digitoxin and Adenocarcinoma

Drug repurposing with a better understanding of the underlying mechanism has provided new avenues to find treatment for malignancies. Esophageal adenocarcinoma (EAC) is a rapidly increasing cancer with a dismal 5-year survival rate of <15%. Lack of efficient treatment options contributes to the high mortality rate of EAC. To find new therapy against EAC we performed unbiased drug screening of an FDA-approved drug library and identified that the cardiac glycosides including Ouabain, Digoxin and Digitoxin efficiently inhibit the proliferation of EAC cell lines (OE33 and OE19) both in vitro and in vivo. RNA-Sequencing analysis combined with RNAi screening revealed that Ouabain suppresses the proliferation of EAC cells through downregulation of p38 MAP-Kinase 6 (MAP2K6, also known as MKK6). Consistently, shRNA-mediated knockdown of MKK6 reduced the proliferation of EAC cells and tumor growth. Further analysis demonstrated that MKK6 inhibition leads to the reduced levels of the transcription factor SOX9. In line with this finding, deletion of SOX9 with CRISPR/Cas9 resulted in decreased proliferation of EACs in 3D organoid culture and reduced tumor growth. Together these findings establish a druggable axis that can be harnessed for therapeutic gain against EAC.

Topics: Adenocarcinoma; Animals; Cell Line, Tumor; Cell Proliferation; Digitoxin; Digoxin; Esophageal Neoplasms; Gene Expression Regulation, Neoplastic; Gene Knockdown Techniques; HEK293 Cells; Humans; MAP Kinase Kinase 6; Mice, Inbred NOD; Ouabain; Protein Kinase Inhibitors; Signal Transduction; SOX9 Transcription Factor; Xenograft Model Antitumor Assays

Lung cancer risk and tumor characteristics differ between sexes. Estrogen has been suggested to counteract lung cancer development. We aimed to test the hypothesis that digitalis use decreases lung cancer risk due to its estrogenic and other anticancer properties in men. This was a nationwide Swedish population-based cohort study between July 1, 2005 and December 31, 2013. Data on the use of digitalis and organic nitrates in all male individuals were derived from the Swedish Prescribed Drug Registry. New lung cancer diagnoses among cohort participants were identified from the Swedish Cancer Registry. Cox proportional hazards regression was employed to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) of lung cancer in digitalis users (exposed participants) compared to users of organic nitrates without digitalis medication (unexposed participants). The study cohort contained 74,437 digitalis users and 297,301 organic nitrates users. Long-term use (≥2 years) of digitalis was associated with decreased HRs of total lung cancer (HR 0.55, 95% CI 0.39-0.79) and squamous cell carcinoma (HR 0.40, 95% CI 0.19-0.87). This large and population-based study suggests decreased risks of lung cancer overall and squamous cell carcinoma associated with long-term use of digitalis in men.

Topics: Adenocarcinoma; Aged; Carcinoma, Squamous Cell; Cohort Studies; Digitalis; Female; Follow-Up Studies; Humans; Incidence; Lung Neoplasms; Male; Middle Aged; Neoplasm Staging; Plant Extracts; Prognosis; Registries; Risk Assessment; Small Cell Lung Carcinoma; Survival Rate; Sweden

Four cardenolide glycosides, glucodigifucoside (2), 3'-O-acetylglucoevatromonoside (9), digitoxigenin 3-O-β-D-glucopyranosyl-(1 → 4)-β-D-glucopyranosyl-(1 → 4)-3-O-acetyl-β-D-digitoxopyranoside (11), and purpureaglycoside A (12), isolated from the seeds of Digitalis purpurea, exhibited potent cytotoxicity against human renal adenocarcinoma cell line ACHN. These compounds exhibited significantly lower IC50 values against ACHN than that against normal human renal proximal tubule-derived cell line HK-2. In particular, 2 exhibited the most potent and carcinoma-specific cytotoxicity, with a sixfold lower IC50 value against ACHN than that against HK-2. Measurement of cyclin-dependent kinase inhibitor levels revealed that upregulation of p21/Cip1 expression was involved in the carcinoma-specific cytotoxicity of 2. Further, compound 2 also exhibited the carcinoma-specific cytotoxicity toward hepatocellular carcinoma cell line.

Topics: Adenocarcinoma; Antineoplastic Agents, Phytogenic; Carcinoma, Hepatocellular; Cardenolides; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p21; Digitalis; Glycosides; Humans; Kidney Neoplasms; Liver Neoplasms; Seeds; Tumor Suppressor Protein p53; Up-Regulation

Recent research has shown the anticancer effects of digitalis compounds suggesting their possible use in medical oncology. Four extracts obtained from the leaves of Digitalis purpurea subsp. heywoodii have been assessed for cytotoxic activity against three human cancer cell lines, using the SRB assay. All of them showed high cytotoxicity, producing IC50 values in the 0.78 - 15 microg/mL range with the methanolic extract being the most active, in non toxic concentrations. Steroid glycosides (gitoxigenin derivatives) were detected in this methanolic extract. Gitoxigenin and gitoxin were evaluated in the SRB assay using the three human cancer cell lines, showing IC50 values in the 0.13 - 2.8 microM range, with the renal adenocarcinoma cancer cell line (TK-10) being the most sensitive one. Morphological apoptosis evaluation of the methanolic extract and both compounds on the TK-10 cell line showed that their cytotoxicity was mediated by an apoptotic effect. Finally, possible mechanisms involved in apoptosis induction by digitalis compounds are discussed.

Topics: Adenocarcinoma; Antineoplastic Agents, Phytogenic; Cardenolides; Cell Line, Tumor; Digitalis; Digoxin; Etoposide; Humans; Inhibitory Concentration 50; Kidney Neoplasms; Phytotherapy; Plant Extracts; Plant Leaves