Novel Insights into the Molecular Regulation of Ribonucleotide Reductase in Adrenocortical Carcinoma Treatment

Abstract

Current systemic treatment options for patients with adrenocortical carcinomas (ACCs) are far from being satisfactory. DNA damage/repair mechanisms, which involve, e.g., ataxia-telangiectasia-mutated (ATM) and ataxia-telangiectasia/Rad3-related (ATR) protein signaling or ribonucleotide reductase subunits M1/M2 (RRM1/RRM2)-encoded ribonucleotide reductase (RNR) activation, commonly contribute to drug resistance. Moreover, the regulation of RRM2b, the p53-induced alternative to RRM2, is of unclear importance for ACC. Upon extensive drug screening, including a large panel of chemotherapies and molecular targeted inhibitors, we provide strong evidence for the anti-tumoral efficacy of combined gemcitabine (G) and cisplatin (C) treatment against the adrenocortical cell lines NCI-H295R and MUC-1. However, accompanying induction of RRM1, RRM2, and RRM2b expression also indicated developing G resistance, a frequent side effect in clinical patient care. Interestingly, this effect was partially reversed upon addition of C. We confirmed our findings for RRM2 protein, RNR-dependent dATP levels, and modulations of related ATM/ATR signaling. Finally, we screened for complementing inhibitors of the DNA damage/repair system targeting RNR, Wee1, CHK1/2, ATR, and ATM. Notably, the combination of G, C, and the dual RRM1/RRM2 inhibitor COH29 resulted in previously unreached total cell killing. In summary, we provide evidence that RNR-modulating therapies might represent a new therapeutic option for ACC.

Stimulated Expression of CXCL12 in Adrenocortical Carcinoma by the PPARgamma Ligand Rosiglitazone Impairs Cancer Progression

“…The effect was similar between the two cell lines at two days, while the MUC-1 seemed to be more resistant than the H295R cells in the longer period. A different sensitivity in the response to cytotoxic agents has already been reported for MUC-1 and H295R cells, with MUC-1 showing to be more chemoresistant than the primary tumor cells due to their metastatic origin [26][27][28][29][30]. The reduced proliferation was paralleled by a significant increase in the CXCL12 gene expression and the decrease in its two receptors only in H295R cells.…”

A Comprehensive Investigation of Steroidogenic Signaling in Classical and New Experimental Cell Models of Adrenocortical Carcinoma

“…MUC-1 was previously presented to be SF-1 and 3βHSD positive and mice bearing MUC-1 xenografts had increased plasma cortisol [15]. Meanwhile, MUC-1 has been implemented in a variety of preclinical ACC studies and demonstrated repeatedly a different response pattern and clinically frequently observed drug resistance phenotype compared to NCI-H295R [20][21][22][23][24][25][26][27][28][29].…”

Thymidine rescues ATR kinase inhibition induced deoxyuridine contamination in genomic DNA, cell death, and Type 1 interferon expression

“…A key step in de novo dTMP biosynthesis is the reduction of UDP to dUDP by RNR. ATRi's were recently reported to induce CDK1-dependent phosphorylation and degradation of RRM2, a subunit of RNR, in Ewing sarcoma cells, acute lymphoblastic leukemia (ALL) cells, and adrenocortical carcinoma cells (Bothou et al, 2021;Koppenhafer et al, 2020;Le et al, 2017), consistent with the well-known CDK1-dependent degradation of RRM2 in G2 (D'Angiolella et al, 2012). Since ATRi and HU both decreased the concentration of dUTP, we hypothesized that ATRi may induce the CDK1dependent degradation of RRM2 in proliferating CD8 + T cells.…”