Digitoxin inhibits ICC cell properties via the NF­κB/ST6GAL1 signaling pathway.

Intrahepatic cholangiocarcinoma (ICC) is a type of liver cancer associated with poor prognosis and increased mortality; the limited treatment strategy highlights the urgent need for investigation. Traditional Chinese Medicine (TCM), used alone or in combination with other treatments, can enhance therapeutic efficacy, improve life quality of patients and extend overall survival. In total, two rounds of screening of a TCM library of 2,538 active compounds were conducted using a Cell Counting Kit­8 assay and ICC cell lines. Cell proliferation and migration abilities were assessed through colony formation, 5­ethynyl­2'­deoxyuridine, would healing and Transwell assays. The impact of digitoxin (DT) on signaling pathways was initially investigated using RNA sequencing and further validated using reverse transcription­quantitative PCR, western blotting, lectin blotting and flow cytometry. ICC cells stably overexpressing ST6 ß­galactoside α­2,6­sialyltransferase 1 (ST6GAL1) were generated through lentiviral transfection. It was shown that DT emerged as a highly effective anti­ICC candidate from two rounds high­throughput library screening. DT could inhibit the proliferation and migration of ICC cells by suppressing NF­κB activation and reducing nuclear phosphorylated­NF­κB levels, along with diminishing ST6GAL1 mRNA and protein expression. The aforementioned biological effects and signal pathways of DT could be counteracted by overexpressing ST6GAL1 in ICC cells. In conclusion, DT suppressed ICC cell proliferation and migration by targeting the NF­κB/ST6GAL1 signaling axis. The findings of the present study indicated the promising therapeutic effects of DT in managing ICC, offering new avenues for treatment strategies.

ST6GAL1 is associated with poor response to chemoradiation in rectal cancer.

INTRODUCTION: Colorectal cancer is the third most common cause of cancer death. Rectal cancer makes up a third of all colorectal cases. Treatment for locally advanced rectal cancer includes chemoradiation followed by surgery. We have previously identified ST6GAL1 as a cause of resistance to chemoradiation in vitro and hypothesized that it would be correlated with poor response in human derived models and human tissues. METHODS: Five organoid models were created from primary human rectal cancers and ST6GAL1 was knocked down via lentivirus transduction in one model. ST6GAL1 and Cleaved Caspase-3 (CC3) were assessed after chemoradiation via immunostaining. A tissue microarray (TMA) was created from twenty-six patients who underwent chemoradiation and had pre- and post-treatment specimens of rectal adenocarcinoma available at our institution. Immunohistochemistry was performed for ST6GAL1 and percent positive cancer cell staining was assessed and correlation with pathological grade of response was measured. RESULTS: Organoid models were treated with chemoradiation and both ST6GAL1 mRNA and protein significantly increased after treatment. The organoid model targeted with ST6GAL1 knockdown was found to have increased CC3 after treatment. In the tissue microarray, 42 percent of patient samples had an increase in percent tumor cell staining for ST6GAL1 after treatment. Post-treatment percent staining was associated with a worse grade of treatment response (p = 0.01) and increased staining post-treatment compared to pre-treatment was also associated with a worse response (p = 0.01). CONCLUSION: ST6GAL1 is associated with resistance to treatment in human rectal cancer and knockdown in an organoid model abrogated resistance to apoptosis caused by chemoradiation.