High intratumor heterogeneity of glioblastoma (GBM) cells and their differential reactivity to chemotherapeutic drug temozolomide (TMZ) contribute to clonal selection of TMZ-resistant clones and the disease recurrence. Numerous molecules contribute to this process; however, an involvement of glycosylated macromolecules remains under investigated. To study their potential contribution to the resistance development, we investigated different molecular and functional characteristics of various GBM cells and their association with TMZ resistance in GBM model in vitro.
Six GBM cell lines (U343, LN215, U87, LN71, LN405, LN18) were characterised for TMZ resistance (IC50), proliferation (growth curve, doubling time) and migration (wound healing assay) rates, clonogenicity. Transcriptional profiling of key proteoglycans (PGs) was performed by RT-PCR. Total content of glycosaminoglycans (GAGs) on the cells surface was determined by staining with dimethylmethylene blue. Content and localization of chondroitin sulfate (CS) were studied by immunocytostaining.
All GBM cell lines were individual in terms of the studied parameters (migration, clonogenicity), expression of some PGs (CD44, chondroitin sulfate proteoglycan 4/NG2, heparan sulfate proteoglycan 2/perlecan, chondroitin sulfate proteoglycan 5, biglycan, glypican-1, syndecan-1, syndecan-3, lumican, phosphacan) and total GAG and CS content, while their proliferation rates were similar. The most TMZ-sensitive cell line was LN215 (IC50=32μM) and the most TMZ-resistant one was LN405 (IC50=319μM). TMZ-resistance was associated with the expression of hyaluronic-acid receptor CSPG CD44 (r=0,83; p<=0,05), a cell surface adhesion molecule, which is often overexpressed on cancer stem cells.
High CD44 expression is glioblastoma cells may help to identify TMZ-resistant patients and thereby optimise the treatment strategy for the patients and overcome TMZ-chemoresistance during GBM chemotherapy.
The authors.
This study was supported by the Government of Novosibirsk region (Grant number 11). A.V.S. was supported by a Scholarship of Russian Federation President for young scientists (SP-4000.2022.4).
All authors have declared no conflicts of interest.