Pax 8

Hematoxylin–eosin (HE) staining and immunohistochemistry (IHC) were adopted to compare the morphology and protein expression of paired patient (PA) and PDX samples. Eight primary antibodies were used: PAX-8 (Abnova, Cat# PAB14858), CK7 (Abcam, Cat# ab154334), CK20 (Abcam, Cat# ab217192), P16 (Abcam, Cat# ab189034), P53 (Abcam, Cat# ab131442), WT-1 (Abcam, Cat# ab180840), ER (Abcam, Cat# ab3575), and PR (Abcam, Cat# ab191138). Sections were then treated with the secondary antibody (anti-rabbit IgG, Abcam, Cat# ab6120), followed by DAB chromogenic and hematoxylin staining.

Formalin-fixed, paraffin-embedded sections from the peritoneal xenografts were examined as previously described [10 (link)]. Visualization was achieved using the EnVision + peroxidase system (Dako, Glostrup, Denmark). The antibodies used were against EpCAM and MUC4 (Abcam, Cambridge, UK), as well as Ber-EP4, carcinoembryonic antigen (CEA), calretinin, WT-1, CK20, CK7 and CDX2 (Dako). In addition the antibodies PAX8 (Abnova, Taipei City, Taiwan), B72.3 (BioGenex, Fremont, CA), Claudin-3 (CLD3) (Zymed, San Fransisco, CA), and Villin (Immunotec, Indianapolis, IN) were used. Negative control consisted of sections that underwent similar staining procedures with nonrelevant rabbit immunoglobulins or a monoclonal antibody of the same isotype as the primary antibody used. For all antibodies, positive controls were included with satisfactory results. The study pathologist (BD) evaluated immunohistochemical staining.