以CpG ODNs (CpG寡核酸)結合HER2/neu單株抗體(Herceptin)增強放射線治療的效果

Abstract

本實驗假設將單株抗體和CpG ODN結合，活化自然殺手細胞，進而增加放射線治療的成效。這樣的假設還沒有被人證明過。本研究的目的為探討以CpG寡核酸結合HER2/neu單株抗體Herceptin增強放射線治療的效果，實驗內容包括小白鼠動物實驗以及細胞實驗，所使用的腫瘤細胞株為CT26HER2/neu，這是一種從BALB/c小鼠為來源的大腸癌細胞，且被轉殖過因而可以大量的表現人類的HER2/neu。當腫瘤在BALB/c小鼠的皮下生長達到4mm的直徑時，每天給予腫瘤內注射CpG ODN 100μ以及腹腔注射Herceptin 200μg，連續三天，第四天再讓小鼠接受局部不同劑量的放射線治療，之後持續的記錄腫瘤的大小以及小鼠的存活比例，並研究放射線治療的半存活劑量TCD50以及觀察再次注射腫瘤的生長情形。至於體外的細胞實驗則藉由在照射放射線之前將CT26HER2/neu以及從小鼠脾臟取出的脾臟細胞共同培養，分別加入或不加入CpG ODN以及Herceptin，觀察其細胞激素的變化以及放射線對腫瘤細胞的傷害的改變。發現在照射放射線之前給予CpG以及Herceptin比單獨給予的組別更能夠延遲腫瘤生長的速度並且增長小鼠存活的時間。細胞實驗也證明了同時存在CpG以及Herceptin能夠更加的刺激小鼠脾臟細胞分泌IFN-r並且使腫瘤細胞在照完放射線後有更高比例的細胞死亡。實驗結果證明結合CpG ODN和Herceptin能夠提高CT26HER2/neu對放射線的敏感度，能夠增加放射線治療的功效。

We hypothesized that targeted therapy with antibody in combination of CpG oligodeoxynucleotides (ODN) would further activate NK cells and resulte in strong radiosensitization effect. This hypothesis has never been proved. The effects of blocking HER2 by Herceptin in combination of CpG ODN on radiosensitization effect were evaluated in this experiment. A BALB/c murine colon carcinoma line overexpressing human HER2/neu, CT26HER2/neu, was used in our experiment. When tumor reaches 4mm in diameter, CpG ODN 100μ intratumorally and Herceptin 200μg intraperitoneally were injected per mice in consecutive three days. Radiation of 800cGy to tumor was performed on day 4. Tumor growth curve, survival rate, TCD50, and tumor rechallenge were studied. In vitro radiosensitization effects were investigated by coculture with CT26HER2/neu with PBMC with or without CpG and Herceptin before radiation. Cytokine profiles changes were also evaluated. The combination of CpG and Herceptin before radiation retard tumor growth and prolong survival of mice in comparison with CpG only or Herceptin only. The long term tumor control rate was increased. In vitro experiments demonstrated that the combination of CpG and Herceptin stimulate more IFN-r (160pg/ml) than CpG only (130pg/ml) or Herceptin only (27pg/ml) on mice splenocytes, and increase the cell lysis percentage caused by RT (44.7%) compared with CpG only (29.94%). Our study indicated that the combination of CpG ODN and Herceptin sensitize CT26HER2/neu to radiation-induced apoptosis. Co-injection CpG and Herceptin may effectively enhance radiotherapy efficacy.