Background Claudin-18 (CLDN18) is a recently identified anticancer therapeutic target with promising results
for various gastrointestinal malignancies. The role of CLDN18 in prostatic carcinoma has not been investigated. The
aim of this study was to investigate CLDN18 and androgen receptor (AR) expression in prostatic carcinoma and to link
these findings with other clinicopathological characteristics. This retrospective study was carried out on 120 cases
of prostatic lesions, including 100 cases of prostatic carcinoma and 20 cases of benign prostatic hyperplasia. The
immunohistochemical staining technique was used to evaluate the expression of both CLDN18 and AR in prostatic
carcinoma in relation to clinicopathological parameters.
Results CLDN18 expression was completely absent in benign prostatic tissue, while it was detected in the membrane of 30 (30%) of studied carcinoma cases, with a statistically significant difference (p=0.046). In contrast
to other variables, a statistically significant relationship was identified between CLDN18 expression and Gleason
Grade group (p=0.000), stage (p=0.03), and nodal metastasis (p=0.000). The expression of the androgen receptor
was detected in the nucleus of 96 (96%) of the cancer cases under study, with no statistically significant difference
between the studied groups (p=0.427). A statistically significant relation was found between AR expression and Gleason Grade group (p=0.03) and stage (p=0.01), while no relation with other variables was detected. AR expression
and CLDN18 expression were shown to be statistically significantly correlated (p=0.002).
Conclusions CLDN18 was expressed in prostatic carcinoma and correlated with an adverse tumor outcome. CLDN18
may be regulated by AR. CLDN18 could be a candidate therapeutic marker for the treatment of prostatic carcinoma.