Vasopressin Analog [V4Q5]dDAVP Exerts Cooperative Anticancer Effects in Combination With Low-Dose 5-Fluorouracil on Aggressive Colorectal Cancer Models

Abstract

Background: Colorectal cancer (CRC) is a leading cause of cancerassociated mortality worldwide. Despite being an essential component of systemic chemotherapy for advanced CRC, 5-fluorouracil (5-FU) clinical use has severe limitations, such as high toxicity, low selectivity and drug resistance. [V4Q5]dDAVP (1-deamino-4-valine-5-glutamine- 8-D-arginine vasopressin) is a peptide vasopressin analog and a selective agonist of the arginine vasopressin type 2 membrane receptor (AVPR2), expressed in microvascular and tumor tissue. This synthetic compound has well-proven antitumor and antimetastatic activity in different tumor types, including metastatic CRC. The objective of this work was to assess the potential combinational benefits in preclinical CRC models after [V4Q5]dDAVP addition to 5-FU. Methods: Effects on cellular viability, cell cycle progression, apoptosis and molecular mechanisms associated to [V4Q5]dDAVP treatment in combination with 5-FU were evaluated in murine CT-26 and human COLO-205 cell lines. In vivo, impact of dual therapy was explored on CRC tumor growth and metastatic spread. Results: In CRC cells, [V4Q5]dDAVP (1 μM) addition to sub-IC50 5-FU concentrations resulted in the enhancement of cytostatic effects induced by chemotherapy. Reduction of cell viability after combined treatment was associated with cell cycle arrest in the G0/G1 phase, induction of apoptosis and increased gene expression of the cyclindependent kinase inhibitor p21 (CDKN1A) and the tumor suppressor p53 (TP53) in malignant cells, as assessed by flow cytometry, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL), and quantitative reverse transcription polymerase chain reaction (qRT-PCR), respectively. In vivo, intravenous administration of [V4Q5]dDAVP (0.3 μg/kg) in combination with safe low doses of 5-FU (50 or 80 mg/kg for CT-26 or COLO-205 tumor models, respectively) effectively abrogated CRC growth, reducing aggressiveness of primary lesions and increasing survival of tumor-bearing mice. In addition, concomitant administration of [V4Q5]dDAVP and 5-FU inhibited pulmonary metastasis formation by CT-26 cells in immunocompetent mice, especially reducing macrometastatic disease. Conclusions: [V4Q5]dDAVP seems to enhance the efficacy of 5-FUbased chemotherapy in CRC by modulating tumor progression, as well as metastatic dissemination, suggesting its potential role as a safe and cost-effective co-adjuvant agent for the management of advanced CRC.