Furfaro Anna Lisa, Loi Giulia, Ivaldo Caterina, Passalacqua Mario, Pietra Gabriella, Mann Giovanni Enrico, Nitti Mariapaola
Department of Experimental Medicine, University of Genoa, Via L.B. Alberti 2, 16132 Genova, Italy.
Laboratory of Immunology, IRCCS Ospedale Policlinico San Martino, 16132 Genova, Italy.
Antioxidants (Basel). 2022 Jun 14;11(6):1171. doi: 10.3390/antiox11061171.
Induction of heme oxygenase 1 (HO-1) favors immune-escape in BRAF melanoma cells treated with Vemurafenib/PLX4032 under standard cell culture conditions. However, the oxygen tension under standard culture conditions (~18 kPa O) is significantly higher than the physiological oxygen levels encountered in vivo. In addition, cancer cells in vivo are often modified by hypoxia. In this study, MeOV-1 primary melanoma cells bearing the BRAF mutation, were adapted to either 5 kPa O (physiological normoxia) or 1 kPa O (hypoxia) and then exposed to 10 μM PLX4032. PLX4032 abolished ERK phosphorylation, reduced Bach1 expression and increased HO-1 levels independent of pericellular O tension. Moreover, cell viability was significantly reduced further in cells exposed to PLX4032 plus Tin mesoporphyrin IX, a HO-1 inhibitor. Notably, our findings provide the first evidence that HO-1 inhibition in combination with PLX4032 under physiological oxygen tension and hypoxia restores and increases the expression of the NK ligands ULBP3 and B7H6 compared to cells exposed to PLX4032 alone. Interestingly, although silencing NRF2 prevented PLX4032 induction of HO-1, other NRF2 targeted genes were unaffected, highlighting a pivotal role of HO-1 in melanoma resistance and immune escape. The present findings may enhance translation and highlight the potential of the HO-1 inhibitors in the therapy of BRAF melanomas.
在标准细胞培养条件下，用维莫非尼/PLX4032处理的BRAF黑色素瘤细胞中，血红素加氧酶1（HO-1）的诱导有利于免疫逃逸。然而，标准培养条件下的氧张力（约18 kPa O）显著高于体内遇到的生理氧水平。此外，体内癌细胞常因缺氧而发生改变。在本研究中，携带BRAF突变的MeOV-1原发性黑色素瘤细胞被分别置于5 kPa O（生理常氧）或1 kPa O（缺氧）环境中适应，然后暴露于10 μM PLX4032。PLX4032消除了ERK磷酸化，降低了Bach1表达，并增加了HO-1水平，而与细胞周围的氧张力无关。此外，在暴露于PLX4032加锡原卟啉IX（一种HO-1抑制剂）的细胞中，细胞活力进一步显著降低。值得注意的是，我们的研究结果首次证明，与单独暴露于PLX4032的细胞相比，在生理氧张力和缺氧条件下，HO-1抑制与PLX4032联合使用可恢复并增加NK配体ULBP3和B7H6的表达。有趣的是，尽管沉默NRF2可阻止PLX4032诱导HO-1，但其他NRF2靶向基因未受影响，这突出了HO-1在黑色素瘤耐药和免疫逃逸中的关键作用。目前的研究结果可能会加强转化研究，并突出HO-1抑制剂在BRAF黑色素瘤治疗中的潜力。
