"Keaping" a lid on lung cancer: the Keap1-Nrf2 pathway
CELL CYCLE
Authors: Best, Sarah A.; Sutherland, Kate D.
Abstract
Lung cancer remains one of the world's deadliest cancers, with effective targeted treatment options available for only a small subset of patients. The rapid expansion of cancer genomics in recent years has provided insight into the genetic landscape of all major lung cancer subtypes and led to new discoveries on the heterogeneous biology underlying lung tumorigenesis. Interestingly, these studies have revealed a high frequency of alterations in the Kelch-like ECG-associated protein 1 (KEAP1)-Nuclear factor erythoid-2-related factor 2 (NRF2) stress response pathway, for which no targeted treatments are currently available. In this review, we describe the molecular mechanisms underlying NRF2 pathway activation in lung cancer cells, with a focus on in vivo functional studies in genetically engineered mouse models. Importantly, potential avenues and implications for therapeutic targeting of KEAP1-NRF2 pathway vulnerabilities for lung cancer patients will be highlighted.
Epigenetic CpG Methylation of the Promoter and Reactivation of the Expression of GSTP1 by Astaxanthin in Human Prostate LNCaP Cells
AAPS JOURNAL
Authors: Yang, Yuqing; Fuentes, Francisco; Shu, Limin; Wang, Chao; Pung, Doug; Li, Wenji; Zhang, Chengyue; Guo, Yue; Kong, Ah-Ng
Abstract
Astaxanthin (AST), a red dietary carotenoid, has synergistic antioxidant effects with polyunsaturated fatty acids at low concentrations via Nuclear factor (erythroid-derived 2)-like 2 (NFE2L2 or Nrf2)/antioxidant response element (ARE) signaling. In addition, chromatin remodeling and DNA methylation-based gene silencing represent a common mechanism in prostate carcinogenesis and tumor progression from normal cells to pre-initiated cells and ultimately to invasive carcinoma. Therefore, the control of epigenetic modification and the transcriptional/translational control of the activation of Nrf2 and Nrf2-target genes, including glutathione S-transferases (GSTs), appear to be an important mechanism that protects cells against injuries from oxidative stress and cancer development. In this study, we aim to investigate the role of AST in reactivating the expression of Nrf2 and GSTP1 through epigenetic modification in human prostate LNCaP cells. Treatment with AST in human LNCaP cells reduced the methylation of 21 CpG sites of the GSTP1 CpG island but did not affect the three CpG sites of the Nrf2 promoter region. AST induced the mRNA expression and protein expression of both Nrf2 and GSTP1. It also increased the mRNA expression of NQO1 in sh-mock LNCaP cells but not in sh-SETD7 LNCaP cells. Furthermore, AST reduced the protein expression of DNMT3b and significantly inhibited DNMT and HDAC activities in vitro. Taken together, these results suggest that AST decreased the methylation status of the GSTP1, and these epigenetic modifying effects may originate from the decreasing activities of epigenetic modification enzymes, contributing to the overall beneficial health effects of AST.