mTORC2 regulates ribonucleotide reductase to promote DNA replication and gemcitabine resistance in non-small cell lung cancer

Neoplasia. 2021 Jul;23(7):643-652. doi: 10.1016/j.neo.2021.05.007. Epub 2021 Jun 11.

Abstract

Ribonucleotide reductase (RNR) is the key enzyme that catalyzes the production of deoxyribonucleotides (dNTPs) for DNA replication and it is also essential for cancer cell proliferation. As the RNR inhibitor, Gemcitabine is widely used in cancer therapies, however, resistance limits its therapeutic efficacy and curative potential. Here, we identified that mTORC2 is a main driver of gemcitabine resistance in non-small cell lung cancers (NSCLC). Pharmacological or genetic inhibition of mTORC2 greatly enhanced gemcitabine induced cytotoxicity and DNA damage. Mechanistically, mTORC2 directly interacted and phosphorylated RNR large subunit RRM1 at Ser 631. Ser631 phosphorylation of RRM1 enhanced its interaction with small subunit RRM2 to maintain sufficient RNR enzymatic activity for efficient DNA replication. Targeting mTORC2 retarded DNA replication fork progression and improved therapeutic efficacy of gemcitabine in NSCLC xenograft model in vivo. Thus, these results identified a mechanism through mTORC2 regulating RNR activity and DNA replication, conferring gemcitabine resistance to cancer cells.

Keywords: DNA replication stress; Gemcitabine; Ribonucleotide reductase; mTORC2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antimetabolites, Antineoplastic / pharmacology
  • Carcinoma, Non-Small-Cell Lung / genetics*
  • Carcinoma, Non-Small-Cell Lung / metabolism*
  • Carcinoma, Non-Small-Cell Lung / pathology
  • Cell Line, Tumor
  • DNA Damage
  • DNA Replication*
  • Deoxycytidine / analogs & derivatives*
  • Deoxycytidine / pharmacology
  • Drug Resistance, Neoplasm* / genetics
  • Gemcitabine
  • Gene Expression Regulation, Neoplastic
  • Gene Knockdown Techniques
  • Histones / metabolism
  • Humans
  • Mechanistic Target of Rapamycin Complex 2 / antagonists & inhibitors
  • Mechanistic Target of Rapamycin Complex 2 / metabolism*
  • Phosphorylation
  • Protein Binding
  • Ribonucleoside Diphosphate Reductase / chemistry
  • Ribonucleoside Diphosphate Reductase / metabolism
  • Ribonucleotide Reductases / chemistry
  • Ribonucleotide Reductases / metabolism*
  • Signal Transduction / drug effects

Substances

  • Antimetabolites, Antineoplastic
  • Histones
  • Deoxycytidine
  • Ribonucleotide Reductases
  • ribonucleotide reductase M2
  • RRM1 protein, human
  • Ribonucleoside Diphosphate Reductase
  • Mechanistic Target of Rapamycin Complex 2
  • Gemcitabine