The 1,2-Diaminocyclohexane Carrier Ligand in Oxaliplatin Induces p53-Dependent Transcriptional Repression of Factors Involved in Thymidylate Biosynthesis

Abstract

Platinum-based chemotherapeutic drugs are widely used as components of combination chemotherapy in the treatment of cancer. One such drug, oxaliplatin, exerts a synergistic effect against advanced colorectal cancer in combination with 5-fluorouracil (5-FU) and leucovorin. In the p53-proficient colorectal cancer cell line HCT116, oxaliplatin represses the expression of deoxyuridine triphosphatase (dUTPase), a ubiquitous pyrophosphatase that catalyzes the hydrolysis of dUTP to dUMP and inhibits dUTP-mediated cytotoxicity. However, the underlying mechanism of this activity has not been completely elucidated, and it remains unclear whether factors other than downregulation of dUTPase contribute to the synergistic effect of 5-FU and oxaliplatin. In this study, we found that oxaliplatin and dachplatin, platinum-based drugs containing the 1,2-diaminocyclohexane (DACH) carrier ligand, repressed the expression of nuclear isoform of dUTPase (DUT-N), whereas cisplatin and carboplatin did not. Oxaliplatin induced early p53 accumulation, upregulation of primary miR-34a transcript expression, and subsequent downregulation of E2F3 and E2F1. Nutlin-3a, which activates p53 nongenotoxically, had similar effects. Introduction of miR-34a mimic also repressed E2F1 and DUT-N expression, indicating that this miRNA plays a causative role. In addition to DUT-N, oxaliplatin repressed, in a p53-dependent manner, the expression of genes encoding enzymes involved in thymidylate biosynthesis. Consequently, oxaliplatin significantly decreased the level of dTTP in the dNTP pool in a p53-dependent manner. These data indicate that the DACH carrier ligand in oxaliplatin triggers signaling via the p53-miR-34a-E2F axis, leading to transcriptional regulation that ultimately results in accumulation of dUTP and reduced dTTP biosynthesis, potentially enhancing 5-FU cytotoxicity. Mol Cancer Ther; 14(10); 2332-42. Ó2015 AACR.

DNA replication stress and cancer chemotherapy

“…This finding may be consistent with a recent report indicating that oxaliplatin kills cells by inducing ribosome biogenesis stress, but not through the DDR pathway . The p53 activation by oxaliplatin causes the transcriptional repression of deoxyuridine triphosphatase, which catalyzes the hydrolysis of dUTP to dUMP and inhibits dUTP‐mediated cytotoxicity, as well as the enzymes involved in thymidylate biosynthesis, such as dihydrofolate reductase, thymidine kinase 1, and thymidylate synthase, through miR‐34a ‐mediated E2F1 and E2F3 downregulation . These effects may elucidate the clinical synergy observed between oxaliplatin and 5‐FU in FOLFOX, a combination regimen of 5‐FU, leucovorin and oxaliplatin, which is superior in the treatment of advanced colorectal cancer patients or for adjuvant therapy for colorectal cancer patients who received curable surgery …”

“…Oxaliplatin, but not cisplatin, represses the expression of proteins involved in DNA replication and G 2 /M progression, Cyclin A and Cyclin B, in a p53‐dependent manner . Intriguingly, oxaliplatin robustly activates p53 and leads to accumulation of p21 in spite of low levels of activation of ATM and ATR . This finding may be consistent with a recent report indicating that oxaliplatin kills cells by inducing ribosome biogenesis stress, but not through the DDR pathway .…”

Thymidine Kinase 1 Loss Confers Trifluridine Resistance without Affecting 5-Fluorouracil Metabolism and Cytotoxicity

“…Intracellular UMP, UDP, UTP, and CTP were quantified using liquid chromatography/triple-stage quadrupole mass spectrometry (LC-QqQ-MS) as described previously (15). All metabolites were detected with optimized selective reaction monitoring transitions in negative ionization mode as follows [precursor ion (m/z)/product ion (m/z) scores are shown]: UMP: 322.7/78.85, 322.7/96.95, 322.7/110.9; UDP: 403/78.95, 403/158.8, 403/ 111; UTP: 482.6/384.85; CTP: 482/158.9.…”

Antitumor Efficacy of Combination Therapy Consisting of S-1, Leucovorin, and Oxaliplatin against Human Gastric Cancer Xenografts

“…In its combined mechanism with 5-FU, oxaliplatin reportedly increases 5-FU antitumor activity via the downregulation of TS in colon-cancer cells [20]. Furthermore, oxaliplatin reportedly potentiates the antitumor activity of 5-FU through the downregulation of deoxyuridine triphosphate nucleotidohydrolase (DUT) [21] and thymidine kinase 1 (TK1) [22]. DUT metabolizes deoxyuridine triphosphate (dUTP) into deoxyuridine monophosphate (dUMP).…”