Histone deacetylase inhibitor-induced sensitization to TNFalpha/TRAIL-mediated apoptosis in cervical carcinoma cells is dependent on HPV oncogene expression

The Emerging Role of Histone Deacetylase Inhibitors in Cervical Cancer Therapy

Cervical carcinoma is one of the most common cancers among women globally. Histone deacetylase inhibitors (HDACIs) constitute anticancer drugs that, by increasing the histone acetylation level in various cell types, induce differentiation, cell cycle arrest, and apoptosis. The aim of the current review is to study the role of HDACIs in the treatment of cervical cancer. A literature review was conducted using the MEDLINE and LIVIVO databases with a view to identifying relevant studies. By employing the search terms "histone deacetylase" and "cervical cancer", we managed to identify 95 studies published between 2001 and 2023. The present work embodies the most up-to-date, comprehensive review of the literature centering on the particular role of HDACIs as treatment agents for cervical cancer. Both well-established and novel HDACIs seem to represent modern, efficacious anticancer drugs, which, alone or in combination with other treatments, may successfully inhibit cervical cancer cell growth, induce cell cycle arrest, and provoke apoptosis. In summary, histone deacetylases seem to represent promising future treatment targets in cervical cancer.

Do or Die: HPV E5, E6 and E7 in Cell Death Evasion

Human papillomaviruses (HPVs) infect the dividing cells of human epithelia and hijack the cellular replication machinery to ensure their own propagation. In the effort to adapt the cell to suit their own reproductive needs, the virus changes a number of processes, amongst which is the ability of the cell to undergo programmed cell death. Viral infections, forced cell divisions and mutations, which accumulate as a result of uncontrolled proliferation, all trigger one of several cell death pathways. Here, we examine the mechanisms employed by HPVs to ensure the survival of infected cells manipulated into cell cycle progression and proliferation.

Regulation of extrinsic apoptotic signaling by c-FLIP: towards targeting cancer networks

The extrinsic pathway is mediated by death receptors (DRs), including CD95 (APO-1/Fas) or TRAILR-1/2. Defects in apoptosis regulation lead to cancer and other malignancies. The master regulator of the DR networks is the cellular FLICE inhibitory protein (c-FLIP). In addition to its key role in apoptosis, c-FLIP may exert other cellular functions, including control of necroptosis, pyroptosis, nuclear factor κB (NF-κB) activation, and tumorigenesis. To gain further insight into the molecular mechanisms of c-FLIP action in cancer networks, we focus on the structure, isoforms, interactions, and post-translational modifications of c-FLIP. We also discuss various avenues to target c-FLIP in cancer cells for therapeutic benefit.

Novel Suberoylanilide Hydroxamic Acid Analogs Inhibit Angiogenesis and Induce Apoptosis in Breast Cancer Cells

BACKGROUND

Histone deacetylases (HDACs) are the enzymes that catalyze the removal of the acetyl group from lysine residues and regulate several biological processes. Suberoylanilide hydroxamic acid (SAHA) is a notable HDAC inhibitor that exhibited remarkable anti-proliferative efficiency by alleviating gene regulation against solid and hematologic cancers.

AIM

The aim of this study was to develop new chemotherapeutic agents for breast cancer treatment, therefore, a novel series of Suberoylanilide hydroxamic acid (SAHA) analogs were investigated as anticancer agents.

METHODS

We designed and synthesized a novel series of analogs derived from SAHA by substituting alkyl, alkoxy, halo, and benzyl groups at different positions of the phenyl ring. The newly synthesized analogs were assessed for their cytotoxic potential against four human cancer cell lines in comparison with healthy cell lines, using several biological assays.

RESULTS

SAHA analogs displayed significant cytotoxic potential with IC50 values ranging from 1.6 to 19.2 µM in various tumor cell lines. Among these analogs, 2d (containing 3-chloro, 4-floro substitutions on phenyl moiety), 2h (containing 3,4-di chloro substitutions on phenyl moiety), and 2j (containing 4-chloro, 3-methyl substitutions on phenyl moiety) showed significant cytotoxic potential with IC50 values ranging from 1.6 to 1.8 µM in MCF-7 (breast carcinoma) cell line. More importantly, these analogs were found to be non-toxic towards healthy primary human hepatocytes (PHH) and mouse fibroblast cells (NIH3T3), which represent their tumor selectivity. These analogs were further analyzed for their effect on cell migration, BrdU incorporation, Annexin V-FITC and cell cycle arrest (Sub-G1 phase). Remarkably, analogs 2d, 2h, and 2j displayed significant HDAC inhibition than the parent SAHA molecule. Further studies also confirmed that these SAHA analogs are efficient in inducing apoptosis, as they regulated the expression of several proteins involved in mitochondrial or intrinsic apoptosis pathways. Findings in the Chick Chorioallantoic Membrane (CAM) assay studies revealed anti-angiogenic properties of the currently described SAHA analogs.

CONCLUSION

From anti-proliferative study results, it is clearly evident that 3,4-substitution at the SAHA phenyl ring improves the anti-proliferative activity of SAHA. Based on these findings, we presume that the synthesized novel SAHA analogs could be potential therapeutic agents in treating breast cancer.

N-(2'-Hydroxyphenyl)-2-Propylpentanamide (HO-AAVPA) Inhibits HDAC1 and Increases the Translocation of HMGB1 Levels in Human Cervical Cancer Cells

N-(2′-hydroxyphenyl)-2-propylpentanamide (HO-AAVPA) is a VPA derivative designed to be a histone deacetylase (HDAC) inhibitor. HO-AAVPA has better antiproliferative effect than VPA in cancer cell lines. Therefore, in this work, the inhibitory effect of HO-AAVPA on HDAC1, HDAC6, and HDAC8 was determined by in silico and in vitro enzymatic assay. Furthermore, its antiproliferative effect on the cervical cancer cell line (SiHa) and the translocation of HMGB1 and ROS production were evaluated. The results showed that HO-AAVPA inhibits HDAC1, which could be related with HMGB1 translocation from the nucleus to the cytoplasm due to HDAC1 being involved in the deacetylation of HMGB1. Furthermore, an increase in ROS production was observed after the treatment with HO-AAVPA, which also could contribute to HMGB1 translocation. Therefore, the results suggest that one of the possible antiproliferative mechanisms of HO-AAVPA is by HDAC1 inhibition which entails HMGB1 translocation and ROS increased levels that could trigger the cell apoptosis.

Extrachromosomal HPV-16 LCR transcriptional activation by HDACi opposed by cellular differentiation and DNA integration

Histone deacetylase inhibitors (HDACi) have been shown to render HPV-carrying cells susceptible to intrinsic and extrinsic apoptotic signals. As such, these epigenetic drugs have entered clinical trials in the effort to treat cervical cancer. Here, we studied the effect of common HDACi, with an emphasis on Trichostatin A (TSA), on the transcriptional activity of the HPV-16 Long Control Region (LCR) in order to better understand the impact of these agents in the context of the HPV life cycle and infection. HDACi strongly induced transcription of the firefly luciferase reporter gene under the control of the HPV-16 LCR in a variety of cell lines. In the HaCaT keratinocyte cell line undergoing differentiation induced by TSA, we observed a reduction in LCR-controlled transcription. Three major AP-1 binding sites in the HPV-16 LCR are involved in the regulation by TSA. However, whatever the status of differentiation of the HaCaT cells, TSA induced integration of extra-chromosomal transfected DNA into the cellular genome. Although these data suggest caution using HDACi in the treatment of HR HPV infection, further in vivo studies are necessary to better assess the risk.

Sensitizing mucoepidermoid carcinomas to chemotherapy by targeted disruption of cancer stem cells

Mucoepidermoid carcinoma (MEC) is the most common malignancy of salivary glands. The response of MEC to chemotherapy is unpredictable, and recent advances in cancer biology suggest the involvement of cancer stem cells (CSCs) in tumor progression and chemoresistance and radioresistance phenotype. We found that histone acetyltransferase inhibitors (HDACi) were capable of disrupting CSCs in MEC. Furthermore, administration of HDACi prior to Cisplatin (two-hit approach) disrupts CSCs and sensitizes tumor cells to Cisplatin. Our findings corroborate to emerging evidence that CSCs play a key role in tumor resistance to chemotherapy, and highlights a pharmacological two-hit approach that disrupts tumor resistance to conventional therapy.

SAHA inhibits the transcription initiation of HPV18 E6/E7 genes in HeLa cervical cancer cells

High risk human papillomavirus (HPV) is a well recognized causative agent of cervical cancer. Suberoylanilide hydroxamic acid (SAHA) is a potential anti-cervical cancer drug; however, its effect on the expression of HPV E6 and E7 genes remains unclear. Here, we show that, in SAHA treated HeLa cells, HPV18 E6 and E7 mRNA and protein levels were reduced, HPV18 promoter activity was decreased, and the association of RNP II with HPV18 promoter was diminished, suggesting that SAHA inhibited the transcription initiation of HPV18 E6 and E7 genes. In SAHA-treated HeLa, although the level of lysine 9-acetylated histone H3 in the whole cell extracts increased obviously, its enrichment on HPV18 promoter was significantly reduced which is correlated with the down-regulation of HPV E6 and E7.

Utilization of Boron Compounds for the Modification of Suberoyl Anilide Hydroxamic Acid as Inhibitor of Histone Deacetylase Class II Homo sapiens

Histone deacetylase (HDAC) has a critical function in regulating gene expression. The inhibition of HDAC has developed as an interesting anticancer research area that targets biological processes such as cell cycle, apoptosis, and cell differentiation. In this study, an HDAC inhibitor that is available commercially, suberoyl anilide hydroxamic acid (SAHA), has been modified to improve its efficacy and reduce the side effects of the compound. Hydrophobic cap and zinc-binding group of these compounds were substituted with boron-based compounds, whereas the linker region was substituted with p-aminobenzoic acid. The molecular docking analysis resulted in 8 ligands with ΔG_binding value more negative than the standards, SAHA and trichostatin A (TSA). That ligands were analyzed based on the nature of QSAR, pharmacological properties, and ADME-Tox. It is conducted to obtain a potent inhibitor of HDAC class II Homo sapiens. The screening process result gave one best ligand, Nova2 (513246-99-6), which was then further studied by molecular dynamics simulations.

Effect of naive and radiolabeled rhTRAIL on the cervical cancer xenografts in mice

BACKGROUND

There is a need for novel treatments of advanced cervical cancer. We investigated the utility of recombinant human TNF-related apoptosis-inducing ligand (rhTRAIL), a molecule capable of inducing apoptosis in cancer cells, for the therapy of CasKi cervical cancer xenografts in nude mice.

RESULTS

CasKi cells proved to be sensitive in vitro to rhTRAIL with an IC50 of 120 ng/ml. (125)I-tagged rhTRAIL specifically accumulated in CasKi tumors in mice with the highest uptake of 9.4% ID/g at 2 h post-injection. Both naive and 200 µCi (188)Re-tagged rhTRAIL administered in the amount of 0.35 mg/kg body weight significantly retarded CasKi tumor growth to the same extent in mice without the side effects of cisplatin chemotherapeutic control.

CONCLUSION

rhTRAIL is a promising novel agent for treatment of advanced cervical cancer.

Nip the HPV encoded evil in the cancer bud: HPV reshapes TRAILs and signaling landscapes

HPV encoded proteins can elicit ectopic protein–protein interactions that re-wire signaling pathways, in a mode that promotes malignancy. Moreover, accumulating data related to HPV is now providing compelling substantiation of a central role played by HPV in escaping immunosurveillance and impairment of apoptotic response. What emerges is an intricate network of Wnt, TGF, Notch signaling cascades that forms higher-order ligand–receptor complexes routing downstream signaling in HPV infected cells. These HPV infected cells are regulated both extracellularly by ligand receptor axis and intracellularly by HPV encoded proteins and impair TRAIL mediated apoptosis. We divide this review into different sections addressing how linear signaling pathways integrate to facilitate carcinogenesis and compounds that directly or indirectly reverse these aberrant interactions offer new possibilities for therapy in cancer. Although HPV encoded proteins mediated misrepresentation of pathways is difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can target dysregulated pathways in HPV infected cervical cancer cells, thus setting the stage for preclinical models and clinical trials.

Anticancer activity of MPT0E028, a novel potent histone deacetylase inhibitor, in human colorectal cancer HCT116 cells in vitro and in vivo

Recently, histone deacetylase (HDAC) inhibitors have emerged as a promising class of drugs for treatment of cancers, especially subcutaneous T-cell lymphoma. In this study, we demonstrated that MPT0E028, a novel N-hydroxyacrylamide-derived HDAC inhibitor, inhibited human colorectal cancer HCT116 cell growth in vitro and in vivo. The results of NCI-60 screening showed that MPT0E028 inhibited proliferation in both solid and hematological tumor cell lines at micromolar concentrations, and was especially potent in HCT116 cells. MPT0E028 had a stronger apoptotic activity and inhibited HDACs activity more potently than SAHA, the first therapeutic HDAC inhibitor proved by FDA. In vivo murine model, the growth of HCT116 tumor xenograft was delayed and inhibited after treatment with MPT0E028 in a dose-dependent manner. Based on in vivo study, MPT0E028 showed stronger anti-cancer efficacy than SAHA. No significant body weight difference or other adverse effects were observed in both MPT0E028-and SAHA-treated groups. Taken together, our results demonstrate that MPT0E028 has several properties and is potential as a promising anti-cancer therapeutic drug.

Histone deacetylase inhibitor-mediated sensitization to TRAIL-induced apoptosis in childhood malignancies is not associated with upregulation of TRAIL receptor expression, but with potentiated caspase-8 activation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has great potential for the treatment of cancer because it targets tumor cells while sparing normal cells. Several cancers, however, fail to respond to TRAIL's antineoplastic effects. These resistant tumors require cotreatment with sensitizing agents in order for TRAIL to exert anticancer activity. Histone deacetylase inhibitors (HDACi) have been recognized as potent TRAIL sensitizers. In searching for the determinants of TRAIL responsiveness, HDACi-mediated TRAIL sensitization has been predominantly attributed to TRAIL receptor upregulation. This explanation, however, has been challenged by a few studies. The aim of the present study was to explore the relevance of TRAIL receptor expression for HDACi-mediated TRAIL sensitization in childhood tumors, i.e., in medulloblastoma, Ewing's sarcoma and osteosarcoma. In previous studies, we had shown that TRAIL and HDACi were synergistic in inducing apoptosis in medulloblastoma and Ewing's sarcoma. In the present study, we demonstrate that HDACi cooperated with TRAIL in eliciting cell death in osteosarcoma. However, HDACi treatment did not alter or even reduced cell surface expression of TRAIL receptors in the three childhood tumors. In gaining insight into the apoptotic pathway involved in TRAIL sensitization, HDACi were found to potentiate TRAIL-induced caspase-8 activation. Taken together, our findings suggest that HDACi-mediated TRAIL sensitization is not the result of TRAIL receptor upregulation, but the result of a receptor-proximal event in childhood tumor cells.

Knockdown of MTDH sensitizes endometrial cancer cells to cell death induction by death receptor ligand TRAIL and HDAC inhibitor LBH589 co-treatment

Understanding the molecular underpinnings of chemoresistance is vital to design therapies to restore chemosensitivity. In particular, metadherin (MTDH) has been demonstrated to have a critical role in chemoresistance. Over-expression of MTDH correlates with poor clinical outcome in breast cancer, neuroblastoma, hepatocellular carcinoma and prostate cancer. MTDH is also highly expressed in advanced endometrial cancers, a disease for which new therapies are urgently needed. In this present study, we focused on the therapeutic benefit of MTDH depletion in endometrial cancer cells to restore sensitivity to cell death. Cells were treated with a combination of tumor necrosis factor-α-related apoptosis-inducing ligand (TRAIL), which promotes death of malignant cells of the human reproductive tract, and histone deacetylase (HDAC) inhibitors, which have been shown to increase the sensitivity of cancer cells to TRAIL-induced apoptosis. Our data indicate that depletion of MTDH in endometrial cancer cells resulted in sensitization of cells that were previously resistant in response to combinatorial treatment with TRAIL and the HDAC inhibitor LBH589. MTDH knockdown reduced the proportion of cells in S and increased cell arrest in G2/M in cells treated with LBH589 alone or LBH589 in combination with TRAIL, suggesting that MTDH functions at the cell cycle checkpoint to accomplish resistance. Using microarray technology, we identified 57 downstream target genes of MTDH, including calbindin 1 and galectin-1, which may contribute to MTDH-mediated therapeutic resistance. On the other hand, in MTDH depleted cells, inhibition of PDK1 and AKT phosphorylation along with increased Bim expression and XIAP degradation correlated with enhanced sensitivity to cell death in response to TRAIL and LBH589. These findings indicate that targeting or depleting MTDH is a potentially novel avenue for reversing therapeutic resistance in patients with endometrial cancer.

TNFα cooperates with IFN-γ to repress Bcl-xL expression to sensitize metastatic colon carcinoma cells to TRAIL-mediated apoptosis

Background

TNF-related apoptosis-inducing ligand (TRAIL) is an immune effector molecule that functions as a selective anti-tumor agent. However, tumor cells, especially metastatic tumor cells often exhibit a TRAIL-resistant phenotype, which is currently a major impediment in TRAIL therapy. The aim of this study is to investigate the synergistic effect of TNFα and IFN-γ in sensitizing metastatic colon carcinoma cells to TRAIL-mediated apoptosis.

Methodology/Principal Findings

The efficacy and underlying molecular mechanism of cooperation between TNFα and IFN-γ in sensitizing metastatic colon carcinoma cells to TRAIL-mediated apoptosis were examined. The functional significance of TNFα- and IFN-γ-producing T lymphocyte immunotherapy in combination with TRAIL therapy in suppression of colon carcinoma metastasis was determined in an experimental metastasis mouse model. We observed that TNFα or IFN-γ alone exhibits minimal sensitization effects, but effectively sensitized metastatic colon carcinoma cells to TRAIL-induced apoptosis when used in combination. TNFα and IFN-γ cooperate to repress Bcl-xL expression, whereas TNFα represses Survivin expression in the metastatic colon carcinoma cells. Silencing Bcl-xL expression significantly increased the metastatic colon carcinoma cell sensitivity to TRAIL-induced apoptosis. Conversely, overexpression of Bcl-xL significantly decreased the tumor cell sensitivity to TRAIL-induced apoptosis. Furthermore, TNFα and IFN-γ also synergistically enhanced TRAIL-induced caspase-8 activation. TNFα and IFN-γ was up-regulated in activated primary and tumor-specific T cells. TRAIL was expressed in tumor-infiltrating immune cells in vivo, and in tumor-specific cytotoxic T lymphocytes (CTL) ex vivo. Consequently, TRAIL therapy in combination with TNFα/IFN-γ-producing CTL adoptive transfer immunotherapy effectively suppressed colon carcinoma metastasis in vivo.

Conclusions/Significance

TNFα and IFN-γ cooperate to overcome TRAIL resistance at least partially through enhancing caspase 8 activation and repressing Bcl-xL expression. Combined CTL immunotherapy and TRAIL therapy hold great promise for further development for the treatment of metastatic colorectal cancer.

c-FLIP degradation mediates sensitization of pancreatic cancer cells to TRAIL-induced apoptosis by the histone deacetylase inhibitor LBH589

Great efforts have been made to develop novel and efficacious therapeutics against pancreatic cancer to improve the treatment outcomes. Tumor-necrosis factor-related apoptosis-inducing ligand (TRAIL) is such a therapeutic cytokine with selective killing effect toward malignant cells. However, some human pancreatic cancers are intrinsically resistant to TRAIL-mediated apoptosis or therapy. In this study, we have shown that the histone deacetylase inhibitor LBH589 can synergize with TRAIL to augment apoptosis even in TRAIL-resistant cells. LBH589 decreased c-FLIP levels in every tested cell line and survivin levels in some of the tested cell lines. Enforced expression of ectopic c-FLIP, but not survivin, abolished the cooperative induction of apoptosis by the combination of LBH589 and TRAIL, indicating that c-FLIP downregulation plays a critical role in LBH589 sensitization of pancreatic cancer cells to TRAIL. Moreover, LBH589 decreased c-FLIP stability and the presence of the proteasome inhibitor MG132 prevented c-FLIP from reduction by LBH589. Correspondingly, we detected increased levels of ubiqutinated c-FLIP in LBH589-treated cells. These data thus indicate that LBH589 promotes ubiqutin/proteasome-mediated degradation of c-FLIP, leading to downregulation of c-FLIP. Collectively, LBH589 induces c-FLIP degradation and accordingly sensitizes pancreatic cancer cells to TRAIL-induced apoptosis, highlighting a novel therapeutic regimen against pancreatic cancer.