利用系統生物學方法研究輻射照後腫瘤微環境的基因體特性

Abstract

腫瘤微環境乃是由癌細胞，基質組織和組織中細胞外基質所構成。 免疫系統是腫瘤微環境的關鍵決定因素。幾種免疫缺陷與小鼠模型研究人類腫瘤發展的增強有關。 近幾年來，腫瘤微環境在腫瘤和腫瘤控制發展中的關鍵作用，包括骨髓源性抑制細胞（Myeloid derived suppressor cells, MDSCs），腫瘤相關巨噬細胞（Tumor-associated macrophages, TAMs）和細胞毒性淋巴細胞 (Cytotoxic T lymphocytes, CTLs)在內的腫瘤浸潤性免疫細胞是癌癥結局的關鍵決定因子。許多研究表明， TAMs密度的增加通過多重抑制機制促進腫瘤進展。腫瘤可以長時間保持休眠，直到微環境改變使其得以生長。TAMs在癌症中的重要性依然未知。研究指出，TAM在結腸直腸腫瘤中具有促炎作用(Inflammatory reaction)，具有抗腫瘤作用，導致有利的預後。原因可能是TAM促進結腸癌細胞中相關基因的表達，這進一步刺激更多的TAMs浸潤，並導致擴增免疫應答（immune response）以破壞腫瘤細胞。然而，在諸如乳腺癌、前列腺癌、卵巢癌、子宮頸癌和皮膚黑素瘤等多種腫瘤中，TAMs證實與抗炎與癌症預後不良有關。它們通常分為兩種類型的M1或M2。 M1型會殺死腫瘤細胞，而M2型可誘導血管生成，腫瘤生長和轉移。此時，TAMs與癌症治療效果和腫瘤大小控制率的關聯，但少有研究具體指出暴露於輻射後TAMs基因表達。本研究以實驗動物模型，通過給定的單次劑量的輻射來評估觀察時間的腫瘤大小的生長情形。選CD11b類型的TAM，並且可以在隨後的每個時間點中研究整個基因組表達關聯性。本研究目的是通過體內前列腺腫瘤局部照射後不同周數的全基因組基因表達或者miRNA模式應用在未來癌症治療用途，了解TAMs基因表達或抑製作用及其調控機制，這些數據將在隨後的腫瘤放療中提供腫瘤治療，並協助評估最佳治療方法。分析使用短時序系列表達探勘（STEM）顯示了時間基因表達譜，並確定了13個重要模式中隨時間表達上調或下調的4個主要基因調控模式，觀察在上調的時間特徵中的基因具有參與細胞內信號傳導，細胞增殖和細胞因子介導的信號傳導途徑的多種功能。

Tumor microenvironment is in the composition of cancer cells, stroma tissue, and extracellular matrix. The immune system is a crucial determinant of tumor microenvironment. Several immune deficiencies have been associated with enhanced tumor development in mouse models and human. In recent decades, the key role of tumor microenvironment in the development of tumor and tumor control has been concerned. Tumor-infiltrating immune cells, including myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages (TAMs) and cytotoxic T lymphocytes (CTLs) are key determinants of cancer outcome. Many studies have shown that increased density of MDSCs and TAMs promotes tumor progression through multiple inhibition mechanisms. The tumor can remain dormant for a long time until the microenvironment becomes easy to grow. The importance of TAMs in cancer remains unknown. It has been pointed that TAM has a proinflammatory role in colorectal tumors, and has an anti-tumor effect, leading to a favorable prognosis. The reasons may be that M1 TAM promotes the expression of related genes in colon cancer cells, which further stimulates more TAMs infiltration and results in the immune response to destroy tumor cells. However, in variety tumors like breast cancer, prostate cancer, ovarian cancer, cervical cancer, and skin melanoma. TAMs is anti-inflammatory and associated with poor prognosis. TAMs are usually divided into two types M1 or M2. The M1 type will kill the tumor cells, while M2 type can induce angiogenesis, tumor growth and metastasis. At this point, few studies have specifically pointed out that the TAMs gene expression after exposure to radiation. We established the animal model of this project, and complete the tumor growth and radiation dose given in mice. The growth curve of tumor size at each preset observation time will be assessed by a given single dose of radiation. The CD11b type of TAMs can be extracted in the follow-up subsequent purification at each time point for the whole genome expression research. The purpose of this study is to compare TAMs in vivo prostate tumor by local irradiation after different weeks with whole genome gene expression or miRNA patterns for future cancer treatment. Understanding TAMs gene expression or inhibition, and its regulation mechanism, these data will be provided tumor with radiation therapy in oncology after the follow-up study and assisted in the evaluation for the best treatment approaches. Analysis using Short Time-Series Expression Miner (STEM) revealed the temporal gene expression profiles and identified 13 significant patterns in four main groups of profiles. The genes in the upregulated temporal profile have diverse functions involved in the intracellular signaling cascade, cell proliferation, and cytokine-mediated signaling pathway.