Targeted Near Infrared Hyperthermia Combined With Immune Stimulation For Optimized Therapeutic Efficacy In Thyroid Cancer Treatment

Treatment of thyroid cancer has incurred much focus because of its high prevalence. As a new strategy treating thyroid cancer, hyperthermia takes several advantages compared with surgery or chemotherapy,including minimal invasion, low systematic toxicity and the ability to enhance the immunogenicity of cancer cells with the expression Hsp70 which serves as Toll-like receptors-4(TLR-4 agonist). However, Hsp70 as a molecular chaperone can protect cells from heat induced apoptosis and therefore compromise the tumor killing effect of hyperthermia. In this study, to solve this problem, a combined hyperthermia therapy was employed to treat thyroid cancer. We prepared a probe with the tumor targeting agent AG to monitor thyroid tumor issue and generate heat to kill tumor cells in vivo. At the same time Quercetin(inhibitor of HSP70)and lipopolysaccharide(LPS)(agonist of TLR-4) were used for the combined hyperthermia therapy. The results showed that compared with free IR820, AG modification facilitated much enhanced cellular uptake and greatly pronounced tumor targeting ability. The combined therapy exhibited the most remarkable tumor inhibition compared with the single treatments both in vitro and in vivo. These findings verified that the new therapeutic combination could significantly improve the effectof hyperthermia and shed light on a novel clinical strategy in thyroid cancer treatment.The six sections of the thesis are as follows.Chapter 1: Introduction Chapter 2: Synthesis and characterization of AG-IR820Conclusions: AG-IR820 was synthesized successfully and its molecular weight was 1105.34, consistent with the theatrical molecular weight. The absorption peak of AG-IR820 was 691 nm and the emission spectra of AG-IR820 was 823 nm, which were identical with the fluorescence property of IR820.Chapter 3: Tumor targeting ability of AG-IR820Conclusions: AG modification enhanced tumor cellular uptake of AG-IR820 probe, AG-IR820 in TT cells was significantly more than the probe in L02 cells. AG-IR820 not only showed satisfying tumor targeting ability but were also observed with fast tumor accumulation for less than 4 hours and distinctive fluorescence signal after 24 h.Chapter 4: Photothermal property of AG-IR820Conclusions: No obvious cytotoxicity was observed in both IR820 and AG-IR820 groups even at 5 μM. The temperatures of AG-IR820 and IR820 solutions elevated to about 43 ℃. Under laser exposure,AG-IR820 group demonstrated potent cytotoxicity effect in a dose department manner.Chapter 5: Antitumor efficacy of combined treatment(AGIR820+Quercetin+LPS) in vitroConclusions: Quercetin at 100μM could effectively reduce the HSP70 expression without obvious cytotoxicity. The macrophages could be effectively activated by LPS at 1μg/m L without obvious cytotoxicity.It is the inhibition of HSP70 that synergize with hyperthermia to kill more cancer cells. LPS was effective in vitro to make immune cells up and kill cancer cells and contribute to improve the therapeutic effect of hyperthermia.Chapter 6: Antitumor efficacy of combined treatment(AGIR820+Quercetin+LPS) in vivoConclusions: The most remarkable tumor shrinkage was achieved in the triple treatment group(AG-IR820+Quercetin+LPS) of the TT tumor model. Heat ablation which combined with HSP70 inhibition and tumor immunogenicity enhancement could strengthen the therapeutic effect.