Doxorubicin and a butyric acid derivative effectively reduce levels of BCL-2 protein in the cells of chronic lymphocytic leukemia patient

Cytotoxicity profiling of deep eutectic solvents to human skin cells

The tailor-made character of deep eutectic solvents (DES) turns them very attractive to be used in several applications, including in health-related areas such as pharmaceutical, nutraceutical, and cosmetic industries. However, although DES has been touted as “green” solvents, several works proved that their potential toxicity should not be neglected. Using the premise of DES applicability in the cosmetic and pharmaceutical sectors, we chose two cell lines to work as a skin model (keratinocytes HaCaT and tumor melanocytes MNT-1), to assess DES cytotoxicity. The effect of three different hydrogen bond acceptors (HBA) ([Chol]Cl, [N₁₁₁₁]Cl and [N₄₄₄₄]Cl) and three different hydrogen bond donors (HBD) (hexanoic and butanoic acid, ethylene glycol, 1-propanol and urea) were evaluated through a common viability assay (MTT assay). Results were promising since [Chol]Cl and [N₁₁₁₁]Cl- based DES showed good biocompatibility for the tested cells. [N₄₄₄₄]Cl-based DES, however, showed cytotoxicity for both cell lines, with the HBA being the driver of the toxicity. Interestingly, some compounds increased cell viability in the HaCaT cell line, namely [Chol]Cl, ethylene glycol, hexanoic acid, urea, and all [Chol]Cl and [N₁₁₁₁]Cl-based DES and should be considered as targets for future studies. These results highlight their possible use in cosmetic or pharmaceutical formulations.

Aberrant epigenetic alteration in Eca9706 cells modulated by nanoliposomal quercetin combined with butyrate mediated via epigenetic-NF-κB signaling

Since the epigenetic alteration in tumor cells can be reversed by the dietary polyphenol quercetin (Q) or butyrate (B) with chemopreventive activity, suggesting that Q or B can be used for chemopreventive as well as therapeutic agent against tumors. In this study the polyphenol flavonoid quercetin (Q) or sodium butyrate (B) suppressed human esophageal 9706 cancer cell growth in dose dependent manner, and Q combined with B (Q+B) could further inhibit Eca9706 cell proliferation than that induced by Q or B alone, compared with untreated control group (C) in MTT assay. The reverse expressions of global DNMT1, NF-κBp65, HDAC1 and Cyclin D1 were down-regulated, while expressions of caspase-3 and p16INK4α were up-regulated, compared with the C group in immunoblotting; the down-regulated HDAC1-IR (-immunoreactivity) with nuclear translocation, and up-regulated E-cadherin-IR demonstrated in immunocytochemistry treated by Q or B, and Q+B also displayed further negatively and positively modulated effects compared with C group. The order of methylation specific (MS) PCR of p16INK4α: C>B/Q>Q+B group, while the order of E-cadherin expression level was contrary, Q+B>Q/B>C group. Thus, Q/B, especially Q+B display reverse effect targeting both altered DNA methylation and histone acetylation, acting as histone deacetylase inhibitor mediated via epigenetic-NF-κB cascade signaling.

Interpreting clinical assays for histone deacetylase inhibitors

As opposed to genetics, dealing with gene expressions by direct DNA sequence modifications, the term epigenetics applies to all the external influences that target the chromatin structure of cells with impact on gene expression unrelated to the sequence coding of DNA itself. In normal cells, epigenetics modulates gene expression through all development steps. When "imprinted" early by the environment, epigenetic changes influence the organism at an early stage and can be transmitted to the progeny. Together with DNA sequence alterations, DNA aberrant cytosine methylation and microRNA deregulation, epigenetic modifications participate in the malignant transformation of cells. Their reversible nature has led to the emergence of the promising field of epigenetic therapy. The efforts made to inhibit in particular the epigenetic enzyme family called histone deacetylases (HDACs) are described. HDAC inhibitors (HDACi) have been proposed as a viable clinical therapeutic approach for the treatment of leukemia and solid tumors, but also to a lesser degree for noncancerous diseases. Three epigenetic drugs are already arriving at the patient's bedside, and more than 100 clinical assays for HDACi are registered on the National Cancer Institute website. They explore the eventual additive benefits of combined therapies. In the context of the pleiotropic effects of HDAC isoforms, more specific HDACi and more informative screening tests are being developed for the benefit of the patients.

Doxorubicin-induced cell death requires cathepsin B in HeLa cells

The cysteine protease cathepsin B acts as a key player in apoptosis. Cathepsin B-mediated cell death is induced by various stimuli such as ischemia, bile acids or TNFα. Whether cathepsin B can be influenced by anticancer drugs, however, has not been studied in detail. Here, we describe the modulation of doxorubicin-induced cell death by silencing of cathepsin B expression. Previously, it was shown that doxorubicin, in contrast to other drugs, selectively regulates expression and activity of cathepsin B. Selective silencing of cathepsin B by siRNA or the cathepsin B specific inhibitor CA074Me modified doxorubicin-mediated cell death in Hela tumor cells. Both Caspase 3 activation and PARP cleavage were significantly reduced in cells lacking cathepsin B. Moreover, mitochondrial membrane permeabilization as well as the release of cytochrome C and AIF from mitochondria into cytosol induced by doxorubicin were significantly diminished in cathepsin B suppressed cells. In addition, doxorubicin associated down-regulation of XIAP was not observed in cathepsin B silenced cells. Lack of cathepsin B significantly modified cell cycle regulatory proteins such as cdk1, Wee1 and p21 without significant changes in G(1), S or G(2)M cell cycle phases maybe indicating further cell cycle independent actions of these proteins. Consequently, cell viability following doxorubicin was significantly elevated in cells with cathepsin B silencing. In summary, our data strongly suggest a role of cathepsin B in doxorubicin-induced cell death. Therefore, increased expression of cathepsin B in various types of cancer can modify susceptibility towards doxorubicin.

Pivanex, a histone deacetylase inhibitor, induces changes in BCR-ABL expression and when combined with STI571, acts synergistically in a chronic myelocytic leukemia cell line

Chronic myelogenous leukemia (CML) is associated with the high TK activity chimeric protein BCR-ABL, known to contribute to cell tumorogenicity, resistance to apoptosis and differentiation. STI571, the TK inhibitor, is the current treatment for CML. One possible approach to overcome STI571 resistance appearing in some cases, involves the combination of histone deacetylase inhibitors (HDI) and STI571. We demonstrated that in K562, the CML cell line, pivaloyloxymethyl butyrate (Pivanex)-induced apoptosis, differentiation and reduced BCR-ABL protein levels and that the combination of Pivanex with STI571 acted synergistically. These data suggest the possible benefit of combining this HDI with STI571 for treatment of CML.

Cytotoxicity of anticancer drugs incorporated in solid lipid nanoparticles on HT-29 colorectal cancer cell line

Solid lipid nanoparticles (SLN) carrying cholesteryl butyrate (chol-but), doxorubicin and paclitaxel had previously been developed, and the antiproliferative effect of SLN formulations versus conventional drug formulations was here evaluated on HT-29 cells. The 50% inhibitory concentration (IC(50) values were interpolated from growth curves obtained by trypan blue exclusion assay. In vitro cytotoxicity of SLN carrying chol-but (IC(50 72 h) 0.3 +/- 0.03 mM vs >0.6 mM) and doxorubicin (IC(50 72 h) 81.87 +/- 4.11 vs 126.57 +/- 0.72 nM) was higher than that of conventional drug formulations. Intracellular doxorubicin was double after 24 h exposure to loaded SLN versus the conventional drug formulation, at the highest concentration evaluated by flow cytometry. In vitro cytotoxicities of paclitaxel-loaded SLN and conventional drug formulation (IC(50 72 h) 37.36 +/- 6.41 vs 33.43 +/-1.17 nM) were similar. Moreover, the combination of low concentrations of chol-but SLN (0.1-0.2 mM) and doxorubicin (1.72 nM) or paclitaxel (1.17 nM) exerted a greater-than-additive antiproliferative effect at 24 h exposure, while the combination of Na-but and doxorubicin or paclitaxel did not. These preliminary in vitro results suggest that SLN could be proposed as alternative drug delivery system.

Phase II trial of the histone deacetylase inhibitor pivaloyloxymethyl butyrate (Pivanex, AN-9) in advanced non-small cell lung cancer

This multicenter phase II trial evaluated the therapeutic activity and safety profile of pivaloyloxymethyl butyrate (Pivanex, AN-9) as a single agent in refractory non-small cell lung cancer (NSCLC). Pivanex (2.34 g/m2 per day) was administered as a 6-h continuous intravenous infusion, daily for 3 days, and repeated every 21 days until disease progression. Forty-seven patients were treated. More than 90% of patients had received both a platinum compound and a taxane and 32% had received three or more prior chemotherapy regimens. The most common toxicities were transient grade 1-2 fatigue (34%), nausea (17%), and dysgeusia (11%). Three patients had partial responses (6.4 and 95%; CI 1.4-18.7%) and 14 patients had stable disease for > or =12 weeks (30%). Median survival for all patients was 6.2 months with 1-year survival of 26%. For patients who received fewer than three prior chemotherapy regimens, median survival was 7.8 months and 1-year survival was 31%. Pivanex is well tolerated and appears to be active as a single agent in patients with advanced NSCLC refractory to previous chemotherapy. Based on its therapeutic activity and favorable safety profile, further studies of Pivanex in NSCLC, particularly in combination with current chemotherapeutic agents, are warranted.

Mcl-1 and Bcl-2/Bax ratio are associated with treatment response but not with Rai stage in B-cell chronic lymphocytic leukemia

Although both Bcl-2/Bax ratio and Mcl-1 have been identified to be of clinical relevance in B-cell chronic lymphocytic leukemia (CLL), there is controversy regarding their role; further, their relative importance is not well delineated. Expression of Bcl-2, Bax, the Bcl-2/Bax ratio, and Mcl-1 in 51 consecutive previously untreated CLL patients and 16 controls was determined by Western blotting. Only 37 patients were treated, all with chlorambucil and prednisone initially. Six patients achieved complete response (CR), 14 were non-responders (NR), and 17 had a partial response (PR), as defined by NCI criteria. There was considerable inter-patient variability in protein expression and overlap with healthy volunteers (P > 0.05). All patients with CR had low Mcl-1 levels compared to the PR + NR group (0.07 +/- 0.02 vs. 0.14 +/- 0.07, P = 0.043). Higher Mcl-1 expression as determined by dichotomizing the data was associated with a failure to achieve CR (P = 0.021). The Bcl-2/Bax ratio was significantly associated with treatment response only when CR and PR were considered together (0.89 +/- 0.53 [CR + PR] vs. 3.38 +/- 4.47 [NR], P = 0.0118). There was no association with Rai stage. Low Mcl-1 appears to be a requirement for CR, while low Bcl-2/Bax ratio is indicative of some response to conventional treatment.

Effect of sodium butyrate combined with chuanhuning on HCT-8 cell line proliferation

AIM

To study the effect of sodium butyrate in combination with chuanhuning on HCT-8 cell line proliferation.

METHODS

Inhibition of HCT-8 cell line by sodium butyric acid in combination with chuanhuning was detected by MTT assay and growth curve, and apoptosis was determined by morphological assay and flow cytometry (FCM). Apoptotic cells were observed electro- microscopically.

RESULTS

Sodium butyric acid showed inhibitory effect on the proliferation of HCT-8 cell line in dose-dependent and time-dependent manner. The inhibitory rates were 15.7%, 20.3%, and 33.3% (P<0.01) in different groups. Differentiation and apoptosis were observed under electronic microscope. Sub-G1 peak was detected by FCM. Cell cycle was blocked in S phase. The apoptotic rate of combined group 1 were 23.5%, 48.6% at 24 h, and 48 h, and the apoptotic rate of combined group 2 were 30.8%, 54.2% at 24 h, and 48 h (P<0.01).

CONCLUSION

Sodium butyric acid can induce apoptosis and differentiation of HCT-8 cells of human colorectal carcinoma, and inhibit proliferation of HCT-8 cells. Apoptotic rate was significantly increased when sodium butyric acid was combined with Chuanhuning.

Role of caspases and apoptosis-inducing factor (AIF) in cladribine-induced apoptosis of B cell chronic lymphocytic leukemia

We have evaluated the role of caspases and the mitochondrial apoptosis inducing-factor (AIF) in apoptosis induced by cladribine (2CdA), in vitro, in cells from patients of B-CLL and in peripheral blood lymphocytes from normal donors. In sensitive B-CLL cells, apoptosis was characterized by cell shrinking, loss of mitochondrial membrane potential (DeltaPsi(m)), phosphatidylserine exposure, activation of caspases 3, 7, 8 and 9, reduction of Mcl-1 levels, translocation of AIF from mitochondria to nucleus and chromatin condensation. No significant variations in the levels of Bcl-2, Bax and Bak proteins were noticed upon treatment with 2CdA. Co-treatment of cells with the pan-caspase inhibitor Z-VAD-fmk attenuated some morphological and biochemical characteristics of apoptosis and delayed 2CdA-induced DeltaPsi(m) loss, but did not prevent cell death. Z-VAD-fmk did not prevent 2CdA-induced AIF translocation but in this case apoptotic cells displayed only peripheral chromatin condensation, characteristic of AIF action. Reduced or negligible caspase 3 expression did not prevent 2CdA toxicity in cells from four patients. Cells from three patients that responded poorly to 2CdA lacked expression of caspases 9 or 3. Cells from another patient resistant to 2CdA expressed caspases 3, 7, 8 and 9 but they were not activated by treatment. These results indicate that execution of apoptosis is carried out independently by AIF and caspases, which are responsible for the development of apoptotic phenotype in response to 2CdA. Although caspases can also collaborate in DeltaPsi(m) loss, proapoptotic proteins from the Bcl-2 superfamily may be the key inducers of DeltaPsi(m) loss and apoptosis in B-CLL cells sensitive to 2CdA.

Histone deacetylase inhibitors in cancer treatment

Histone deacetylase (HDAC) inhibitors are emerging as an exciting new class of potential anticancer agents for the treatment of solid and hematological malignancies. In recent years, an increasing number of structurally diverse HDAC inhibitors have been identified that inhibit proliferation and induce differentiation and/or apoptosis of tumor cells in culture and in animal models. HDAC inhibition causes acetylated nuclear histones to accumulate in both tumor and normal tissues, providing a surrogate marker for the biological activity of HDAC inhibitors in vivo. The effects of HDAC inhibitors on gene expression are highly selective, leading to transcriptional activation of certain genes such as the cyclin-dependent kinase inhibitor p21WAF1/CIP1 but repression of others. HDAC inhibition not only results in acetylation of histones but also transcription factors such as p53, GATA-1 and estrogen receptor-alpha. The functional significance of acetylation of non-histone proteins and the precise mechanisms whereby HDAC inhibitors induce tumor cell growth arrest, differentiation and/or apoptosis are currently the focus of intensive research. Several HDAC inhibitors have shown impressive antitumor activity in vivo with remarkably little toxicity in preclinical studies and are currently in phase I clinical trial. The focus of this review is the development and clinical application of HDAC inhibitors for the treatment of cancer.