Synergistic induction of apoptosis and chemosensitization of human colorectal cancer cells by histone deacetylase inhibitor, scriptaid, and proteasome inhibitors: potential mechanisms of action

Patient-Derived Organoid Serves as a Platform for Personalized Chemotherapy in Advanced Colorectal Cancer Patients

Background

Addition of oxaliplatin to adjuvant 5-FU has significantly improved the disease-free survival and served as the first line adjuvant chemotherapy in advanced colorectal cancer (CRC) patients. However, a fraction of patients remains refractory to oxaliplatin-based treatment. It is urgent to establish a preclinical platform to predict the responsiveness toward oxaliplatin in CRC patients as well as to improve the efficacy in the resistant patients.

Methods

A living biobank of organoid lines were established from advanced CRC patients. Oxaliplatin sensitivity was assessed in patient-derived tumor organoids (PDOs) in vitro and in PDO-xenografted tumors in mice. Based on in vitro oxaliplatin IC₅₀ values, PDOs were classified into either oxaliplatin-resistant (OR) or oxaliplatin-sensitive (OS) PDOs. The outcomes of patients undergone oxaliplatin-based treatment was followed. RNA-sequencing and bioinformatics tools were performed for molecular profiling of OR and OS PDOs. Oxaliplatin response signatures were submitted to Connectivity Map algorithm to identify perturbagens that may antagonize oxaliplatin resistance.

Results

Oxaliplatin sensitivity in PDOs was shown to correlate to oxaliplatin-mediated inhibition on PDO xenograft tumors in mice, and parallelled clinical outcomes of CRC patients who received FOLFOX treatment. Molecular profiling of transcriptomes revealed oxaliplatin-resistant and -sensitive PDOs as two separate entities, each being characterized with distinct hallmarks and gene sets. Using Leave-One-Out Cross Validation algorithm and Logistic Regression model, 18 gene signatures were identified as predictive biomarkers for oxaliplatin response. Candidate drugs identified by oxaliplatin response signature-based strategies, including inhibitors targeting c-ABL and Notch pathway, DNA/RNA synthesis inhibitors, and HDAC inhibitors, were demonstrated to potently and effectively increase oxaliplatin sensitivity in the resistant PDOs.

Conclusions

PDOs are useful in informing decision-making on oxaliplatin-based chemotherapy and in designing personalized chemotherapy in CRC patients.

Anti-cancer Effects of Epigenetics Drugs Scriptaid and Zebularine in Human Breast Adenocarcinoma Cells

BACKGROUND

High relapse and metastasis progression in breast cancer patients have prompted the need to explore alternative treatments. Epigenetic therapy has emerged as an attractive therapeutic strategy due to the reversibility of epigenome structures.

OBJECTIVE

This study investigated the anti-cancer effects of epigenetic drugs scriptaid and zebularine in human breast adenocarcinoma MDA-MB-231 and MCF-7 cells.

METHODS

First, the half maximal inhibitory concentration (IC50) of scriptaid, zebularine and the combination of both drugs on human breast adenocarcinoma MDA-MB-231 cells was determined. Next, MDA-MB-231 and MCF-7 cells were treated with scriptaid, zebularine and the combination of both. After treatments, the anti-cancer effects were evaluated via cell migration assay, cell cycle analysis and apoptotic studies, which included histochemical staining and reverse-transcriptase polymerase chain reaction (RT-PCR) of the apoptotic genes.

RESULTS

Both epigenetic drugs inhibited cell viability in a dose-dependent manner with 2 nM scriptaid, 8 µM zebularine and combination of 2 nM scriptaid and 2 µM zebularine. Both MDA-MB-231 and MCF-7 cells exhibited a reduction in cell migration after the treatments. In particular, MDA-MB-231 cells exhibited a significant reduction in cell migration (p < 0.05) after the treatments of zebularine and the combination of scriptaid and zebularine. Besides, cell cycle analysis demonstrated that scriptaid and the combination of both drugs could induce cell cycle arrest at the G0/G1 phase in both MDA-MB-231 and MCF-7 cells. Furthermore, histochemical staining allowed the observation of apoptotic features, such as nuclear chromatin condensation, cell shrinkage, membrane blebbing, nuclear chromatin fragmentation and cytoplasmic extension, in both MDA-MB-231 and MCF-7 cells after the treatments. Further apoptotic studies revealed that the upregulation of pro-apoptotic Bax, downregulation of anti-apoptotic Bcl-2 and elevation of Bax/Bcl-2 ratio were found in MDA-MB-231 cells treated with zebularine and MCF-7 cells treated with all drug regimens.

CONCLUSION

Collectively, these findings suggest that scriptaid and zebularine are potential anti-cancer drugs, either single or in combination, for the therapy of breast cancer. Further investigations of the gene regulatory pathways directed by scriptaid and zebularine are definitely warranted in the future.

Passiflora caerulea L. fruit extract and its metabolites ameliorate epileptic seizure, cognitive deficit and oxidative stress in pilocarpine-induced epileptic mice

The anticonvulsant potential of aqueous fruit extract of Passiflora caerulea (PCAE) was evaluated in swiss albino mice induced by pilocarpine. The antioxidant activities of PCAE were determined which showed strong antioxidant activity and the polyphenol compounds such as ginsenoside, naringenin, chrysoeriol 8-c-glucoside, luteolin-6-C-glucoside, apigenin-6,8-di-C-β-D-glucopyranoside were profiled through RP-HPLC and UPLC-ESI-MS/MS. Chronic effects of PCAE on pilocarpine (85 mg/kg; i.p)-induced convulsions were evaluated in Swiss adult male albino mice. PCAE at 100 and 200 mg/kg, (p.o.) and diazepam (5 mg/kg, i.p) were administered once daily for 15 days. In Y-maze test, percentage of correct entry by pilocarpine administered animals were significantly lower when compared to control, whereas PCAE at both doses improved the alteration score significantly. Administration of higher dose (200 mg/kg) of PCAE significantly delayed onset of convulsions and decreased duration of clonic convulsions. Association of ROS production during seizure period was further confirmed by histopathological studies revealing loss of normal neuronal cells in hippocampus region. The data obtained showed anticonvulsant activity and improved cognitive function; reduced the oxidative damage and significantly activated the cholinergic neurotransmission in a dose dependent manner similar to diazepam which is evident in the biochemical parameters and histopathological study, suggesting therapeutic potential for epilepsy and neurodegeneration.

Sodium Butyrate as a Histone Deacetylase Inhibitor Affects Toll-Like Receptor 4 Expression in Colorectal Cancer Cell Lines

We assessed the effect of sodium butyrate (SB) as a histone deacetylase inhibitor (HDACi) on Toll-like receptor 4 (TLR4) gene expression levels, in low TLR4 expressing (HCT116) and high TLR4 expressing (SW480) colorectal cancer cells. The cytotoxic effect of SB was assessed by culturing SW480 and HCT116 cell lines using a broad spectrum of times and concentrations of SB. The MTT assay was done to check the cytotoxic properties of different SB concentrations. Gene expression levels of TLR4 was then evaluated for non-cytotoxic SB concentrations. Morphological analysis and MTT assay confirmed that SB concentrations equal to or less than 5mM were not cytotoxic for both cell lines. At 5mM concentration of SB in SW480 cell line and 1mM concentration of SB in HCT116 cell line, TLR4 gene expression level significantly increased from 24 to 48 hrs and decreased significantly from 48 to 72 hrs with an "early increased and late decreased pattern". At 1mM concentration of SB in SW480 cell line and 5mM concentration of SB in HCT116 cell line, TLR4 expression had a "gradually increased pattern". This study focuses on the dose-time-effect of SB in the pathogenesis of colorectal cancer. SB alters the expression level of TLR4 in colorectal cancer cells. This effect may depend on the cell type, treatment duration and SB concentration. The alterations in TLR4 expression may be due to the direct effect of SB on TLR4 and/or the expression changes of in other genes which may indirectly affect the TLR4 expression. Abbreviations: TLR4: Toll-like receptor 4; HDACi: histone deacetylase inhibitor; SB: sodium Butyrate; CRC: colorectal cancer; SCFA: short-chain fatty acid; hrs: hours.

Gait disorder as a predictor of spatial learning and memory impairment in aged mice

Objective

To investigate whether gait dysfunction is a predictor of severe spatial learning and memory impairment in aged mice.

Methods

A total of 100 12-month-old male mice that had no obvious abnormal motor ability and whose Morris water maze performances were not significantly different from those of two-month-old male mice were selected for the study. The selected aged mice were then divided into abnormal or normal gait groups according to the results from the quantitative gait assessment. Gaits of aged mice were defined as abnormal when the values of quantitative gait parameters were two standard deviations (SD) lower or higher than those of 2-month-old male mice. Gait parameters included stride length, variability of stride length, base of support, cadence, and average speed. After nine months, mice exhibiting severe spatial learning and memory impairment were separated from mice with mild or no cognitive dysfunction. The rate of severe spatial learning and memory impairment in the abnormal and normal gait groups was tested by a chi-square test and the correlation between gait dysfunction and decline in cognitive function was tested using a diagnostic test.

Results

The 12-month-old aged mice were divided into a normal gait group (n = 75) and an abnormal gait group (n = 25). Nine months later, three mice in the normal gait group and two mice in the abnormal gait group had died. The remaining mice were subjected to the Morris water maze again, and 17 out of 23 mice in the abnormal gait group had developed severe spatial learning and memory impairment, including six with stride length deficits, 15 with coefficient of variation (CV) in stride length, two with base of support (BOS) deficits, five with cadence dysfunction, and six with average speed deficits. In contrast, only 15 out of 72 mice in the normal gait group developed severe spatial learning and memory impairment. The rate of severe spatial learning and memory impairment was significantly higher in the abnormal gait group as compared to that in the normal gait group (x = 21.986, P < 0.001). All five parameters used to assess gait predicted severe spatial learning and memory impairment in aged mice (P < 0.01). However, the difference of the area under the ROC (receiver operating characteristic) curve for each quantitative gait parameter was not statistically significant.

Conclusion

Gait disorders are a predictor of severe spatial learning and memory impairment in aged mice, and stride length, variability of stride length, base of support, cadence, and average speed are all sensitive parameters for assessing gait.

The 26S proteasome is a multifaceted target for anti-cancer therapies

Proteasomes play a critical role in the fate of proteins that are involved in major cellular processes, including signal transduction, gene expression, cell cycle, replication, differentiation, immune response, cellular response to stress, etc. In contrast to non-specific degradation by lysosomes, proteasomes are highly selective and destroy only the proteins that are covalently labelled with small proteins, called ubiquitins. Importantly, many diseases, including neurodegenerative diseases and cancers, are intimately connected to the activity of proteasomes making them an important pharmacological target. Currently, the vast majority of inhibitors are aimed at blunting the proteolytic activities of proteasomes. However, recent achievements in solving structures of proteasomes at very high resolution provided opportunities to design new classes of small molecules that target other physiologically-important enzymatic activities of proteasomes, including the de-ubiquitinating one. This review attempts to catalog the information available to date about novel classes of proteasome inhibitors that may have important pharmacological ramifications.

Prolonged proteasome inhibition cyclically upregulates Oct3/4 and Nanog gene expression, but reduces induced pluripotent stem cell colony formation

There is ample evidence that the ubiquitin-proteasome system is an important regulator of transcription and its activity is necessary for maintaining pluripotency and promoting cellular reprogramming. Moreover, proteasome activity contributes to maintaining the open chromatin structure found in pluripotent stem cells, acting as a transcriptional inhibitor at specific gene loci generally associated with differentiation. The current study was designed to understand further the role of proteasome inhibition in reprogramming and its ability to modulate endogenous expression of pluripotency-related genes and induced pluripotent stem cells (iPSCs) colony formation. Herein, we demonstrate that acute combinatorial treatment with the proteasome inhibitors MG101 or MG132 and the histone deacetylase (HDAC) inhibitor valproic acid (VPA) increases gene expression of the pluripotency marker Oct3/4, and that MG101 alone is as effective as VPA in the induction of Oct3/4 mRNA expression in fibroblasts. Prolonged proteasome inhibition cyclically upregulates gene expression of Oct3/4 and Nanog, but reduces colony formation in the presence of the iPSC induction cocktail. In conclusion, our results demonstrate that the 26S proteasome is an essential modulator in the reprogramming process. Its inhibition enhances expression of pluripotency-related genes; however, efficient colony formation requires proteasome activity. Therefore, discovery of small molecules that increase proteasome activity might lead to more efficient cell reprogramming and generation of pluripotent cells.

Association between interleukin-4 gene intron 3 VNTR polymorphism and cancer risk

BACKGROUND

Interleukin-4(IL-4) is a critical inflammatory cytokine and has been involved in pathogenesis of cancer. To date, several studies have investigated the association between IL-4 intron 3 variable number of tandem repeats (VNTR) polymorphism and cancer risk in humans; however, the results remain controversial. We performed this meta-analysis to find a more conclusive association between this polymorphism and cancer risk.

METHODS

Eight eligible case-control studies were identified through searching electronic databases, including 1583 cases and 1638 controls. Odds ratio (OR) and corresponding 95% confidence interval (CI) were used to estimate the strength of the association.

RESULTS

The results of overall analyses indicated that the variant RP2 allele was associated with a decreased cancer risk compared with the RP1 allele (RP2/RP2 vs. RP1/RP1, OR = 0.64, 95% CI = 0.44-0.94; RP2/RP2 vs. RP1/RP1 + RP1/RP2, OR = 0.75, 95% CI = 0.60-0.92; RP2 vs. RP1, OR = 0.72, 95% CI = 0.56-0.92). In subgroup analyses stratified by ethnicity, there was evidence in the Asian population for an association between this polymorphism and cancer risk (RP2/RP2 vs. RP1/RP1 + RP1/RP2, OR = 0.79, 95% CI = 0.63-0.99; RP2 vs. RP1, OR = 0.77, 95% CI = 0.61-0.97).

CONCLUSIONS

IL-4 intron 3 VNTR polymorphism could influence the risk of human cancer. Due to the limitations of this meta-analysis, further well-designed and functional researches should be performed to validate our results.

Overexpression of histone deacetylases in cancer cells is controlled by interplay of transcription factors and epigenetic modulators

Histone deacetylases (HDACs) that deacetylate histone and nonhistone proteins play crucial roles in a variety of cellular processes. The overexpression of HDACs is reported in many cancer types and is directly linked to accelerated cell proliferation and survival. However, little is known about how HDAC expression is regulated in cancer cells. In this study, we found that HDAC1 and HDAC2 promoters are regulated through collaborative binding of transcription factors Sp1/Sp3 and epigenetic modulators, including histone H3K4 methyltransferase SET1 and histone acetyltransferase p300, whose levels are also elevated in colon cancer cell lines and patient samples. Interestingly, Sp1 and Sp3 differentially regulate HDAC1 and HDAC2 promoter activity. In addition, Sp1/Sp3 recruits SET1 and p300 to the promoters. SET1 knockdown (KD) results in a loss of the H3K4 trimethylation mark at the promoters, as well as destabilizes p300 at the promoters. Conversely, p300 also influences SET1 recruitment and H3K4me3 level, indicating a crosstalk between p300 and SET1. Further, SET1 KD reduces Sp1 binding to the HDAC1 promoter through the increase of Sp1 acetylation. These results indicate that interactions among transcription factors and epigenetic modulators orchestrate the activation of HDAC1 and HDAC2 promoter activity in colon cancer cells.

Association between IRS-1 Gly972Arg polymorphism and colorectal cancer risk

In order to make a comprehensive assessment of the potential association between one genetic variant in the insulin receptor substrate 1 (IRS-1) gene, rs1801278, and colorectal cancer (CRC) risk, we conducted a meta-analysis of four epidemiological studies, which included 3,708 CRC cases and 4,176 controls. The data showed that rs1801278 polymorphism was not associated with increased CRC risk in the overall population. When stratifying by the race, the results showed that the rs1801278 polymorphism was associated with increased CRC risk under dominant model in mixed populations. Based on this meta-analysis, we conclude that the IRS-1 rs1801278 polymorphism might be a risk factor for CRC development in mixed populations. Further studies, either with larger sample size or involving other single nucleotide polymorphisms (SNPs) and haplotypes of the IRS-1 gene, are necessary to clarify the contribution of IRS-1 rs1801278 in colorectal carcinogenesis.

Association between IL-4 -589C>T polymorphism and colorectal cancer risk

In order to make a comprehensive assessment of the potential association between interleukin-4 (IL-4) -589C>T and colorectal cancer (CRC) susceptibility, we conducted a meta-analysis of six epidemiological studies, which included 1,317 CRC patients and 1,659 controls. The data showed that IL-4 -589C>T was not associated with increased CRC risk in the overall population. In the subgroup analysis of IL-4 -589C>T, the results did not change when the analyses were restricted to race. Based on this meta-analysis, we conclude that IL-4 -589C>T may be not a risk factor for CRC development. Further research is needed to assess possible gene-gene or gene-environment-lifestyle interactions on CRC.

Superior antimitogenic and chemosensitization activities of the combination treatment of the histone deacetylase inhibitor apicidin and proteasome inhibitors on human colorectal cancer cells

Despite the effectiveness of histone deacetylase inhibitors, proteasome inhibitors and cytotoxic drugs on human cancers, none of these types of treatments by themselves has been sufficient to eradicate the disease. The combination of different modalities may hold enormous potential for eliciting therapeutic results. In the current study, we examined the effects of treatment with the histone deacetylase inhibitor (HDACI) apicidin (APC) in combination with proteasome inhibitors on human colorectal cancer cells. The molecular mechanisms of the combined treatments and their potential to sensitize colorectal cancer cells to chemotherapies were also investigated. Cancer cells were exposed to the agents alone and in combination, and cell growth inhibition was determined by MTT and colony formation assays. HDAC, proteasome and NF-κB activities as well as reactive oxygen species (ROS) were monitored. Cell cycle perturbation and induction of apoptosis were assessed by flow cytometry. The expression of cell cycle/apoptosis- and cytoprotective/stress-related genes was determined by quantitative PCR and EIA, respectively. The potentiation of cancer cell sensitivity to chemotherapies upon APC/PI combination treatment was also studied. The combination of APC and MG132, PI-1 or epoxomicin potently inhibited cancer cell growth, disrupted the cell cycle, induced apoptosis, decreased NF-κB activity and increased ROS production. These events were accompanied by the altered expression of genes associated with the cell cycle, apoptosis and cytoprotection/stress regulation. The combination treatment markedly enhanced the chemosensitivity of colorectal cancer cells (50-3.7 x 10(4)-fold) in a drug-, APC/PI combination- and colorectal cancer subtype-dependent manner. The results of this study have implications for the development of com-binatorial treatments that include HDACIs, PIs and conventional chemotherapeutic drugs, suggesting a potential therapeutic synergy with general applicability to various types of cancers.

The complexity of NF-κB signaling in inflammation and cancer

The NF-κB family of transcription factors has an essential role in inflammation and innate immunity. Furthermore, NF-κB is increasingly recognized as a crucial player in many steps of cancer initiation and progression. During these latter processes NF-κB cooperates with multiple other signaling molecules and pathways. Prominent nodes of crosstalk are mediated by other transcription factors such as STAT3 and p53 or the ETS related gene ERG. These transcription factors either directly interact with NF-κB subunits or affect NF-κB target genes. Crosstalk can also occur through different kinases, such as GSK3-β, p38, or PI3K, which modulate NF-κB transcriptional activity or affect upstream signaling pathways. Other classes of molecules that act as nodes of crosstalk are reactive oxygen species and miRNAs. In this review, we provide an overview of the most relevant modes of crosstalk and cooperativity between NF-κB and other signaling molecules during inflammation and cancer.

NF-κB in colorectal cancer

Colorectal cancer (CRC) is a leading cause of morbidity and mortality worldwide, responsible for more than half a million deaths annually. CRC is a multistep process that entails the accumulation of genetic/epigenetic aberrations, which lead to the simultaneous failure of protective mechanisms and the activation of tumorigenic pathways. In most cases of CRC a deregulation of the Wnt-signaling pathway is required. The transcription factor nuclear factor κB (NF-κB) has been recognized as a key player in the initiation and propagation of CRC. Under physiological conditions, NF-κB orchestrates the inflammatory process and participates in the modulation of various steps of cell cycle and survival. It is normally kept in an inactive state in the cytoplasm by binding to a group of inhibitory proteins. Upon receipt of a signal, its inhibitor is phosphorylated and proteolytically degraded and NF-κB is actively translocated to the nucleus, where it facilitates target-gene transcription. Recent experimental data reveal the important role of NF-κB in tumor cells as well as in the surrounding "cancerous" and reactive microenvironment. Various tumor cell-derived and contextual cues feed constantly this vicious circuitry sustaining inflammation and promoting proliferation, angiogenesis, invasion and eventually metastasis. Therefore NF-κB along with its upstream and downstream network presents a rational target for therapeutic interventions. Numerous small molecules, inhibitory peptides, antisense RNAs, natural compounds, as well as gene therapy strategies interfere with multiple steps of the NF-κΒ signaling cascade. The design of NF-κΒ-targeted treatment may aid the efforts towards the pursuit of more efficient therapeutic measures devoid of severe systemic side-effects.