Apoptotic mechanism of paclitaxel-induced cell death in human head and neck tumor cell lines

Preparation and application of modified three-dimensional cellulose microspheres for paclitaxel targeted separation

In this article, we successfully prepared three-dimensional cellulose microspheres modified by molecularly imprinted polymer for paclitaxel recognition and separation (3D-CM &PTX&MIPs). The material was characterized by Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscope (SEM), Thermogravimetric Analysis (TG) and diffraction of X-rays (XRD). Under the optimized adsorption conditions, the maximum adsorption capacity reached 65.7 mg/g. And after 5 runs of reuse, (3D-CM&PTX&MIPs) still maintained a reusability rate of 90%. Besides, (3D-CM&PTX&MIPs) showed excellent selectivity for target PTX. Finally, (3D-CM&PTX&MIPs) was used for PTX recognition and separation in the extracts of yew leaves. This research laid a good foundation and scientific basis for the efficient, environmentally friendly, and rapid enrichment of metabolites in plants using bio-based molecularly imprinted polymers.

Role of JNK activation in paclitaxel-induced apoptosis in human head and neck squamous cell carcinoma

It has been reported that paclitaxel activates cell cycle arrest and increases caspase protein expression to induce apoptosis in head and neck squamous cell carcinoma (HNSCC) cell lines. However, the potential signaling pathway regulating this apoptotic phenomenon remains unclear. The present study used OEC-M1 cells to investigate the underlying molecular mechanism of paclitaxel-induced apoptosis. Following treatment with paclitaxel, cell viability was assessed via the MTT assay. Necrosis, apoptosis, cell cycle and mitochondrial membrane potential (∆Ψm) were analyzed via flow cytometric analyses, respectively. Western blot analysis was performed to detect the expression levels of proteins associated with the MAPK and caspase signaling pathways. The results demonstrated that low-dose paclitaxel (50 nM) induced apoptosis but not necrosis in HNSCC cells. In addition, paclitaxel activated the c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase or p38 mitogen-activated protein kinase. The paclitaxel-activated JNK contributed to paclitaxel-induced apoptosis, activation of caspase-3, -6, -7, -8 and -9, and reduction of ∆Ψm. In addition, caspase-8 and -9 inhibitors, respectively, significantly decreased paclitaxel-induced apoptosis. Notably, Bid was truncated following treatment with paclitaxel. Taken together, the results of the present study suggest that paclitaxel-activated JNK is required for caspase activation and loss of ∆Ψm, which results in apoptosis of HNSCC cells. These results may provide mechanistic basis for designing more effective paclitaxel-combining regimens to treat HNSCC.

Self-Assembly of pH-Labile Polymer Nanoparticles for Paclitaxel Prodrug Delivery: Formulation, Characterization, and Evaluation

The efficacy of paclitaxel (PTX) is limited due to its poor solubility, poor bioavailability, and acquired drug resistance mechanisms. Designing paclitaxel prodrugs can improve its anticancer activity and enable formulation of nanoparticles. Overall, the aim of this work is to improve the potency of paclitaxel with prodrug synthesis, nanoparticle formation, and synergistic formulation with lapatinib. Specifically, we improve potency of paclitaxel by conjugating it to α-tocopherol (vitamin E) to produce a hydrophobic prodrug (Pro); this increase in potency is indicated by the 8-fold decrease in half maximal inhibitory concentration (IC50) concentration in ovarian cancer cell line, OVCA-432, used as a model system. The efficacy of the paclitaxel prodrug was further enhanced by encapsulation into pH-labile nanoparticles using Flash NanoPrecipitation (FNP), a rapid, polymer directed self-assembly method. There was an 1100-fold decrease in IC50 concentration upon formulating the prodrug into nanoparticles. Notably, the prodrug formulations were 5-fold more potent than paclitaxel nanoparticles. Finally, the cytotoxic effects were further enhanced by co-encapsulating the prodrug with lapatinib (LAP). Formulating the drug combination resulted in synergistic interactions as indicated by the combination index (CI) of 0.51. Overall, these results demonstrate this prodrug combined with nanoparticle formulation and combination therapy is a promising approach for enhancing paclitaxel potency.

Gold nanoparticle‑mediated delivery of paclitaxel and nucleic acids for cancer therapy (Review)

Paclitaxel is a potent antineoplastic agent, but poor solubility and resistance have limited its use. Gold nanoparticles (AuNPs) are widely studied as drug carriers because they can be engineered to prevent drug insolubility, carry nucleic acid payloads for gene therapy, target specific tumor cell lines, modulate drug release and amplify photothermal therapy. Consequently, the conjugation of paclitaxel with AuNPs to improve antiproliferative and pro‑apoptotic potency may enable improved clinical outcomes. There are currently a number of different AuNPs under development, including simple drug or nucleic acid carriers and targeted AuNPs that are designed to deliver therapeutic payloads to specific cells. The current study reviewed previous research on AuNPs and the development of AuNP‑based paclitaxel delivery.

Rapid Self-Assembly of Polymer Nanoparticles for Synergistic Codelivery of Paclitaxel and Lapatinib via Flash NanoPrecipitation

Taxol, a formulation of paclitaxel (PTX), is one of the most widely used anticancer drugs, particularly for treating recurring ovarian carcinomas following surgery. Clinically, PTX is used in combination with other drugs such as lapatinib (LAP) to increase treatment efficacy. Delivering drug combinations with nanoparticles has the potential to improve chemotherapy outcomes. In this study, we use Flash NanoPrecipitation, a rapid, scalable process to encapsulate weakly hydrophobic drugs (logP < 6) PTX and LAP into polymer nanoparticles with a coordination complex of tannic acid and iron formed during the mixing process. We determine the formulation parameters required to achieve uniform nanoparticles and evaluate the drug release in vitro. The size of the resulting nanoparticles was stable at pH 7.4, facilitating sustained drug release via first-order Fickian diffusion. Encapsulating either PTX or LAP into nanoparticles increases drug potency (as indicated by the decrease in IC-50 concentration); we observe a 1500-fold increase in PTX potency and a six-fold increase in LAP potency. When PTX and LAP are co-loaded in the same nanoparticle, they have a synergistic effect that is greater than treating with two single-drug-loaded nanoparticles as the combination index is 0.23 compared to 0.40, respectively.

Metformin Suppresses Hypopharyngeal Cancer Growth by Epigenetically Silencing Long Non-coding RNA SNHG7 in FaDu Cells

Local recurrence after therapy remains a challenging problem for hypopharyngeal cancer (HPC) due to the chemotherapy resistance. Metformin is associated with reduced cancer risk through promoting global DNA methylation in cancer cells by controlling S-adenosylhomocysteine (SAHH) activity. However, the mechanisms by which metformin inhibits HPC remain elusive. In this study, we aim to investigate the role of metformin in HPC and illustrate the mechanism by which metformin regulates long non-coding RNAs (lncRNAs) expression. CCK-8 and annexin-V/PI double staining were performed to analyze the cell viability and apoptosis. LncRNA microarray analysis, QPCR, methylation specific PCR, Western blot and RNA Immunoprecipitation were performed to analyze the molecular mechanism, Here, we report that metformin inhibits FaDu cell proliferation in time- and dose-dependent manner by suppressing lncRNA SNHG7. Further investigations revealed that SNHG7 interacted with SAHH and metformin decreased SNHG7 expression by activating SAHH activity. Increased SAHH activity resulted in upregulating DNMT1 expression, leading to hypermethylation of SNHG7 promotor. In addition, upregulation of SNHG7 was associated with advanced stage. The patients with high SNHG7 have lower overall survival than that of with low SNHG7. Interestingly, SNHG7 levels were higher in taxol resistant patients than in taxol sensitive patients. Metformin sensitizes FaDu cells to taxol and irradiation through decreasing SNHG7. In conclusion, our recent study demonstrates that metformin inhibits FaDu cell proliferation by decreasing SNHG7 expression via SAHH-mediated DNA methylation. These findings indicate that combined metformin with paclitaxel or irradiation would be a novel therapeutic strategy to overcome resistance and prevent recurrence in HPC.

Ectopic high endothelial venules in pancreatic ductal adenocarcinoma: A unique site for targeted delivery

BACKGROUND

Nanomedicine offers an excellent opportunity to tackle treatment-refractory malignancies by enhancing the delivery of therapeutics to the tumor site. High endothelial venules (HEVs) are found primarily in lymph nodes or formed de novo in peripheral tissues during inflammatory responses. They express peripheral node addressin (PNAd), which is recognized by the monoclonal antibody MECA79.

METHODS

Here, we demonstrated that HEVs form de novo in human pancreatic ductal adenocarcinoma (PDAC). We engineered MECA79 coated nanoparticles (MECA79-NPs) that recognize these ectopic HEVs in PDAC.

FINDINGS

The trafficking of MECA79-NPs following intravenous delivery to human PDAC implanted in a humanized mouse model was more robust than non-conjugated NPs. Treatment with MECA79-Taxol-NPs augmented the delivery of Paclitaxel (Taxol) to the tumor site and significantly reduced the tumor size. This effect was associated with a higher apoptosis rate of PDAC cells and reduced vascularization within the tumor.

INTERPRETATION

Targeting the HEVs of PDAC using MECA79-NPs could lay the ground for the localized delivery of a wide variety of drugs including chemotherapeutic agents. FUND: National Institutes of Health (NIH) grants: T32-EB016652 (B·B.), NIH Cancer Core Grant CA034196 (L.D.S.), National Institute of Allergy and Infectious Diseases grants R01-AI126596 and R01-HL141815 (R.A.).

Cell culture models of oral mucosal barriers: A review with a focus on applications, culture conditions and barrier properties

Understanding the function of oral mucosal epithelial barriers is essential for a plethora of research fields such as tumor biology, inflammation and infection diseases, microbiomics, pharmacology, drug delivery, dental and biomarker research. The barrier properties are comprised by a physical, a transport and a metabolic barrier, and all these barrier components play pivotal roles in the communication between saliva and blood. The sum of all epithelia of the oral cavity and salivary glands is defined as the blood-saliva barrier. The functionality of the barrier is regulated by its microenvironment and often altered during diseases. A huge array of cell culture models have been developed to mimic specific parts of the blood-saliva barrier, but no ultimate standard in vitro models have been established. This review provides a comprehensive overview about developed in vitro models of oral mucosal barriers, their applications, various cultivation protocols and corresponding barrier properties.

The long noncoding RNA ANRIL acts as an oncogene and contributes to paclitaxel resistance of lung adenocarcinoma A549 cells

Long non-coding RNAs (lncRNAs) are a family of non-protein-coding RNAs that might affect Lung adenocarcinoma (LAD) chemo-resistance and most of them could be used as biomarkers and therapy targets. However, the potential function of lncRNA ANRIL contributed paclitaxel chemo-resistance in LAD is still unknown. This study aimed to observe the expression of ANRIL in LAD, evaluate its biological role in the resistance of LAD cells to paclitaxel and explore the apoptosis role in the ANRIL associated mechanism. Our results showed that ANRIL functioning as a potential oncogene was up-regulated in LAD, and promoted the acquisition of chemo-resistance in paclitaxel partly through the mitochondrial pathway by modulating the expression of apoptosis-related protein cleaved-PARP and Bcl-2. These findings might improve LAD patients' paclitaxel treatment and made ANRIL to be a new target for paclitaxel-based chemotherapy in LAD.

Proinflammatory Factors Mediate Paclitaxel-Induced Impairment of Learning and Memory

The chemotherapeutic agent paclitaxel is widely used for cancer treatment. Paclitaxel treatment impairs learning and memory function, a side effect that reduces the quality of life of cancer survivors. However, the neural mechanisms underlying paclitaxel-induced impairment of learning and memory remain unclear. Paclitaxel treatment leads to proinflammatory factor release and neuronal apoptosis. Thus, we hypothesized that paclitaxel impairs learning and memory function through proinflammatory factor-induced neuronal apoptosis. Neuronal apoptosis was assessed by TUNEL assay in the hippocampus. Protein expression levels of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) in the hippocampus tissue were analyzed by Western blot assay. Spatial learning and memory function were determined by using the Morris water maze (MWM) test. Paclitaxel treatment significantly increased the escape latencies and decreased the number of crossing in the MWM test. Furthermore, paclitaxel significantly increased the number of TUNEL-positive neurons in the hippocampus. Also, paclitaxel treatment increased the expression levels of TNF-α and IL-1β in the hippocampus tissue. In addition, the TNF-α synthesis inhibitor thalidomide significantly attenuated the number of paclitaxel-induced TUNEL-positive neurons in the hippocampus and restored the impaired spatial learning and memory function in paclitaxel-treated rats. These data suggest that TNF-α is critically involved in the paclitaxel-induced impairment of learning and memory function.

Synergistic Effect of Notch-3-Specific Inhibition and Paclitaxel in Non-Small Cell Lung Cancer (NSCLC) Cells Via Activation of The Intrinsic Apoptosis Pathway

BACKGROUND Lung cancers are resistant to conventional chemotherapeutic interventions such as paclitaxel. Notch signaling is crucial in the chemoresistance of lung cancer cells. The Notch inhibitor gamma-secretase inhibitor (GSI) inhibits the Notch signaling pathway. MATERIAL AND METHODS Here, we evaluated how Notch-3 inhibition by GSI can enhance the sensitivity of lung cancer cells to paclitaxel. To study how Notch-3-specific inhibition affects non-small cell lung cancer (NSCLC), we compared the cell viability, apoptosis, and colony formation of A549 and H1299 cells treated with Notch-3 siRNA and GSI. RESULTS The expression levels of Notch-3 or Notch intracellular domain 3 (NICD3) and apoptosis-related proteins were measured and compared between different groups. Notch-3 was significantly overexpressed in both cell lines, and Notch-3 expression was elevated after paclitaxel treatment, indicating activation of the Notch signaling pathway. Inhibition of the Notch signaling pathway by GSI and Notch-3 siRNA reduced cell proliferation and induced apoptosis in A549 and H1299 cells, thereby boosting sensitivity of the cell lines to paclitaxel. Concomitant treatment with paclitaxel and GSI or siRNA downregulated Bcl-2 expression and upregulated Bax expression levels. CONCLUSIONS These results indicate a synergistic effect of Notch-3-specific inhibition and paclitaxel through alteration of the intrinsic apoptosis pathway, which was involved in Notch-3-induced chemoresistance in NSCLC cells, and GSI inhibited Notch-3-induced chemoresistance in a concentration-dependent manner. This approach that combines Notch-3-specific inhibition and paclitaxel would be likely to apply in NSCLC.

Chidamide in FLT3-ITD positive acute myeloid leukemia and the synergistic effect in combination with cytarabine

Chidamide, a novel histone deacetylase inhibitor (HDACi), has been approved for treatment of T-cell lymphomas in multiple clinical trials. It has been demonstrated that chidamide can inhibit cell cycle, promote apoptosis and induce differentiation in leukemia cells, whereas its effect on acute myeloid leukemia (AML) patients with FLT3-ITD mutation has not been clarified. In this study, we found that chidamide specifically induced G0/G1 arrest and apoptosis in FLT3-ITD positive AML cells in a concentration and time-dependent manner. We also found chidamide had the cytotoxicity effect on FLT3-ITD positive and negative AML cells. Moreover, with respect to relapsed/refractory patients, chidamide showed the same effectiveness as that in de novo AML patients. Notably, chidamide synergistically enhanced apoptosis caused by cytarabine. Our results support chidamide alone or combine with cytarabine may be used as an alternative therapeutic choice for AML patients especially those with FLT3-ITD mutation or relapsed/refractory ones.

Knockdown of the M2 Isoform of Pyruvate Kinase (PKM2) with shRNA Enhances the Effect of Docetaxel in Human NSCLC Cell Lines In Vitro

PURPOSE

The aim of our study was to explore the relationships between the M2 isoform of pyruvate kinase (PKM2) and the sensitivity of human non-small cell lung cancer (NSCLC) cells to docetaxel in vitro.

MATERIALS AND METHODS

With the method of plasmid transfection, we silenced the expression of PKM2 successfully in A549 and H460 cells. Western blotting and real-time PCR were applied to detect PKM2 expression at protein and gene levels. Cell viability was examined by CCK8 assay. Cell cycle distribution and apoptosis were examined by flow cytometry. P21 and Bax were detected.

RESULTS

Expression of PKM2 mRNA and protein were significantly decreased by shRNA targeting PKM2. Silencing of PKM2 increased docetaxel sensitivity of human NSCLC A549 and H460 cells in a collaborative manner, resulting in strong suppression of cell viability. The results of flow cytometric assays suggested that knockdown of PKM2 or docetaxel treatment, whether used singly or in combination, blocked the cells in the G2/M phase, which is in consistent with the effect of the two on the expression of p21. Cells with PKM2 silencing were more likely to be induced into apoptosis by docetaxel although knockdown of PKM2 alone can't induce apoptosis significantly, which is in consistent with the effect of the two on Bax expression.

CONCLUSION

The results suggest that PKM2 knockdown could serve as a chemosensitizer to docetaxel in non-small lung cancer cells through targeting PKM2, leading to inhibition of cell viability, increase of cell arrest of G2/M phase and apoptosis.

Nanocarrier-based immunotherapy in cancer management and research

Research in cancer immunotherapy has gained momentum in the last two decades, with many studies and clinical trials showing positive therapeutic outcomes. Immunotherapy can elicit not only a strong anticancer immune response which could even control metastases, but could also induce immunological memory, resulting in long-lasting protection in the prophylactic setting and protection against possible recurrence. Nanocarriers offer an attractive means for delivery of a multitude of therapeutic immunomodulators which are readily taken up by immune cells and can initiate a particular arm of an immunostimulatory cascade leading to tumor cell killing. This review focuses on recent advances in nanocarrier-mediated immunotherapy for the treatment of cancer. Both in vitro and in vivo studies as well as clinical progress are discussed in various sections. Description of the specific role of nanoparticle technology in immunotherapy highlights the way particles can be tailor-made in terms of size, structure, payload, and surface properties for active targeting to antigen-presenting cells and/or enhanced accumulation in the solid tumor.

Recent progress in the development of polysaccharide conjugates of docetaxel and paclitaxel

Taxanes are one of the most potent and broadest spectrum chemotherapeutics used clinically, but also induce significant side effects. Different strategies have been developed to produce a safer taxane formulation. Development of polysaccharide drug conjugates has increased in the recent years because of the demonstrated biocompatibility, biodegradability, safety, and low cost of the biopolymers. This review focuses on polysaccharide-taxane conjugates and provides an overview on various conjugation strategies and their effect on the efficacy. Detailed analyses on the designing factors of an effective polysaccharide-drug conjugate are provided with a discussion on the future direction of this field. For further resources related to this article, please visit the WIREs website.

CONFLICT OF INTEREST

The authors have declared no conflicts of interest for this article.

The dual pathway inhibitor rigosertib is effective in direct patient tumor xenografts of head and neck squamous cell carcinomas

The dual pathway inhibitor rigosertib inhibits phosphoinositide 3-kinase (PI3K) pathway activation as well as polo-like kinase 1 (PLK1) activity across a broad spectrum of cancer cell lines. The importance of PIK3CA alterations in squamous cell carcinoma of the head and neck (HNSCC) has raised interest in exploring agents targeting PI3K, the product of PIK3CA. The genetic and molecular basis of rigosertib treatment response was investigated in a panel of 16 HNSCC cell lines, and direct patient tumor xenografts from eight patients with HNSCC [four HPV-serotype16 (HPV16)-positive]. HNSCC cell lines and xenografts were characterized by pathway enrichment gene expression analysis, exon sequencing, gene copy number, Western blotting, and immunohistochemistry (IHC). Rigosertib had potent antiproliferative effects on 11 of 16 HPV(-) HNSCC cell lines. Treatment sensitivity was confirmed in two cell lines using an orthotopic in vivo xenograft model. Growth reduction after rigosertib treatment was observed in three of eight HNSCC direct patient tumor lines. The responsive tumor lines carried a combination of a PI3KCA-activating event (amplification or mutation) and a p53-inactivating event (either HPV16- or mutation-mediated TP53 inactivation). In this study, we evaluated the in vitro and in vivo efficacy of rigosertib in both HPV(+) and HPV(-) HNSCCs, focusing on inhibition of the PI3K pathway. Although consistent inhibition of the PI3K pathway was not evident in HNSCC, we identified a combination of PI3K/TP53 events necessary, but not sufficient, for rigosertib sensitivity.

Generation of reactive oxygen species by polyenylpyrroles derivatives causes DNA damage leading to G2/M arrest and apoptosis in human oral squamous cell carcinoma cells

Oral squamous cell carcinoma (OSCC) accounts for 5.8% of all malignancies in Taiwan and the incidence of OSCC is on the rise. OSCC is also a common malignancy worldwide and the five-year survival rate remains poor. Therefore, new and effective treatments are needed to control OSCC. In the present study we have investigated the efficacy and associated mechanisms of polyenylpyrroles and their analogs in both in vitro cell culture and in vivo nude mice xenografts. Auxarconjugatin B (compound 1a) resulted in cell cycle arrest in the G2/M phase and caspase-dependent apoptosis in OEC-M1 and HSC-3 cells by activating DNA damage and mitochondria dysfunction through the loss of mitochondrial membrane potential, release of cytochrome c, increase in B-cell lymphoma-2-associated X protein level, and decrease in B-cell lymphoma-2 level. Compound 1a-induced generation of intracellular reactive oxygen species through cytochrome P450 1A1 was identified as a major mechanism of its effect for DNA damage, mitochondria dysfunction and apoptosis, which was reversed by antioxidant N-acetylcysteine as well as cytochrome P450 1A1 inhibitor and specific siRNA. Furthermore, compound 1a-treated nude mice showed a reduction in the OEC-M1 xenograft tumor growth and an increase in the caspase-3 activation in xenograft tissue. These results provide promising insights as to how compound 1a mediates cytotoxicity and may prove to be a molecular rationale for its translation into a potential therapeutic against OSCC.

Anticancer and immunostimulatory activity by conjugate of paclitaxel and non-toxic derivative of LPS for combined chemo-immunotherapy

PURPOSE

Cancer is a multifactorial syndrome; hence, multidimensional therapy with a chemo-immunotherapeutic conjugate could be more effective in curing the disease.

METHODS

We used SP-LPS, a bio-polymer having potent immunostimulatory activity, for conjugation with paclitaxel to make a chemo-immunotherapeutic conjugate. Its physicochemical characterization was done by HPLC, NMR and IR spectra. Stability was measured at different pH, temperature and in tissue homogenates. Chemotherapeutic and immunostimulatory activity was evaluated in vitro and also in tumor microenvironment.

RESULTS

The conjugate self assembled into nanoparticulate structure, probably due to micelle formation. Stability was pH and temperature dependent. The conjugate exhibited chemotherapeutic and immunotherapeutic activity in vitro. In vivo antitumor activity was significantly higher and a higher percentage of activated immune cells were found in the tumor microenvironment of the conjugate-treated mice as compared to Taxol®-treated group.

CONCLUSIONS

This conjugate is a potential chemo-immunotherapeutic compound for the treatment of cancer with advantages over present day chemotherapy with Taxol in terms of higher anticancer activity, less toxicity and ease of delivery.

Allosteric modulation by protein kinase Cε leads to modified responses of EGF receptor towards tyrosine kinase inhibitors

Recently, we described a novel function of over-expressed protein kinase Cε (PKCε) as a negative allosteric modulator of EGFR signalling in several head and neck squamous carcinoma (HNSCC) cell lines. Extending this work, here we present several lines of evidence for the potency of PKCε to differently modulate the efficacy of EGFR tyrosine kinase inhibitors (TKIs) such as gefitinib and lapatinib. Using the HNSCC cell line FaDu as a model, we demonstrate by co-immunoprecipitation the physical association of over-expressed PKCε with the EGFR which is stabilised by gefitinib and leads to an increase in gefitinib-induced inhibition of EGFR downstream signalling and elevated EGFR-ErbB2 heterodimerisation. Cell cycle and Western blot analysis revealed that the gefitinib-induced apoptosis was enhanced whereas the pro-apoptotic effect of lapatinib that requires another EGFR conformation was reduced by PKCε. Our findings suggest that due to elevated expression PKCε may associate with the EGFR resulting in conformational changes and different allosteric modulation of the EGFR behaviour towards TKIs. This surprising capacity indicates PKCε as a novel predictive marker protein in molecular cancer therapy with EGFR tyrosine kinase inhibitors.

Antiproliferative effect of Tualang honey on oral squamous cell carcinoma and osteosarcoma cell lines

Background

The treatment of oral squamous cell carcinomas (OSCC) and human osteosarcoma (HOS) includes surgery and/or radiotherapy which often lead to reduced quality of life. This study was aimed to study the antiproliferative activity of local honey (Tualang) on OSCC and HOS cell lines.

Methods

Several concentrations of Tualang honey (1% - 20%) were applied on OSCC and HOS cell lines for 3, 6, 12, 24, 48 and 72 hours. Morphological characteristics were observed under light and fluorescent microscope. Cell viability was assessed using MTT assay and the optical density for absorbance values in each experiment was measured at 570 nm by an ELISA reader. Detection of cellular apoptosis was done using the Annexin V-FITC Apoptosis Detection Kit.

Results

Morphological appearance showed apoptotic cellular changes like becoming rounded, reduction in cell number, blebbed membrane and apoptotic nuclear changes like nuclear shrinkage, chromatin condensation and fragmented nucleus on OSCC and HOS cell lines. Cell viability assay showed a time and dose-dependent inhibitory effect of honey on both cell lines. The 50% inhibitory concentration (IC₅₀) for OSCC and HOS cell lines was found to be 4% and 3.5% respectively. The maximum inhibition of cell growth of ≥80% was obtained at 15% for both cell lines. Early apoptosis was evident by flow cytometry where percentage of early apoptotic cells increased in dose and time dependent manner.

Conclusion

Tualang honey showed antiproliferative effect on OSCC and HOS cell lines by inducing early apoptosis.

A novel histone deacetylase inhibitor Chidamide induces apoptosis of human colon cancer cells

Many studies have demonstrated that histone deacetylase (HDAC) inhibitors induce various tumor cells to undergo apoptosis, and such inhibitors have been used in different clinical trials against different human cancers. In this study, we designed and synthesized a novel HDAC inhibitor, Chidamide. We showed that Chidamide was able to increase the acetylation levels of histone H3 and to inhibit the PI3K/Akt and MAPK/Ras signaling pathways, which resulted in arresting colon cancer cells at the G1 phase of the cell cycle and promoting apoptosis. As a result, the proliferation of colon cancer cells was suppressed in vitro. Our data support the potential application of Chidamide as an anticancer agent in treating colon cancer. Future studies are needed to demonstrate its in vivo efficacy.