Selective targeting of antiapoptotic BCL-2 proteins in cancer

Anti-Cancer Potential of Linear β-(1→6)-D-Glucan from Agaricus bisporus on Estrogen Receptor-Positive (ER+) Breast Cancer Cells

Mushroom β-D-glucans can be isolated from several species, including the widely consumed Agaricus bisporus. Besides immunomodulatory responses, some β-D-glucans may exhibit direct antitumoral effects. It was previously observed that a β-(1→6)-D-glucan (BDG16) has indirect cytotoxicity on triple-negative breast cancer cells. In this study, the cytotoxicity of this same glucan was observed on estrogen receptor-positive (ER+) breast cancer cells (MCF-7). Cell viability was determined by multiple methods to assess metabolic activity, lysosomal membrane integrity, and adhesion capacity. Assays to evaluate cell respiration, cell cycle, apoptosis, necroptosis, and oxidative stress were performed to determine the action of BDG16 on MCF-7 cells. A gradual and significant cell viability reduction was observed when the cells were treated with BDG16 (10-1000 µg/mL). This result could be associated with the inhibition of the basal state respiration after incubation with the β-D-glucan. The cells showed a significant arrest in G1 phase population at 1000 µg/mL, with no induction of apoptosis. However, an increase in necrosis and necroptosis at the same concentration was observed. No difference in oxidative stress-related molecules was observed. Altogether, our findings demonstrate that BDG16 directly induces toxicity in MCF-7 cells, primarily by impairing mitochondrial respiration and promoting necroptosis. The specific mechanisms that mediate this action are being investigated.

The Drug Transporter P-Glycoprotein and Its Impact on Ceramide Metabolism-An Unconventional Ally in Cancer Treatment

The tumor-suppressor sphingolipid ceramide is recognized as a key participant in the cytotoxic mechanism of action of many types of chemotherapy drugs, including anthracyclines, Vinca alkaloids, the podophyllotoxin etoposide, taxanes, and the platinum drug oxaliplatin. These drugs can activate de novo synthesis of ceramide or stimulate the production of ceramide via sphingomyelinases to limit cancer cell survival. On the contrary, dysfunctional sphingolipid metabolism, a prominent factor in cancer survival and therapy resistance, blunts the anticancer properties of ceramide-orchestrated cell death pathways, especially apoptosis. Although P-glycoprotein (P-gp) is famous for its role in chemotherapy resistance, herein, we propose alternate interpretations and discuss the capacity of this multidrug transporter as a "ceramide neutralizer", an unwelcome event, highlighting yet another facet of P-gp's versatility in drug resistance. We introduce sphingolipid metabolism and its dysfunctional regulation in cancer, present a summary of factors that contribute to chemotherapy resistance, explain how P-gp "neutralizes" ceramide by hastening its glycosylation, and consider therapeutic applications of the P-gp-ceramide connection in the treatment of cancer.

Vesicular approach of cubosomes, its components, preparation techniques, evaluation and their appraisal for targeting cancer cells

Cancer has been characterized by abnormal and uncontrolled proliferation of cells. Majority of drugs given through chemotherapy produce unwanted and adverse effects of chemotherapeutic agents to the other healthy cells and tissues of body. Various nanocarriers have now been considered for treatment of cancer. Among various nanocarriers, cubosomes are the nano sized dispersions that have drawn interest of researchers recently. Cubosomes are defined as dispersions of colloidal nature containing cubic crystalline liquid formations in aqueous medium in presence of suitable surfactant molecules. The unique capacity to encapsulate lipophilic, hydrophilic, and amphiphilic compounds inside their structure distinguishes them among others. Top- down method and hydrotrope method are most often employed methods for cubosomes preparation. Cubosomes can be characterized by Polarized light microscopy Photon correlation spectroscopy X-ray scattering (SAXS), Transmission electron microscopy and various stability studies. Cubic lipid nanoparticles have a very stable cubic structure that enables slower dissociation rate, increased retention and site-specific delivery of drugs. Cubosomes containing extracts of cornelian cherry for boosting anti-cancerous effects in cancer of colorectal cells by preventing against GIT destruction. When applied for skin cancer, cubosomes have shown to be having enhanced permeation of the drug. In liver cancer, increased bioavailability of drug was observed via cubosomes. This current review elaborates the advancement of cubosomes and their effective role in the treatment of cancer. This review aims to describe vesicular approach of cubosomes, its composition and method of preparation, characterization tests as well as elaborates various applications of cubosomes in cancer.

The mechanism of anticancer effects of some pyrrolopyrimidine derivatives on HT-29 human colon cancer cells

In the present work, the mechanism of anticancer activity of some pyrrolopyrimidine derivatives was evaluated. Compounds 5 and 8 exhibiting significant antiproliferative activity against HT-29 cells with IC50 values of 4.17 μM and 2.96, arrested the cells at the G2/M phase and significantly induced apoptosis. The apoptotic potential of the compounds has been verified via ELISA assay, which resulted in increased BAX, PUMA, BIM, and cleaved caspase 3 expression and decreased BCL-XL and MCL-1 protein levels in HT-29 cells. Moreover, the immunofluorescence technique showing that compounds 5 and 8-treatment reduced Ki67 immunolocalization and increased the caspase 3 and p53 immunolocalization confirmed the apoptotic activity. While treatment of HT-29 cells to compounds 5 and 8 inhibited Akt and ERK1/2, there are no alterations in JNK and p38 signaling pathways. According to molecular docking results, compounds 5 and 8 occupied the active site of Akt kinase and showed important hydrogen bonding interactions with key amino acids. Also, siRNA-mediated depletion of BIM, PUMA, and BAX/BAK expression decreased apoptotic response in HT-29 cells upon exposure to compound 5 and compound 8. Compounds 5 and 8 trigger the activation of mitochondrial apoptosis in HT-29 cells. Additionally, we found that proapoptotic BH3-only proteins BIM and PUMA are required for the full engagement of mitochondrial apoptosis signaling. However, p53 was dispensable for compound 5- or compound 8-induced apoptosis in HT-29 cells.

Biomimetic nanotherapeutics for homotypic-targeting photothermal/chemotherapy of oral cancer

Given the inherent complexity of cancer treatment and the limitations of singular therapeutic modalities, the development of an optimal nanocarrier system capable of facilitating synergistic organic therapy remains a profound challenge. Herein, a synergetic chemo/photothermal therapy nanoplatform was exploited to specifically tailor for the augmented treatment of oral cancer. A cancer cell membrane-camouflaged nanocarrier was developed with a polymeric core encapsulating doxorubicin (DOX). The designed nanoparticles (CC@DOXNPs) inherited the functional membrane proteins from the source cancer cells, endowing their remarkable ability to selectively target cancer cells delivery both in vitro and in vivo. Moreover, indocyanine green (ICG), modified with the phospholipid polymer DSPE-PEG2000, was introduced into the cancer cell membrane to enable photothermal therapy. Remarkably, as evaluated in a preclinical subcutaneous and orthotopic mice model of oral cancer, biomimetic composite nanotherapeutics (lip-CC@DOXNPs) could significantly accumulate into tumor lesion and effectively suppress tumor growth under the near-infrared (NIR, 808 nm) irradiation, without causing the undesirable systematic toxicity. Moreover, RNA sequence analyses indicated that chemo/photothermal therapy triggers the intrinsic mitochondria-mediated apoptosis through the p53 signaling pathway. Combined with gene expression results, this intrinsic mitochondria-mediated apoptosis pathway was further demonstrated. Collectively, this multifaceted nanoplatforms possess a remarkable capability for tumor-targeting drug delivery, and the proficient photothermal conversion ability, rendering them an ideal therapeutic approach for oral cancer treatment.

Design, Synthesis, and Potent Anticancer Activity of Novel Indole-Based Bcl-2 Inhibitors

The Bcl-2 family plays a crucial role in regulating cell apoptosis, making it an attractive target for cancer therapy. In this study, a series of indole-based compounds, U1-6, were designed, synthesized, and evaluated for their anticancer activity against Bcl-2-expressing cancer cell lines. The binding affinity, safety profile, cell cycle arrest, and apoptosis effects of the compounds were tested. The designed compounds exhibited potent inhibitory activity at sub-micromolar IC50 concentrations against MCF-7, MDA-MB-231, and A549 cell lines. Notably, U2 and U3 demonstrated the highest activity, particularly against MCF-7 cells. Respectively, both U2 and U3 showed potential BCL-2 inhibition activity with IC50 values of 1.2 ± 0.02 and 11.10 ± 0.07 µM using an ELISA binding assay compared with 0.62 ± 0.01 µM for gossypol, employed as a positive control. Molecular docking analysis suggested stable interactions of compound U2 at the Bcl-2 binding site through hydrogen bonding, pi-pi stacking, and hydrophobic interactions. Furthermore, U2 demonstrated significant induction of apoptosis and cell cycle arrest at the G1/S phase. Importantly, U2 displayed a favourable safety profile on HDF human dermal normal fibroblast cells at 10-fold greater IC50 values compared with MDA-MB-231 cells. These findings underscore the therapeutic potential of compound U2 as a Bcl-2 inhibitor and provide insights into its molecular mechanisms of action.

Structures of p53/BCL-2 complex suggest a mechanism for p53 to antagonize BCL-2 activity

Mitochondrial apoptosis is strictly controlled by BCL-2 family proteins through a subtle network of protein interactions. The tumor suppressor protein p53 triggers transcription-independent apoptosis through direct interactions with BCL-2 family proteins, but the molecular mechanism is not well understood. In this study, we present three crystal structures of p53-DBD in complex with the anti-apoptotic protein BCL-2 at resolutions of 2.3-2.7 Å. The structures show that two loops of p53-DBD penetrate directly into the BH3-binding pocket of BCL-2. Structure-based mutations at the interface impair the p53/BCL-2 interaction. Specifically, the binding sites for p53 and the pro-apoptotic protein Bax in the BCL-2 pocket are mostly identical. In addition, formation of the p53/BCL-2 complex is negatively correlated with the formation of BCL-2 complexes with pro-apoptotic BCL-2 family members. Defects in the p53/BCL-2 interaction attenuate p53-mediated cell apoptosis. Overall, our study provides a structural basis for the interaction between p53 and BCL-2, and suggests a molecular mechanism by which p53 regulates transcription-independent apoptosis by antagonizing the interaction of BCL-2 with pro-apoptotic BCL-2 family members.

The roles of protocadherin-7 in colorectal cancer cells on cell proliferation and its chemoresistance

Despite the high mutation frequencies of KRAS, NRAS, and BRAF in colorectal cancer (CRC), there are no effective and reliable inhibitors for these biomarkers. Protocadherin-7 (PCDH7) is regarded as a potentially targetable surface molecule in cancer cells and plays an important role in their proliferation, metastasis, and drug resistance. However, the roles and underlying mechanisms of PCDH7 in CRC remain unclear. In the current study, we found that different colorectal cancer cells expressed PCDH7 over a wide range. The levels of PCDH7 expression were positively associated with cell proliferation and drug resistance in CRC cells but negatively correlated with the potential for cell migration and invasion. Our data indicated that PCDH7 mediated the resistance of CRC cells to ABT-263 (a small-molecule Bcl-2 inhibitor that induces apoptosis) by inhibiting cell apoptosis, which was supported by the downregulation of caspase-3, caspase-9, and PARP cleavage. We found that PCDH7 effectively promoted Mcl-1 expression at both mRNA and protein levels. Furthermore, PCDH7 activated the Wnt signaling pathway, which was confirmed by the increase in β-catenin and c-Myc expression. Finally, and notably, S63845, a novel Mcl-1 inhibitor, not only effectively attenuated the inhibitory effect of PCDH7 on cell apoptosis induced by ABT-263 in vitro but also sensitized PCDH7-overexpressed CRC cell-derived xenografts to ABT-263 in vivo. Taken together, although PCDH7 inhibited the migration and invasion of CRC cells, it could facilitate the development of drug resistance in colorectal cancer cells by positively modulating Mcl-1 expression. The application of the Mcl-1 inhibitor S63845 could be a potential strategy for CRC chemotherapy, especially in CRC with high levels of PCDH7.

Enzyme-Enhanced Codelivery of Doxorubicin and Bcl-2 Inhibitor by Electrospun Nanofibers for Synergistic Inhibition of Prostate Cancer Recurrence

One of the great challenges of postoperative prostate cancer management is tumor recurrence. Although postoperative chemotherapy presents benefits to inhibit unexpected recurrence, it is still limited due to the drug resistance or intolerable complications of some patients. Electrospun nanofiber, as a promising drug carrier, demonstrating sustained drug release behavior, can be implanted into the tumor resection site during surgery and is conductive to tumor inhibition. Herein, we fabricated electrospun nanofibers loaded with doxorubicin (DOX) and ABT199 to synergistically prevent postoperative tumor recurrence. Enzymatic degradation of the biodegradable electrospun nanofibers facilitated the release of the two drugs. The primarily released DOX from the electrospun nanofibers effectively inhibited tumor recurrence. However, the sustained release of DOX led to drug resistance of the tumor cells, yielding unsatisfactory eradication of the residual tumor. Remarkably, the combined administration of DOX and ABT199, simultaneously released from the nanofibers, not only prolonged the chemotherapy by DOX but also overcame the drug resistance via inhibiting the Bcl-2 activation and thereby enhancing the apoptosis of tumor cells by ABT199. This dual-drug-loaded implant system, combining efficient chemotherapy and anti-drug resistance, offers a prospective strategy for the potent inhibition of postoperative tumor recurrence.

From the divergence of senescent cell fates to mechanisms and selectivity of senolytic drugs

Senescence is a cellular stress response that involves prolonged cell survival, a quasi-irreversible proliferative arrest and a modification of the transcriptome that sometimes includes inflammatory gene expression. Senescent cells are resistant to apoptosis, and if not eliminated by the immune system they may accumulate and lead to chronic inflammation and tissue dysfunction. Senolytics are drugs that selectively induce cell death in senescent cells, but not in proliferative or quiescent cells, and they have proved a viable therapeutic approach in multiple mouse models of pathologies in which senescence is implicated. As the catalogue of senolytic compounds is expanding, novel survival strategies of senescent cells are uncovered, and variations in sensitivity to senolysis between different types of senescent cells emerge. We propose herein a mechanistic classification of senolytic drugs, based on the level at which they target senescent cells: directly disrupting BH3 protein networks that are reorganized upon senescence induction; downregulating survival-associated pathways essential to senescent cells; or modulating homeostatic processes whose regulation is challenged in senescence. With this approach, we highlight the important diversity of senescent cells in terms of physiology and pathways of apoptosis suppression, and we describe possible avenues for the development of more selective senolytics.

Anticancer effects of putative and validated BH3-mimetic drugs in head and neck squamous cell carcinomas: An overview of current knowledge

The purpose of this review was to summarise available literature concerning the anticancer effects of both putative and validated BH3-mimetics in head and neck squamous cell carcinomas. A literature search was performed and studies assessing malignant cell lines, xenograft models, and/or humans were considered eligible. A total of 501 studies were identified, of which 40 were included. One phase-II clinical trial assessing gossypol (combined with docetaxel) was found. The remaining 39 preclinical studies investigated cell lines and/or xenograft models involving the use of six validated BH3-mimetics (A-1210477, A-1331852, ABT-737, navitoclax, S63845, venetoclax) and six putative BH3-mimetics (ApoG2, gossypol, obatoclax, sabutoclax, TW-37, and YC137). In preclinical settings, most validated BH3-mimetics were capable of inducing apoptosis (in-vitro) and tumour growth inhibition (in-vivo). The majority of putative BH3-mimetics were also capable of inducing cell death, although important off-target effects, such as autophagy induction, were also described. Combinations with conventional anticancer drugs, ionising radiation, or multiple BH3-mimetics generally resulted in enhanced anticancer effects, such as increased sensitivity to apoptotic stimuli, especially considering some cell lines that showed resistance to either treatment alone. In conclusion, although clinical data are still insufficient to evaluate the anticancer effects of BH3-mimetics in head and neck squamous cell carcinomas, promising results in preclinical settings were observed concerning induction of cell death and inhibition of tumour growth. Therefore, further clinical trials are highly encouraged.

Development, Therapeutic Evaluation and Theranostic Applications of Cubosomes on Cancers: An Updated Review

Cancer is a group of disorders characterized by aberrant gene function and alterations in gene expression patterns. In 2020, it was anticipated that 19 million new cancer cases would be diagnosed globally, with around 10 million cancer deaths. Late diagnosis and interventions are the leading causes of cancer-related mortality. In addition, the absence of comprehensive cancer therapy adds to the burden. Many lyotropic non-lamellar liquid-crystalline-nanoparticle-mediated formulations have been developed in the last few decades, with promising results in drug delivery, therapeutics, and diagnostics. Cubosomes are nano-structured liquid-crystalline particles made of specific amphiphilic lipids in particular proportions. Their ability to encapsulate lipophilic, hydrophilic, and amphiphilic molecules within their structure makes them one of a kind. They are biocompatible, versatile drug carriers that can deliver medications through various routes of administration. Many preclinical studies on the use of cubosomes in cancer treatment and theranostic applications have been conducted. However, before cubosomes may be employed in clinical practice, significant technical advances must be accomplished. This review summarizes the development of cubosomes and their multifunctional role in cancer treatment based on the most recent reports.

A novel aryl-guanidinium derivative, VP79s, targets the signal transducer and activator of transcription 3 signaling pathway, downregulates myeloid cell leukaemia-1 and exhibits preclinical activity against multiple myeloma

AIMS

We have recently described a novel guanidinium-based compound, VP79s, which induces cytotoxicity in various cancer cell lines. Here, we aim to investigate the activity of VP79s and associated mechanisms of action in multiple myeloma (MM) cells in vitro and ex vivo.

MAIN METHODS

The effects of VP79s on cell viability and induction of apoptosis was examined in a panel of drug-sensitive and drug-resistant MM cell lines, as well as ex vivo patient samples and normal donor lymphocytes and platelets. Cell signaling pathways associated with the biological effects of VP79s were analysed by immunoblotting and flow cytometry. Gene expression changes were assessed by quantitative real-time PCR analysis.

KEY FINDINGS

VP79s was found to rapidly inhibit both constitutively active and IL-6-induced STAT3 signaling with concurrent downregulation of the IL-6 receptors, CD130 and CD126. VP79s induced a rapid and dose-dependent downregulation of anti-apoptotic Bcl-2 family member, myeloid cell leukaemia-1 (MCL-1). VP79s enhanced bortezomib induced cell death and was also found to overcome bone marrow stromal cell induced drug resistance. VP79s exhibited activity in ex vivo patient samples at concentrations which had no effect on peripheral blood mononuclear cells, lymphocytes and platelets isolated from healthy donors.

SIGNIFICANCE

As VP79s resulted in rapid inhibition of the key IL-6/STAT3 signaling pathway and downregulation of MCL-1 expression with subsequent selective anti-myeloma activity, VP79s may be a potential therapeutic agent with a novel mechanism of action in MM cells.

Development of a multi-target anticancer Sn(ii) pyridine-2-carboxaldehyde thiosemicarbazone complex

In this study, we proposed to design effective multi-target anticancer agents based on the chelation of nontoxic metals with ligands that possess anticancer activity. In total, five Sn(ii) pyridine-2-carboxaldehyde thiosemicarbazone complexes are synthesized and their activities are tested. Among these complexes, C5 is found to show the highest cytotoxicity on investigating their structure-activity relationships. In addition, C5 not only exhibits an effective inhibitory effect against tumor growth in vivo, but also suppresses angiogenesis and restricts the metastasis of cancer cells in vitro. Multiple mechanisms underlie the antitumor effect of C5, and they include acting against DNA, inducing apoptosis, and inhibiting the activities of anti-apoptotic Bcl-xL protein, metalloproteinase MMP2 and topoisomerase II.

Kinome-wide RNAi screening for mediators of ABT-199 resistance in breast cancer cells identifies Wee1 as a novel therapeutic target

Antiapoptotic and proapoptotic BCL-2 protein family members regulate mitochondrial apoptotic pathway. Small molecule inhibitors of antiapoptotic BCL-2 proteins including BCL-2-specific inhibitor ABT-199 (Venetoclax) are in clinical development. However, the efficiency of ABT-199 as a single agent in solid tumors is limited. We performed a high-throughput RNAi kinome screen targeting 691 kinases to identify potentially targetable kinases to enhance ABT-199 response in breast cancer cells. Our studies identified Wee1 as the primary target kinase to overcome resistance to ABT-199. Depletion of Wee1 by siRNA-mediated knockdown or inhibition of Wee1 by the small molecule Wee1 inhibitor AZD1775 sensitized SKBR3, MDA-MB-468, T47D and CAMA-1 breast cancer cells to ABT-199 along with decreased MCL1. BH3-only proteins PUMA and BIM functionally contribute to apoptosis signaling following co-targeting BCL-2 and Wee1. Suppression of Wee1 function increased mitochondrial cell death priming. Furthermore, we found that Wee1 inhibition altered MCL1 phosphorylation and protein stability, which led to HUWE1-mediated MCL1 degradation. Our findings suggest that Wee1 inhibition can overcome resistance to ABT-199 and provide a rationale for further translational investigation of BCL-2 inhibitor/Wee1 inhibitor combination in breast cancer.

Role of BCL-2 Family Proteins in Apoptosis and its Regulation by Nutrients

In the body, millions of cells die and proliferate each day to maintain normal function and cooperation of all tissues, organs, and systems. Thus, programmed cell death, or apoptosis, is critical to sustain growth, development, and body health. The vital role of B-cell leukemia/lymphoma-2 (BCL-2) family proteins in apoptosis has been identified. The BCL-2 family includes both pro- and antiapoptotic proteins, which are structurally and functionally related, containing up to four BCL-2 homology (BH) motifs (BH1-4). There are also some nutritional factors that regulate apoptosis via the BCL-2 family proteins. In this review, the BCL-2 family proteins and their apoptosis-inducing mechanism have been discussed, along with the nutrient factors that regulate apoptosis through the BCL-2 family proteins.

SOX9 promotes epidermal growth factor receptor-tyrosine kinase inhibitor resistance via targeting β-catenin and epithelial to mesenchymal transition in lung cancer

AIMS

The first-generation epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI), gefitinib, continues to be a primary treatment option for lung cancer patients. However, acquisition of resistance to gefitinib is a major obstacle in lung cancer treatment and its cause is poorly understood. The present study aimed to implicate the role of SOX9-β-catenin in developed resistance to gefitinib through epithelial to mesenchymal transition (EMT) in lung cancer in vitro and ex vivo.

MAIN METHODS

Expression effect of SOX9 on survivability of lung cancer patients was demonstrated through online available Kaplan-Meier Plotter data base. Then, cell viability assay, colony forming assay, cell migration and invasion assays, flow cytometry, drug efflux assay, qRT-PCR, and western blotting were conducted to confirmed the role of SOX9 in gefitinib resistance in lung cancer cells. Dual-luciferase assay established the regulatory relation between SOX9 and β-catenin. Multicellular spheroid assay further explored that down regulation of SOX9 could reverse gefitinib resistance ex vivo.

KEY FINDINGS

Kaplan-Meier method correlated the higher expression of SOX9 and β-catenin with poor overall survival of lung cancer patients. Upregulation of SOX9 was associated gefitinib resistance with increased cell proliferation, migration and invasion, single-cell colony-forming ability, reduced apoptosis, and gefitinib intake in lung cancer cells. Moreover, upregulated SOX9 promoted EMT via targeting β-catenin and knockdown of SOX9 reversed the resistance and EMT phenotype. Similarly, we found that multicellular spheroid of gefitinib resistant cells showed larger surface area with more dispersion and viability of cells, while SOX9 knockdown abolished these induced properties ex vivo.

SIGNIFICANCE

SOX9 expression could provide an innovative perspective as biomarker to understand the EGFR-TKIs resistance in lung cancer.

Histone methyltransferase WHSC1 inhibits colorectal cancer cell apoptosis via targeting anti-apoptotic BCL2

WHSC1 is a histone methyltransferase that facilitates histone H3 lysine 36 dimethylation (H3K36me2), which is a permissive mark associated with active transcription. In this study, we revealed how WHSC1 regulates tumorigenesis and chemosensitivity of colorectal cancer (CRC). Our data showed that WHSC1 as well as H3K36me2 were highly expressed in clinical CRC samples, and high WHSC1 expression is associated with poorer prognosis in OS patients. WHSC1 reduction promoted colon cancer cell apoptosis both in vivo and in vitro. We found that B cell lymphoma-2 (BCL2) expression, an anti-apoptotic protein, is markedly decreased in after WHSC1 depletion. Mechanistic characterization indicated that WHSC1 directly binds to the promoter region of BCL2 gene and regulate its H3K36 dimethylation level. What's more, our study indicated that WHSC1 depletion promotes chemosensitivity in CRC cells. Together, our results suggested that WHSC1 and H3K36me2 modification might be optimal therapeutic targets to disrupt CRC progression and WHSC1-targeted therapy might potentially overcome the resistance of chemotherapeutic agents.

A cytotoxic nitrido-osmium(VI) complex induces caspase-mediated apoptosis in HepG2 cancer cells

The osmium(vi) nitrido complex [OsVI(N)(sap)(py)Cl] is a potential anti-cancer drug with promising in vitro antiproliferative activities toward a panel of cancer cell lines, including cisplatin-resistant cells (IC50 values of 2.8-13.8 μM). This drug targets DNA and changes its conformation via covalent binding and insertion. In vitro studies indicate that the drug induces HepG2 cells G2/M phase arrest, disrupts the mitochondrial membrane potential and causes caspase-mediated apoptosis. Further in vivo studies using HepG2-bearing nude mice reveal that this drug not only shows good antitumor efficacy of inhibiting tumor growth, but also does not show the side effect of weight loss.

Targeting Bcl-2 Proteins in Acute Myeloid Leukemia

B cell lymphoma 2 (BCL-2) family proteins play an important role in intrinsic apoptosis. Overexpression of BCL-2 proteins in acute myeloid leukemia can circumvent resistance to apoptosis and chemotherapy. Considering this effect, the exploration of anti-apoptotic BCL-2 inhibitors is considered to have tremendous potential for the discovery of novel pharmacological modulators in cancer. This review outlines the impact of BCL-2 family proteins on intrinsic apoptosis and the development of acute myeloid leukemia (AML). Furthermore, we will also review the new combination therapy with venetoclax that overcomes resistance to venetoclax and discuss biomarkers of treatment response identified in early-phase clinical trials.

Fruticuline A, a chemically-defined diterpene, exerts antineoplastic effects in vitro and in vivo by multiple mechanisms

Natural products have been recognized as important bioactive compounds on the basis of their wide biological properties. Here we investigated the antitumor effect and molecular mechanisms of the diterpene Fruticuline A (fruti) from Salvia lachnostachys, in human cancer cell lineages and Solid Ehrlich Carcinoma in mice. Fruti reduced MCF-7 and HepG2 proliferation by the reduction of Cyclin D1 levels and decreased NF-κB gene levels in both cell types. Furthermore, fruti also induced apoptosis in HepG2 cells, reduced Bcl-2 gene expression and induced necroptosis by increasing Ripk in MCF-7 cells. In mice, fruti prevented tumor development and reduced Cyclin D1, Bcl-2 and Rela gene levels, and reduced the p-NF-κB/NF-κB ratio in tumor tissue. Furthermore, fruti induced necrosis and apoptosis, increased N-acetyl-β-D-glucosaminidase and TNF-α levels and reduced IL-10 and Vegf levels in tumor tissue. Collectively, fruti exerts antitumor effects through the inhibition of the NF-κB pathway, reducing Cyclin D1 and Bcl-2 levels. In vitro the apoptosis and necroptosis pathways are involved in the cellular death, whereas in vivo, cells undergo necrosis by increased tumor inflammation and reduction of angiogenesis. Thus, fruticuline A acts in tumor cells by multiple mechanisms and represents a promising molecule for drug development in cancer treatment.

The Multifaceted Roles of the BCL-2 Family Member BOK

BCL-2-related ovarian killer (BOK) is-despite its identification over 20 years ago-an incompletely understood member of the BCL-2 family. BCL-2 family proteins are best known for their critical role in the regulation of mitochondrial outer membrane permeabilization during the intrinsic apoptotic pathway. Based on sequence and structural similarities to BAX and BAK, BOK is grouped with these "killers" within the effector subgroup of the family. However, the mechanism of how exactly BOK exerts apoptosis is not clear and controversially discussed. Furthermore, and in accordance with reports on several other BCL-2 family members, BOK seems to be involved in the regulation of a variety of other, "apoptosis-independent" cellular functions, including the unfolded protein response, cellular proliferation, metabolism, and autophagy. Of note, compared with other proapoptotic BCL-2 family members, BOK levels are often reduced in cancer by various means, and there is increasing evidence for BOK modulating tumorigenesis. In this review, we summarize and discuss apoptotic- and non-apoptotic-related functions of BOK, its regulation as well as its physiological and pathophysiological roles.

Multiple myeloma with 1q21 amplification is highly sensitive to MCL-1 targeting

Prosurvival BCL-2 family proteins are potent inhibitors of apoptosis and often overexpressed in lymphoid malignancies. In multiple myeloma (MM), MCL-1 expression contributes to survival of malignant plasma cells, and overexpression correlates with poor prognosis. In this study, we investigated whether sensitivity to the novel MCL-1 inhibitor S63845 could be predicted using cytogenetics, focusing on amplification of 1q21, the chromosomal region that contains the MCL1 locus. In addition, we studied the relation of MCL-1 inhibitor sensitivity with other diagnostic characteristics and BCL-2 family protein expression. In 31 human myeloma cell lines and in bone marrow aspirates from 47 newly diagnosed MM patients, we measured the effect of S63845 alone, or combined with BCL-2 inhibitor ABT-199 (venetoclax), and BCL-XL inhibitor A-1155463 or A-1331852 on cell viability. We demonstrated for the first time that MM cells from patients with 1q21 amplification are significantly more sensitive to inhibition of MCL-1. We suggest that this increased sensitivity results from high relative MCL1 expression resulting from amplification of 1q21. Additionally, and partially independent from 1q21 status, high serum β2 microglobulin level and presence of renal insufficiency correlated with increased sensitivity to MCL-1 inhibitor treatment. Combining S63845 with other BH3 mimetics synergistically enhanced apoptosis compared with single inhibitors, and sensitivity to inhibitor combinations was found in a large proportion of MM insensitive to MCL-1 inhibition alone. Collectively, our data indicate that amplification of 1q21 identifies an MM subset highly sensitive to MCL-1 inhibitor treatment and can be used as a predictive marker to guide selection of therapy.

RAB25 confers resistance to chemotherapy by altering mitochondrial apoptosis signaling in ovarian cancer cells

Ovarian cancer remains one of the most frequent causes of cancer-related death in women. Many patients with ovarian cancer suffer from de novo or acquired resistance to chemotherapy. Here, we report that RAB25 suppresses chemotherapy-induced mitochondrial apoptosis signaling in ovarian cancer cell lines and primary ovarian cancer cells. RAB25 blocks chemotherapy-induced apoptosis upstream of mitochondrial outer membrane permeabilization by either increasing antiapoptotic BCL-2 proteins or decreasing proapoptotic BCL-2 proteins. In particular, BAX expression negatively correlates with RAB25 expression in ovarian cancer cells. BH3 profiling assays corroborated that RAB25 decreases mitochondrial cell death priming. Suppressing RAB25 by means of RNAi or RFP14 inhibitory hydrocarbon-stapled peptide sensitizes ovarian cancer cells to chemotherapy as well as RAB25-mediated proliferation, invasion and migration. Our data suggest that RAB25 is a potential therapeutic target for ovarian cancer.

The Effect of TIGAR Knockdown on Apoptotic and Epithelial-Mesenchymal Markers Expression in Doxorubicin-Resistant Non-Small Cell Lung Cancer A549 Cell Lines

Resistance to chemotherapeutic drugs is a critical problem in cancer therapy, but the underlying mechanism has not been fully elucidated. TP53-induced glycolysis regulatory phosphatase (TIGAR), an important glycolysis and apoptosis regulator, plays a crucial role in cancer cell survival by protecting cells against oxidative stress-induced apoptosis. In the present study, we investigated whether TIGAR is involved in epithelial-mesenchymal transition (EMT) in doxorubicin (DOX)-resistant human non-small cell lung cancer (NSCLC), A549/DOX cells. We found that the expression of TIGAR was significantly higher in A549/DOX cells than in the parent A549 cell lines. siRNA-mediated TIGAR knockdown reduced migration, viability and colony survival of doxorubicin-resistant lung cancer cells. Also, TIGAR knockdown decreased pro-survival protein Bcl-2 and increased pro-apoptotic Bax and cleaved poly (ADP-ribose) polymerase (PARP). Moreover, TIGAR depletion significantly up-regulated both caspase-3 and caspase-9 expression. Furthermore, TIGAR depletion up-regulated the expression of E-cadherin and down-regulated the expression of vimentin. These results indicate that TIGAR knockdown may inhibit EMT in doxorubicin (DOX)-resistant human NSCLC and may represent a therapeutic target for a non-small lung cancer cells chemoresistance.

Novel pyrrolopyrimidine derivatives induce p53-independent apoptosis via the mitochondrial pathway in colon cancer cells

A series of novel pyrrolopyrimidine urea derivatives were synthesized and evaluated for their anticancer activity against colon cancer cell lines. Compounds showed the remarkable cytotoxic activity on HCT-116 wt cell line. The most potent compound 4c (IC₅₀ = 0.14 μM) induced apoptosis in HCT-116 wt and HCT-116 p53-/- cell lines. Otherwise, treatment of HCT-116 BAX-/-BAK-/- cells with compound 4c didn't lead to activation of apoptosis, suggesting that compound 4c induces apoptotic cell death by activating BAX/BAK-dependent pathway. Moreover, while the compound 4c increase the activation of caspase-3 and caspase-9 levels in HCT-116 wt and HCT-116 p53-/- cells, caspase-3 or caspase-9 activation was not observed in HCT-116 BAX-/-BAK-/- cells. In addition, compound 4c induced mitochondrial apoptosis in cells grown as oncospheroids, which better mimic the in vivo milieu of tumors. 4c treatment also activated JNK along with inhibition of prosurvival kinases such as Akt and ERK 1/2 in HCT-116 wt and HCT-116 p53 -/- cells as well as in HCT-116 BAX-/-BAK-/- cells. Notably, our results indicated that compound 4c induced mitochondrial apoptosis through activation p53-independent apoptotic signaling pathways.

HMGN5 Silencing Suppresses Cell Biological Progression via AKT/MAPK Pathway in Human Glioblastoma Cells

HMGN5 regulates biological function and molecular transcription via combining with a nucleosome. There has been growing evidence that aberrant expression of HMGN5 is associated with malignant neoplasm development and progression. In the present study, we found that the expression of HMGN5 is significantly higher in high-grade glioblastoma tissues than in low-grade samples. To clarify the function of HMGN5 in glioblastoma, we knocked down HMGN5 in U87 and U251 glioblastoma cells via siRNA. The results demonstrated that HMGN5 was involved in the regulation of proliferation and apoptosis, migration, and invasion of glioblastoma cells. These outcomes also indicated that silencing HMGN5 possibly suppressed the expression of p-AKT and p-ERK1/2. Taken together, our research reveals that HMGN5 might be an efficient target for glioblastoma-targeted therapy.

Chemical, Physical and Biological Triggers of Evolutionary Conserved Bcl-xL-Mediated Apoptosis

Background: The evidence that pan-Bcl-2 or Bcl-xL-specific inhibitors prematurely kill virus-infected or RNA/DNA-transfected cells provides rationale for investigating these apoptotic inducers further. We hypothesized that not only invasive RNA or DNA (biological factors) but also DNA/RNA-damaging chemical or physical factors could trigger apoptosis that have been sensitized with pan-Bcl-2 or Bcl-xL-specific agents; Methods: We tested chemical and physical factors plus Bcl-xL-specific inhibitor A-1155463 in cells of various origins and the small roundworms (C. elegans); Results: We show that combination of a A-1155463 along with a DNA-damaging agent, 4-nitroquinoline-1-oxide (4NQO), prematurely kills cells of various origins as well as C. elegans. The synergistic effect is p53-dependent and associated with the release of Bad and Bax from Bcl-xL, which trigger mitochondrial outer membrane permeabilization. Furthermore, we found that combining Bcl-xL-specific inhibitors with various chemical compounds or physical insults also induced cell death; Conclusions: Thus, we were able to identify several biological, chemical and physical triggers of the evolutionarily conserved Bcl-xL-mediated apoptotic pathway, shedding light on strategies and targets for novel drug development.

Overview of Mitochondrial E3 Ubiquitin Ligase MITOL/MARCH5 from Molecular Mechanisms to Diseases

The molecular pathology of diseases seen from the mitochondrial axis has become more complex with the progression of research. A variety of factors, including the failure of mitochondrial dynamics and quality control, have made it extremely difficult to narrow down drug discovery targets. We have identified MITOL (mitochondrial ubiquitin ligase: also known as MARCH5) localized on the mitochondrial outer membrane and previously reported that it is an important regulator of mitochondrial dynamics and mitochondrial quality control. In this review, we describe the pathological aspects of MITOL revealed through functional analysis and its potential as a drug discovery target.

Disruption of conserved polar interactions causes a sequential release of Bim mutants from the canonical binding groove of Mcl1

Mcl1 is an important anti-apoptotic member of the Bcl2 family proteins that are upregulated in several cancer malignancies. The canonical binding groove (CBG) located at the surface of Mcl1 exhibits a critical role in binding partners selectively via the BH3-domain of pro-apoptotic Bcl2 family members that trigger the downregulation of Mcl1 function. There are several crystal structures of point-mutated pro-apoptotic Bim peptides in complex with Mcl1. However, the mechanistic effects of such point-mutations towards peptide binding and complex stability still remain unexplored. Here, the effects of the reported point mutations in Bim peptides and their binding mechanisms to Mcl1 were computationally evaluated using atomistic-level steered molecular dynamics (SMD) simulations. A range of external-forces and constant-velocities were applied to the Bim peptides to uncover the mechanistic basis of peptide dissociation from the CBG of Mcl1. Although the peptides showed similarities in their dissociation pathways, the peak rupture forces varied significantly. According to simulations results, the disruption of the conserved polar contacts at the complex interface causes a sequential release of the peptides from the CBG of Mcl1. Overall, the results obtained from the current study may provide valuable insights for the development of novel anti-cancer peptide-inhibitors that can downregulate Mcl1's function.

Co-targeting bromodomain and extra-terminal proteins and MCL1 induces synergistic cell death in melanoma

The treatment of melanoma has been markedly improved by the introduction of targeted therapies and checkpoint blockade immunotherapy. Unfortunately, resistance to these therapies remains a limitation. Novel anticancer therapeutics targeting the MCL1 anti-apoptotic protein have shown impressive responses in haematological cancers but are yet to be evaluated in melanoma. To assess the sensitivity of melanoma to new MCL1 inhibitors, we measured the response of 51 melanoma cell lines to the novel MCL1 inhibitor, S63845. Additionally, we assessed combination of this drug with inhibitors of the bromodomain and extra-terminal (BET) protein family of epigenetic readers, which we postulated would assist MCL1 inhibition by downregulating anti-apoptotic targets regulated by NF-kB such as BCLXL, BCL2A1 and XIAP, and by upregulating pro-apoptotic proteins including BIM and NOXA. Only 14% of melanoma cell lines showed sensitivity to S63845, however, combination of S63845 and I-BET151 induced highly synergistic apoptotic cell death in all melanoma lines tested and in an in vivo xenograft model. Cell death was dependent on caspases and BAX/BAK. Although the combination of drugs increased the BH3-only protein, BIM, and downregulated anti-apoptotic proteins such as BCL2A1, the importance of these proteins in inducing cell death varied between cell lines. ABT-199 or ABT-263 inhibitors against BCL2 or BCL2 and BCLXL, respectively, induced further cell death when combined with S63845 and I-BET151. The combination of MCL1 and BET inhibition appears to be a promising therapeutic approach for metastatic melanoma, and presents opportunities to add further BCL2 family inhibitors to overcome treatment resistance.

Discovery of small molecule inhibitors through pharmacophore modeling, molecular docking, molecular dynamics simulation and experimental validation against myeloid cell leukemia-1 (Mcl-1)

Myeloid cell leukemia-1 (Mcl-1) protein is a family of Bcl-2 (B cell lymphoma 2) rich proteases of the most common increase threshold for genetic aberrations observed in human cancer, including lung, breast, pancreatic, cervical, and ovarian cancers as well as leukemia and lymphoma. Mcl-1 is recognized as an attractive drug target in number of diseases, including cancer. In the present study we surveyed and collected queries compounds from PDB database of Mcl-1 protein and generated pharmacophore-based models adapted to screen the drug-like compounds from FDA approved database. The 206 best lead molecules from pharmacophore-screening were further evaluated by molecular docking, molecular dynamics simulation, MM-GBSA calculation, as well as experimental validation. Two hits, ZINC00601272 and ZINC00002166, showed the best docking scores, which showed a tendency to inhibit cell viability of HL60 and K562 leukemia cells with Mcl-1 expressions. Conclusively, the present study provides structural information of Mcl-1 inhibitors for next generations of cancer therapeutics through computational and experimental validation approach.Communicated by Ramaswamy H. Sarma.

A Novel BCL-2 Inhibitor APG-2575 Exerts Synthetic Lethality With BTK or MDM2-p53 Inhibitor in Diffuse Large B-Cell Lymphoma

Despite therapeutic advances, the effective treatment for relapsed or refractory diffuse large B-cell lymphoma (DLBCL) remains a major clinical challenge. Evasion of apoptosis through upregulating antiapoptotic B-cell lymphoma-2 (BCL-2) family members and p53 inactivation, and abnormal activation of B-cell receptor signaling pathway are two important pathogenic factors for DLBCL. In this study, our aim is to explore a rational combination of BCL-2 inhibitor plus Bruton’s tyrosine kinase (BTK) blockade or p53 activation for treating DLBCL with the above characteristics. We demonstrated that a novel BCL-2 selective inhibitor APG-2575 effectively suppressed DLBCL with BCL-2 high expression via activating the mitochondrial apoptosis pathway. BTK inhibitor ibrutinib combined with BCL-2 inhibitors showed synergistic antitumor effect in DLBCL with mean expression of BCL-2 and myeloid cell leukemia-1 (MCL-1) through upregulating the expression level of BIM and modulating MCL-1 and p-Akt expression. For p53 wild-type DLBCL with high expression of BCL-2, APG-2575 showed strong synergic effect with mouse double minute 2 (MDM2)–p53 inhibitor APG-115 that can achieve potent antitumor effect and markedly prolong survival in animal models. Collectively, our data provide an effective and precise therapeutic strategy through rational combination of BCL-2 and BTK or MDM2–p53 inhibitors for DLBCL, which deserves further clinical investigation.

Genistein-3'-sodium sulphonate protects against lipopolysaccharide-induced lung vascular endothelial cell apoptosis and acute lung injury via BCL-2 signalling

Under septic conditions, Lipopolysaccharide (LPS)‐induced apoptosis of lung vascular endothelial cells (ECs) triggers and aggravates acute lung injury (ALI), which so far has no effective therapeutic options. Genistein‐3′‐sodium sulphonate (GSS) is a derivative of native soy isoflavone, which has neuro‐protective effects through its anti‐apoptotic property. However, whether GSS protects against sepsis‐induced lung vascular endothelial cell apoptosis and ALI has not been determined. In this study, we found that LPS‐induced Myd88/NF‐κB/BCL‐2 signalling pathway activation and subsequent EC apoptosis were effectively down‐regulated by GSS in vitro. Furthermore, GSS not only reversed the sepsis‐induced BCL‐2 changes in expression in mouse lungs but also blocked sepsis‐associated lung vascular barrier disruption and ALI in vivo. Taken together, our results demonstrated that GSS might be a promising candidate for sepsis‐induced ALI via its regulating effects on Myd88/NF‐κB/BCL‐2 signalling in lung ECs.

Combined inhibition of Bcl-2 and NFκB synergistically induces cell death in cutaneous T-cell lymphoma

Therapeutic options for cutaneous T-cell lymphoma (CTCL) are limited and curative treatment regimens are not available. Thus, new targeted and well-tolerated therapeutic approaches are urgently needed. In this respect, we have recently shown that dimethyl fumerate (DMF) inhibits NF-κB acting as a survival factor in CTCL. Similarly, inhibition of the antiapoptotic protein B-cell lymphoma 2 (Bcl-2) has been shown to induce cell death in CTCL especially when combined with histone deacetylase inhibitors. Therefore, we hypothesized that inhibition of Bcl-2 should potentiate NF-κB inhibition in a novel combination treatment of CTCL. We show that, in vitro, the Bcl-2 inhibitors ABT-199 and ABT-263 induced specific cell death in primary CD4⁺ cells from CTCL patients as well as in the CTCL cell line SeAx, but not in T cells of healthy donors nor in the CTCL cell line HH, which lacks Bcl-2. Combined treatment with ABT-199 and DMF caused synergistic cell death specifically in CTCL cells engaging 2 independent signaling pathways. To verify these findings in vivo, we performed combined ABT-199 and DMF treatment in a xenograft mouse model for CTCL. The combined treatment effectively reduced tumor growth and increased overall survival via synergistic induction of CTCL cell death and suppression of tumor cell proliferation. Essentially, the combination treatment was superior to ABT-199 monotherapy with respect to both efficacy and tolerability. To sum up, our data provide proof of principle for the therapeutic potential of combining Bcl-2 and NF-κB inhibitors in treating CTCL. Next, this potential should be explored further in a clinical study.

Investigating the Molecular Basis of N-Substituted 1-Hydroxy-4-Sulfamoyl-2-Naphthoate Compounds Binding to Mcl1

Myeloid cell leukemia-1 (Mcl1) is an anti–apoptotic protein that has gained considerable attention due to its overexpression activity prevents cell death. Therefore, a potential inhibitor that specifically targets Mcl1 with higher binding affinity is necessary. Recently, a series of N-substituted 1-hydroxy-4-sulfamoyl-2-naphthoate compounds was reported that targets Mcl1, but its binding mechanism remains unexplored. Here, we attempted to explore the molecular mechanism of binding to Mcl1 using advanced computational approaches: pharmacophore-based 3D-QSAR, docking, and MD simulation. The selected pharmacophore—NNRRR—yielded a statistically significant 3D-QSAR model containing high confidence scores (R2 = 0.9209, Q2 = 0.8459, and RMSE = 0.3473). The contour maps—comprising hydrogen bond donor, hydrophobic, negative ionic and electron withdrawal effects—from our 3D-QSAR model identified the favorable regions crucial for maximum activity. Furthermore, the external validation of the selected model using enrichment and decoys analysis reveals a high predictive power. Also, the screening capacity of the selected model had scores of 0.94, 0.90, and 8.26 from ROC, AUC, and RIE analysis, respectively. The molecular docking of the highly active compound—C40; 4-(N-benzyl-N-(4-(4-chloro-3,5-dimethylphenoxy) phenyl) sulfamoyl)-1-hydroxy-2-naphthoate—predicted the low-energy conformational pose, and the MD simulation revealed crucial details responsible for the molecular mechanism of binding with Mcl1.

Rising horizon in circumventing multidrug resistance in chemotherapy with nanotechnology

Multidrug resistance (MDR) is one of the key barriers in chemotherapy, leading to the generation of insensitive cancer cells towards administered therapy. Genetic and epigenetic alterations of the cells are the consequences of MDR, resulted in drug resistivity, which reflects in impaired delivery of cytotoxic agents to the cancer site. Nanotechnology-based nanocarriers have shown immense shreds of evidence in overcoming these problems, where these promising tools handle desired dosage load of hydrophobic chemotherapeutics to facilitate designing of safe, controlled and effective delivery to specifically at tumor microenvironment. Therefore, encapsulating drugs within the nano-architecture have shown to enhance solubility, bioavailability, drug targeting, where co-administered P-gp inhibitors have additionally combat against developed MDR. Moreover, recent advancement in the stimuli-sensitive delivery of nanocarriers facilitates a tumor-targeted release of the chemotherapeutics to reduce the associated toxicities of chemotherapeutic agents in normal cells. The present article is focused on MDR development strategies in the cancer cell and different nanocarrier-based approaches in circumventing this hurdle to establish an effective therapy against deadliest cancer disease.

ABT-263 exhibits apoptosis-inducing potential in oral cancer cells by targeting C/EBP-homologous protein

PURPOSE

ABT-263 is a potent BH3 mimetic that possesses anticancer potential against various types of cancer. In general, this potential is due to its high binding affinity to anti-apoptotic proteins in the Bcl-2 family that disrupt sequestration of pro-apoptotic proteins. In the present study, we sought to identify an alternative regulatory mechanism responsible for ABT-263-mediated anticancer activity in human oral cancer.

METHODS

We investigated the in vitro anti-cancer effects of ABT-263 using a trypan blue exclusion assay, Western blotting, DAPI staining, immunofluorescence staining, a live/dead assay, microarray-based expression profiling, and quantitative real-time PCR. In vivo anti-tumorigenic effects of ABT-263 were examined using a nude mouse tumor xenograft model, a TUNEL assay, and immunohistochemistry.

RESULTS

We found that ABT-263 suppressed viability and induced apoptosis in human oral cancer-derived cell lines HSC-3 and HSC-4. Subsequent microarray-based gene expression profiling revealed 55 differentially expressed genes in the ABT-263-treatead group, including 12 genes associated with "endoplasmic reticulum stress and apoptosis." Consistent with the microarray results, the mRNA expression levels of the top four genes (CHOP, TRB3, ASNS, and STC2) were found to be significantly increased. In addition, we found that ABT-263 considerably enhanced the expression levels of the C/EBP-homologous protein (CHOP) and its mRNA, resulting in apoptosis induction in four other human oral cancer-derived cell lines (MC-3, YD-15, HN22, and Ca9.22). Extending our in vitro findings, we found that ABT-263 reduced the growth of HSC-4 cells in vivo at a dosage of 100 mg/kg/day without any change in body weight. TUNEL-positive cells were also found to be increased in tumors of ABT-263-treated mice without any apparent histopathological changes in liver or kidney tissues.

CONCLUSIONS

These results provide evidence that ABT-263 may serve as an effective therapeutic agent for the treatment of human oral cancer.

Paris polyphylla 26 triggers G2/M phase arrest and induces apoptosis in HepG2 cells via inhibition of the Akt signaling pathway

Objectives

Paris polyphylla 26 (PP-26) is a monomer purified from Paris polyphylla, which has traditionally been used as an antimicrobial, hemostatic, and anticancer agent in China. The anti-proliferation effect and underlying molecular mechanism of PP-26 were investigated in vitro.

Methods

The effects of PP-26 on various tumor cells were detected by MTT assay. PP-26-affected cell cycle and cell cycle-related proteins in HepG2 cells were detected by flow cytometry and western blotting, respectively. Apoptosis in response to PP-26 was assessed by Hoechst 33258 staining and flow cytometry. PP-26-affected apoptosis-related proteins and Akt signaling were detected by western blotting. The inhibitory effect of PP-26 on HepG2 cells, when combined with 5-fluorouracil (5-FU), was also assessed.

Results

PP-26 inhibited proliferation of HepG2 cells in a dose-dependent manner by triggering G2/M-phase arrest. Moreover, PP-26 induced apoptosis of HepG2 cells. Expression levels of apoptosis proteins caspase 9, caspase 3, PARP, Bcl-2, Bcl-xL, and Mcl-1 were downregulated, while the expression level of apoptosis protein Bax was upregulated. Expression levels of p-Akt, p-GSK-3β, and p-Foxo3 were downregulated. Combination with PP-26 enhanced 5-FU inhibition of HepG2 cell proliferation.

Conclusions

PP-26 triggers G2/M-phase arrest and induces apoptosis in HepG2 cells via inhibition of the Akt signaling pathway.

The regulatory protein GADD34 inhibits TRAIL-induced apoptosis via TRAF6/ERK-dependent stabilization of myeloid cell leukemia 1 in liver cancer cells

GADD34 (growth arrest and DNA damage-inducible gene 34) plays a critical role in responses to DNA damage and endoplasmic reticulum stress. GADD34 has opposing effects on different stimuli-induced cell apoptosis events, but the reason for this is unclear. Here, using immunoblotting analyses and various molecular genetic approaches in HepG2 and SMMC-7721 cells, we demonstrate that GADD34 protects hepatocellular carcinoma (HCC) cells from tumor necrosis factor-related apoptosis-inducing ligand (TRAIL)-induced apoptosis by stabilizing a BCL-2 family member, myeloid cell leukemia 1 (MCL-1). We found that GADD34 knockdown decreased MCL-1 levels and that GADD34 overexpression up-regulated MCL-1 expression in HCC cells. GADD34 did not affect MCL-1 transcription but enhanced MCL-1 protein stability. The proteasome inhibitor MG132 abrogated GADD34 depletion-induced MCL-1 down-regulation, suggesting that GADD34 inhibits the proteasomal degradation of MCL-1. Furthermore, GADD34 overexpression promoted extracellular signal-regulated kinase (ERK) phosphorylation through a signaling axis that consists of the E3 ubiquitin ligase tumor necrosis factor receptor-associated factor 6 (TRAF6) and transforming growth factor-β-activated kinase 1 (MAP3K7)-binding protein 1 (TAB1), which mediated the up-regulation of MCL-1 by GADD34. Of note, TRAIL up-regulated both GADD34 and MCL-1 levels, and knockdown of GADD34 and TRAF6 suppressed the induction of MCL-1 by TRAIL. Correspondingly, GADD34 knockdown potentiated TRAIL-induced apoptosis, and MCL-1 overexpression rescued TRAIL-treated and GADD34-depleted HCC cells from cell death. Taken together, these findings suggest that GADD34 inhibits TRAIL-induced HCC cell apoptosis through TRAF6- and ERK-mediated stabilization of MCL-1.

A Novel Systems Pharmacology Method to Investigate Molecular Mechanisms of Scutellaria barbata D. Don for Non-small Cell Lung Cancer

Non-small cell lung cancer (NSCLC) is the most ordinary type of lung cancer which leads to 1/3 of all cancer deaths. At present, cytotoxic chemotherapy, surgical resection, radiation, and photodynamic therapy are the main strategies for NSCLC treatment. However, NSCLC is relatively resistant to the above therapeutic strategies, resulting in a rather low (20%) 5-year survival rate. Therefore, there is imperative to identify or develop efficient lead compounds for the treatment of NSCLC. Here, we report that the herb Scutellaria barbata D. Don (SBD) can effectively treat NSCLC by anti-inflammatory, promoting apoptosis, cell cycle arrest, and angiogenesis. In this work, we analyze the molecular mechanism of SBD for NSCLC treatment by applying the systems pharmacology strategy. This method combines pharmacokinetics analysis with pharmacodynamics evaluation to screen out the active compounds, predict the targets and assess the networks and pathways. Results show that 33 compounds were identified with potential anti-cancer effects. Utilizing these active compounds as probes, we predicted that 145 NSCLC related targets mainly involved four aspects: apoptosis, inflammation, cell cycle, and angiogenesis. And in vitro experiments were managed to evaluate the reliability of some vital active compounds and targets. Overall, a complete overview of the integrated systems pharmacology method provides a precise probe to elucidate the molecular mechanisms of SBD for NSCLC. Moreover, baicalein from SBD effectively inhibited tumor growth in an LLC tumor-bearing mice models, demonstrating the anti-tumor effects of SBD. Our findings further provided experimental evidence for the application in the treatment of NSCLC.

Bcl-2 Inhibition to Overcome Resistance to Chemo- and Immunotherapy

Abstract: According to the World Health Organization (WHO), cancer is a leading cause of death worldwide. The identification of novel targets for cancer treatment is an area of intense work that has led Bcl-2 over-expression to be proposed as one of the hallmarks of cancer and Bcl-2 inhibition as a promising strategy for cancer treatment. In this review, we describe the different pathways related to programmed cell death, the role of Bcl-2 family members in apoptosis resistance to anti-cancer treatments, and the potential utility of Bcl-2 inhibitors to overcome resistance to chemo- and immunotherapy.