Patient-derived xenograft model

The cryopreserved pancreatic adenocarcinoma tissues (3rd passage) in our lab [24] were subcutaneously engrafted into the right anterior axillary fossa of BALB/c nude mice (6 weeks). When it grew to ~ 1.5cm³ volume, tumor was removed and once again subcutaneously engrafted into nude mice (6 weeks). The length and the width were measured every two or three days for ~ 6 weeks. Tumor volume was calculated using the formula (volume = 0.5 × length × width²). When tumor volume reached ~500mm³, miR-193a antagonist (RiboBio, China) was used for intra-tumor injection of the irradiated mice. Every mouse was injected 10 nmol miR-193a antagonist in 100 μl volume at twice one week for 4 weeks. The mice were sacrificed around 38 days after injection for in vivo proliferation, repopulation and metastasis assay, and around 50 days for in vivo survival assay, respectively. Tumor tissues and livers were obtained from the mice for further tests.