Reversal effect of ouabain on multidrug resistance in esophageal carcinoma EC109/CDDP cells by inhibiting the translocation of Wnt/β-catenin into the nucleus

Metabolomic approach to characterize the metabolic phenotypes and varied response to ouabain of diffuse large B-cell lymphoma cells

Germinal center B-cell-like (GCB) and activated B-cell-like (ABC) subtype diffuse large B-cell lymphoma (DLBCL) showed differential prognosis. Our results suggested that ouabain induced stronger inhibition of growth in Su-DHL4 (GCB), and it triggered obvious apoptosis in Su-DHL4 rather than in OCI-Ly3 (ABC). Two subtype cell lines also showed distinct metabolic phenotypes involving remarkable enrichment of Ribulose-5-Phosphate, hypoxanthine, and guanine in Su-DHL4 cells. Ouabain disturbed metabolic patterns of both cell lines dose-dependently manifested inhibition of free fatty acids and amino acids metabolism, among which ornithine was further identified as potential quantitative marker. Up-regulated Ribulose-5-Phosphate and NADPH/NADP⁺ level, SOD1, and CAT expression by ouabain enabled OCI-Ly3 cells to resist ROS, while enhanced hypoxanthine and guanine oxidation promoting ROS generation by ouabain, and lowered capacity of scavenging ROS indicated by lowered SOD1 and CAT expression and NADPH/NADP⁺ levels in Su-DHL4 cells made it more vulnerable to apoptosis through caspase 7 pathway.

Paeonol exerts anti‑tumor activity against colorectal cancer cells by inducing G0/G1 phase arrest and cell apoptosis via inhibiting the Wnt/β‑catenin signaling pathway

Paeonol is a simple phenolic compound isolated from herbal root bark, which has been reported to possess numerous biological and pharmacological characteristics, including a desirable anti‑tumor effect. To date, the effect of paeonol against colorectal cancer (CRC) cells is yet to be fully elucidated. Therefore, the present study aimed to identify the underlying mechanism via which paeonol exerts its anti‑tumor activity on HCT116 cells. After incubation with various concentrations of paeonol (7.8125, 15.625, 31.25, 62.5, 125, 250 and 500 µg/ml), the inhibitory effect of paeonol on cell viability was assessed using a Cell Counting Kit‑8 assay. Cell apoptosis and cell cycle distribution were measured using flow cytometry. Moreover, caspase activity was measured using a colorimetric caspase assay. Luciferase assay was also used to determine the β‑catenin‑mediated transcriptional activity of T‑cell specific transcription factor/lymphoid‑enhancer binding factor (TCF/LEF), and western blotting analysis was performed to measure the related expression of proteins. The results indicated that paeonol exhibited a notable effect against HCT116 cells by inducing G0/G1‑phase arrest, as demonstrated by downregulation of the cell cycle regulators cyclin‑dependent kinase 4 and cyclin D1 and upregulation of p21Cip1 in a dose‑dependent manner. Furthermore, paeonol dose‑dependently induced cell apoptosis, accompanied by an increase in the Bax/Bcl‑2 ratio, release of cytochrome c and further activation of caspases. Paeonol also dose‑dependently blocked the activation of the Wnt/β‑catenin signaling pathway by suppressing the expression of β‑catenin, resulting in a decrease in β‑catenin‑mediated activity of TCF/LEF and downregulation of downstream target genes, including cyclin D1, survivin and c‑Myc. Therefore, the present results suggested that paeonol exerted its anti‑tumor effects on CRC cells, including the inhibition of cell proliferation, induction of cell cycle arrest and initiation of apoptosis, at least partly by suppressing the Wnt/β‑catenin pathway, which may offer a promising therapeutic strategy for CRC.

New insights into germ cell tumor genomics

BACKGROUND

Testicular germ cell tumors (GCTs) represent the most common malignancy in young men. While GCTs represent a model for curable solid tumors due to exquisite chemosensitivity, mortality for patients with GCT comprises the most life years lost for non-pediatric malignancies. Given limited options for patients with platinum-resistant disease, improved insight into GCT biology could identify novel therapeutic options for patients with platinum-resistant disease. Recent studies into molecular characteristics of both early stage and advanced germ cell tumors suggest a role for rationally targeted agents and potentially immunotherapy.

RECENT DEVELOPMENTS

Recent GWAS meta-analyses have uncovered additional susceptibility loci for GCT and provide further evidence that GCT risk is polygenic. Chromosome arm level amplifications and reciprocal loss of heterozygosity have been described as significantly enriched in GCT compared to other cancer types. Contemporary analyses confirm ubiquitous gain of isochromosome 12 and mutations in addition to previously described GCT-associated genes such as KIT and KRAS. Alterations within the TP53-MDM2 signal transduction pathway appear to be enriched among patients with platinum-resistant disease. Potentially actionable targets, including alterations in TP53-MDM2, Wnt/β-catenin, PI3K, and MAPK signaling, are present in significant proportions of patients with platinum-resistant disease and may be exploited as therapeutic options. Pre-clinical and early clinical data also suggest a potential role for immunotherapy among patients with GCTs.

CONCLUSION

Molecular characterization of GCT patients may provide biologic rationale for novel treatment options in patients with platinum-resistant disease.

Telocinobufagin and Marinobufagin Produce Different Effects in LLC-PK1 Cells: A Case of Functional Selectivity of Bufadienolides

Bufadienolides are cardiotonic steroids (CTS) identified in mammals. Besides Na⁺/K⁺-ATPase inhibition, they activate signal transduction via protein–protein interactions. Diversity of endogenous bufadienolides and mechanisms of action may indicate the presence of functional selectivity and unique cellular outcomes. We evaluated whether the bufadienolides telocinobufagin and marinobufagin induce changes in proliferation or viability of pig kidney (LLC-PK1) cells and the mechanisms involved in these changes. In some experiments, ouabain was used as a positive control. CTS exhibited an inhibitory IC₅₀ of 0.20 (telocinobufagin), 0.14 (ouabain), and 3.40 μM (marinobufagin) for pig kidney Na⁺/K⁺-ATPase activity and concentrations that barely inhibited it were tested in LLC-PK1 cells. CTS induced rapid ERK1/2 phosphorylation, but corresponding proliferative response was observed for marinobufagin and ouabain instead of telocinobufagin. Telocinobufagin increased Bax:Bcl-2 expression ratio, sub-G0 cell cycle phase and pyknotic nuclei, indicating apoptosis. Src and MEK1/2 inhibitors blunted marinobufagin but not telocinobufagin effect, which was also not mediated by p38, JNK1/2, and PI3K. However, BIO, a GSK-3β inhibitor, reduced proliferation and, as telocinobufagin, phosphorylated GSK-3β at inhibitory Ser9. Combination of both drugs resulted in synergistic antiproliferative effect. Wnt reporter activity assay showed that telocinobufagin impaired Wnt/β-catenin pathway by acting upstream to β-catenin stabilization. Our findings support that mammalian endogenous bufadienolides may exhibit functional selectivity.

ABC Transporters and Their Role in the Neoadjuvant Treatment of Esophageal Cancer

The prognosis of esophageal cancer (EC) is poor, despite considerable effort of both experimental scientists and clinicians. The tri-modality treatment consisting of neoadjuvant chemoradiation followed by surgery has remained the gold standard over decades, unfortunately, without significant progress in recent years. Suitable prognostic factors indicating which patients will benefit from this tri-modality treatment are missing. Some patients rapidly progress on the neoadjuvant chemoradiotherapy, which is thus useless and sometimes even harmful. At the same time, other patients achieve complete remission on neoadjuvant chemoradiotherapy and subsequent surgery may increase their risk of morbidity and mortality. The prognosis of patients ranges from excellent to extremely poor. Considering these differences, the role of drug metabolizing enzymes and transporters, among other factors, in the EC response to chemotherapy may be more important compared, for example, with pancreatic cancer where all patients progress on chemotherapy regardless of the treatment or disease stage. This review surveys published literature describing the potential role of ATP-binding cassette transporters, the genetic polymorphisms, epigenetic regulations, and phenotypic changes in the prognosis and therapy of EC. The review provides knowledge base for further research of potential predictive biomarkers that will allow the stratification of patients into defined groups for optimal therapeutic outcome.