AIM: To enhance the radiosensitivity of human colon cancer cells by docetaxel. single dose irradiation, strongly radiopotentiating effects of immunoliposomal docetaxel on LoVo cells were Ceftiofur hydrochloride supplier observed. A low dose of immunoliposomal docetaxel could yield sufficient radiosensitivity. Immunoliposomal docetaxel were achieved both specificity of the conjugated antibody and drug radiosensitization. Combined with radiation, immunoliposomal docetaxel significantly increased the percentage of G2/M cells and induced apoptosis, but significantly decreased the percentage of cells in G2/G1 and S phase by comparison with liposomal docetaxel. Immunohistochemical analysis showed that this brown stained survivin was mainly in cytoplasm of LoVo cells. Semi-quantitative analysis of the survivin immunostaining showed that the expression of survivin in LoVo cells under irradiation with immunoliposomal docetaxel was significantly decreased. CONCLUSION: Immunoliposomal docetaxel is usually strongly effective for target radiosensitation in LoVo colon carcinoma cells, and may offer the potential to improve local radiotherapy. < 0.05). No significant radiopotentiating effects were found after treatment with liposomal docetaxel. Physique 3 Target radiopotentiating effects of docetaxel immunoliposomes on LoVo cells. Cell cycle effects To determine whether immunoliposomal docetaxel in combination with radiation could increase cellular sensitivity to radiation through cell cycle redistribution, we analyzed the LoVo cells by flow cytometry. After treatment with immunoliposomal docetaxel or liposomal docetaxel, all cells were irradiated at 2 Gy. The response of LoVo cell cycle to radiation is usually shown in Figure ?Physique4.4. Compared to treatment with liposomal docetaxel, the percentage of G2/M cells treated with immunoliposomal docetaxel was significantly increased (< 0.01), but the percentages of cells both in G2/G1 phase and in S phase were decreased significantly (< 0.05). Apoptosis was also monitored by flow cytometry (Physique ?(Figure4).4). Apoptosis was significantly increased in LoVo cells due to the combined effects of immunoliposomal docetaxel and radiation. Physique 4 Combined of effect immunoliposomal docetaxel and radiation on cell cycle distribution and apoptosis. Immunohistochemical analysis of survivin Survivin expression in LoVo cells after irradiation and treatment with immunoliposomal docetaxel was verified by immunocytochemistry. Survivin was positively stained with anti-survivin monoclonal antibody. Representative results are shown in Physique ?Figure55. Physique 5 Expression of survivin in LoVo cells. Semiquantitative assessment of survivin staining Positive staining of survivin was mainly present as diffuse cytoplasmic staining with variable intensity. Integral optical density of survivin was detected semiquantitatively by immunohistochemical staining combined with image analysis. For density measurement, color-images were directly analyzed using D801 morphologic analysis system. The semiquantitative data reported here were directly comparable to image analysis data. Survivin expression in LoVo cells after irradiation and treatment with immunoliposomal docetaxel was significantly decreased in comparision to treatment with liposomal docetaxel (< 0.001, Figure ?Physique66). Physique 6 Survivin expression in LoVo cells were determined by quantitative image analysis. DISCUSSION Docetaxel plays an important role Ceftiofur hydrochloride supplier in the treatment of human malignancies, particularly ovarian and breast cancer[17,18]. It inhibits mitotic progression and induces programmed cell death[19]. For systemic toxicity of docetaxel, the optimal usage is the targeted delivery. Liposome is used as a potential vector for targeted delivery of radiosensitizers[20]. Liposome is usually a phospholipid bilayer membrane-bound vesicle capable of encapsulating a wide variety of substances either within their lipid membrane or their central aqueous core. Liposome incorporates polyethylene glycol components and has a prolonged circulation half-life. Liposomal doxorubicin is usually understanding clinical phase II pilot study in patients with inoperable squamous cell cancer of the head and neck[21]. Maruyama et al[22] introduced a PEG-PE derived lipid with a terminal maleimide group for the reaction with thiolated antibodies. Allen et al[23] synthesized a thiol-reactive PEG anchor for reaction with maleimide-containing antibodies. The terminal coupled antibody shows an increased target binding ability compared with conventional immuno-liposomes[24]. A drawback of these coupling procedures is the need of derivation for the attachment of antibody. Two reagents are needed to activate PEG-derivatives with carboxy groups. In this study, a new liposomal membrane anchor was introduced for the covalent attachment of antibody to liposomes. Anti-CEA-antibody is simply and rapidly coupled to cyanuric chloride at the PEG terminus of liposome without previous derivatization. Immunoliposomal docetaxel may be an attractive strategy for target radiopotentiation because it can radiosensitize LoVo cells. Docetaxel is usually targeted by specific anti-CEA-antibody. Our study demonstrate that docetaxel conjugated to a monoclonal antibody specific for CEA tumor-associated antigen could exert efficient and specific cytotoxicity to CEA-expressing LoVo cells. Immuno-liposomal docetaxel alone showed dose-dependent cytotoxicity to LoVo cells. Furthermore, anti-CEA-antibody enhanced the target effects of docetaxel and led to radiosensitization. Immunoliposomal docetaxel achieved both specificity of the Mouse monoclonal to FABP4 conjugated antibody and drug radiosensitization. Using a low dose of immunoliposomal docetaxel could yield sufficient radiosensitization. Radiation combined with Ceftiofur hydrochloride supplier immunoliposomal.