Development of a novel cell-based assay system EPISSAY for screening epigenetic drugs and liposome formulated decitabine

Decitabine Treatment Induces a Viral Mimicry Response in Cervical Cancer Cells and Further Sensitizes Cells to Chemotherapy

PURPOSE

To investigate the anti-cancer, chemosensitizing and/or immunomodulating effects of decitabine (DAC) to be used as a potential therapeutic agent for the treatment of cervical cancer (CC).

METHODS

Cervical cancer cell lines were treated with low doses of DAC treatment used as a single agent or in combination with chemotherapy. End-point in vitro assays were developed as indicators of the anti-cancer and/or immunomodulating effects of DAC treatment in CC cells. These assays include cell viability, cell cycle analysis, apoptosis, induction of a viral-mimicry response pathway, expression of MHC-class I and PD-L1 and chemosensitivity.

RESULTS

High and low doses of DAC treatment induced reduction in cell viability in HeLa (HPV18+), CaSki (HPV16+) and C33A (HPV-) cells. Specifically, a time-dependent reduction in cell viability of HeLa and CaSki cells was observed accompanied by robust cell cycle arrest at G2/M phase and alterations in the cell cycle distribution. Decrease in cell viability was also observed in a non-transformed immortal keratinocyte (HaCat) suggesting a non-cancer specific target effect. DAC treatment also triggered a viral mimicry response through long-term induction of cytoplasmic double-stranded RNA (dsRNA) and activation of downstream IFN-related genes in both HPV+ and HPV- cells. In addition, DAC treatment increased the number of CC cells expressing MHC-class I and PD-L1. Furthermore, DAC significantly increased the proportion of early and late apoptotic CC cells quantified using FACS. Our combination treatments showed that low dose DAC treatment sensitizes cells to chemotherapy.

CONCLUSIONS

Low doses of DAC treatment promotes robust induction of a viral mimicry response, immunomodulating and chemosensitizing effects in CC, indicating its promising therapeutic role in CC in vitro.

A comparison and column selection of Hydrophilic Interaction Liquid Chromatography and Reversed-Phase High-Performance Liquid Chromatography for detection of DNA methylation

5-methylcytosine (5mC) is an epigenetic mark which has a profound effect on various fundamental processes in cells. In present study, at first Hydrophilic Interaction Liquid Chromatography (HILIC) was compared with Reversed-Phase High-Performance Liquid Chromatography (RP-HPLC) based on their selectivity (α), retention factor (k), and resolution (R) for cytosine (C) and 5mC nucleobases. We tried to justify the separation mechanism on the basis of mobile phase and solute polarity, structural characterization of solute and stationary phases, log Do/w, and pk_a under both modes. Then, these two modes were compared in order to select the best column for measurement of methylation level in two real samples with less analytical complexity (i.e. animal and bacteria) and a highly complex sample (i.e. plant), after chemical hydrolysis of DNA. In this favor, diol and cyano (CN) columns in HILIC mode as well as C₈ and C₁₈ in RP-HPLC were investigated. Optimum separation and the best validation parameters were obtained for CN column with Limit of Detection (LOD) of 1.4 pmol and Limit of Quantification (LOQ) of 4.8 pmol for 5mC. When the CN column was used in HILIC-UV procedure, separation of 5mC and C bases was achieved in all types of hydrolyzed DNA solutions.

The alteration of temoporfin distribution in multicellular tumor spheroids by β-cyclodextrins

To be effective anticancer drugs must penetrate tissue efficiently, reaching all target population of cancer cells in a concentration sufficient to exert a therapeutic effect. This study aimed to investigate the ability of methyl-β-cyclodextrin (Me-β-CD) and 2-hydroxypropyl-β-cyclodextrin (Hp-β-CD) to alter the penetration and diffusion of temoporfin (mTHPC) in HT29 multicellular tumor spheroids. mTHPC had а nonhomogenous distribution only on the periphery of spheroids. The presence of β-CDs significantly altered the distribution of mTHPC consisting in the increase of both the depth of photosensitizer penetration and accumulation in HT29 spheroids. We suggest that this improvement is related to the nanoshuttle mechanism of β-CD action, when β-CDs facilitate mTHPC transportation to the cells in the inner layers of spheroids. As a result of mTHPC distribution improvement, β-CDs enhance mTHPC photosensitizing activity towards HT29 multicellular tumor spheroids. The observed effects strongly depend on the type of β-CD. Thus, varying the type of β-CD we can finely tune the possibility of using mTHPC for diagnostic (delimitation of tumor margins) or therapeutic purposes.

Advancements in the delivery of epigenetic drugs

INTRODUCTION

Advancements in epigenetic treatments are not only coming from new drugs, but also from modifications or encapsulation of the existing drugs into different formulations leading to greater stability and enhanced delivery to the target site. The epigenome is highly regulated and complex; therefore, it is important that off-target effects of epigenetic drugs be minimized. The step from in vitro to in vivo treatment of these drugs often requires development of a method of effective delivery for clinical translation.

AREAS COVERED

This review covers epigenetic mechanisms such as DNA methylation, chromatin remodeling and small-RNA-mediated gene regulation. There is a section in the review with examples of diseases where epigenetic alterations lead to impaired pathways, with an emphasis on cancer. Epigenetic drugs, their targets and clinical status are presented. Advantages of using a delivery method for epigenetic drugs as well as examples of current advancements and challenges are also discussed.

EXPERT OPINION

Epigenetic drugs have the potential to be very effective therapy against a number of diseases, especially cancers and neurological disorders. As with many chemotherapeutics, undesired side effects need to be minimized. Finding a suitable delivery method means reducing side effects and achieving a higher therapeutic index. Each drug may require a unique delivery method exploiting the drug's chemistry or other physical characteristic requiring interdisciplinary participation and would benefit from a better understanding of the mechanisms of action.