Ribonucleotide reductase regulatory subunit M2 drives glioblastoma TMZ resistance through modulation of dNTP production

Abstract

During therapy, adaptations driven by cellular plasticity are partly responsible for driving the inevitable recurrence of glioblastoma (GBM). To investigate plasticity-induced adaptation during standard-of-care chemotherapy temozolomide (TMZ), we performed in vivo single-cell RNA sequencing in patient-derived xenograft (PDX) tumors of GBM before, during, and after therapy. Comparing single-cell transcriptomic patterns identified distinct cellular populations present during TMZ therapy. Of interest was the increased expression of ribonucleotide reductase regulatory subunit M2 ( RRM2 ), which we found to regulate dGTP and dCTP production vital for DNA damage response during TMZ therapy. Furthermore, multidimensional modeling of spatially resolved transcriptomic and metabolomic analysis in patients’ tissues revealed strong correlations between RRM2 and dGTP. This supports our data that RRM2 regulates the demand for specific dNTPs during therapy. In addition, treatment with the RRM2 inhibitor 3-AP (Triapine) enhances the efficacy of TMZ therapy in PDX models. We present a previously unidentified understanding of chemoresistance through critical RRM2-mediated nucleotide production.

Synergistic Effect of a Combination of Proteasome and Ribonucleotide Reductase Inhibitors in a Biochemical Model of the Yeast Saccharomyces cerevisiae and a Glioblastoma Cell Line

“…This is in good agreement with the data on the severe delay in colony formation and reduced survival of wild-type yeast under the conditions of 4-NQO action [21,22]. Similarly, in mammals, various modes of transcriptional repression or targeting RRM2 result in the suppression of tumor growth, including GBM [44,59,60]. RNR catalyzes the synthesis of dNTP by a radical mechanism [24], which can be counteracted by the formation of reactive oxygen species.…”

“…So, high antitumor activity of the combination of bortezomib and 4-hydroxysalicylanilide (a specific inhibitor of the RRM2 subunit of RNR) was shown against MM cell lines, including primary cells obtained from a patient with MM refractory to bortezomib [41]. Recent work shows that drugs that target RNR or inhibit its expression sensitize GBM to standard therapy [42][43][44]. To our knowledge, RNR inhibitors in combination with proteasome inhibitors have not yet been investigated for GBM treatment [12].…”

Proteomics Identifies LUC7L3 as a Prognostic Biomarker for Hepatocellular Carcinoma

“…One of the co-down-regulated proteins identified in the LUC7L3-knockdown group was ribonucleotide reductase subunit M2 (RRM2), which had been reported to contribute to the progression of multiple cancers [27,28] and serve as a potential therapeutic target. More specifically, several studies have suggested that the overexpression of RRM2 was involved in the development of acquired resistance to chemotherapeutic agents such as gemcitabine, temozolomide, and so on [29][30][31].…”

Spatial transcriptomics in glioblastoma: is knowing the right zip code the key to the next therapeutic breakthrough?

“…As the composition of the TME has been more fully elucidated with research studies looking into the functional consequences of interaction with these surrounding cells have begun to illuminate a dynamic cellular crosstalk between GBM itself and its TME. Studies examining GBM and its complex TME have uncovered critical insights including wide immunosuppression ( 29 , 77 – 80 ), integration with neuronal firing ( 81 – 84 ), hijacking of angiogenesis ( 85 – 89 ), changes in cellular metabolism ( 29 , 90 , 91 ), and disruption of normal ph. and oxygen levels ( 29 , 92 ).…”