title: Bone marrow endothelium-targeted therapeutics for metastatic breast cancer.
abstract: Effective treatment of cancer metastasis to the bone relies on bone marrow drug accumulation. The surface proteins in the bone marrow vascular endothelium provide docking sites for targeted drug delivery. We have developed a thioaptamer that specifically binds to E-selectin that is overexpressed in the vasculature of tumor and inflammatory tissues. In this study, we tested targeted delivery of therapeutic siRNA loaded in the E-selectin thioaptamer-conjugated multistage vector (ESTA-MSV) drug carrier to bone marrow for the treatment of breast cancer bone metastasis. We evaluated tumor type- and tumor growth stage-dependent targeting in mice bearing metastatic breast cancer in the bone, and carried out studies to identify factors that determine targeting efficiency. In a subsequent study, we delivered siRNA to knock down expression of the human STAT3 gene in murine xenograft models of human MDA-MB-231 breast tumor, and assessed therapeutic efficacy. Our studies revealed that the CD31(+)E-selectin(+) population accounted for 20.8%, 26.4% and 29.9% of total endothelial cells respectively inside the femur of mice bearing early, middle and late stage metastatic MDA-MB-231 tumors. In comparison, the double positive cells remained at a basal level in mice with early stage MCF-7 tumors, and jumped to 23.9% and 28.2% when tumor growth progressed to middle and late stages. Accumulation of ESTA-MSV inside the bone marrow correlated with the E-selectin expression pattern. There was up to 5-fold enrichment of the targeted MSV in the bone marrow of mice bearing early or late stage MDA-MB-231 tumors and of mice with late stage, but not early stage, MCF-7 tumors. Targeted delivery of STAT3 siRNA in ESTA-MSV resulted in knockdown of STAT3 expression in 48.7% of cancer cells inside the bone marrow. Weekly systemic administration of ESTA-MSV/STAT3 siRNA significantly extended survival of mice with MDA-MB-231 bone metastasis. In conclusion, targeting the overexpressed E-selectin provides an effective approach for tissue-specific drug delivery to the bone marrow. Tumor growth in the bone can be effectively inhibited by blockage of the STAT3 signaling.
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA.
authors.forename: Junhua
authors.initials: J
authors.lastname: Mai
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA; Biomedical Analysis Center, Third Military Medical University, Chongqing 400038, PR China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA.
authors.forename: Chaofeng
authors.initials: C
authors.lastname: Mu
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA.
authors.forename: Guodong
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA.
authors.forename: Rong
authors.initials: R
authors.lastname: Xu
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA; Department of Breast Cancer Pathology and Research Laboratory, Key Laboratory of Breast Cancer of Breast Cancer Prevention and Therapy, Tianjin Medical University Cancer Institute and Hospital, Tianjin 300060, PR China.
authors.forename: Xiaojing
authors.initials: X
authors.lastname: Guo
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA.
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Xia
authors.affiliation: Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, 1825 Hermann Pressler, Houston 77030, USA.
authors.forename: David E
authors.initials: DE
authors.lastname: Volk
authors.affiliation: Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, 1825 Hermann Pressler, Houston 77030, USA.
authors.forename: Ganesh L
authors.initials: GL
authors.lastname: Lokesh
authors.affiliation: Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, 1825 Hermann Pressler, Houston 77030, USA.
authors.forename: Varatharasa
authors.initials: V
authors.lastname: Thiviyanathan
authors.affiliation: Institute of Molecular Medicine, The University of Texas Health Science Center at Houston, 1825 Hermann Pressler, Houston 77030, USA.
authors.forename: David G
authors.initials: DG
authors.lastname: Gorenstein
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA.
authors.forename: Xuewu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA; Department of Medicine, Weill Cornell Medical College, 1300 York Avenue, New York 10065, USA. Electronic address: mferrari@houstonmethodist.org.
authors.forename: Mauro
authors.initials: M
authors.lastname: Ferrari
authors.affiliation: Department of Nanomedicine, Houston Methodist Research Institute, 6670 Bertner Ave., Houston 77030, USA; Department of Cell and Developmental Biology, Weill Cornell Medical College, 1300 York Avenue, New York 10065, USA. Electronic address: hshen@houstonmethodist.org.
authors.forename: Haifa
authors.initials: H
authors.lastname: Shen
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry; D001853:Bone Marrow / Q000378:metabolism*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000556:secondary; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000473:pathology; D045744:Cell Line, Tumor; D004337:Drug Carriers / Q000008:administration & dosage* / Q000737:chemistry; D019040:E-Selectin / Q000737:chemistry / Q000378:metabolism*; D042783:Endothelial Cells / Q000378:metabolism; D004727:Endothelium / Q000378:metabolism; D005260:Female; D005269:Femur; D006801:Humans; D061986:MCF-7 Cells; D051379:Mice; D008819:Mice, Nude; D034741:RNA, Small Interfering / Q000008:administration & dosage*; D050796:STAT3 Transcription Factor / Q000235:genetics; D012825:Silicon / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D004337:Drug Carriers; D019040:E-Selectin; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; D012825:Silicon
keywords: Bone metastasis; Breast cancer; E-selectin; Silicon particle; Targeted siRNA delivery; Thioaptamer