Cancer therapeutics based on BCL-2 functional conversion

Cholesteryl ester transfer protein knock-down in conjunction with a cholesterol-depleting agent decreases tamoxifen resistance in breast cancer cells

The cholesterogenic phenotype, encompassing de novo biosynthesis and accumulation of cholesterol, aids cancer cell proliferation and survival. Previously, the role of cholesteryl ester (CE) transfer protein (CETP) has been implicated in breast cancer aggressiveness, but the molecular basis of this observation is not clearly understood, which this study aims to elucidate. CETP knock-down resulted in a >50% decrease in cell proliferation in both 'estrogen receptor-positive' (ER+; Michigan Cancer Foundation-7 (MCF7) breast cancer cells) and 'triple-negative' breast cancer (TNBC; MDA-MB-231) cell lines. Intriguingly, the abrogation of CETP together with the combination treatment of tamoxifen (5 μM) and acetyl plumbagin (a cholesterol-depleting agent) (5 μM) resulted in twofold to threefold increase in apoptosis in both cell lines. CETP knockdown also showed decreased intracellular CE levels, lipid raft and lipid droplets in both cell lines. In addition, RT2 Profiler PCR array (Qiagen, Germany)-based gene expression analysis revealed an overall downregulation of genes associated in cholesterol biosynthesis, lipid signalling and drug resistance in MCF7 cells post-CETP knock-down. On the contrary, resistance in MDA-MB-231 cells was reduced through increased expression in cholesterol efflux genes and the expression of targetable surface receptors by endocrine therapy. The pilot xenograft mice study substantiated CETP's role as a cancer survival gene as knock-down of CETP stunted the growth of TNBC tumour by 86%. The principal findings of this study potentiate CETP as a driver in breast cancer growth and aggressiveness and thus targeting CETP could limit drug resistance via the reduction in cholesterol accumulation in breast cancer cells, thereby reducing cancer aggressiveness.

Small Molecule Functional Converter of B-Cell Lymphoma-2 (Bcl-2) Suppresses Breast Cancer Lung Metastasis

The B-cell lymphoma-2 (Bcl-2) family of proteins plays a vital role in tumorigenesis. Cancer cells utilize the expression of Bcl-2 to evade therapy and develop resistance. Bcl-2 overexpression also causes cancer cells to be more invasive and metastatic. About 80% of cancer deaths are due to metastases, and yet targeted therapies for metastatic cancers are scarce. We discovered a small molecule, BFC1103, which changes the conformation of Bcl-2 to convert the antiapoptotic protein to a proapoptotic protein. BFC1103-induced apoptosis is dependent on the expression levels of Bcl-2, with higher levels causing more apoptosis. BFC1103 suppressed the growth of breast cancer lung metastasis. BFC1103 has the potential for further optimization and development for clinical testing in metastatic cancers that express Bcl-2. This study demonstrates a new approach to target Bcl-2 using a small molecule, BFC1103, to suppress metastatic disease.

Identification and Characterization of a Small Molecule Bcl-2 Functional Converter

Cancer cells exploit the expression of anti-apoptotic protein Bcl-2 to evade apoptosis and develop resistance to therapeutics. High levels of Bcl-2 leads to sequestration of pro-apoptotic proteins causing the apoptotic machinery to halt. In this study, we report discovery of a small molecule, BFC1108 (5-chloro-N-(2-ethoxyphenyl)-2-[(4-methoxybenzyol)amino]benzamide), which targets Bcl-2 and converts it into a pro-apoptotic protein. The apoptotic effect of BFC1108 is not inhibited, but rather potentiated, by Bcl-2 overexpression. BFC1108 induces a conformational change in Bcl-2, resulting in the exposure of its BH3 domain both in vitro and in vivo. BFC1108 suppresses the growth of triple-negative breast cancer xenografts with high Bcl-2 expression and inhibits breast cancer lung metastasis. This study demonstrates a novel approach to targeting Bcl-2 using BFC1108, a small molecule Bcl-2 functional converter that effectively induces apoptosis in Bcl-2-expressing cancers.

SIGNIFICANCE

We report the identification of a small molecule that exposes the Bcl-2 killer conformation and induces death in Bcl-2-expressing cancer cells. Selective targeting of Bcl-2 and elimination of cancer cells expressing Bcl-2 opens up new therapeutic avenues.

Phase separation of Nur77 mediates XS561-induced apoptosis by promoting the formation of Nur77/Bcl-2 condensates

The orphan nuclear receptor Nur77 is a critical regulator of the survival and death of tumor cells. The pro-death effect of Nur77 can be regulated by its interaction with Bcl-2, resulting in conversion of Bcl-2 from a survival to killer. As Bcl-2 is overexpressed in various cancers preventing them from apoptosis and promoting their resistance to chemotherapy, targeting the apoptotic pathway of Nur77/Bcl-2 may lead to new cancer therapeutics. Here, we report our identification of XS561 as a novel Nur77 ligand that induces apoptosis of tumor cells by activating the Nur77/Bcl-2 pathway. In vitro and animal studies revealed an apoptotic effect of XS561 in a range of tumor cell lines including MDA-MB-231 triple-negative breast cancer (TNBC) and MCF-7/LCC2 tamoxifen-resistant breast cancer (TAMR) in a Nur77-dependent manner. Mechanistic studies showed XS561 potently induced the translocation of Nur77 from the nucleus to mitochondria, resulting in mitochondria-related apoptosis. Interestingly, XS561-induced accumulation of Nur77 at mitochondria was associated with XS561 induction of Nur77 phase separation and the formation of Nur77/Bcl-2 condensates. Together, our studies identify XS561 as a new activator of the Nur77/Bcl-2 apoptotic pathway and reveal a role of phase separation in mediating the apoptotic effect of Nur77 at mitochondria.

MicroRNAs and their vital role in apoptosis in hepatocellular carcinoma: miRNA-based diagnostic and treatment methods

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies with high invasive and metastatic capability. Although significant advances have been made in the treatment of HCC, the overall survival rate of patients is still low. It is essential to explore accurate biomarkers for early diagnosis and prognosis along with therapeutic procedures to increase the survival rate of these patients. Anticancer therapies can contribute to induce apoptosis for the elimination of cancerous cells. However, dysregulated apoptosis and proliferation signaling pathways lead to treatment resistance, a significant challenge in improving efficient therapies. MiRNAs, short non-coding RNAs, play crucial roles in the progression of HCC, which regulate gene expression through post-transcriptional inhibition and targeting mRNA degradation in cancers. Dysregulated expression of multiple miRNAs is associated with numerous biological processes, including cell proliferation, apoptosis, invasion and metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and drug resistance in HCC. This review summarizes the role and potential efficacy of miRNAs in promoting and inhibiting cell proliferation and apoptosis in HCC, as well as the role of miRNAs in therapy resistance in HCC.

Cancer Cell Membrane Wrapped Nanoparticles for the Delivery of a Bcl-2 Inhibitor to Triple-Negative Breast Cancer

Overexpression of the antiapoptotic protein B-cell lymphoma 2 (Bcl-2) is correlated with poor survival outcomes in triple-negative breast cancer (TNBC), making Bcl-2 inhibition a promising strategy to treat this aggressive disease. Unfortunately, Bcl-2 inhibitors developed to date have limited clinical success against solid tumors, owing to poor bioavailability, insufficient tumor delivery, and off-target toxicity. To circumvent these problems, we loaded the Bcl-2 inhibitor ABT-737 in poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) that were wrapped with phospholipid membranes derived from 4T1 murine mammary cancer cells, which mimic the growth and metastasis of human TNBC. We show that the biomimetic cancer cell membrane coating enabled the NPs to preferentially target 4T1 TNBC cells over noncancerous mammary epithelial cells in vitro and significantly increased NP accumulation in orthotopic 4T1 tumors in mice after intravenous injection by over 2-fold compared to poly(ethylene glycol)-poly(lactide-co-glycolic) (PEG-PLGA) copolymer NPs. Congruently, the ABT-737 loaded, cancer cell membrane-wrapped PLGA NPs (ABT CCNPs) induced higher levels of apoptosis in TNBC cells in vitro than ABT-737 delivered freely or in PEG-PLGA NPs. When tested in a syngeneic spontaneous metastasis model, the ABT CCNPs significantly increased apoptosis (evidenced by elevated active caspase-3 and decreased Bcl-2 staining) and decreased proliferation (denoted by reduced Ki67 staining) throughout tumors compared with saline or ABT-loaded PEG-PLGA NP controls. Moreover, the ABT CCNPs did not alter animal weight or blood composition, suggesting that the specificity afforded by the TNBC cell membrane coating mitigated the off-target adverse effects typically associated with ABT-737. Despite these promising results, the low dose of ABT CCNPs administered only modestly reduced primary tumor growth and metastatic nodule formation in the lungs relative to controls. We posit that increasing the dose of ABT CCNPs, altering the treatment schedule, or encapsulating a more potent Bcl-2 inhibitor may yield more robust effects on tumor growth and metastasis. With further development, drug-loaded biomimetic NPs may safely treat solid tumors such as TNBC that are characterized by Bcl-2 overexpression.

Tanshinone IIA inhibits endometrial carcinoma growth through the MAPK/ERK/TRIB3 pathway

Endometrial carcinoma is the most common gynecological tumor in developed countries. Tanshinone IIA is a traditional herbal medicine which is to treat cardiovascular disease and has been shown to have various biological effects, such as anti-inflammatory, antioxidative and antitumor activities. However, there has been no study about the effect of tanshinone IIA on endometrial carcinoma. Thus, the aim of this study was to determine the antitumor activity of tanshinone IIA against endometrial carcinoma and investigate the associated molecular mechanism. We demonstrated that tanshinone IIA induced cell apoptosis and inhibited migration. We further demonstrated that tanshinone IIA activated the intrinsic (mitochondrial) apoptotic pathway. Mechanistically, tanshinone IIA induced apoptosis by upregulating TRIB3 expression and inhibiting the MAPK/ERK signaling pathway. In addition, knockdown of TRIB3 with an shRNA lentivirus accelerated proliferation and attenuated inhibition mediated by tanshinone IIA. Finally, we further demonstrated that tanshinone IIA inhibited tumor growth by inducing TRIB3 expression in vivo. In conclusion, these findings suggest that tanshinone IIA has a significant antitumor effect by inducing apoptosis and may be used as a drug for the treatment of endometrial carcinoma.

Partridge and embryonated partridge egg as new preclinical models for candidiasis

Candida albicans (C. albicans) is the most common cause of candidiasis in humans and animals. This study was established to a new experimental infection model for systemic candidiasis using partridge and embryonated partridge egg. First, we tested the induction of systemic candidiasis in partridge and embryonated partridge egg. Finally, interaction between virulence factors of C. albicans and Bcl-2 family members was predicted. We observed that embryonic infection causes a decrease in survival time and at later embryonic days (11–12th), embryos showed lesions. Morphometric analysis of the extra-embryonic membrane (EEM) vasculature showed that vascular apoptotic effect of C. albicans was revealed by a significant reduction in capillary area. In immunohistochemistry assay, low expression of Bcl-2 and increased expression of Bax confirmed apoptosis. The gene expression of Bax and Bcl-2 was also altered in fungi-exposed EEM. Ourin silico simulation has shown an accurate interaction between aspartic proteinase, polyamine oxidase, Bcl-2 and BAX. We observed that the disease was associated with adverse consequences, which were similar to human candidiasis. Acquired results support the idea that partridge and embryonated partridge egg can be utilized as appropriate preclinical models to investigate the pathological effects of candidiasis.

Embryo-toxicity of docosahexaenoic and eicosapentaenoic acids: In vivo and in silico investigations using the chick embryo model

OBJECTIVE

The objective of the current study was to evaluate the embryo-toxicity of omega-3 fatty acids.

METHODS

Firstly, the embryo-toxicity of docosahexaenoic (DHA) and eicosapentaenoic acids (EPA), as well as their interaction with Bcl-2 family members, were predicted using an in silico assay. In the next step, the embryonic pathological lesions and amniotic fluid biochemical changes following omega-3 treatment were investigated using a chick embryo model. Finally, the drug's vascular apoptotic effect on the chick's yolk sac membrane (YSM) was assessed.

RESULTS

In silico simulations revealed the embryo-toxicity, tissue-toxicity (respiratory and cardiovascular), and vascular-toxicity (apoptotic activity) of DHA and EPA. There was also an accurate interaction between DHA and EPA with Bax (Binding affinity: -7.6 and -10.6 kcal/mol) and Bcl-2 (Binding affinity: -8.0 and -12.2 kcal/mol), respectively. Moreover, DHA and EPA administrations were related to various adverse consequences, including weight loss and lesions in the respiratory and cardiovascular systems. Histopathological findings consisted of pulmonary edema, airway dilatation, increased interstitial tissue, and hyperemia in the lungs, heart, liver, kidney, and brain. Morphometric evaluation of the YSM vasculature revealed that the vascular apoptotic effect of omega-3was associated with a significant reduction in mean capillary area. In immunohistochemistry assay, increased expression of BAX and low expression of Bcl-2 affirmed apoptosis in YSM vessels.

CONCLUSION

According to the results of this study, one could confirm that the possible embryo-toxicity of omega-3 was approved by data presented in this research. The obtained results also support the suspicion that alteration of the apoptotic-related proteins in vessels is an essential pathway in embryo-toxicity of omega-3.

Downregulation of CDC20 Increases Radiosensitivity through Mcl-1/p-Chk1-Mediated DNA Damage and Apoptosis in Tumor Cells

Radiotherapy is an important modality for the local control of human cancers, but the radioresistance induced by aberrant apoptotic signaling is a hallmark of cancers. Restoring the aberrant apoptotic pathways is an emerging strategy for cancer radiotherapy. In this study, we determined that targeting cell division cycle 20 (CDC20) radiosensitized colorectal cancer (CRC) cells through mitochondrial-dependent apoptotic signaling. CDC20 was overexpressed in CRC cells and upregulated after radiation. Inhibiting CDC20 activities genetically or pharmacologically suppressed the proliferation and increased radiation-induced DNA damage and intrinsic apoptosis in CRC cells. Mechanistically, knockdown of CDC20 suppressed the expression of antiapoptotic protein Mcl-1 but not other Bcl-2 family proteins. The expressions of CDC20 and Mcl-1 respond to radiation simultaneously through direct interaction, as evidenced by immunoprecipitation and glutathione S-transferase (GST) pull-down assays. Subsequently, decreased Mcl-1 expression inhibited the expression level of phosphorylated checkpoint kinase 1 (p-Chk1), thereby resulting in impaired DNA damage repair through downregulating the homologous recombination repair protein Rad51 and finally causing apoptotic signaling. In addition, both CDC20 and Chk1 inhibitors together, through in vivo studies, confirmed the radiosensitizing effect of CDC20 via inhibiting Mcl-1 and p-Chk1 expression. In summary, our results indicate that targeting CDC20 is a promising strategy to improve cancer radiotherapy.