Nrf2 status affects tumor growth, HDAC3 gene promoter associations, and the response to sulforaphane in the colon

Abstract

BackgroundThe dietary agent sulforaphane (SFN) has been reported to induce nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2)-dependent pathways as well as inhibiting histone deacetylase (HDAC) activity. The current investigation sought to examine the relationships between Nrf2 status and HDAC expression in preclinical and translational studies.ResultsWild type (WT) and Nrf2-deficient (Nrf2−/+) mice were treated with the colon carcinogen 1,2-dimethylhydrazine (DMH) followed by 400 ppm SFN in the diet (n = 35 mice/group). WT mice were more susceptible than Nrf2−/+ mice to tumor induction in the colon. Tumors from WT mice had higher HDAC levels globally and locally on genes such as cyclin-dependant kinase inhibitor 2a (Cdkn2a/p16) that were dysregulated during tumor development. The average tumor burden was reduced by SFN from 62.7 to 26.0 mm3 in WT mice and from 14.6 to 11.7 mm3 in Nrf2−/+ mice. The decreased antitumor activity of SFN in Nrf2−/+ mice coincided with attenuated Cdkn2a promoter interactions involving HDAC3. HDAC3 knockdown in human colon cancer cells recapitulated the effects of SFN on p16 induction. Human subjects given a broccoli sprout extract supplement (200 μmol SFN equivalents), or reporting more than five cruciferous vegetable servings per week, had increased p16 expression that was inversely associated with HDAC3 in circulating peripheral blood mononuclear cells (PBMCs) and in biopsies obtained during screening colonoscopy.ConclusionsNrf2 expression varies widely in both normal human colon and human colon cancers and likely contributes to the overall rate of tumor growth in the large intestine. It remains to be determined whether this influences global HDAC protein expression levels, as well as local HDAC interactions on genes dysregulated during human colon tumor development. If corroborated in future studies, Nrf2 status might serve as a biomarker of HDAC inhibitor efficacy in clinical trials using single agent or combination modalities to slow, halt, or regress the progression to later stages of solid tumors and hematological malignancies.Electronic supplementary materialThe online version of this article (doi:10.1186/s13148-015-0132-y) contains supplementary material, which is available to authorized users.

Heterocyclic Analogs of Sulforaphane Trigger DNA Damage and Impede DNA Repair in Colon Cancer Cells: Interplay of HATs and HDACs

“…Whole cell extracts were prepared and immunoblotted as described previously . Frozen samples of colon tumors and/or adjacent tissue were thawed and subjected to immunoblotting using the reported methodology . Briefly, proteins (20 μg per lane) were separated by SDS‐PAGE on 4–12% Bis–Tris gel, and transferred to nitrocellulose membranes (Invitrogen).…”

Reciprocal regulation of BMF and BIRC5 (Survivin) linked to Eomes overexpression in colorectal cancer

“…Proteins were immunoblotted using the methodologies reported [17–23]. Primary antibodies were from the following sources: Eomes/anti-TBR2 (Abcam); poly(ADP-ribose)polymerase (PARP), cleaved caspase 3, cleaved caspase 7, Survivin and Bmf (Cell Signaling, Beverly, MA, USA); β -actin (Sigma, St. Louis, MO, USA).…”

“…Primary antibodies were from the following sources: Eomes/anti-TBR2 (Abcam); poly(ADP-ribose)polymerase (PARP), cleaved caspase 3, cleaved caspase 7, Survivin and Bmf (Cell Signaling, Beverly, MA, USA); β -actin (Sigma, St. Louis, MO, USA). Proteins were visualized and quantified as reported [18,19,23]. …”

Oncogenic targets Mmp7, S100a9, Nppb and Aldh1a3 from transcriptome profiling of FAP and Pirc adenomas are downregulated in response to tumor suppression by Clotam

“…All studies were approved by the Institutional Animal Care & Use Committee under protocol # 2014–0217‐IBT. Frozen colon tumor samples and their matched controls were thawed and prepared for molecular analysis as reported, including RNA quality verification and cDNA library generation . Sequencing of human samples was performed on an Illumina HiSeq 2000 sequencer at the MD Anderson Sequencing Core Facility, whereas rat samples were run on an Illumina HiSeq 2500 instrument in the Texas A&M Genomics and Bioinformatics Services Core.…”