An experimental study on riboflavin photosensitization treatment for inactivation of circulating HCT116 tumor cells.

Surgical resection is one of the most common radical treatments for cancers. However, tumors may be compressed or the local intravascular pressure may be increased during surgical manipulation, causing the shedding and entry of tumor cells into the blood circulation and hence distant recurrence and metastasis of tumors. We have preliminarily established a method of riboflavin photosensitization treatment (RPT) for inactivation of circulating tumor cells. This technology promises to solve the problems of shedding and entry of solid tumor cells into blood circulation before surgical manipulation, and almost unavoidable hematogenous dissemination of tumor cells during surgical resection. In the present study, apoptosis detection and tumorigenicity experiment in immunodeficient mice were conducted to evaluate the effect of RPT for inactivation of circulating tumor cells respectively. Next, functional evaluation was carried out for the immune cells through detecting apoptosis rate and cytokine secretion of lymphocyte. Finally, thromboelastography (TEG) and free hemoglobin were detected to assess peripheral blood coagulation and red blood cell damage. The results showed that RPT (50 μmol/L riboflavin, 10.8 J/cm2 UV) could effectively make tumor cell lose the ability of proliferation in the peripheral blood. In the meantime, the damage caused to peripheral blood coagulation, immune cell function and red blood cells was generally acceptable. The results of the study showed that RPT had huge potential in addressing the problems of shedding and entry of solid tumor cells into blood circulation before surgical manipulation, and almost unavoidable hematogenous dissemination of tumor cells during surgical resection. This therapy is expected to be an auxiliary and supportive method to reduce the risk of hematogenous metastasis and recurrence of cancers, and to increase the surgical success rate of malignant solid tumors.