化學治療誘發之胰臟間質細胞早發老化對胰臟腺癌復發及抗藥性之異源性影響

The Heterotypic Influences on Chemotherapeutic Agent-induced Prematurely Senescent Stromal Cells on the Malignant Progression of Pancreatic Adenocarcinoma

張智翔(Tze Sian Chan)

指導教授 ： 連吉時

共同指導教授 ： 蔡坤志

臺北醫學大學/醫學院/臨床醫學研究所/碩士(2010年)

https://doi.org/10.6831/TMU.2010.00144

摘要

背景：腫瘤基質的微環境 (Microenvironment) 會極度影響上皮腫瘤發生的許多步驟。胰臟星狀細胞 (Pancreatic stellate cells) 是造成胰臟腺癌腫瘤纖維化基質 (Desmoplastic stroma) 微環境的主要原因。胰臟星狀細胞和腫瘤細胞間的異源交互作用 (Heterotypic interaction) 在腫瘤的惡性進展 (Malignant progression) 過程也扮演著重要的角色。最近的研究發現，胰臟星狀細胞會被因暴露於低於致死的傷源（如游離輻射及細胞毒性之化學治療藥物）後被誘發進行類似於細胞老化 (Cell senescence) 的變化。更有趣的是，表現這種壓力誘發性早發細胞老化 (Stress-induced premature senescence) 的細胞也會藉由分泌蛋白及細胞外蛋白來對鄰近細胞產生旁分泌作用。延續這種說法，壓力誘發性早發細胞老化之基質纖維細胞也被證實能夠促進多種人類腺體腫瘤的成長及侵犯。

目的：我們假設壓力誘發性早發老化之胰臟星狀細胞在接受臨床使用之化學治療藥物劑量後會累積於胰臟的基質組織，進而逐漸形成一個允許胰臟癌產生抗藥及覆發之惡性腫瘤進展的允許微環境 (Permissive microenvironments)。

方法和結果：在臨床使用劑量下，胰臟星狀細胞確實可以藉由不同種類的細胞毒性化學治療藥物導致壓力誘發之早發老化之特質。在所有的藥物中，Gemcitabine在其臨床使用劑量（10μM x 30分鐘）最能有效地促成早發老化之表現。利用基因體的分析方式，我們發現壓力誘發性早發老化之胰臟星狀細胞能夠調增和壓力、傷口癒合及細胞凋零相關基因的表現。更重要的是，壓力誘發性早發老化之胰臟星狀細胞更會製造多種和細胞素卅趨化素之訊息傳遞及細胞間質重塑相關之蛋白。我們也進一步的利用三次元細胞共同培養之模式證明了早發老化之胰臟星狀細胞對腫瘤惡性進展的促成。為了進一步證實活體外之發現，當被和胰臟癌細胞同時被植入有免疫缺陷的老鼠時，早發老化之胰臟星狀細胞確實能促進腫瘤的發展。
結論：我們的觀察發現，當胰臟星狀細胞受到細胞毒性化學藥物的反覆暴露後，特別是gemcitabine，星狀細胞可以被誘發類似老化之顯性特徵。壓力誘發性早發老化之胰臟星狀細胞不管在活體外或體內的條件之下均可產生一個類似於傷口癒合過程且有利於腫瘤發展的微允許環境。胰臟星狀細胞和胰癌細胞之間的異源交互作用或許是胰臟癌在治療抗性之機轉，同時也可能成為未來潛在的治療靶標。

關鍵字

胰臟癌 ； 基質 ； 微環境 ； 星狀細胞 ； 化學治療 ； 細胞老化

並列摘要

Background: The stromal microenvironments in which tumors develop profoundly influence many steps of epithelial tumorigenesis. Pancreatic stellate cells (PaSCs) are the major contributors of the desmoplastic stromal microenvironment of pancreatic adenocarcinoma and play a crucial role in malignant progression through their heterotypic interactions with tumor cells. Recent evidence suggests that cells may develop a senescent-like growth arrest program when they are exposed to sub-lethal injuries such as ionizing radiation and/or cytotoxic agents. Intriguingly, cells displaying this stress-induced premature senescence (SIPS) phenotype can elicit paracrine signaling through their induced production of a variety of secretory factors and extracellular proteins. Along this line, SIPS stromal fibroblasts have been shown to promote tumor growth and invasion in several types of human glandular malignancies,

Aim: We hypothesize that SIPS PaSCs may accumulate in the pancreatic stroma over time following cytotoxic chemotherapies at a clinically relevant manner and which may gradually create more permissive microenvironments for the ensuing malignant progression of treatment-resistant or relapsing pancreatic cancers.

Result: A SIPS phenotype was induced in PaSCs by different cytotoxic chemotherapeutic agents that have been used clinically for the treatment of pancreatic cancer. Among them, gemcitabine was most effective in the induction of the SIPS phenotype, which occurred at clinically relevant concentrations (10 μM for 30 minutes). Using genomic profiling approach, we show that SIPS PaSCs upregulated the expressions of several groups of genes involved in stress and wound response, and apoptosis. Most importantly, SIPS PaSCs secreted proteins involved in cytokine/chemokine signaling and extracellular matrix remodeling. Using an in vivo-like three dimensional culture system, we further demonstrated that SIPS PaSCs promoted the invasive growth of co-cultivated pancreatic cancer cells. Corroborating the in vitro findings, SIPS PaSCs, when co-implanted with pancreatic cancer cells subcutaneously into immunocompromised mice, can significantly promoted the growth of xenografted pancreatic tumors.

Conclusion: Our observations suggest that repeatitive exposure of PaSCs to cytotoxic chemotherapeutic agents, especially gemcitabine, induces phenotypical changes in PaSCs resembling senescence. SIPS PaSCs can create a permissive microenvironment similar to that created during the wound healing process and promote tumor progression both in vitro and in vivo. The heterotypic interactions between SIPS PaSCs and pancreatic carcinoma cells may shed a new light on the mechanistic basis of treatment refractoriness in pancreatic adenocarcinoma and may serve as potential therapeutic targets thereof.

並列關鍵字

pancreatic cancer ； stroma ； microenvironments ； stellate cells ； chemotherapy ； senescence.

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