cell lines, patient-derived cells and non-neoplastic brain cells to assess the non-canonical surface protein translocation, in particular 7 endoplasmic reticulum chaperones, for the first time in both adult and paediatric HGG models. Using publicly available datasets, we also investigated the transcriptomic and proteomic expression levels in adult and paediatric HGG, compared to non-neoplastic samples.

Results

Analysis of the MS data identified 7 key ER chaperones translocated to the surface of adult HGG and paediatric HGG. Specifically, the surface translocation of the ER chaperones GRP78, GRP94, PDI, CALR, CANX, HSP47 and GRP170 were present in adult and paediatric HGG. Moreover, genomic, transcriptomic, and total proteomic analyses confirmed a poor association between mRNA or total protein levels, and the surface presence of these non-canonical membrane proteins. These analyses revealed a significant upregulation of ER chaperone mRNA expression in adult HGG, which was associated with poor patient survival for HSPA5, HSP90B1, P4HB and SERPINH1. Furthermore, a low mutational burden (<2.5%) in the ER chaperone genes of interest was identified. Notably, these non-canonical membrane proteins were detected at the surface of non-neoplastic brain cell lines of foetal origin (human astrocytes, pericytes and endothelial cells), demonstrating concerns regarding cancer target selectivity.

Conclusion

Our findings highlight the importance of surfaceome analysis with filtration parameters that allow for the discovery of non-canonical surface proteins to advance targeted immunotherapies against this devastating disease.