H. Sugano1,2, Y. Shirai1, N. Saito1,2, T. Horiuchi1,2, H. Shiba1, K. Eto1, T. Uwagawa3, T. Ohashi2, K. Yanaga1 1The Jikei University School Of Medicine,Department Of Surgery,Minato-ku, TOKYO, Japan 2The Jikei University School Of Medicine,Department Of Gene Therapy, Research Center For Medical Science,Minato-ku, TOKYO, Japan 3The Jikei University School Of Medicine,Department Of Hematology And Medical Oncology,Minato-ku, TOKYO, Japan
Introduction:
Colorectal cancer is the third most commonly diagnosed malignancy and the fourth leading cause of cancer death in the world. Most patients with CRC are diagnosed at advanced stages, and the prognosis of such patients remains very poor. Neoadjuvant chemoradiothrapy (CRT) followed by radical surgery is currently the standard of care for patients with locally advanced low rectal cancer. CRT has the potential to downsize tumors before surgery and to decrease locoregional recurrence. However, previous findings indicate that irradiation promotes tumor migration, distant metastasis, and the invasive potential of cancer cells. This radiation-induced invasiveness is associated with an increased expression of matrix metalloproteinase (MMP) through nuclear factor kappa B (NF-κB) pathways. Irradiation also activates NF-κB that plays an important role in the regulation of cell apoptosis, inflammation, and oncogenesis including invasion and angiogenesis. We previously reported that nafamostat mesilate, a synthetic serine protease inhibitor, inhibited NF-κB activation and induced antitumor effects for pancreatic cancer. We hypothesized that nafamostat mesilate may inhibit radiation-induced NF-κB activation and tumor invasiveness, and improve therapeutic outcome of colorectal cancer.
Methods:
We assessed NF-κB activity, cell viability, induction of caspase cascade, quantification of apoptosis, and cell invasiveness of human colorectal cancer cell line (SW620) in the following four groups: 1) radiation alone, 2) nafamostat mesilate alone, 3) combination (radiation and nafamostat mesilate), or 4) vehicle as control. In combination therapy, we incubated the cells with nafamostat mesilate at 3 hour before radiation therapy.
Results:
NF-κB activity in radiation group was higher than that in vehicle group (p<0.001). NF-kB activity was significantly surpressed in nafamostat mesilate group and combination group as compared with radiation group (p<0.001). Cell viability in combination group was lower than that in radiation group (p<0.001). Cleaved caspase-3, 8, and 9 level in combination group was the greatest in the 4 groups. Apoptosis in combination group was significantly higher than that in radiation group. In the assessment of cell invasiveness, invasive ability in radiation group was higher than that in vehicle group (p<0.01). Invasive ability was significantly suppressed in nafamostat mesilate group and combination group as compared with radiation group (p<0.001). MMP expression in nafamostat mesilate and combination groups was lower than that in radiation group.
Conclusion:
Nafamostat mesilate enhanced the antitumor effect of radiation therapy, degraded radiation-induced tumor invasiveness, and inhibited MMP through downregulation of NF-κB in colorectal cancer cell.