Induction of heme oxygenase-1 in normal and malignant B lymphocytes by 15-deoxy-Δ12,14-prostaglandin J2 requires Nrf2

Heme-oxygenase-1 (HO-1) is induced in response to oxidative stress and is believed to be a cytoprotective and anti-inflammatory enzyme. It is unknown whether normal or malignant human B-lineage cells express HO-1. 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) is an interesting electrophilic lipid mediator able to increase oxidative stress in B cells. Here, we tested normal and malignant human B-lineage cells for their ability to express HO-1 in response to 15d-PGJ2, as well as the signaling pathways required for HO-1 expression. 15d-PGJ2 potently induced HO-1 protein expression in normal and malignant B cells. Malignant B cells exhibited a greater induction of HO-1 protein compared to normal B lymphocytes. Using siRNA directed against the transcription factor Nrf2 and B cells isolated from Nrf2-deficient mice, we show that HO-1 induction by 15d-PGJ2 is dependent on Nrf2. These results show that, compared to normal B lymphocytes, malignant B cells have a greater capacity to increase their HO-1 protein levels in response to 15d-PGJ2. We speculate that the ability to highly express HO-1 by malignant B cells could confer a survival advantage.