Reduced expression of semaphorin 4D and plexin-B in breast cancer is associated with poorer prognosis and the potential linkage with oestrogen receptor.

Involvement of semaphorin 4D (Sema4D) and the receptor proteins of the plexins B family (plexin-B1, -B2 and -B3) in solid tumours suggests they play a role in breast cancer. In the present study, the expression of Sema4D and plexin-Bs was examined in a breast cancer cohort. The expression of Sema4D and plexin-Bs was examined in 147 tumours together with 22 normal mammary tissues using quantitative PCR along with clinicopathological patient data, as well as in MCF-7 and MDA-MB-231 cell lines treated with selective oestrogen receptor modulators (SERMs). The expression of Sema4D, plexin-B1 and -B2 was markedly reduced in tumours with local recurrence, compared to the patients that remained disease-free. The reduced Sema4D expression was associated with poorer disease-free survival (median, 111.6 months, 95% CI, 96.5-126.7), compared to the patients with a higher expression (median, 144.0 months; 95% CI, 130.8-157.3; p=0.033). A reduced expression of plexin-B1 was observed in tumours with poorer differentiation and was associated with poorer overall and disease-free survival. No similar association was identified in relation to plexin-B2 and -B3. A higher expression of Sema4D and plexin-B1 was observed in the ERα-positive tumours compared to the ERα-negative tumours. The expression of these molecules was largely regulated in breast cancer cells exposed to SERMs. A decreased expression of Sema4D, plexin-B1 and -B2 was associated with local recurrence and poor prognosis. Response to SERMs indicated potential perspectives of these molecules in clinical assessment and management of diseases.