ORIGINAL ARTICLE Downregulation of CD73 in 4T1 breast cancer cells through siRNA-loaded chitosan-lactate nanoparticles Farhad Jadidi-Niaragh 1,2,3 & Fatemeh Atyabi 4,5 & Ali Rastegari 4 & Esmail Mollarazi 6 & Melika Kiani 4 & Alireza Razavi 1 & Mehdi Yousefi 2,3 & Nasim Kheshtchin 7 & Hadi Hassannia 1 & Jamshid Hadjati 7 & Fazel Shokri 1,8 Received: 22 November 2015 /Accepted: 21 December 2015 /Published online: 5 January 2016 # International Society of Oncology and BioMarkers (ISOBM) 2016 Abstract The immunosuppressive factors in tumor microen- vironment enhance tumor growth and suppress anti-tumor im- mune responses. Adenosine is an important immunosuppres- sive factor which can be secreted by both tumor and immune cells trough action of two cell surface ecto-nucleotidase mol- ecules CD39 and CD73. Blocking the adenosine generating molecules has emerged as an effective immunotherapeutic approach for treatment of cancer. In this study, CD73-siRNA encapsulated into chitosan-lactate (ChLa) nanoparticles (NPs) was employed to suppress the expression of CD73 molecule on 4T1 breast tumor cells, in vitro. ChLa NPs were generated through ionic gelation of ChLa by tripolyphosphate (TPP). Small interfering RNA (SiRNA)-loaded NPs had about 100 nm size with a polydispersive index below 0.3 and a zeta potential about 13. Our results showed that ChLa NPs with Ch 50 kDa exhibit the best physicochemical features with the high siRNA encapsulation capacity. Synthesized NPs were able to fully bind with siRNA, protect them against serum and heparin degradation, and promote the transfection pro- cess. While the NPs exhibited low toxicity during 72 h cell culture, the transfection of Ch-plasmid expressing green fluo- rescent protein (pEGFP) NPs was efficient in 4T1 cells with a transfection rate of 53.6 % as detected by flow cytometry. In addition, CD73-siRNA-loaded ChLa NPs could efficiently suppress the expression of CD73 as assayed by real-time po- lymerase chain reaction and flow cytometry. As a conclusion, CD73-siRNA-loaded ChLa NPs may be considered as a promising therapeutic tool for cancer therapy; however, fur- ther in vivo investigations are necessary. Keywords CD73 . siRNA . Nanoparticle . Cancer . Treatment Introduction Immunosuppressive factors in tumor microenvironment pro- mote tumor growth through the inhibition of anti-tumor re- sponses [1]. Several immune cells such as regulatory T (Treg) cells [ 2 , 3], myeloid derived suppressor cells (MDSCs) [4, 5], tumor associated macrophages [6], type II natural killer T (NKT II) [7, 8], and regulatory B (Breg) cells [9] can exert immunosuppressive effects which help to pro- mote tumor growth. In addition to immunosuppressive cells, various soluble factors such as interleukin (IL)-10, IL-35, transforming growth factor (TGF)-β, hypoxia-inducible * Fatemeh Atyabi atyabifa@tums.ac.ir * Fazel Shokri fshokri@tums.ac.ir 1 Department of Immunology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran 2 Immunology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran 3 Department of Immunology, Faculty of Medicine, Tabriz University of Medical Sciences, Tabriz, Iran 4 Department of Pharmaceutical Nanotechnology, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran 1714614411, Iran 5 Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran 6 Food and Drug Control Laboratories and Food and Drug Laboratory Research Centre, MOHME, Tehran, Iran 7 Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran 8 Monoclonal Antibody Research Center, Avicenna Research Institute, ACECR, Tehran, Iran Tumor Biol. (2016) 37:8403–8412 DOI 10.1007/s13277-015-4732-0