Study On The Effects Of Preactivated Photofrin Ⅱ Combined With Chemotherapy On Tumor Cells

Objective Photodynamic therapy (PDT) is a new treatment for malignancy being developed in these twenty years .Traditional PDT is efficacious for malignancy, but it was limited by the depth of light's penetration, so PDT is not effective for bulky or deep-seated cancer. Chemotherapy is influenced by multiple drug resistance (MDR) . This study attempt to research the effects of preactivated photofrin II and it's combination with common anti-tumor drugs on tumor cells, value it's suppressive rates for tumor cells, in order to enhance the efficiency of chemotherapy and extend PDT's anti-tumor range, give a experimental proof for PDT's systemic use. Methods K562, A549,LOVO cell lines were cultured in vitro with RPMI Medium 1640.With logarithmic growth cells, confected into a cell concentration of 1×10~5/ml, inoculated 100ul tumor cell in 96 cell culture cluster combined with experimental drugs, placed into the culture-box (37℃, 5%CO2) for 72 hours, 4 hours before ending the experiment, added 5% MTT(5mg/ml) 20ul each cell, keep on cultivating; 4 hours, then anhydrated the culture cluster, dropped 100ul DMSO in each cell, measured the OD data with MTT method. The experiment was designed drug-dealed group, cell compare group and empty group. Each concentration designed 3 cells. Cell compare group each cell inoculate 100ul tumor cell and 100ul RPMI Medium 1640 , empty group each cell only drop in 200ul RPMI Medium 1640. Preactivated group was irradiated with laser light at awavelength of 632nm by a dose of 100mJ/cm2in darkroom after adding photofrin II, after irradiation then drop in tumor cells. Later activated group was irradiated after drop in tumor cells and experimental drugs. We calculated the growth inhibition rate by the following formula: inhibition rate = {l-[ ( drug-dealed group OD data-empty group OD data) /( cell compare group OD data - empty group OD data) ]} X 100%.UsingBurgi theorem to value the combination effect. According to the different inhibition rate of preactivated photofrin II combined with DDP, 5-FU, ADM, using amend Burgi theorem to value the combined efficiency, q= E (A+B) /(EA+EB-EAX EB),EA is combined efficiency, EA is the inhibition rate of the single use of preactivated photofrin Hand EB is the inhibition rate of the single use of chemotherapy drugs, q>1.15 means increasing effect, 0.85^q^ 1.15 means additional effect and q<0.85 means counteractive effect. The effect of photofrin II is analyzed by SPSS 10.0 software and get IC50 data. Results Preactivated photofrin II can inhibit tumor cell proliferation significantly, and this effect was dose dependent, both preactivated and later activated photofrin II can highly inhibit tumor cell proliferation, but the effect of preactivated photofrin II was lower. For K562 cell line, the respective IC50 data of preactivated and later activated photofrin II was 10.024ug/ml and 5.155ug/ml,for A549 cell line was 28.24ug/ml and 8.03ug/ml, for A549 cell line was 18.06ug/ml and 8.72ug/ml.The inhibition rate of 3.lug/ml preactivated photofrin II waslO.2%. In the combined group, the combined use of preactivated photofrin II can enhance DDP, 5-FU and ADM's inhibition rates respectively, which proves it has additional effects. The q-tata was 1.036,0.959 and 0.891 respectively. Conclusions The theory for PDT to treat cancer is that photosensitizer can specially accumulate in tumor tissues, it can be activated by light of specifically wavelength, and then kill tumor cellsthrough photic and chemic reaction or photic and biological reaction. Compared to traditional methods like surgery, chemotherapy and radiotherapy, PDT can specially kill tumor cells, and it has little side effects and is little harmful to normal tissues. So it especially fit for those who are old or valetudinary and can not endure surgery or chemotherapy. In recent years, some researchers have studied the effects of the combination of PDT and chemotherapy, their studies show that DDP, ADM and CPT-11 combined with PDT have increasing anti-tumor effects. Gulliya KS et al's study shows that MC540, a photosensitizer, being preactivated, can kill 70-90% HL-60^ H-69 cell lines without further irradiation, it can also kill virus, but more than 85% normal cells were survived. And the preactivated MC540 can keep it's anti-tumor activity for one month or longer by keeping under -135 °C . This experiment shows that preactivated photofrin II can also kill tumor cell lines without further irradiation. And it has an additional effect being combined with DDP, 5-FU, and ADM on K562 cell line. The biological mechanism is not very clear. A traditional theory was XO2 and 3C>2 caused oxidation reaction. PDT can react on micro blood vessel, obdurate the vessel and result in anoxic and malnourished reaction on tumor tissues, it can also stimulate the release of prostaglandin, lymphokine. Some basic researches showed PDT could induce immunological changes, made the cells create new antigen, caused a series immunoreaction. Some researchers reported that PDT could enhance the activity of radiotherapy. So PDT killing tumor cells may have multiple mechanisms. Photosentizers have few side effects like marrow suppression, alimentary canal responses, which chemotherapy may causes. Compared to the combination with multiple traditional chemical drugs, PDT has a superiority ,for it's combination with chemotherapy does not increase the side effects. Moreover, preactivated photofrin II can kill tumor cells without further irradiation in vitro. If it has anti-tumor activity invivo, this will resolve the problem of PDT's limitation on tumor treatment. PDT is a new therapy for cancer that hurt body little, can cure early tumor and is efficient for terminal tumor, following new photosensitizers and long wave laser device being produced, PDT will be used more widely and become a new therapy or assistant therapy for tumor.