Novel nuclear role of HDAC6 in prognosis and therapeutic target for colorectal cancer

Abstract

Histone deacetylase 6 (HDAC6) inhibition is a potential treatment of a wide range of cancer types via the acetylation of diverse proteins in the cytoplasm. However, the regulation of histone acetylation and the maintenance of higher-order chromatin structure remains unidentified. Here, we investigated the effect of selective inhibition of HDAC6 by histone acetylation, chromatin relaxation assays, co-immunoprecipitation, acetylome peptide array and in vivo RNA microarray. Our data shows that nuclear HDAC6 physically interacts with the Histone 4 lysine 12 residue, and that HDAC6 inhibition increases acetylation specifically at this residue in several cancer types. Inhibition induces major chromatin structure modulation, but has no equivalent effect on knockout HDAC6-/- MEF cells. We identified several novel HDAC6-deacetylated substrates and high expression of HDAC6 in colorectal cancer (CRC) tissue association with reduced levels of H4K12ac and independent of the key CRC driver mutations, but positively associated with EGFR expression. Furthermore, in vivo HDAC6 inhibition induces significant tumor regression in a CRC xenograft mice model with significant changes in the expression of functional nuclear genes. We also demonstrated that a DNA damaging agent in combination with selective HDAC6 inhibition is effective and acts synergistically, inducing chromatin relaxation and increased cell death in CRC cells. CRC tissues (Normal versus tumor; n=58 matched pairs) together with TCGA data analysis of 467 CRC patients showed that high HDAC6 expression is associated with metastasis, overall and disease-free survival, and is an independent risk factor of CRC stage progression. Our findings designate a new role for nuclear HDAC6 both in cancer prognosis and as a new therapeutic target for CRC and other types of cancer.

HDAC6 Inhibition Reverses Cisplatin-Induced Mechanical Hypersensitivity via Tonic Delta Opioid Receptor Signaling

“…Although HDAC6 primarily acts in the cytosol ( Hubbert et al, 2002 ; Bali et al, 2005 ), the normalization of Oprd1 expression following treatment with the HDAC6 inhibitor points to transcriptional control. In vitro studies show that residual nuclear HDAC6 can acetylate histones directly, or indirectly through repression of histone aceytltransferases ( Girdwood et al, 2003 ; Liu et al, 2012 ; García-Domínguez et al, 2020 ). HDAC6 may also regulate Oprd1 indirectly through cytosolic interactions with unknown negative regulators.…”

Selective inhibition of HDAC6 regulates expression of the oncogenic driver EWSR1-FLI1 through the EWSR1 promoter in Ewing sarcoma

“…2B) with no changes in HDAC6 expression levels after a 24 h BML-281 treatment in either cytoplasm or nucleus. We also explored nuclear HDAC6 activity in EWS by evaluating the deacetylation of H4K12ac, which we have previously shown to be the specific histone-residue target [17]. HDAC6 inhibition strongly induced H4K12 residue acetylation in EWS cell lines (Fig.…”

“…In fact, several studies revealed a role of HDAC6 in regulating the activity of transcription factor modulators [15,16]. Recently, we identified that HDAC6 specifically regulates histone acetylation at a specific residue, H4K12, in several types of cancer, including EWS [17]. From a clinical point of view, HDAC6 overexpression in many tumor types is associated with poor prognosis, drug resistance, cancer cell proliferation and migration [16,18,19].…”

Role of Histone Deacetylase 6 and Histone Deacetylase 6 Inhibition in Colorectal Cancer

“…HDAC6 regulates signaling pathways that are involved in tumor cell growth, survival, and invasiveness and are often overexpressed in the majority of malignancies, including CRC. An increased expression of HDAC6 was reported in colon cancer tissue compared to the adjacent noncancerous tissue and is often associated with unfavorable disease prognosis [ 18 , 19 ].…”

“…Aside from its deacetylase activity, HDAC6, through the catalytic CD1 domain, exhibits E3 ubiquitin ligase activity [ 21 ]. Proteins in the cytoplasm that are identified as substrates for deacetylation by HDAC6 include α-tubulin, cortactin, heat shock protein (Hsp) 90, heat shock transcription factor-1 (HSF-1), Ku70, p53, peroxiredoxins, signal transducer and activator of transcription (STAT) 3, forkhead box protein O1 (FOXO1), and β-Catenin [ 17 , 18 , 23 , 24 , 25 ] ( Table 1 ).…”