Hessmann E, Patzak M S, Klein L, Chen N, Kari V, Ramu I, Bapiro T E, Frese K K, Gopinathan A, Richards F M, Jodrell D I, Verbeke C, Li X, Heuchel R, Löhr J M, Johnsen S A, Gress T M, Ellenrieder V, Neesse A
Department Gastroenterology and Gastrointestinal Oncology, University Medical Centre Goettingen, Goettingen, Germany.
Department of General, Visceral and Pediatric Surgery, University Medical Center Goettingen, Goettingen, Germany.
Gut. 2018 Mar;67(3):497-507. doi: 10.1136/gutjnl-2016-311954. Epub 2017 Jan 10.
Desmoplasia and hypovascularity are thought to impede drug delivery in pancreatic ductal adenocarcinoma (PDAC). However, stromal depletion approaches have failed to show clinical responses in patients. Here, we aimed to revisit the role of the tumour microenvironment as a physical barrier for gemcitabine delivery.
Gemcitabine metabolites were analysed in ; ; (KPC) murine tumours and matched liver metastases, primary tumour cell lines, cancer-associated fibroblasts (CAFs) and pancreatic stellate cells (PSCs) by liquid chromatography-mass spectrometry/mass spectrometry. Functional and preclinical experiments, as well as expression analysis of stromal markers and gemcitabine metabolism pathways were performed in murine and human specimen to investigate the preclinical implications and the mechanism of gemcitabine accumulation.
Gemcitabine accumulation was significantly enhanced in fibroblast-rich tumours compared with liver metastases and normal liver. In vitro, significantly increased concentrations of activated 2',2'-difluorodeoxycytidine-5'-triphosphate (dFdCTP) and greatly reduced amounts of the inactive gemcitabine metabolite 2',2'-difluorodeoxyuridine were detected in PSCs and CAFs. Mechanistically, key metabolic enzymes involved in gemcitabine inactivation such as hydrolytic cytosolic 5'-nucleotidases (Nt5c1A, Nt5c3) were expressed at low levels in CAFs in vitro and in vivo, and recombinant expression of Nt5c1A resulted in decreased intracellular dFdCTP concentrations in vitro. Moreover, gemcitabine treatment in KPC mice reduced the number of liver metastases by >50%.
Our findings suggest that fibroblast drug scavenging may contribute to the clinical failure of gemcitabine in desmoplastic PDAC. Metabolic targeting of CAFs may thus be a promising strategy to enhance the antiproliferative effects of gemcitabine.
促结缔组织增生和血管减少被认为会阻碍胰腺导管腺癌（PDAC）的药物递送。然而，基质耗竭方法在患者中未能显示出临床反应。在此，我们旨在重新审视肿瘤微环境作为吉西他滨递送物理屏障的作用。
通过液相色谱 - 质谱/质谱分析了KPC小鼠肿瘤及其匹配的肝转移灶、原发性肿瘤细胞系、癌症相关成纤维细胞（CAF）和胰腺星状细胞（PSC）中的吉西他滨代谢产物。在小鼠和人类样本中进行了功能和临床前实验，以及基质标志物和吉西他滨代谢途径的表达分析，以研究吉西他滨蓄积的临床前意义及机制。
与肝转移灶和正常肝脏相比，富含成纤维细胞的肿瘤中吉西他滨蓄积显著增强。在体外，PSC和CAF中检测到活化的2',2'-二氟脱氧胞苷-5'-三磷酸（dFdCTP）浓度显著增加，而无活性的吉西他滨代谢产物2',2'-二氟脱氧尿苷的量大大减少。机制上，参与吉西他滨失活的关键代谢酶，如胞质水解5'-核苷酸酶（Nt5c1A、Nt5c3）在体外和体内的CAF中表达水平较低，Nt5c1A的重组表达导致体外细胞内dFdCTP浓度降低。此外，KPC小鼠接受吉西他滨治疗后，肝转移灶数量减少了50%以上。
我们的研究结果表明，成纤维细胞对药物的清除可能导致吉西他滨在促结缔组织增生性PDAC临床应用中的失败。因此，对CAF进行代谢靶向可能是增强吉西他滨抗增殖作用的一种有前景的策略。
