探討Siglec-5和Siglec-14在巨噬細胞與腫瘤微環境交互作用中所扮演的角色

The role of Siglec-5 and Siglec-14 in the crosstalk between macrophage and tumor microenvironment

林思妘(Si-Yun Lin)

指導教授 ： 張永祺

國立臺灣大學/醫學院/微生物學研究所/碩士(2022年)

https://doi.org/10.6342/NTU202202339

摘要

Siglec-5與Siglec-14為一對主要表現在巨噬細胞上paired Siglec receptor，由於兩者位於細胞外的配體結合位序列相似，因此能結合相同的配體，但是在被鍵結後經由膜內的ITIM motif和ITAM motif分別傳遞抑制型與活化型兩種相反的訊號來調控巨噬細胞的功能。先前研究顯示腫瘤細胞大多具有過度唾液酸化的特徵，並且會與腫瘤微環境中巨噬細胞表面的Siglec產生交互作用而影響巨噬細胞的表型。我們實驗室先前的研究發現，Siglec-14會促使人類THP-1巨噬細胞在大腸直腸癌細胞株SW620培養液(CM)刺激之下表現更多腫瘤相關巨噬細胞(TAM)的特徵，而我進一步以含有中和Siglec-5/14抗體的SW620 CM處理THP-1巨噬細胞，來探究Siglec-14對巨噬細胞極化的影響。接著為了探討表現不同Siglec的巨噬細胞經SW620 CM處理後之培養液是否會影響整個腫瘤微環境，我利用經SW620 CM處理後之巨噬細胞培養液刺激大腸癌細胞以及臍靜脈內皮細胞後，並觀測這些細胞增生、遷移、與幹細胞特性的變化。我發現表現Siglec-14的巨噬細胞的培養液雖然並不影響大腸直腸癌細胞的生長、癌細胞群落與球體的形成，但卻可以顯著促進內皮細胞存活。總之，我們證實了在SW620 CM的刺激之下，Siglec-14可以促進腫瘤微環境中的巨噬細胞極化為TAM，並且其產生的巨噬細胞培養液能有助於內皮細胞的存活。

關鍵字

Siglec-14 ； 巨噬細胞極化 ； 腫瘤相關巨噬細胞 ； 腫瘤微環境

並列摘要

Siglec-5 and Siglec-14 are paired receptors that are mainly expressed on macrophages. Siglec-5 and Siglec-14 show similar ligand binding preference due to the nearly identical sequence in their ligand-binding domain; however, they transduce opposite signal through their downstream ITIM and ITAM motif, respectively, to regulate macrophages function. Previous studies have demonstrated that most tumor cells are featured with hypersialylation, which could interact with various Siglecs to affect macrophage polarization. We have previously found that expression of Siglec-14 on THP-1 cells enhances the polarization of THP-1 cells into tumor-associated macrophage (TAM) in the presence of colorectal cancer cell SW620 conditioned medium (CM). I further investigated the contribution of Siglec-14 in THP-1 polarization by blocking Siglec-5/-14 activity on THP-1 cells by neutralizing antibodies. Next, I investigated whether the conditioned medium collected from Siglec-5- or Siglec-14-expressing post SW620 CM treatment differentially affects the cells composed the tumor microenvironment. Colorectal cancer cells and umbilical vein endothelial cells were treated with macrophage conditioned medium to observe their proliferation, migration, and stemness. Despite the conditioned medium collected from Siglec-14-expressing macrophages did not enhance the proliferation, colonies formation and spheroids growth of colorectal cancer cells, it significantly promoted the survival of endothelial cells. In summary, we demonstrated that Siglec-14 could promote TAM polarization upon SW620 CM treatment, and CM collected from Siglec-14-expressing macrophages enhanced endothelial cell survival in tumor microenvironment.

並列關鍵字

Siglec-14 ； macrophage polarization ； tumor-associated macrophage ； tumor microenvironment

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