Ullah Mujib, Akbar Asma, Ng Nathan Norton, Concepcion Waldo, Thakor Avnesh S
Interventional Regenerative Medicine and Imaging Laboratory, Stanford University School of Medicine, Department of Radiology, Palo Alto, CA 94304, USA.
Mid-Florida Research and Education Center, Department of Pathology, University of Florida, Apopka, FL 32703, USA.
Oncotarget. 2019 May 28;10(37):3435-3450. doi: 10.18632/oncotarget.26952.
The development of chemotherapy drug resistance remains a significant barrier for effective therapy in several cancers including breast cancer. Bone marrow-derived mesenchymal stem cells (BMMSCs) have previously been shown to influence tumor progression and the development of chemoresistance. In the present study, we showed that when GFP labelled BMMSCs and RFP labelled HCC1806 cells are injected together , they create tumors which contain a new hybrid cell that has characteristics of both BMMSCs and HCC1806 cells. By labelling these cells prior to their injection, we were then able to isolate new hybrid cell from harvested tumors using FACS (DP-HCC1806:BMMSCs). Interestingly, when DP-HCC1806:BMMSCs were then injected into the mammary fat pad of NOD/SCID mice, they produced xenograft tumors which were smaller in size, and exhibited resistance to chemotherapy drugs (i.e. doxorubicin and 5-fluorouracil), when compared tumors from HCC1806 cells alone. This chemoresistance was shown to associated with an increased expression of tetraspanins (CD9, CD81) and drug resistance proteins (BCRP, MDR1). Subsequent siRNA-mediated knockdown of BMMSC-CD9 in DP-HCC1806:BMMSCs resulted in an attenuation of doxorubicin and 5-fluorouracil chemoresistance associated with decreased BCRP and serum cytokine expression (CCL5, CCR5, CXCR12). Our findings suggest that within the tumor microenvironment, CD9 is responsible for the crosstalk between BMMSCs and HCC1806 breast cancer cells (via CCL5, CCR5, and CXCR12) which contributes to chemoresistance. Hence, BMMSC-CD9 may serve as an important therapeutic target for the treatment of breast cancer.
化疗耐药性的发展仍然是包括乳腺癌在内的几种癌症有效治疗的重大障碍。先前已证明骨髓来源的间充质干细胞（BMMSCs）会影响肿瘤进展和化疗耐药性的发展。在本研究中，我们发现当绿色荧光蛋白标记的BMMSCs和红色荧光蛋白标记的HCC1806细胞一起注射时，它们会形成含有兼具BMMSCs和HCC1806细胞特征的新杂交细胞的肿瘤。通过在注射前标记这些细胞，我们随后能够使用荧光激活细胞分选术（FACS）从收获的肿瘤中分离出新的杂交细胞（DP-HCC1806:BMMSCs）。有趣的是，当将DP-HCC1806:BMMSCs注射到NOD/SCID小鼠的乳腺脂肪垫中时，与单独来自HCC1806细胞的肿瘤相比，它们产生的异种移植肿瘤体积更小，并且对化疗药物（即阿霉素和5-氟尿嘧啶）具有抗性。这种化疗抗性与四跨膜蛋白（CD9、CD81）和耐药蛋白（BCRP、MDR1）的表达增加有关。随后，通过小干扰RNA介导的DP-HCC1806:BMMSCs中BMMSC-CD9的敲低导致阿霉素和5-氟尿嘧啶化疗抗性减弱，这与BCRP和血清细胞因子表达（CCL5、CCR5、CXCR12）降低有关。我们的研究结果表明，在肿瘤微环境中，CD9负责BMMSCs与HCC1806乳腺癌细胞之间的串扰（通过CCL5、CCR5和CXCR12），这导致化疗抗性。因此，BMMSC-CD9可能是治疗乳腺癌的重要治疗靶点。
