The combined anti-tumor effects of 5-fluorouracil and neurokinin receptor inhibitor, aprepitant, against colorectal cancer: In vitro and in vivo study

BACKGROUND

Colorectal cancer (CRC) is one of the world's largest health concerns with growing global incidence and mortality. The potential value of the neurokinin-1 receptor as a therapeutic target has been reported in several tumor types, including CRC. Here we examined the potential anti-tumor effects of a clinically approved neurokinin-1 receptor antagonist, aprepitant, alone and its combination with 5-Fluorouracil (5-FU) as a first choice CRC chemotherapeutic drug, in both in vitro and in vivo models of CRC.

METHODS

MTT assay was employed for assessing cell proliferation. mRNA expression levels were determined by quantitative real-time PCR (qRT-PCR). Flow cytometric analysis of apoptosis was performed using an Annexin-V/propidium iodide assay kit. We finally conducted an in vivo experiment in a mouse model of CRC to confirm the in vitro antiproliferative activity of aprepitant and 5-FU.

RESULTS

We found that aprepitant and 5-FU significantly reduced CRC cell viability. The combination of drugs exhibited potent synergistic growth inhibitory effects on CRC cells. Moreover, aprepitant and 5-FU induced apoptosis and altered the levels of apoptotic genes (up-regulation of Bax, and p53 along with downregulation of Bcl-2). Importantly, the aprepitant and 5-FU combination showed a more pronounced impact on apoptosis and associated genes than either of the agents alone. Furthermore, aprepitant reduced tumor growth in vivo and led to significantly longer survival time, and this effect was more prominent when using the aprepitant and 5-FU combination.

CONCLUSIONS

Collectively, combinatory treatment with aprepitant and 5-FU potentially exerts synergistic growth inhibition and apoptosis induction in CRC, deserving further consideration as a novel strategy for CRC patients.

The Status of Nitric Oxide and its Backup, Heme Oxygenase 1, in Thromboangiitis Obliterans

BACKGROUND

Until recently, a gene polymorphism in the promoter region of endothelial nitric oxide synthase has been suggested as a risk factor for thromboangiitis obliterans (TAO) development. The aim of this study was to compare the metabolites of nitric oxide (NO) and its backup, heme-oxygenase-1 (HMOX1), between TAO patients and those of a smoking control group matched by race, age, sex, and smoking habits.

METHODS

Twenty-four male Caucasian TAO patients and 20 male Caucasian controls enrolled in the study. Their smoking habits were matched based on the serum cotinine levels of 17 of the TAO patients and the 20 controls. A colorimetric kit was used to measure NO, and an enzyme-linked immunosorbent assay kit was used to measure cotinine and HMOX1 levels.

RESULTS

The mean serum level of NO metabolites in the TAO group was significantly less than in the controls (p = 0.03) and also significantly less in the patients with below-knee amputations than in non-amputees (p= 0.018). Also, HMOX1 was significantly greater in the TAO patients than in the controls (p= 0.01). No significant correlation was found between NO and HMOX1 (p = 0.054).

CONCLUSION

Nitric oxide may play a pivotal role in TAO development and its outcome. However, the intact HMOX1 pathway may demonstrate the unique role of NO, which cannot be compensated for by HMOX1 and whose absence may make patients susceptible to developing TAO. In addition, another pathway besides NO, with influence on vascular tone and hemostasis, might be involved in TAO development, such as the autonomic nervous system. Further studies are suggested regarding these issues.