Alzahrani Faisal A, El-Magd Mohammed A, Abdelfattah-Hassan Ahmed, Saleh Ayman A, Saadeldin Islam M, El-Shetry Eman S, Badawy Abdelnaser A, Alkarim Saleh
Department of Biological Sciences, Rabigh College of Science and Arts, King Abdulaziz University (Jeddah), Rabigh Branch, Rabigh 21911, Saudi Arabia.
Department of Biochemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
Stem Cells Int. 2018 Aug 27;2018:8058979. doi: 10.1155/2018/8058979. eCollection 2018.
Cross talk, mediated by exosomes, between normal stem cells and cancer stem cells (CSCs) in the tumor microenvironment has been given less attention so far. In addition, no publications are available in the literature that address the impact of exosomes derived from CSCs and mesenchymal stem cells (MSCs) on progression of long-term hepatocellular carcinoma (HCC). Herein, we hypothesized that transfer of exosomes among the cells in the HCC microenvironment could either induce or inhibit tumor growth and metastasis depending on their source. To check this hypothesis, we investigated the effect of exosomes coming from two different stem cell populations, hepatic CSCs and bone marrow (BM) MSCs, on progression of long-term DEN-induced HCC in rats and the involved underlying mechanisms. CSCs-exosomes induced a significant increase in liver relative weight and serum levels of cancer markers (AFP and GGT) and liver enzymes (ALT, AST, and ALP), intensive immunostaining for the HCC marker GST-P, and an increased number and area of tumor nodules as compared to HCC rats injected by PBS. CSCs-exosomes also decreased apoptosis (marked by downregulation of and and upregulation of , and increased immunostaining of PCNA), increased angiogenetic activity (revealed by upregulation of ), enhanced metastasis and invasiveness (indicated by upregulation of P13K and ERK proteins and their downstream target and downregulation of ), and induced epithelial mesenchymal transition (marked by increased serum and hepatic level of TGF1 mRNA and protein). Notably, CSCs-exosomes also elevated HCC exosomal microRNA (miR) 21, exosomal long noncoding (lnc) RNA Tuc339, lncHEIH, and the HCC lncHOTAIR and decreased liver miR122 and HCC miRs (miR148a, miR16, and miR125b). All these cellular, functional, and molecular changes were reversed following injection of BM-MSCs-exosomes. However, both CSCs- and MSCs-exosomes failed to change the elevated oxidative stress or the inhibited antioxidant activities induced by HCC. Collectively, our results revealed a tumor stimulatory effect (induction of tumor growth, progression, and metastasis) for exosomes derived from CSCs and an inhibitory effect for exosomes derived from MSCs. These results provide valuable insight on the effect of CSCs- and MSCs-exosomes on HCC growth and progression , which may be helpful to understand the mechanism of HCC development.
到目前为止，肿瘤微环境中正常干细胞与癌症干细胞（CSCs）之间由外泌体介导的串扰较少受到关注。此外，文献中尚无关于CSCs和间充质干细胞（MSCs）来源的外泌体对长期肝细胞癌（HCC）进展影响的报道。在此，我们假设HCC微环境中细胞间外泌体的转移可能根据其来源诱导或抑制肿瘤生长和转移。为验证这一假设，我们研究了来自两种不同干细胞群体，即肝脏CSCs和骨髓（BM）MSCs的外泌体对大鼠长期二乙基亚硝胺（DEN）诱导的HCC进展的影响及其潜在机制。与注射PBS的HCC大鼠相比，CSCs来源的外泌体显著增加了肝脏相对重量、癌症标志物（甲胎蛋白和γ-谷氨酰转肽酶）及肝酶（谷丙转氨酶、谷草转氨酶和碱性磷酸酶）的血清水平，增强了HCC标志物谷胱甘肽S-转移酶胎盘型（GST-P）的免疫染色强度，并增加了肿瘤结节的数量和面积。CSCs来源的外泌体还减少了细胞凋亡（表现为Bax和Caspase-3下调及Bcl-2上调，增殖细胞核抗原（PCNA）免疫染色增强），增加了血管生成活性（表现为血管内皮生长因子上调），增强了转移和侵袭能力（表现为磷脂酰肌醇-3激酶（P13K）和细胞外信号调节激酶（ERK）蛋白及其下游靶点基质金属蛋白酶-9上调及E-钙黏蛋白下调），并诱导上皮-间质转化（表现为转化生长因子β1（TGF1）mRNA和蛋白的血清及肝脏水平升高）。值得注意的是，CSCs来源的外泌体还提高了HCC外泌体微小RNA（miR）21、外泌体长链非编码（lnc）RNA Tuc339、lncHEIH以及HCC lncHOTAIR的水平，并降低了肝脏miR122及HCC miRs（miR148a、miR16和miR125b）的水平。注射BM-MSCs来源的外泌体后，所有这些细胞、功能和分子变化均发生逆转。然而，CSCs和MSCs来源的外泌体均未能改变HCC诱导的氧化应激升高或抗氧化活性抑制。总体而言，我们的结果揭示了CSCs来源的外泌体具有肿瘤刺激作用（诱导肿瘤生长、进展和转移），而MSCs来源的外泌体具有抑制作用。这些结果为CSCs和MSCs来源的外泌体对HCC生长和进展的影响提供了有价值的见解，可能有助于理解HCC的发生发展机制。
