Therapeutic Small Molecules Target Inhibitor of Apoptosis Proteins in Cancers with Deregulation of Extrinsic and Intrinsic Cell Death Pathways

Gemigliptin, a novel dipeptidyl peptidase-IV inhibitor, exerts a synergistic cytotoxicity with the histone deacetylase inhibitor PXD101 in thyroid carcinoma cells

PURPOSE

The influence of the dipeptidyl peptidase-IV inhibitor gemigliptin alone or in combination with the histone deacetylase inhibitor PXD101 on survival of thyroid carcinoma cells was investigated.

METHODS

SW1736, TPC-1, 8505C and BCPAP human thyroid carcinoma cells were used. To assess cell survival, cell viability, the percentage of viable cells and dead cells, cytotoxic activity, ATP levels and FACS analysis were measured. To validate the impact of gemigliptin combined with PXD101, the interactions were estimated by obtaining combination index in cells treated with two agents.

RESULTS

In cells treated with gemigliptin or PXD101, cell viability, the percentage of viable cells and ATP levels were reduced, and the percentage of dead cells and cytotoxic activity were elevated. In cells treated with both gemigliptin and PXD101, compared with PXD101 alone, cell death was augmented, and all of the combination index values were lower than 1.0, suggesting the synergism between gemigliptin and PXD101. The percentage of apoptotic cells, and the protein levels of Bcl2 and cleaved poly (ADP-ribose) polymerase were elevated, and the protein levels of xIAP and survivin were reduced. The protein levels of phospho-Akt and phospho-AMPK were elevated, and cell migration was reduced.

CONCLUSIONS

Our results demonstrate that gemigliptin induces cytotoxicity in thyroid carcinoma cells. Moreover, gemigliptin has a synergistic activity with PXD101 in the induction of cell death through involvement of Bcl2 family proteins, xIAP and survivin as well as mediation of Akt and AMPK in thyroid carcinoma cells.

ASTX660, a Novel Non-peptidomimetic Antagonist of cIAP1/2 and XIAP, Potently Induces TNFα-Dependent Apoptosis in Cancer Cell Lines and Inhibits Tumor Growth

Because of their roles in the evasion of apoptosis, inhibitor of apoptosis proteins (IAP) are considered attractive targets for anticancer therapy. Antagonists of these proteins have the potential to switch prosurvival signaling pathways in cancer cells toward cell death. Various SMAC-peptidomimetics with inherent cIAP selectivity have been tested clinically and demonstrated minimal single-agent efficacy. ASTX660 is a potent, non-peptidomimetic antagonist of cIAP1/2 and XIAP, discovered using fragment-based drug design. The antagonism of XIAP and cIAP1 by ASTX660 was demonstrated on purified proteins, cells, and in vivo in xenograft models. The compound binds to the isolated BIR3 domains of both XIAP and cIAP1 with nanomolar potencies. In cells and xenograft tissue, direct antagonism of XIAP was demonstrated by measuring its displacement from caspase-9 or SMAC. Compound-induced proteasomal degradation of cIAP1 and 2, resulting in downstream effects of NIK stabilization and activation of noncanonical NF-κB signaling, demonstrated cIAP1/2 antagonism. Treatment with ASTX660 led to TNFα-dependent induction of apoptosis in various cancer cell lines in vitro, whereas dosing in mice bearing breast and melanoma tumor xenografts inhibited tumor growth. ASTX660 is currently being tested in a phase I-II clinical trial (NCT02503423), and we propose that its antagonism of cIAP1/2 and XIAP may offer improved efficacy over first-generation antagonists that are more cIAP1/2 selective. Mol Cancer Ther; 17(7); 1381-91. ©2018 AACR.

[Effect of cordycepin on apoptosis and autophagy of tongue cancer cells in vitro and the molecular mechanism]

OBJECTIVE

To study the effect of cordycepin on cell cycle, apoptosis and autophagy of human tongue cancer TCA-8113 cells and explore the mechanism of cordycepin for inhibiting the occurrence of tongue cancer.

METHODS

CCK-8 method was used to assess the inhibitory effect of cordycepin on TCA-8113 cell proliferation in vitro. The cell cycle and cell apoptosis of TCA-8113 cells treated with different concentrations of cordycepin were analyzed using flow cytometry. The expressions of apoptosis-related genes caspase-3, caspase-9, Bcl-2, and Bax were examined using quantitative real-time PCR and Western blotting, and immunohistochemistry was used to detect the expressions of autophagy-related proteins LC-3β, P62, p-mTOR, and AMPK.

RESULTS

CCK-8 assay showed that cordycepin significantly inhibited the proliferation of TCA-8113 cells in a concentration-dependent manner with an IC50 of 3.548 mg/mL at 24 h and an IC50 of 1.185 mg/mL at 48 h. Flow cytometric analysis showed that cordycepin caused cell cycle arrest at S phase and dose-dependently increased the apoptotic rate of TCA-8113 cells. Treatment of the cells with cordycepin enhanced the expressions of Bax, caspase-3 and caspase-9 at both the mRNA and protein levels and inhibited the expression of the antiapoptotic gene Bcl-2. Immunohistochemistry demonstrated that cordycepin promoted the expression of LC-3β and AMPK and inhibited the expression of P62 and p-mTOR.

CONCLUSION

Cordycepin inhibits the proliferation and induces apoptosis of HCT-116 cells through the mitochondrial pathway and induces autophagy via the AMPK/mTOR pathway.

[Effect of cordycepin on apoptosis and autophagy of tongue cancer cells in vitro and the molecular mechanism]

OBJECTIVE

To study the effect of cordycepin on cell cycle, apoptosis and autophagy of human tongue cancer TCA-8113 cells and explore the mechanism of cordycepin for inhibiting the occurrence of tongue cancer.

METHODS

CCK-8 method was used to assess the inhibitory effect of cordycepin on TCA-8113 cell proliferation in vitro. The cell cycle and cell apoptosis of TCA-8113 cells treated with different concentrations of cordycepin were analyzed using flow cytometry. The expressions of apoptosis-related genes caspase-3, caspase-9, Bcl-2, and Bax were examined using quantitative real-time PCR and Western blotting, and immunohistochemistry was used to detect the expressions of autophagy-related proteins LC-3β, P62, p-mTOR, and AMPK.

RESULTS

CCK-8 assay showed that cordycepin significantly inhibited the proliferation of TCA-8113 cells in a concentration-dependent manner with an IC₅₀ of 3.548 mg/mL at 24 h and an IC₅₀ of 1.185 mg/mL at 48 h. Flow cytometric analysis showed that cordycepin caused cell cycle arrest at S phase and dose-dependently increased the apoptotic rate of TCA-8113 cells. Treatment of the cells with cordycepin enhanced the expressions of Bax, caspase-3 and caspase-9 at both the mRNA and protein levels and inhibited the expression of the antiapoptotic gene Bcl-2. Immunohistochemistry demonstrated that cordycepin promoted the expression of LC-3β and AMPK and inhibited the expression of P62 and p-mTOR.

CONCLUSION

Cordycepin inhibits the proliferation and induces apoptosis of HCT-116 cells through the mitochondrial pathway and induces autophagy via the AMPK/mTOR pathway.

Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smoking and/or human papillomavirus (HPV). SCCs harbor 3q, 5p, and other recurrent chromosomal copy-number alterations (CNAs), DNA mutations, and/or aberrant methylation of genes and microRNAs, which are correlated with the expression of multi-gene programs linked to squamous cell stemness, epithelial-to-mesenchymal differentiation, growth, genomic integrity, oxidative damage, death, and inflammation. Low-CNA SCCs tended to be HPV(+) and display hypermethylation with repression of TET1 demethylase and FANCF, previously linked to predisposition to SCC, or harbor mutations affecting CASP8, RAS-MAPK pathways, chromatin modifiers, and immunoregulatory molecules. We uncovered hypomethylation of the alternative promoter that drives expression of the ΔNp63 oncogene and embedded miR944. Co-expression of immune checkpoint, T-regulatory, and Myeloid suppressor cells signatures may explain reduced efficacy of immune therapy. These findings support possibilities for molecular classification and therapeutic approaches.

Design, synthesis, and biological evaluation of novel ubiquitin-activating enzyme inhibitors

Ubiquitin-activating enzyme (E1), which catalyzes the activation of ubiquitin in the initial step of the ubiquitination cascade, is a potential therapeutic target in multiple myeloma and breast cancer treatment. However, only a few E1 inhibitors have been reported to date. Moreover, there has been little medicinal chemistry research on the three-dimensional structure of E1. Therefore, in the present study, we attempted to identify novel E1 inhibitors using structure-based drug design. Following the rational design, synthesis, and in vitro biological evaluation of several such compounds, we identified a reversible E1 inhibitor (4b). Compound 4b increased p53 levels in MCF-7 breast cancer cells and inhibited their growth. These findings suggest that reversible E1 inhibitors are potential anticancer agents.

IAPs cause resistance to TRAIL-dependent apoptosis in follicular thyroid cancer

Follicular thyroid cancer's (FTC) excellent long-term prognosis is mainly dependent on postoperative radioactive iodine (RAI) treatment. However, once the tumour becomes refractory, the 10-year disease-specific survival rate drops below 10%. The aim of our study was to evaluate the prognostic and biological role of the TRAIL system in FTC and to elucidate the influence of small-molecule-mediated antagonisation of inhibitor of apoptosis proteins (IAPs) on TRAIL sensitivity in vitro Tissue microarrays were constructed from forty-four patients with histologically confirmed FTC. Expression levels of TRAIL and its receptors were correlated with clinicopathological data and overall as well as recurrence-free survival. Non-iodine-retaining FTC cell lines TT2609-bib2 and FTC133 were treated with recombinant human TRAIL alone and in combination with Smac mimetics GDC-0152 or Birinapant. TRAIL-R2/DR5 as well as TRAIL-R3/DcR1 and TRAIL-R4/DcR2 were significantly higher expressed in advanced tumour stages. Both decoy receptors were negatively associated with recurrence-free and overall survival. TRAIL-R4/DcR2 additionally proved to be an independent negative prognostic marker in FTC (HR = 1.446, 95% CI: 1.144-1.826; P < 0.001). In vitro, the co-incubation of Birinapant or GDC-0152 with rh-TRAIL-sensitised FTC cell lines for TRAIL-induced apoptosis, through degradation of cIAP1/2. The TRAIL system plays an important role in FTC tumour biology. Its decoy receptors are associated with poor prognosis as well as earlier recurrence. The specific degradation of cIAP1/2 sensitises FTC cells to TRAIL-induced apoptosis and might highlight a new point of attack in patients with RAI refractory disease.

Apoptosis-sensitizing activity of birinapant in head and neck squamous cell carcinoma cell lines

Inhibitor of apoptosis proteins, which are overexpressed in head and neck squamous cell carcinoma (HNSCC), may cause therapeutic resistance. Using SMAC mimetic compounds, including birinapant, to degrade and/or inhibit these proteins and sensitize apoptosis may enhance therapies in HNSCC. Fas expression was analyzed in nine HNSCC cell lines and one keratinocyte cell line via flow cytometry. These cell lines were treated with Fas ligand-Fc (FasL) and birinapant, a bivalent SMAC mimetic, in mono and combination therapies. Cytotoxicity was measured using a crystal violet assay. Annexin V assay was performed for detection of apoptosis. The treatment efficacy of mono and combination therapies was statistically analyzed. Nonlinear regression analysis was performed to determine the inhibitory concentration (IC₁₀) of birinapant. Fas expression was detected in each cell line tested. Mono treatment with FasL revealed minor to no apoptotic effects in the majority of the cell lines. Crystal violet and Annexin V staining revealed increased apoptosis rates for all cell lines following incubation with birinapant in mono treatment. Combination treatment with FasL and birinapant (IC₁₀) revealed additional and synergistic effects in eight out of the ten cell lines. To the best of our knowledge, the present study provided the first evidence of the apoptosis-sensitizing activity of combination treatment with FasL and birinapant in HNSCC cell lines.

Rabdocoestin B exhibits antitumor activity by inducing G2/M phase arrest and apoptosis in esophageal squamous cell carcinoma

PURPOSE

Esophageal squamous cell carcinoma (ESCC) is one of the most aggressive squamous cell carcinomas and is generally resistant to chemotherapy. In the present study, the cytotoxic activity of Rabdocoestin B (Rabd-B) against ESCC and the underlying mechanisms were investigated.

METHODS

The inhibitory effect of Rabd-B on KYSE30 and KYSE450 was evaluated by Cell Counting Kit-8 (CCK8) and colony formation assays in vitro. The cell cycle distribution and apoptosis of cells treated with Rabd-B were determined by flow cytometry. The mechanisms underlying the effects of Rabd-B were systematically examined by Western blot. The in vivo anti-tumor ability of Rabd-B was measured in mouse xenograft models and cisplatin (DDP) was used as positive control.

RESULTS

Rabd-B efficiently induced G2/M phase arrest in ESCC cells by upregulating the Chk1/Chk2-Cdc25C axis to inhibit the G2→M transition facilitated by Cdc2/Cyclin B1. Furthermore, Rabd-B suppressed ATM/ATR phosphorylation, thereby inhibiting BRCA1-mediated DNA repair, which resulted in mitotic catastrophe and induced cell apoptosis. Rabd-B also decreased the activity of the Akt and NF-κB survival signaling pathways and ultimately initiated the caspase-9-dependent intrinsic apoptotic pathway in ESCC cells. The apoptosis induced by Rabd-B could be partially reversed by a caspase-9-specific inhibitor (Z-LEHD-FMK) and a pan-caspase inhibitor (Z-VAD-FMK). Moreover, Rabd-B effectively suppressed tumor growth in mouse xenografts which was comparable to that of DDP without significant injuries to the mice.

CONCLUSION

Taken together, these findings indicate that Rabd-B is a promising precursor compound that may be useful as a treatment for ESCC and thus warrants further investigation.

[Sanggenon C induces apoptosis of prostate cancer PC3 cells by activating caspase 3 and caspase 9 pathways]

OBJECTIVE

To investigate the effects of Sanggenon C in inducing apoptosis of prostate cancer PC3 cell line and explore the underlying mechanism.

METHODS

The proliferation of PC3 cells treated for 24 h with 1, 5, 20, 50, and 100 µmol/L sanggenon C or treated with 20 µmol/L Sanggenon C for 0, 6, 12, 24 and 48 h was evaluated using MTT assay. Flow cytometry was performed for analysis of apoptosis of PC3 cells after exposure to sanggenon C with different treatment protocols, and the activity of caspase 3 was detected using spectrofluorometry. The inhibitory effect of sanggenon C on PC3 cells pretreated with DMSO, z-DEVD-fmk, z-LEHD-fmk or z-IETD-fmk for 1 h was detected by MTT assay.

RESULTS

Sanggenon C inhibited the proliferation of PC3 cells in a dose- and time-dependent manner (P<0.05 except for 1 µmol/L group) with a 24-h IC₅₀ of 18.76 µmol/L. Sanggenon C at 20 µmol/L caused inhibition rates of PC3 cells of 10.57%, 27.09%, 51.88%, 80.73% and 87.99% after treatment for 6, 12, 24, 48, and 72 h, respectively (P<0.05), and resulted in apoptosis rates of 7.43%, 20.91% and 37.56% at 12 h, 24 h and 48 h, respectively. Sanggenon C significantly increased caspase-3 activity in the cells, and its effect on PC3 cell proliferation was partially reversed by caspase 3 and caspase 9 inhibitors.

CONCLUSION

Sanggenon C can dose-dependently induce growth inhibition and apoptosis of PC3 cells possibly by activating caspase 9 and caspase 3 pathways.

[Sanggenon C induces apoptosis of prostate cancer PC3 cells by activating caspase 3 and caspase 9 pathways]

OBJECTIVE

To investigate the effects of Sanggenon C in inducing apoptosis of prostate cancer PC3 cell line and explore the underlying mechanism.

METHODS

The proliferation of PC3 cells treated for 24 h with 1, 5, 20, 50, and 100 µmol/L sanggenon C or treated with 20 µmol/L Sanggenon C for 0, 6, 12, 24 and 48 h was evaluated using MTT assay. Flow cytometry was performed for analysis of apoptosis of PC3 cells after exposure to sanggenon C with different treatment protocols, and the activity of caspase 3 was detected using spectrofluorometry. The inhibitory effect of sanggenon C on PC3 cells pretreated with DMSO, z-DEVD-fmk, z-LEHD-fmk or z-IETD-fmk for 1 h was detected by MTT assay.

RESULTS

Sanggenon C inhibited the proliferation of PC3 cells in a dose- and time-dependent manner (P<0.05 except for 1 µmol/L group) with a 24-h IC50 of 18.76 µmol/L. Sanggenon C at 20 µmol/L caused inhibition rates of PC3 cells of 10.57%, 27.09%, 51.88%, 80.73% and 87.99% after treatment for 6, 12, 24, 48, and 72 h, respectively (P<0.05), and resulted in apoptosis rates of 7.43%, 20.91% and 37.56% at 12 h, 24 h and 48 h, respectively. Sanggenon C significantly increased caspase-3 activity in the cells, and its effect on PC3 cell proliferation was partially reversed by caspase 3 and caspase 9 inhibitors.

CONCLUSION

Sanggenon C can dose-dependently induce growth inhibition and apoptosis of PC3 cells possibly by activating caspase 9 and caspase 3 pathways.

Genomics and advances towards precision medicine for head and neck squamous cell carcinoma

Objective

To provide a review of emerging knowledge from genomics and related basic science, preclinical, and clinical precision medicine studies in head and neck squamous cell carcinoma (HNSCC).

Data Sources

The Cancer Genome Atlas Network (TCGA) publications, PubMed‐based literature review, and ClinicalTrials.gov.

Review Methods

TCGA publications, PubMed, and ClinicalTrials.gov were queried for genomics and related basic science, preclinical, and developmental clinical precision medicine studies in HNSCC.

Results

TCGA reported comprehensive genomic analyses of 279 HNSCC, defining the landscape and frequency of chromosomal copy number alterations, mutations, and expressed genes that contribute to pathogenesis, prognosis, and resistance to therapy. This provides a road map for basic science and preclinical studies to identify key pathways in cancer and cells of the tumor microenvironment affected by these alterations, and candidate targets for new small molecule and biologic therapies.

Conclusion

Recurrent chromosomal abnormalities, mutations, and expression of genes affecting HNSCC subsets are associated with differences in prognosis, and define molecules, pathways, and deregulated immune responses as candidates for therapy. Activity of molecularly targeted agents appears to be enhanced by rational combinations of these agents and standard therapies targeting the complex alterations that affect multiple pathways and mechanisms in HNSCC.

Level of Evidence

NA.