Correlation of expression of Major Vault Protein with androgen receptor and immune checkpoint protein B7-H3, and with poor prognosis in prostate cancer

Prostate cancer diagnosis and early stratification is an important aspect to avoid undertreatment of high-risk prostate cancer patients. Major Vault Protein (MVP) has been proposed as a prognostic biomarker in prostate cancer. PTEN and the immune checkpoint protein B7-H3 interact with MVP and are important in prostate cancer progression and therapy response. We evaluated the expression of MVP by immunohistochemistry of tissue microarray samples from a retrospective cohort consisting of 119 prostate cancer patients. We correlated the protein expression of MVP with clinicopathological characteristics, and protein expression of androgen receptor (AR), PTEN, immune checkpoint proteins B7-H3 and PD-L1. We found MVP to be expressed in 53 % of prostate tumors, and correlated positively with biochemical recurrence (rho = 0.211/p = 0.021). Furthermore, we found positive correlation of MVP expression with expression of AR (rho = 0.244/p = 0.009) and the immune checkpoint protein B7-H3 (rho = 0.200/p = 0.029), but not with PD-L1 (rho = 0.152/p = 0.117) or PTEN expression (rho = -0.034/p = 0.721). Our findings support the notion that expression of MVP is associated with poor prognosis in prostate cancer. The correlation between MVP and immune checkpoint protein B7-H3 in prostate cancer suggests a role for MVP in immunoregulation and drug resistance.

Automated summary

MVP is expressed in prostate cancer and positively correlated with biochemical recurrence, and it is also positively correlated with androgen receptor and immune checkpoint protein B7-H3, but not with PD-L1 or PTEN expression. MVP may play a significant role in immune regulation and drug resistance in prostate cancer.