Fig. 1

Immunohistochemical analysis of CLDN1 expression in post-chemotherapy colorectal cancer liver metastasis specimens. (A) Representative images of liver metastases from colorectal cancers after chemotherapy with various CLDN1 expression levels: no detectable signal (a), weak (b), moderate (c), and strong signal intensity (d); immunoperoxidase x400. (B) CLDN1 membrane expression in a non-treated metastasis (a), in residual tumor cells of liver metastasis specimens that displayed minor response (b) and major response (c) to chemotherapy; immunoperoxidase x400. (C) Comparison of CLDN1 expression in untreated (n = 26), major response (n = 48) and minor response (n = 41) metastasis specimens from patients with colorectal cancer. * p = 0.018 and **p = 0.002 (Kruskal-Wallis test). (D) CLDN1 RNA expression before/after chemotherapy in metastasis specimens from one responder (R) and one non-responder (NR) patients with colorectal cancer according to the RECIST response criteria: R (-87%), NR (0%). Quantitative RT-PCR was performed twice on each of the two different RNA samples from the same metastatic biopsy both prior to treatment and after treatment (n = 4). ****p < 0.0001 (one-way ANOVA test)