Induction of MAGE-3 expression in lung and esophageal cancer cells

Novel molecular targeted therapy for esophageal cancer

Esophageal cancers are highly lethal neoplasms which are generally refractory to conventional multidisciplinary interventions. Recent elucidation of the mechanisms of esophageal carcinogenesis, as well as preclinical studies utilizing chromatin remodeling agents and inhibitors of oncogene signaling in conjunction with conventional chemotherapeutic agents provide new opportunities for the development of potentially efficacious molecular targeted therapies for these malignancies.

Nuclear accumulation of histone deacetylase 4 (HDAC4) coincides with the loss of androgen sensitivity in hormone refractory cancer of the prostate

OBJECTIVES

To examine the effect of androgen treatment upon histone deacetylase 4 (HDAC4) localisation and, thus, enzymatic function in androgen sensitive prostate cancer (CaP) models. To study HDAC4 expression in benign prostatic hyperplasia, primary and hormone refractory (HR) CaP and to investigate the involvement of histone deacetylase activity in the development of the androgen insensitive phenotype.

METHODS

Immunohistochemical staining of prostate sections of both benign tissue and primary and hormone relapsed prostate cancer, as well as of the CWR22 mouse xenograft model, and indirect quantitative immunofluorescence staining of endogenous HDAC4 in LNCaP cells.

RESULTS

HDAC4 is recruited to the nuclei of HR cancer cells, where it may exert an inhibitory effect on differentiation and contribute to the development of the aggressive phenotype of late stage CaP. The above may result from the loss of androgen responsiveness characterising HR CaP, since HDAC4 nuclear localisation is regulated by androgens in androgen responsive systems (i.e. LNCaP, CWR22) reflecting earlier phase disease.

CONCLUSIONS

HDAC4 may contribute to the development of HR CaP and, therefore, constitute a potential therapeutic target, particularly in the most lethal phase of androgen independence.

Upregulation and nuclear recruitment of HDAC1 in hormone refractory prostate cancer

BACKGROUND

Histone deacetylase 1 (HDAC1) is a co-repressor involved in differentiation and proliferation control. It is upregulated in malignant compared to benign tissue, and targets a number of transcription factors including p53.

METHODS

By immunohistochemistry, HDAC1 protein expression was investigated in human prostate specimens and the CWR22 mouse xenograft model. Flow cytometry and deconvolution immunofluorescence were also performed.

RESULTS

HDAC1 was upregulated in pre-malignant and malignant lesions, with the highest increase in expression in hormone refractory (HR) cancer. Using the CWR22 xenograft model we showed androgen dependent regulation of HDAC1. HDAC1 overexpression led to a significant increase in proliferation and a shift towards the undifferentiated cytokeratin (CK) profile in a PC3M derivative clone constitutively expressing HDAC1.

CONCLUSION

This study underlines the importance of HDAC1 in cell proliferation and the development of prostate cancer (CaP) and proposes a mechanism for HDAC1 nuclear recruitment. HDAC1 may constitute a crucial therapeutic target particularly in the most lethal phase of androgen independence.

Genomic Surgery for Lung Cancer

An emerging body of literature indicates that reversible alterations in chromatin structure modulate gene expression during malignant transformation. Chromatin structure is regulated in part by DNA methylation and histone acetylation; these independent yet highly interrelated epigenetic processes are influenced by a variety of signal transduction pathways. The present review highlights recent advances regarding cancer epigenetics, focusing on the potential utilization of chromatin remodeling agents to induce apoptosis and enhance the immunogenicity of thoracic malignancies.

Active, specific immunotherapy for lung cancer: hurdles and strategies using genetic modification

Active immunotherapy for lung cancer has been a challenge because of the poor antigenic characterization of these tumors and their ability to escape the immune response. However, knowledge of the mechanisms of anti-tumor immunity has expanded significantly over the past decade, leading to the development of more novel, specific strategies for augmenting the immune response. Genetic manipulation of tumor cells, immune cells, or both, may help overcome some of the previously encountered difficulties of immunotherapy. Laboratory and clinical investigations are currently ongoing to evaluate the feasibility and potential benefit of these novel approaches.

Epigenetic targets for immune intervention in human malignancies

Emerging evidences suggest that epigenetic events associated with tumor development and progression, such as deregulated methylation of CpG dinucleotides and aberrant histone acetylation, may impair the immunogenic potential of cancer cells. In fact, DNA hypermethylation and/or histone deacetylation contribute to the absent or downregulated expression of different components of the 'tumor recognition complex' (i.e., HLA class I antigens, cancer/testis antigens and accessory/costimulatory molecules) in solid and hemopoietic human malignancies. However, pharmacologic agents that induce DNA hypomethylation or inhibit histone deacetylation can modify these epigenetic phenomena, restoring the defective expression of selected components of the 'tumor recognition complex' in cancer cells. These antigenic modifications positively modulate the immunogenicity and the immune recognition of cancer cells, making epigenetic drugs attractive agents to design new combined chemoimmunotherapeutic strategies for the treatment of cancer patients.

Ineffectiveness of histone deacetylase inhibitors to induce apoptosis involves the transcriptional activation of NF-kappa B through the Akt pathway

Histone deacetylase (HDAC) inhibitors are emerging as a new class of anticancer agents for the treatment of solid and hematological malignancies. Although HDAC inhibitors induce cell death through an apoptotic process, little is known about the molecular events that control their effectiveness. In this study, we demonstrate that HDAC inhibitors are limited in their ability to induce apoptosis in non-small cell lung cancer (NSCLC) cell lines despite their ability to effectively inhibit deacetylase activity. Because the anti-apoptotic transcription factor NF-kappa B has been shown to be under the control of HDAC-mediated repression, we analyzed whether HDAC inhibitors activated NF-kappa B in NSCLC cells. HDAC inhibitors effectively stimulated endogenous NF-kappa B-dependent gene expression by up-regulating IL-8, Bcl-XL, and MMP-9 transcripts. The ability of HDAC inhibitors to increase NF-kappa B transcriptional activity was not associated with signaling events that stimulated nuclear translocation, but rather modulated the transactivation potential of the RelA/p65 subunit of NF-kappa B. The inhibition of HDAC activity was associated with the recruitment of the p300 transcriptional co-activator to chromatin in an Akt-dependent manner. Moreover, Akt directly phosphorylated p300 in vitro and was required for stimulating the transactivation potential of the co-activator following the addition of HDAC inhibitors. Selective inhibition of either the phosphoinositide 3-kinase/Akt pathway, or NF-kappa B itself blocked the ability of HDAC inhibitors to activate NF-kappa B and dramatically sensitized NSCLC cells to apoptosis following of the addition of HDAC inhibitors. Our study indicates that the ineffectiveness of HDAC inhibitors to induce apoptosis in NSCLC cancer cells is associated with the ability of these molecules to stimulate NF-kappa B-dependent transcription and cell survival.

Interaction of 5-aza-2'-deoxycytidine and depsipeptide on antineoplastic activity and activation of 14-3-3sigma, E-cadherin and tissue inhibitor of metalloproteinase 3 expression in human breast carcinoma cells

Genes that suppress tumorigenesis can be silenced by epigenetic events, such as aberrant DNA methylation and modification of chromatin structure. Inhibitors of DNA methylase and histone deacetylase (HDAC) can potentially reverse these events. The aim of this study was to determine the in vitro antineoplastic activity of 5-aza-2'-deoxycytidine (5-AZA-CdR), a potent inhibitor of DNA methylase, in combination with depsipeptide (depsi), an inhibitor of HDAC, on human breast carcinoma cells. We observed a synergistic antineoplastic interaction between 5-AZA-CdR and depsi in their capacity to inhibit colony formation of Hs578T and MCF-7 breast carcinoma cells. In order to understand the molecular mechanism of this interaction, we investigated the effect of these drugs on the activation of the 14-3-3sigma, E-cadherin and tissue inhibitor of metalloproteinase 3 (TIMP3) cancer-related genes, which were reported to be silenced by aberrant methylation in many breast tumor cell lines. 14-3-3sigma was reported to produce G cell cycle arrest following DNA damage. E-cadherin and TIMP3 function as suppressors of tumor metastasis. Semi-quantitative RT-PCR was used to determine the effect of the co-administration of 5-AZA-CdR and depsi on four breast carcinoma cell lines for the reactivation of these genes. We observed a synergistic activation of E-cadherin by the combination in Hs578T, MDA-MB-231 and MDA-MB-435 tumor cells. For 14-3-3sigma, we demonstrated an additive to synergistic activation by the combination for Hs578T and MDA-MB-435 tumor cells, respectively. In the MCF-7 tumor cells, the drug combination produced a synergistic activation of TIMP3. The association between the synergistic antineoplastic activity and the synergistic activation of the target genes in this study suggests that the mechanism of anticancer activity of 5-AZA-CdR, in combination with depsi, is probably related to their enhanced activation of different types of tumor suppressor genes that have been silenced by epigenetic events.(2)

A novel combination of suicide gene therapy and histone deacetylase inhibitor for treatment of malignant melanoma

One major problem associated with application of gene therapy to treatment of tumors is poor transgene expression. Although suicide gene therapy with the herpes simplex virus-thymidine kinase gene (HSV-tk) followed by administration of ganciclovir (GCV) was effective in the treatment of melanoma, it was still difficult to induce complete remission to cancer. A novel histone deacetylase inhibitor drug FR901229 was found to enhance transgene expression in tumor cells both in vitro and in vivo. Combination therapy with HSV-tklGCV and FR901228 by direct injection into tumor enhanced antimelanoma effects. The number of apoptotic cells in melanoma tumors was increased significantly (P<.05) after combined suicide gene therapy and FR901228. Six times injection of HSV-tk/GCV and FR901228 prolonged mice survival compared to that of HSV-tk/GCV injection alone (P=.021). In total, 56% (10 of 18) of the mice survived 120 days after combined suicide gene therapy and FR901228 treatment, and no new tumors appeared in the surviving mice. However, only 19% (3 of 16) of the mice survived when treated with suicide gene therapy alone. This novel strategy may be applicable as a therapeutic regimen for the treatment of aggressive types of cancers.

The role of quantitative PCR for the immune monitoring of cancer patients

Human tumour immunology is at a standstill whereas implemented cancer vaccines have shown effectiveness in inducing immune responses detectable in circulating lymphocytes. In most circumstances, however, such immune responses are not sufficient to induce cancer regression. This paradoxical observation could be explained in several ways depending upon the immunological endpoint used for immune monitoring. For instance, analysis of immune responses in circulating lymphocytes that address the presence of T cells bearing T-cell receptors specific for the epitope used for vaccination, can accurately enumerate the number of T cells elicited by the vaccines but does not yield information about their functional status. Other monitoring strategies may yield general information about the reactivity of various T cells in response to a relevant stimulus and, therefore, may provide information more relevant to the purpose of the immunisation. Furthermore, the material used to monitor immune responses may, in itself, determine the significance of the findings obtained. In the assessment of the therapeutic efficacy of specific cancer treatment, analysis of immune responses in circulating lymphocytes (systemic response) may not be as relevant as the analysis of the same effector populations within the tumour microenvironment (peripheral response). This review will describe a novel approach that allows extreme flexibility in the analysis of systemic and peripheral responses by accurately measuring the level of expression of relevant genes using quantitative real-time reverse transcriptase polymerase chain reaction.

Expression of SSX genes in the neoplastic cells of Hodgkin's lymphoma

The cancer/testis antigen (CTA) group of tumor-associated proteins have been reported to be expressed in various cancers and in adult testis but they are essentially not found in any other normal adult nonneoplastic tissues. Prompted by the frequent detection of SSX1 in a previous comprehensive expression profile of the Hodgkin's lymphoma (HL) cell line L428, we analyzed SSX expression by nonnested reverse-transcription polymerase chain reaction (RT-PCR) in 4 HL cell lines (L428, L540, HD-MY-Z, and KM-H2) and 32 tumor samples of HL. The cellular localization of SSX expression in the tumor samples was further analyzed by in situ hybridization (ISH). All 4 HL cell lines were positive by RT-PCR using SSX consensus primers. Using primers specific to individual SSX genes, all 4 cell lines expressed multiple SSX family members. Five tumor samples (15.6%) were positive by RT-PCR using SSX consensus primers and direct sequencing of the RT-PCR products showed that 4 of 5 expressed more than 1 SSX family member. ISH confirmed that SSX expression originated in HL cells in all 5 RT-PCR-positive tumor samples. Furthermore, ISH demonstrated SSX-positive HL cells in 6 of 11 cases (55%) that were negative by RT-PCR. Our results suggest that members of the SSX family of CTA are expressed in most HL. This subset of HL may be a candidate for immunotherapy approaches directed at SSX proteins.

Immunologic monitoring of cancer vaccine therapy: results of a workshop sponsored by the Society for Biological Therapy

The Society for Biological Therapy held a Workshop last fall devoted to immune monitoring for cancer immunotherapy trials. Participants included members of the academic and pharmaceutical communities as well as the National Cancer Institute and the Food and Drug Administration. Discussion focused on the relative merits and appropriate use of various immune monitoring tools. Six breakout groups dealt with assays of T-cell function, serologic and proliferation assays to assess B cell and T helper cell activity, and enzyme-linked immunospot assay, tetramer, cytokine flow cytometry, and reverse transcription polymerase chain reaction assays of T-cell immunity. General conclusions included: (1) future vaccine studies should be designed to determine whether T-cell dysfunction (tumor-specific and nonspecific) correlated with clinical outcome; (2) tetramer-based assays yield quantitative but not functional data (3) enzyme-linked immunospot assays have the lowest limit of detection (4) cytokine flow cytometry have a higher limit of detection than enzyme-linked immunospot assay, but offer the advantages of speed and the ability to identify subsets of reactive cells; (5) antibody tests are simple and accurate and should be incorporated to a greater extent in monitoring plans; (6) proliferation assays are imprecise and should not be emphasized in future studies; (7) the reverse transcription polymerase chain reaction assay is a promising research approach that is not ready for widespread application; and (8)there is a critical need to validate these assays as surrogates for vaccine potency and clinical effect. Current data and opinion support the use of a functional assay like the enzyme-linked immunospot assay or cytokine flow cytometry in combination with a quantitative assay like tetramers for immune monitoring. At present, assays appear to be most useful as measures of vaccine potency. Careful immune monitoring in association with larger scale clinical trials ultimately may enable the correlation of monitoring results with clinical benefit.

Histone deacetylase as a therapeutic target

The maintenance of health depends on the coordinated and tightly regulated expression of genetic information. Certain forms of leukemia have become paradigms for the pathogenic role of aberrant repression of differentiation genes. In these acute leukemias, fusion proteins generated by chromosomal translocations no longer function as transcriptional activators, but instead repress target genes by recruiting histone deacetylases (HDACs). The potential benefit of HDAC inhibition has been established by the use of enzyme inhibitors in vitro and in a single reported case of experimental therapy. Because recently identified HDAC inhibitors appear to overcome many drawbacks of early inhibitory compounds in clinical use, the stage is set to test the therapeutic value of HDAC inhibition in leukemias and in other diseases, including solid tumors and aberrant hormonal signaling. This review summarizes the range of diseases expected to respond to HDAC inhibition.

Sequential 5-Aza-2 deoxycytidine-depsipeptide FR901228 treatment induces apoptosis preferentially in cancer cells and facilitates their recognition by cytolytic T lymphocytes specific for NY-ESO-1

Global alterations in chromatin structure profoundly influence gene expression in thoracic neoplasms, silencing tumor suppressors while facilitating the expression of various cancer testis antigens such as NY-ESO-1. Although recent studies have shown that histone deacetylase inhibitors can potentiate tumor suppressor gene induction mediated by demethylating agents in cancer cells, the ability of these agents to augment cancer testis antigen expression have not been fully defined. The authors designed the current study to determine whether the histone deacetylase inhibitor, depsipeptide FR901228 (DP), could enhance NY-ESO-1 induction mediated by the DNA demethylating agent 5-Aza-2'-deoxycytidine (DAC) in cell lines established primarily from thoracic cancers. Quantitative reverse-transcriptase polymerase chain reaction analysis revealed that, under exposure conditions potentially achievable in clinical settings, DAC dramatically induced NY-ESO-1 expression in cultured cancer lines. DP alone mediated negligible target gene induction but significantly augmented DAC-mediated induction of NY-ESO-1. After DAC or sequential DAC-DP treatment, HLA-A*0201 cancer cells were recognized by an HLA-A*0201 CTL specific for NY-ESO-1. Although sequential DAC/DP exposure did not uniformly enhance immune recognition of target cells compared with DAC alone, this treatment mediated profound induction of apoptosis in cancer cells but not normal human bronchial epithelia. The apoptotic effects of DAC, DP, or sequential DAC-DP did not correlate in an obvious manner with histology, or the magnitude of NY-ESO-1 induction in cancer cells. Although the mechanisms have not been fully defined, sequential DAC-DP treatment may be a novel strategy to augment antitumor immunity in cancer patients.