Research highlights. MCL1 and FBW7 as new predictive candidate biomarkers of anti-tubulin agents

Inhibitory Effect of Lotus Leaf-Enriched Flavonoid Extract on the Growth of HT-29 Colon Cancer Cells through the Expression of PI3K-Related Molecules

Objectives

Lotus leaf is rich in flavonoids, and this study is aimed at examining the inhibitory effect of lotus leaf-enriched flavonoid extract (LLEFE) on HT-29 colon cancer cells through phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) expression regulation.

Methods

Lotus leaves were extracted by ethanol and purified using FL-3 macroporous resin to create the LLEFE. HT-29 colon cancer cells were tested using various methods: their proliferation was observed by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, their survival status was observed by fluorescence staining, their oxidative stress level was observed by biochemical kits, and their mRNA expression was determined by quantitative polymerase chain reaction (qPCR) assay. Additionally, the composition of the flavonoids in lotus leaf was determined by HPLC.

Results

The results showed that the proliferation of NCM460 normal human colon cells was not affected by 0-500 μg/mL LLEFE but the proliferation of HT-29 human colon cancer cells decreased. LLEFE increased the LDH level in an HT-29 colon cancer cell culture medium; also increased the superoxide dismutase (SOD), catalase (CAT) activities, and glutathione (GSH) level in HT-29 cells; and decreased the malondialdehyde (MDA) level. Further experimental results showed that LLEFE upregulated the expression of SOD1, CAT, and GSH mRNA and downregulated the expression of PI3K, Akt, and mammalian target of rapamycin (mTOR) in HT-29 cells. The high-performance liquid chromatography (HPLC) results showed that kaempferin, hyperoside, astragaloside, phloridzin, and quercetin were the main chemical constituents of lotus leaf.

Conclusion

Lotus leaves contain functional flavonoids that inhibit the proliferation of HT-29 colon cancer cells and regulate the expression of PI3K/Akt through five important chemicals.

FBW7 increases the chemosensitivity of pancreatic cancer cells to gemcitabine through upregulation of ENT1

F-box and WD repeat domain-containing 7 (FBW7) has been characterized as a tumor suppressor, and its mutation or decreased expression has been observed in many types of human cancers. Our recent studies have uncovered that in pancreatic cancer, the KRAS mutation decreased FBW7 expression through phosphorylation and subsequent ubiquitination. Moreover, FBW7 inhibited aerobic glycolysis in pancreatic cancer via induction of thioredoxin-interacting protein (TXNIP), a mitochondrial localized tumor suppressor. The roles of FBW7 in anti-apoptosis and drug resistance via proteosomal degradation of myeloid cell leukemia-1 (MCL-1), which is an anti-apoptotic factor have been reported. However, the role of FBW7 in the chemotherapeutic resistance of pancreatic cancer to gemcitabine has seldom been reported. In the present study, we demonstrated that overexpression of FBW7 in pancreatic cancer cells rendered increased sensitivity to gemcitabine. Mechanistically, FBW7 promoted gemcitabine sensitivity via upregulation of equilibrative nucleoside transporter 1 (ENT1) at the protein level rather than the transcriptional level. In depth analysis demonstrated that the ENT1 protein level could be increased by lysosome inhibition. Taken together, our results demonstrated that FBW7 could be a target for improving the therapeutic efficacy of gemcitabine by induction of ENT1.