Ribonucleotide Reductase Regulatory Subunit M2 as a Driver of Glioblastoma TMZ-Resistance through Modulation of dNTP Production

Abstract

Glioblastoma (GBM) remains one of the most resistant and fatal forms of cancer. Previous studies have examined primary and recurrent GBM tumors, but it is difficult to study tumor evolution during therapy where resistance develops. To investigate this, we performed an in vivo single-cell RNA sequencing screen in a patient-derived xenograft (PDX) model. Primary GBM was modeled by mice treated with DMSO control, recurrent GBM was modeled by mice treated with temozolomide (TMZ), and during therapy GBM was modeled by mice euthanized after two of five TMZ treatments. Our analysis revealed the cellular population present during therapy to be distinct from primary and recurrent GBM. We found the Ribonucleotide Reductase gene family to exhibit a unique signature in our data due to an observed subunit switch to favor RRM2 during therapy. GBM cells were shown to rely on RRM2 during therapy causing RRM2-knockdown (KD) cells to be TMZ-sensitive. Using targeted metabolomics, we found RRM2-KDs to produce less dGTP and dCTP than control cells in response to TMZ (p<0.0001). Supplementing RRM2-KDs with deoxycytidine and deoxyguanosine rescued TMZ-sensitivity, suggesting an RRM2-driven mechanism of chemoresistance, established by regulating the production of these nucleotides. In vivo, tumor-bearing mice treated with the RRM2-inhibitor, Triapine, in combination with TMZ, survived longer than mice treated with TMZ alone (p<0.01), indicating promising clinical opportunities in targeting RRM2. Our data present a novel understanding of RRM2 activity, and its alteration during therapeutic stress as response to TMZ-induced DNA damage.

Cellular heterogeneity and dynamics of the human uterus in healthy premenopausal women

“…This cluster contains a relatively small number of cells (~100) and we did not subcluster it further. Imm-10 shows a similar match profile as Imm-9 when compared with Tan et al (26) (Supplemental Figure 6B), but unlike Imm-9, it specifically expresses cell proliferation markers and apoptosis inhibitors: MKI67, CDK1, BIRC5, ASPM, RRM2, TOP2A (Figure 2C) (72)(73)(74)(75)(76). Two of the hematopoietic progenitor markers, CD38 and ITGB1, are specifically expressed in both Imm-9 and Imm-10, although at a higher level in Imm-9, suggesting a close lineage relationship between the two (Supplemental Table 7).…”

KHDRBS3 facilitates self-renewal and temozolomide resistance of glioblastoma cell lines

“…(Raghava Kurup et al , 2022), NSUN5 (Zhou et al , 2023), RRM2 (Perrault et al , 2023) and MEX3A (Gan et al , 2022). Regarding mRNA alternative splicing, dysregulation of the process is associated with resistance against temozolomide in glioblastoma (Dowdell et al , 2023, Tiek et al , 2022.…”

Delineating the glioblastoma stemness by genes involved in cytoskeletal rearrangements and metabolic alterations

“…Available literature also links the RRM2 to the cytoskeleton via hPLIC1; the latter decreases during RRM2 downregulation, which entails actin cytoskeleton re-organization[ 42 ]. Perrault et al [ 121 ] have suggested that RRM2 can be a chemoresistance driver that dictates how GBM cells respond to TMZ. The same authors further verified that RRM2 -overexpressing cells had enhanced DNA repair efficiency.…”

“…The same authors further verified that RRM2 -overexpressing cells had enhanced DNA repair efficiency. Moreover, the use of a selective FDA-approved RRM2 inhibitor, 3-AP Triapine, enabled Perrault et al [ 121 ] to observe that in comparison to both TMZ and control, glioblastoma treated with the 3AP + TMZ formed fewer neurospheres that were also significantly smaller. Another group found that RRM2 expression dramatically declined after 12 d of dasatinib treatment compared to naïve GSCs of the GSC8 cell line[ 122 ].…”