Tissue inhibitor of metalloproteinase-1 (TIMP-1) is an important regulator of extracellular matrix turnover that has been traditionally regarded as a potential tumor suppressor owing to its inhibitory effects of matrix metalloproteinases. Intriguingly, this interpretation has been challenged by the consistent observation that increased expression of TIMP-1 is associated with poor prognosis in virtually all cancer types including lung cancer, supporting a tumor-promoting function. However, how TIMP-1 is dysregulated within the tumor microenvironment and how it drives tumor progression in lung cancer is poorly understood. We analyzed the expression of TIMP-1 and its cell surface receptor CD63 in two major lung cancer subtypes: lung adenocarcinoma (ADC) and squamous cell carcinoma (SCC), and defined the tumor-promoting effects of their interaction. We found that TIMP-1 is aberrantly overexpressed in tumor-associated fibroblasts (TAFs) in ADC compared to SCC. Mechanistically, TIMP-1 overexpression was mediated by the selective hyperactivity of the pro-fibrotic TGF-β1/SMAD3 pathway in ADC-TAFs. Likewise, CD63 was upregulated in ADC compared to SCC cells. Genetic analyses revealed that TIMP-1 secreted by TGF-β1-activated ADC-TAFs is both necessary and sufficient to enhance growth and invasion of ADC cancer cells in culture, and that tumor cell expression of CD63 was required for these effects. Consistently, in vivo analyses revealed that ADC cells co-injected with fibroblasts with reduced SMAD3 or TIMP-1 expression into immunocompromised mice attenuated tumor aggressiveness compared to tumors bearing parental fibroblasts. We also found that high TIMP1 and CD63 mRNA levels combined define a stronger prognostic biomarker than TIMP1 alone. Our results identify an excessive stromal TIMP-1 within the tumor microenvironment selectively in lung ADC, and implicate it in a novel tumor-promoting TAF-carcinoma crosstalk, thereby pointing to TIMP-1/CD63 interaction as a novel therapeutic target in lung cancer.

金属蛋白酶组织抑制剂-1 (TIMP-1) 是细胞外基质周转的重要调节剂，由于其对基质金属蛋白酶的抑制作用，传统上被认为是潜在的肿瘤抑制剂。有趣的是，这种解释受到了一致观察的挑战，即 TIMP-1 表达增加与包括肺癌在内的几乎所有癌症类型的不良预后相关，支持肿瘤促进功能。然而，人们对 TIMP-1 在肿瘤微环境中如何失调以及它如何驱动肺癌肿瘤进展知之甚少。我们分析了两种主要肺癌亚型：肺腺癌（ADC）和鳞状细胞癌（SCC）中 TIMP-1 及其细胞表面受体 CD63 的表达，并确定了它们相互作用的促肿瘤作用。我们发现，与 SCC 相比，ADC 中的肿瘤相关成纤维细胞 (TAF) 中 TIMP-1 异常过度表达。从机制上讲，TIMP-1 过表达是由 ADC-TAF 中促纤维化 TGF-β1/SMAD3 通路的选择性过度活跃介导的。同样，与 SCC 细胞相比，ADC 中的 CD63 表达上调。遗传分析表明，TGF-β1 激活的 ADC-TAF 分泌的 TIMP-1 对于增强培养物中 ADC 癌细胞的生长和侵袭来说是必要且充分的，并且肿瘤细胞表达 CD63 是这些作用所必需的。体内分析一致表明，与携带亲本成纤维细胞的肿瘤相比，将 ADC 细胞与 SMAD3 或 TIMP-1 表达降低的成纤维细胞共同注射到免疫功能低下的小鼠中，可以减弱肿瘤的侵袭性。我们还发现，高TIMP1和CD63 mRNA 水平相结合定义了比单独使用TIMP1更强的预后生物标志物。我们的结果在肺 ADC 中选择性地识别出肿瘤微环境中过量的基质 TIMP-1，并将其与新型肿瘤促进 TAF-癌串扰有关，从而指出 TIMP-1/CD63 相互作用作为肺癌的新型治疗靶点。