Intensified antineoplastic effect by combining an HDAC-inhibitor, an mTOR-inhibitor and low dosed interferon alpha in prostate cancer cells

Transcriptomic and Epigenomic Profiling of Histone Deacetylase Inhibitor Treatment Reveals Distinct Gene Regulation Profiles Leading to Impaired Neutrophil Development

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The clinical use of histone deacetylase inhibitors (HDACi) for the treatment of bone marrow failure and hematopoietic malignancies has increased dramatically over the last decades. Nonetheless, their effects on normal myelopoiesis remain poorly evaluated. Here, we treated cord blood derived CD34+ progenitor cells with two chemically distinct HDACi inhibitors MS-275 or SAHA and analyzed their effects on the transcriptome (RNA-seq), epigenome (H3K27ac ChIP-seq) and functional and morphological characteristics during neutrophil development. MS-275 (entinostat) selectively inhibits class I HDACs, with a preference for HDAC1, while SAHA (vorinostat) is a non-selective class I/II HDACi. Treatment with individual HDACi resulted in both overlapping and distinct effects on both transcriptome and epigenome, whereas functional effects were relatively similar. Both HDACi resulted in reduced expansion and increased apoptosis in neutrophil progenitor cells. Morphologically, HDACi disrupted normal neutrophil differentiation what was illustrated by decreased percentages of mature neutrophils. In addition, while SAHA treatment clearly showed a block at the promyelocytic stage, MS-275 treatment was characterized by dysplastic features and skewing towards the monocytic lineage. These effects could be mimicked using shRNA-mediated knockdown of HDAC1. Taken together, our data provide novel insights into the effects of HDAC inhibition on normal hematopoietic cells during neutrophil differentiation. These findings should be taken into account when considering the clinical use of MS-275 and SAHA, and can be potentially utilized to tailor more specific, hematopoietic-directed HDACi in the future.

HDAC Inhibition Counteracts Metastatic Re-Activation of Prostate Cancer Cells Induced by Chronic mTOR Suppression

This study was designed to investigate whether epigenetic modulation by histone deacetylase (HDAC) inhibition might circumvent resistance towards the mechanistic target of rapamycin (mTOR) inhibitor temsirolimus in a prostate cancer cell model. Parental (par) and temsirolimus-resistant (res) PC3 prostate cancer cells were exposed to the HDAC inhibitor valproic acid (VPA), and tumor cell adhesion, chemotaxis, migration, and invasion were evaluated. Temsirolimus resistance was characterized by reduced binding of PC3^res cells to endothelium, immobilized collagen, and fibronectin, but increased adhesion to laminin, as compared to the parental cells. Chemotaxis, migration, and invasion of PC3^res cells were enhanced following temsirolimus re-treatment. Integrin α and β receptors were significantly altered in PC3^res compared to PC3^par cells. VPA significantly counteracted temsirolimus resistance by down-regulating tumor cell–matrix interaction, chemotaxis, and migration. Evaluation of integrin expression in the presence of VPA revealed a significant down-regulation of integrin α5 in PC3^res cells. Blocking studies demonstrated a close association between α5 expression on PC3^res and chemotaxis. In this in vitro model, temsirolimus resistance drove prostate cancer cells to become highly motile, while HDAC inhibition reversed the metastatic activity. The VPA-induced inhibition of metastatic activity was accompanied by a lowered integrin α5 surface level on the tumor cells.

Acquired resistance to temsirolimus is associated with integrin α7 driven chemotactic activity of renal cell carcinoma in vitro

The mechanistic target of the rapamycin (mTOR) inhibitor, temsirolimus, has significantly improved the outcome of patients with renal cell carcinoma (RCC). However, development of temsirolimus-resistance limits its effect and metastatic progression subsequently recurs. Since integrin α7 (ITGA7) is speculated to promote metastasis, this investigation was designed to investigate whether temsirolimus-resistance is associated with altered ITGA7 expression in RCC cell lines and modified tumor cell adhesion and invasion. Caki-1, KTCTL-26, and A498 RCC cell lines were driven to temsirolimus-resistance by exposing them to temsirolimus over a period of 12 months. Subsequently, adhesion to human umbilical vein endothelial cells, to immobilized fibronectin, or collagen was investigated. Chemotaxis was evaluated with a modified Boyden chamber assay and ITGA7 expression by flow cytometry and western blotting. Chemotaxis significantly decreased in temsirolimus-sensitive cell lines upon exposure to low-dosed temsirolimus, but increased in temsirolimus-resistant tumor cells upon reexposure to the same temsirolimus dose. The increase in chemotaxis was accompanied by elevated ITGA7 at the cell surface membrane with simultaneous reduction of intracellular ITGA7. ITGA7 knock-down significantly diminished motility of temsirolimous-sensitive cells but elevated chemotactic activity of temsirolimus-resistant Caki-1 and KTCTL-26 cells. Therefore, ITGA7 appears closely linked to adhesion and migration regulation in RCC cells. It is postulated that temsirolimus-resistance is associated with translocation of ITGA7 from inside the cell to the outer surface. This switch forces RCC migration forward. Whether ITGA7 can serve as an important target in combatting RCC requires further investigation.

Hyper-acetylation contributes to the sensitivity of chemo-resistant prostate cancer cells to histone deacetylase inhibitor Trichostatin A

Therapeutic agents are urgently needed for treating metastatic castration‐refractory prostate cancer (mCRPC) that is unresponsive to androgen deprivation and chemotherapy. Our screening assays demonstrated that chemotherapy‐resistant prostate cancer (PCa) cells are more sensitive to HDAC inhibitors than paired sensitive PCa cells, as demonstrated by cell proliferation and apoptosis in vitro and in vivo. Kinetic study revealed that TSA‐induced apoptosis was significantly dependent on enhanced transcription and protein synthesis in an early stage, which subsequently caused ER stress and apoptosis. ChIP analysis indicated that TSA increased H4K16 acetylation, promoting ER stress gene transcription. The changes in Ac‐H4K16, ATF3 and ATF4 were also validated in TSA‐treated animals. Further study revealed the higher enzyme activity of HDACs and an increase in acetylated proteins in resistant cells. The higher nucleocytoplasmic acetyl‐CoA in resistant cells was responsible for elevated acetylation status of protein and a more vigorous growth state. These results strongly support the pre‐clinical application of HDAC inhibitors for treating chemotherapy‐resistant mCRPC.

Combined genetic and epigenetic interferences with interferon signaling expose prostate cancer cells to viral infection

Interferons (IFNs) induce anti-viral programs, regulate immune responses, and exert anti-proliferative effects. To escape anti-tumorigenic effects of IFNs, malignant cells attenuate JAK/STAT signaling and expression of IFN stimulated genes (ISGs). Such attenuation may enhance the susceptibility of tumor cells to oncolytic virotherapy. Here we studied genetic and epigenetic mechanisms of interference with JAK/STAT signaling and their contribution to susceptibility of prostate cancer cells to viral infection. Bioinformatics analysis of gene-expression in cohorts of prostate cancer patients revealed genetic and epigenetic interference with the IFN program. To correlate lack of IFN signaling and susceptibility to viral infection and oncolysis; we employed LNCaP prostate cancer cells as cellular model, and the human metapneumovirus and the epizootic hemorrhagic disease virus as infectious agents. In LNCaP cells, JAK1 is silenced by bi-allelic inactivating mutations and epigenetic silencing, which also silences ISGs. Chemical inhibition of epigenetic silencing partially restored IFN-sensitivity, induced low levels of expression of selected ISGs and attenuated, but failed to block, viral infection and oncolysis. Since viral infection was not blocked by epigenetic modifiers, and these compounds may independently-induce anti-tumor effects, we propose that epigenetic modifiers and virotherapy are compatible in treatment of prostate tumors defective in JAK1 expression and IFN signaling.

Synergistic antitumor activity of histone deacetylase inhibitors and anti-ErbB3 antibody in NSCLC primary cultures via modulation of ErbB receptors expression

ErbB3, a member of the ErbB family receptors, has a key role in the development and progression of several cancers, including non-small cell lung cancer (NSCLC), and in the establishment of resistance to therapies, leading to the development of anti-ErbB3 therapies.

In this study we demonstrated, in a set of malignant pleural effusion-derived cultures of NSCLC, the synergistic antitumor effect of a histone deacetylase inhibitor (HDACi), such as vorinostat or valproic acid (VPA), in combination with the anti-ErbB3 monoclonal antibody (MoAb) A3. Synergistic interaction was observed in 2D and in 3D cultures conditions, both in fully epithelial cells expressing all ErbB receptors, and in cells that had undergone epithelial to mesenchymal transition and expressed low levels of ErbB3. We provided evidences suggesting that differential modulation of ErbB receptors by vorinostat or VPA, also at low doses corresponding to plasma levels easily reached in treated patients, is responsible for the observed synergism. In details, we showed in epithelial cells that both vorinostat and VPA induced time- and dose-dependent down-regulation of all three ErbB receptors and of downstream signaling. On the contrary, in A3-resistant mesenchymal cells, we observed time- and dose-dependent increase of mRNA and protein levels as well as surface expression of ErbB3, paralleled by down-regulation of EGFR and ErbB2. Our results suggest that the combination of a HDACi plus an anti-ErbB3 MoAb represents a viable strategy that warrants further evaluation for the treatment of NSCLC patients.

HDAC inhibition as a treatment concept to combat temsirolimus-resistant bladder cancer cells

Introduction

Although the mechanistic target of rapamycin (mTOR) might be a promising molecular target to treat advanced bladder cancer, resistance develops under chronic exposure to an mTOR inhibitor (everolimus, temsirolimus). Based on earlier studies, we proposed that histone deacetylase (HDAC) blockade might circumvent resistance and investigated whether HDAC inhibition has an impact on growth of bladder cancer cells with acquired resistance towards temsirolimus.

Results

The HDAC inhibitor valproic acid (VPA) significantly inhibited growth, proliferation and caused G0/G1 phase arrest in RT112^res and UMUC-3^res. cdk1, cyclin B, cdk2, cyclin A and Skp1 p19 were down-regulated, p27 was elevated. Akt-mTOR signaling was deactivated, whereas acetylation of histone H3 and H4 in RT112^res and UMUC-3^res increased in the presence of VPA. Knocking down cdk2 or cyclin A resulted in a significant growth blockade of RT112^res and UMUC-3^res.

Materials And Methods

Parental (par) and resistant (res) RT112 and UMUC-3 cells were exposed to the HDAC inhibitor VPA. Tumor cell growth, proliferation, cell cycling and expression of cell cycle regulating proteins were then evaluated. siRNA blockade was used to investigate the functional impact of the proteins.

Conclusions

HDAC inhibition induced a strong response of temsirolimus-resistant bladder cancer cells. Therefore, the temsirolimus-VPA-combination might be an innovative strategy for bladder cancer treatment.

Interferon-α Promotes the Expression of Cancer Stem Cell Markers in Oral Squamous Cell Carcinoma

Objectives: IFNα can stimulate an antitumor immune response and has a direct inhibition on cancer cells. This study is to test whether IFNα can activate dormant cancer stem cell (CSC) in oral squamous cell carcinoma (OSCC) to facilitate their elimination by chemotherapy. Materials and methods: Nude mouse transplantation tumor model was established and administrated with IFNα and saline. The influence on CD44 and ALDH1A1 expression under IFNα treatment was detected by in vivo experiments. Flow cytometry, western blot, and immunofluorescence were used to detect the expression of CD44 and ALDH1A1 after INFa treatment in OSCC cell lines. Tumorsphere formation assay was conducted under incubation with IFNα for 2 weeks. Chromatin immunoprecipitation (ChIP) assays was used to examine the IFNα-induced transcriptional regulation of CD44 and ALDH1A1 expression. That IFNα-primed enhanced killing effect of chemotherapy was evaluated by MTT and western blot. Results: IFNα transcriptionally activated the expression of CD44 and ALDH1A1 expression both in vivo and in vitro. IFNα-primed enhanced the cytotoxic inhibition effect of CDDP, erlotinib and nimotuzumab on OSCC cells. Conclusion: These results suggest that IFNα could be administrated to patients prior to chemotherapeutic drugs, which will facilitate the killing of cancer stem cells in OSCC.

Gd-Metallofullerenol Nanomaterial Suppresses Pancreatic Cancer Metastasis by Inhibiting the Interaction of Histone Deacetylase 1 and Metastasis-Associated Protein 1

The treatment of pancreatic cancer frequently fails due to local recurrence and hepatic metastasis. Our previous study found that Gd@C82(OH)22 can suppress pancreatic cancer by inhibiting MMP-2/9 expression. In this study, we further explored the epigenetic mechanism of Gd@C82(OH)22 in human pancreatic cancer metastasis. Gd@C82(OH)22 suppressed tumor metastasis through down-regulation of metastasis-associated protein 1 (MTA1), HDAC1, HIF-1α, and MMP-2/9 and up-regulation of reversion-cysteine protein with the Kazal motif (RECK). The level of acetylation was increased in the promoter region of the RECK gene after Gd@C82(OH)22 treatment. The interaction of MTA1, HDAC1, and HIF-1α was inhibited by Gd@C82(OH)22. Furthermore, large-scale molecular dynamics simulations revealed Gd@C82(OH)22 could serve as an effective HDAC inhibitor to the protein-protein association between HDAC1 and MTA1, especially through MTA1's SANT and ELM2 dimerization domains. Our findings implicate Gd@C82(OH)22 as a novel HDAC inhibitor acting to increase RECK expression by suppressing the MTA1/HDAC1 co-repressor complex. Gd@C82(OH)22 may serve as a potential HDAC1 inhibitor to suppress pancreatic cancer cell invasion and metastasis both in vitro and in vivo. According to computer analysis and experimental validation, Gd@C82(OH)22 activates RECK expression by inhibiting the interaction of HDAC1 and MTA1.