The intestinal mucosa is a complex functional layer which is formed from a diverse range of cell types that include epithelial cells (within crypts and villi) and an array of mesenchymal cells. Many intestinal diseases involve loss of the surface mucosa which can be difficult to restore, and which delays healing and return to normal function. We reason that development of a transplantable intestinal mucosal tissue graft may be a potential therapeutic strategy to aid healing. To be clinically useful, such a tissue graft would need to be capable of rapid production, avoid the risk of host rejection and be demonstrably safe. To create a potential intestinal graft, we developed a novel early-stage human induced pluripotent stem cell (hiPSC) co-differentiation platform capable of generating multiple intestinal cell lineages (epithelial, mesenchymal and endothelial) in 8 days. This protocol is simple to implement, serum-free and greatly reduces the use of animal products. We confirmed the identity of cells by demonstrating that these cells had RNA and protein expression profiles typical of intestinal cell lineages. In particular, we used bulk and single-cell RNA sequencing to characterise global cellular transcriptional profiles robustly and showed that the cells have intestinal identity with early polarisation towards colonic differentiation. The results were replicated across multiple hiPSC lines and in an independent centre. We further cultured the derived cells on collagen hydrogels to form colon-like intestinal patches (CL-IPs). When transplanted into mouse subcutis, CL-IPs formed into colon-like tissue structures, including crypts, stromal and muscle layers. They also developed human-origin vasculature which underwent anastomosis with the murine vasculature to transport murine blood into the graft. Teratoma assays and molecular analyses showed no evidence of residual pluripotency. While at an early stage, this platform shows great potential for further development as a potential source for novel intestinal mucosal regeneration therapy. In addition, the platform is physiologically relevant and thus shows promise as the basis for a new generation of in vitro models of intestinal pathobiology.

Bone marrow-derived circulating monocytes continuously replenish intestinal macrophages, which become dysregulated in inflammatory bowel disease (IBD) and contribute to disease pathology. The origins of this dysregulation remain poorly understood. Here, we investigate the reprogramming of circulating monocytes in IBD prior to tissue recruitment using single-cell transcriptomic, epigenomic and functional approaches. We characterise blood monocyte heterogeneity in newly diagnosed, treatment-naïve IBD patients and healthy controls and show that monocytes in Crohn's disease (CD) display a distinct transcriptional profile and altered distributions across inferred developmental trajectories; less pronounced changes are observed in ulcerative colitis (UC). We link CD-associated transcriptional changes to alterations in chromatin accessibility and identify NFB, EGR, KLF and AP-1 family transcription factors as putative regulators of an inflammatory gene program in blood monocytes from CD patients. We uncover a potential role for IFN- in priming blood monocytes for inflammatory function in CD by limiting their capacity to be regulated by IL-10. Finally, we show that the transcriptional and functional alterations in monocytes from CD patients are maintained in monocyte-derived cells from the intestine. Together these data suggest that intestinal macrophage dysfunction in CD is, at least in part, pre-established by systemic signals prior to tissue recruitment.

IntroductionA considerable body of recent evidence supports citrate transport as a major regulator of organismal lifespan and healthspan. Citrate accumulates outside senescent cells in vitro and in vivo. However, the detailed mechanism of senescent cell extracellular citrate (EC) accumulation is not clear.MethodsEC following various drug and cytokine treatments was measured in human fibroblast and keratinocyte conditioned medium by gas chromatography/mass spectroscopy and liquid chromatography/mass spectroscopy. Membrane transporters in similar human fibroblasts cultures were measured by western blotting and more extensively by reverse transcription and quantitative polymerase chain reaction (qPCR) in human fibroblasts, keratinocytes, myoblasts, adipocytes and astrocytes. Mouse tissues were tested for senescence markers and by qPCR, immunofluorescence and immunoFISH telomere associated foci (TAF) staining. Cytokine levels in conditioned medium were measured by the enzyme-linked immunosorbent assay and in mouse brain tissue and plasma samples using the V-PLEX proinflammatory panel 1 mouse kit.Results and DiscussionWe show here that EC is partially mediated by a newly described plasma membrane citrate transporter ANKH/SLC62A1 (progressive human ankylosis -ANKH) in senescent fibroblasts. Analogous to interleukin 6 (IL-6), EC and/or ANKH are regulated by telomere dysfunction, the p38 mitogen-activated kinase axis, transforming growth factor beta and p53, but in contrast not by steroids, sodium butyrate, or Ataxia Telangiectasia Mutated (ATM). ANKH was upregulated in other senescent cell types relevant to ageing but not keratinocytes. In contrast, EC and ANKH were inhibited by interleukin 1α (IL-1α) in dividing and senescent fibroblasts, accompanied by an increase in IL-6 secretion. Loss- and gain of function mutations of ANKH/Ank are associated with disease and interestingly, Ank is also downregulated in both aged mouse liver and brain tissues in parallel with increased senescence markers and several cytokines, suggesting that inflammatory cytokines could inhibit EC production in vivo. These data identify ANKH/Ank as a novel regulator of senescence-derived EC in both humans and mice.

Background and Aims: Survival rates for esophageal squamous cell carcinoma (ESCC) are extremely low due to the late diagnosis of most cases. An understanding of the early molecular processes that lead to ESCC may facilitate opportunities for early diagnosis; however, these remain poorly defined. Tylosis with esophageal cancer (TOC) is a rare syndrome associated with a high lifetime risk of ESCC and germline mutations in RHBDF2, encoding iRhom2. Using TOC as a model of ESCC predisposition, this study aimed to identify early-stage transcriptional changes in ESCC development. Methods: Esophageal biopsies were obtained from control and TOC individuals, the latter undergoing surveillance endoscopy, and adjacent diagnostic biopsies were graded as having no dysplasia or malignancy. Bulk RNA-Seq was performed, and findings were compared with sporadic ESCC vs normal RNA-Seq datasets. Results: Multiple transcriptional changes were identified in TOC samples, relative to controls, and many were detected in ESCC. Accordingly, pathway analyses predicted an enrichment of cancer-associated processes linked to cellular proliferation and metastasis, and several transcription factors were predicted to be associated with TOC and ESCC, including negative enrichment of GRHL2. Subsequently, a filtering strategy revealed 22 genes that were significantly dysregulated in both TOC and ESCC. Moreover, Keratin 17, which was upregulated in TOC and ESCC, was also found to be overexpressed at the protein level in ‘normal’ TOC esophagus tissue. Conclusion: Transcriptional changes occur in TOC esophagus prior to the onset of dysplasia, many of which are associated with ESCC. These findings support the utility of TOC to help reveal the early molecular processes that lead to sporadic ESCC.

Retinoic acid, produced by intestinal dendritic cells (DCs), promotes T cell trafficking to the intestinal mucosa by upregulating α4β7 integrin and inhibiting the generation of cutaneous leukocyte Ag (CLA) required for skin entry. In the present study, we report that activation of human naive CD4 T cells in an APC-free system generates cells expressing α4β7 alone; in contrast, activation by intestinal DCs that produce retinoic acid and induce high levels of α4β7 also results in CLA expression, generating CLA+α4β7+ "dual tropic" cells, with both gut and skin trafficking potential, that also express high levels of α4β1 integrin. DC generation of CLA+α4β7+ T cells is associated with upregulation of FUT7, a fucosyltransferase involved in CLA generation; requires cell contact; and is enhanced by IL-12/IL-23. The blood CD4+ T cell population contains CLA+α4β7+ cells, which are significantly enriched for cells capable of IFN-γ, IL-17, and TNF-α production compared with conventional CLA-α4β7+ cells. Dual tropic lymphocytes are increased in intestinal tissue from patients with Crohn's disease, and single-cell RNA-sequencing analysis identifies a transcriptionally distinct cluster of FUT7-expressing cells present only in inflamed tissue; expression of genes associated with cell proliferation suggests that these cells are undergoing local activation. The expression of multiple trafficking molecules by CLA+α4β7+ T cells can enable their recruitment by alternative pathways to both skin and gut; they may contribute to both intestinal and cutaneous manifestations of inflammatory bowel disease.

BACKGROUND AND AIMS:No effective therapeutic intervention exists for intestinal fibrosis in Crohn's disease [CD]. We characterized fibroblast subtypes, epigenetic and metabolic changes, and signalling pathways in CD fibrosis to inform future therapeutic strategies. METHODS:We undertook immunohistochemistry, metabolic, signalling pathway and epigenetic [Transposase-Accessible Chromatin using sequencing] analyses associated with collagen production in CCD-18Co intestinal fibroblasts and primary fibroblasts isolated from stricturing [SCD] and non-stricturing [NSCD] CD small intestine. SCD/NSCD fibroblasts were cultured with TGFβ and valproic acid [VPA]. RESULTS:Stricturing CD was characterized by distinct histone deacetylase [HDAC] expression profiles, particularly HDAC1, HDAC2, and HDAC7. As a proxy for HDAC activity, reduced numbers of H3K27ac+ cells were found in SCD compared to NSCD sections. Primary fibroblasts had increased extracellular lactate [increased glycolytic activity] and intracellular hydroxyproline [increased collagen production] in SCD compared to NSCD cultures. The metabolic effect of TGFβ stimulation was reversed by the HDAC inhibitor VPA. SCD fibroblasts appeared 'metabolically primed' and responded more strongly to both TGFβ and VPA. Treatment with VPA revealed TGFβ-dependent and TGFβ-independent Collagen-I production in CCD-18Co cells and primary fibroblasts. VPA altered the epigenetic landscape with reduced chromatin accessibility at the COL1A1 and COL1A2 promoters. CONCLUSIONS:Increased HDAC expression profiles, H3K27ac hypoacetylation, a significant glycolytic phenotype and metabolic priming characterize SCD-derived as compared to NSCD fibroblasts. Our results reveal a novel epigenetic component to Collagen-I regulation and TGFβ-mediated CD fibrosis. HDAC inhibitor therapy may 'reset' the epigenetic changes associated with fibrosis.

Single cell RNA sequencing of human full thickness Crohn's disease (CD) small bowel resection specimens was used to identify potential therapeutic targets for stricturing (S) CD. Using an unbiased approach, 16 cell lineages were assigned within 14,539 sequenced cells from patient-matched SCD and non-stricturing (NSCD) preparations. SCD and NSCD contained identical cell types. Amongst immune cells, B cells and plasma cells were selectively increased in SCD samples. B cell subsets suggested formation of tertiary lymphoid tissue in SCD and compared with NSCD there was an increase in IgG, and a decrease in IgA plasma cells, consistent with their potential role in CD fibrosis. Two Lumican-positive fibroblast subtypes were identified and subclassified based on expression of selectively enriched genes as fibroblast clusters (C) 12 and C9. Cells within these clusters expressed the profibrotic genes Decorin (C12) and JUN (C9). C9 cells expressed ACTA2; ECM genes COL4A1, COL4A2, COL15A1, COL6A3, COL18A1 and ADAMDEC1; LAMB1 and GREM1. GO and KEGG Biological terms showed extracellular matrix and stricture organization associated with C12 and C9, and regulation of WNT pathway genes with C9. Trajectory and differential gene analysis of C12 and C9 identified four sub-clusters. Intra sub-cluster gene analysis detected 13 co-regulated gene modules that aligned along predicted pseudotime trajectories. CXCL14 and ADAMDEC1 were key markers in module 1. Our findings support further investigation of fibroblast heterogeneity and interactions with local and circulating immune cells at earlier time points in fibrosis progression. Breaking these interactions by targeting one or other population may improve therapeutic management for SCD.

<p>Supplementary Materials and Methods. Description of additional methods and procedures used in the study.</p>

Tumour budding (TB) describes single or small groups of neoplastic cells that lack continuity with an advancing tumour front. Poorly differentiated clusters (PDCs) are larger and qualitatively different. TB grade and PDCs may predict a worse outcome in colorectal carcinoma and other cancers and fall into the category of ‘invasive front prognostic markers’ that also includes intratumoural stroma type. Epithelial–mesenchymal transition (EMT) allows the adoption by epithelial cells of mesenchymal characteristics such as dyscohesion, migration, and stromal invasion. TB and PDCs harbor alterations in EMT‐related proteins and RNAs and may be morphological manifestations of EMT. However, persistence of epithelioid features and absence of a full complement of typical alterations in TB and PDCs may indicate ‘partial EMT’, i.e. an intermediate/hybrid state. Recently, Pavlič et al asserted that TB and PDCs in colorectal cancer represent different manifestations of partial EMT and, perhaps controversially, that TB is closer than PDCs to complete transition. In clinical practice, low inter‐observer agreement for invasive front prognostic markers is a potential problem. The UK colorectal cancer pathology dataset advises assessment of TB and recommends the use of an international consensus system, but time will tell if we are adopting reliable prognostic markers or reinventing the wheel. Additional studies of TB, PDCs, and EMT will presumably allow greater insight into their role in tumour development and progression. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Supplementary Figures S1-S5. Colon length in wild-type and KitW-sh mice during colitis progression (S1); Il22 and Il22bp relative expression in colon in wild-type and KitW-sh mice (S2); Polyps count in colon of WT and KitW-sh mice (S3); Colorectal cancer development in WT, KitW-sh and KitW-sh REC mice (S4); Summary of MC activity in intestinal mucosal healing and in transformation toward malignancy (S5).

Colonic disease causes significant morbidity and an accurate model of the human colon is urgently needed. Here we describe a 15-day protocol which simultaneously generates intestinal epithelial and mesenchymal cell populations from human induced pluripotent stem cells. Cells were seeded on collagen to create colonic patches (CoPs) and cultured in vitro . Single-cell sequencing of CoPs identified similar cell populations to those seen in normal colon. Engraftment of CoPs into mouse subcutis showed development of mucosa containing epithelial crypts (with enterocytes, goblet cells and neuroendocrine cells), multiple stromal populations, smooth muscle and human blood vessels anastomosed to murine vasculature. We also demonstrate the versatility of our in-vitro model in studies of fibrosis and epithelial-mesenchymal interaction. Stimulation of CoPs with different cytokines resulted in cytokine-specific fibrogenic activity. When iPSC-derived mesenchyme was isolated and co-cultured with different epithelial cancer cell lines, there was cell line-specific alteration of mesenchymal gene expression. As well as utility in disease modelling, the transplantability of CoPs raises their possible use as therapeutic autologous grafts for damaged colon.### Competing Interest StatementThe authors have declared no competing interest.

Abstract Intestinal fibrosis and stricture formation is an aggressive complication of Crohns disease (CD), linked to increased morbidity and costs. The present study investigates the contribution of Wingless-Int-1 (Wnt) signalling to intestinal fibrogenesis, considers potential cross-talk between Wnt and transforming growth factor β1 (TGFβ) signalling pathways, and assesses the therapeutic potential of small-molecule Wnt inhibitors. β-catenin expression was explored by immunohistochemistry (IHC) in formalin-fixed paraffin embedded (FFPE) tissue from patient-matched nonstrictured (NSCD) and strictured (SCD) intestine (n=6 pairs). Functional interactions between Wnt activation, TGFβ signalling, and type I collagen (Collagen-I) expression were explored in CCD-18Co cells and primary CD myofibroblast cultures established from surgical resection specimens (n=16) using small-molecule Wnt inhibitors and molecular techniques, including siRNA-mediated gene knockdown, immunofluorescence (IF), Wnt gene expression arrays, and western blotting. Fibrotic SCD tissue was marked by an increase in β-catenin-positive cells. In vitro, activation of Wnt-β-catenin signalling increased Collagen-I expression in CCD-18Co cells. Conversely, ICG-001, an inhibitor of β-catenin signalling, reduced Collagen-I expression in cell lines and primary CD myofibroblasts. TGFβ increased β-catenin protein levels but did not activate canonical Wnt signalling. Rather, TGFβ up-regulated WNT5B, a noncanonical Wnt ligand, and the Wnt receptor FZD8, which contributed directly to the up-regulation of Collagen-I through a β-catenin-independent mechanism. Treatment of CCD-18Co fibroblasts and patient-derived myofibroblasts with the FZD8 inhibitor 3235-0367 reduced extracellular matrix (ECM) expression. Our data highlight small-molecule Wnt inhibitors of both canonical and noncanonical Wnt signalling, as potential antifibrotic drugs to treat SCD intestinal fibrosis. They also highlight the importance of the cross-talk between Wnt and TGFβ signalling pathways in CD intestinal fibrosis.

Various methods exist to monitor wildlife populations and estimate trends in their distribution and abundance. For American beaver (Castor canadensis), aerial surveys provide a means to obtain abundance data over large areas and typically involve observers searching watercourses and shorelines for active beaver presence. Here, we describe a systematic aerial photographic census we designed and executed in autumn to quantify annual beaver colony abundance on the 184-km(2) Michipicoten Island, Ontario, from 2015 to 2019. Aerial photographs were stitched together into orthophotomosaics after each census and visually searched for beaver food caches, with each food cache representing an independent beaver colony. Our methods revealed that beaver colony abundance declined substantially from a peak of 6.1 colonies/km(2) in 2015, the highest reported across North America, to 0.4 colonies/km(2) in 2018. Beaver abundance remained low through 2019. Although photographing the entire isolated study area required relatively little time and effort, even when beaver density was very high, post-census processing work was time-consuming. Lessons learned will improve efficiencies of our future censuses and aid other researchers. Our method is advantageous over traditional aerial wildlife surveys in that it provides a digital and visual record that can be used for additional analyses.

Background:Mutations in the tumor suppressor gene Adenomatous Polyposis Coli (APC) are found in 80% of sporadic colorectal cancer (CRC) tumors and are also responsible for the inherited form of CRC, Familial adenomatous polyposis (FAP).Methods:To identify novel therapeutic strategies for the treatment of APC mutated CRC, we generated a drug screening platform that incorporates a human cellular model of APC mutant CRC using CRISPR-cas9 gene editing and performed an FDA-approved drug screen targeting over 1000 compounds.Results:We have identified the group of HMG-CoA Reductase (HMGCR) inhibitors known as statins, which cause a significantly greater loss in cell viability in the APC mutated cell lines and in in vivo APC mutated patient derived xenograft (PDX) models, compared to wild-type APC cells. Mechanistically, our data reveals this new synthetic lethal relationship is a consequence of decreased Wnt signalling and, ultimately, a reduction in the level of expression of the anti-apoptotic protein Survivin, upon statin treatment in the APC-mutant cells only. This mechanism acts via a Rac1 mediated control of beta-catenin.Conclusion:Significantly, we have identified a novel synthetic lethal dependence between APC mutations and statin treatment, which could potentially be exploited for the treatment of APC mutated cancers.

Abstract Background Histone acetylation/deacetylation and microRNAs (MiRNA) are epigenetic mechanisms involved in the pathogenesis of inflammatory bowel diseases (IBD). Histone deacetylase (HDAC) inhibitors, such as valproic acid (VPA), demonstrated anti-inflammatory and anti-tumour effects in animal models of colitis.1,2 Modulation of MiRNAs is hypothesized to be a possible mechanism of action of HDAC inhibition.3 Recently, VPA was shown to modulate histone-3 (H3) acetylation and cytokine production in the human gut.4 In this study, we analysed whether VPA influences MiRNA expression in ex-vivo biopsies from IBD patients. Methods Colonic biopsies from IBD patients collected during routine endoscopic procedures were cultured with VPA (5 mM) or control media for 24 hours. Total RNA was extracted and a MiRNA array was performed (miScript™ miRNA PCR Array), profiling the expression of 84 MiRNAs predicted to regulate pro- or anti-inflammatory genes. Significantly altered MiRNAs were then validated in an independent cohort of samples using quantitative (q) RT-PCR. Caco-2 (ATCC® HTB-37™) cell cultures treated with VPA (5 mM) or control media were used to confirm changes of H3 acetylation and MiRNA expression. After 24 hours, H3 acetylation was evaluated by immunofluorescence and apoptotic markers were analysed by qPCR. Results Colonic biopsies from inflamed mucosa of 6 IBD patients (2 with Crohn’s disease (CD) and 4 with ulcerative colitis (UC)) were cultured with VPA or control media. MiRNA analysis showed a significant increase of miR449a, miR373-3p, miR300 and miR520d-3p in treated biopsies compared to control (p=0.004, p=0.024, p=0.04 and p=0.014, respectively). Validation was performed in an independent cohort of 14 IBD patients (7 CD; 7 UC), confirming a significant increase of MiR449a (p=0.026) in VPA treated biopsies. VPA treated Caco-2 cell cultures showed a significant increase of H3 acetylation density level (p=0.02), confirming the HDAC inhibitory activity. Gene expression analysis showed increased Caspase-3 (p=0.015), a pro-apoptotic marker, and decreased BCL-3 (p<0.01), an anti-apoptotic marker. The level of MiR449a expression in VPA treated cells was significantly elevated (p<0.01). Conclusion VPA increases the expression of MiR449a in cultured ex-vivo biopsies and in Caco-2 cells. This MiRNA has recently demonstrated to be involved in IBD pathogenesis and in colitis-associated colon cancer. This may represent a new insight into IBD pathogenesis and colitis-associated colon cancer development. Further work is required to determine the functional significance of miR-499a in the human intestine. References

Abstract Background Histone-deacetylase (HDAC) enzymes are a broad class of ubiquitously expressed enzymes that modulate histone acetylation, chromatin accessibility and gene expression. In models of Inflammatory bowel disease (IBD), HDAC inhibitors, such as Valproic acid (VPA) are proven anti-inflammatory agents and evidence suggests that they also inhibit fibrosis in non-intestinal organs. However, the role of HDAC enzymes in stricturing Crohn’s disease (CD) has not been characterised; this is key to understanding the molecular mechanism and developing novel therapies. Methods To evaluate HDAC expression in the intestine of SCD patients, we performed unbiased single-cell RNA sequencing (sc-RNA-seq) of over 10,000 cells isolated from full-thickness surgical resection specimens of non-SCD (NSCD; n=2) and SCD intestine (n=3). Approximately, 1000 fibroblasts were identified for further analysis, including a distinct cluster of myofibroblasts. Changes in gene expression were compared between myofibroblasts and other resident intestinal fibroblasts using the sc-RNA-seq analysis pipeline in Partek. Changes in HDAC expression and markers of HDAC activity (H3K27ac) were confirmed by immunohistochemistry in FFPE tissue from patient matched NSCD and SCD intestine (n=14 pairs). The function of HDACs in intestinal fibroblasts in the CCD-18co cell line and primary CD myofibroblast cultures (n=16 cultures) was assessed using VPA, a class I HDAC inhibitor. Cells were analysed using a variety of molecular techniques including ATAC-seq, gene expression arrays, qPCR, western blot and immunofluorescent protein analysis. Results Class I HDAC (HDAC1, p= 2.11E-11; HDAC2, p= 4.28E-11; HDAC3, p= 1.60E-07; and HDAC8, p= 2.67E-03) expression was increased in myofibroblasts compared to other intestinal fibroblasts subtypes. IHC also showed an increase in the percentage of stromal HDAC2 positive cells, coupled with a decrease in the percentage of H3K27ac positive cells, in the mucosa overlying SCD intestine relative to matched NSCD areas. In the CCD-18co cell line and primary myofibroblast cultures, VPA reduced chromatin accessibility at Collagen-I gene promoters and suppressed their transcription. VPA also inhibited TGFB-induced up-regulation of Collagen-I, in part by inhibiting TGFB1|1/SMAD4 signalling. TGFB1|1 was identified as a mesenchymal specific target of VPA and siRNA knockdown of TGFB1|1 was sufficient suppress TGFB-induced up-regulation of Collagen-I. Conclusion In SCD patients, class I HDAC expression is increased in myofibroblasts. Class I HDACs inhibitors impair TGFB-signalling and inhibit Collagen-I expression. Selective targeting of TGFB1|1 offers the opportunity to increase treatment specificity by selectively targeting meschenymal cells.

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. Highlight Histone deacetylases 6 activity; Chromatin relaxation; Histone modifications; Gene array; DOX: doxorubicin; OXA: oxaliplatin; 5-FU: fluorouracil; Ac: acetylation; MNase: Micrococal nuclease. ### Competing Interest Statement The authors have declared no competing interest.