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Let-7a enhances the sensitivity of hepatocellular carcinoma cells to cetuximab by regulating STAT3 expression
Fei Xue1, Yanhui Liu2, Hongwei Zhang1
1Department of Hepatobiliary and Pancreatic Surgery, Henan Provincial People's Hospital, Zhengzhou University People's Hospital, Zhengzhou, People's Republic of China.
Background:
Let-7 miRNAs are reported to play an inhibitory role in carcinogenesis, tumor progression, recurrence, and pluripotency of cancer. However, few studies have reported the relationship between let-7 and drug sensitivity, especially for let-7a (a subtype of let-7). This study aimed to investigate the function of let-7a in regulating the sensitivity of hepatocellular carcinoma (HCC) cell lines to cetuximab.
Methods:
The cytotoxicity of cetuximab on HCC cell lines (Huh7, Hep3B, HepG2, SNU449, and SNU387) was evaluated using a cell viability assay (the Cell Counting Kit-8 assay) and a cell proliferation assay (the Click-iT EdU Imaging Kit) in the presence of a control, a let-7a mimic, and a let-7a inhibitor. Small interfering RNA to knockdown the expression of signal transducer and activator of transcription 3 (STAT3) were employed. Protein and mRNA expression levels were determined using quantitative polymerase chain reaction and Western blot analysis.
Results:
It was found that let-7a enhances the sensitivity of HCC cells with an epithelial phenotype (Huh7, Hep3B, and HepG2) to cetuximab, but has no effect on cells with the mesenchymal phenotype (SNU449 and SNU387). It was determined that STAT3 was a target mRNA of let-7a using TargetScan. Expression of STAT3 and let-7a mRNA were negatively correlated in HCC cell lines. Moreover, let-7a altered the protein and mRNA expression of STAT3. Furthermore, STAT3 knockdown enhanced the function of cetuximab on HCC cell lines with epithelial phenotypes, but not on HCC cell lines with mesenchymal phenotypes. Finally, a rescue experiment confirmed that let-7a affected the sensitivity of HCC cell lines to cetuximab by interacting with STAT3.
Conclusions:
There is a functional link between let-7a and STAT3 in enhancing the sensitivity of HCC cells with an epithelial phenotype to cetuximab. Our results provide novel insight into new methodologies for combating HCC drug resistance.
Insights
Let-7a enhances hepatocellular carcinoma (HCC) cell sensitivity to cetuximab by targeting STAT3 in epithelial cells. This finding offers new strategies to overcome drug resistance in HCC treatment.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Let-7 microRNAs (miRNAs) are known tumor suppressors.
- The role of let-7a in cancer drug sensitivity, particularly for hepatocellular carcinoma (HCC), remains under-explored.
- This study investigates let-7a's function in modulating HCC cell sensitivity to cetuximab.
Purpose of the Study:
- To determine the effect of let-7a on cetuximab sensitivity in various HCC cell lines.
- To elucidate the molecular mechanism underlying let-7a's influence on cetuximab response.
- To identify potential therapeutic targets for overcoming cetuximab resistance in HCC.
Main Methods:
- Cytotoxicity and proliferation assays (Cell Counting Kit-8, EdU) were performed on HCC cell lines.
- let-7a mimic and inhibitor were used to modulate let-7a levels.
- Signal transducer and activator of transcription 3 (STAT3) was targeted using small interfering RNA (siRNA).
- Quantitative PCR and Western blot analyzed gene and protein expression.
Main Results:
- let-7a significantly enhanced cetuximab sensitivity in epithelial HCC cell lines (Huh7, Hep3B, HepG2), but not in mesenchymal ones (SNU449, SNU387).
- STAT3 was identified as a direct target of let-7a, with inverse correlation in expression.
- STAT3 knockdown mimicked the effect of let-7a, increasing cetuximab sensitivity in epithelial HCC cells.
- Rescue experiments confirmed let-7a's interaction with STAT3 mediates cetuximab sensitivity.
Conclusions:
- A functional link exists between let-7a and STAT3 in enhancing cetuximab sensitivity of epithelial HCC cells.
- Targeting the let-7a-STAT3 pathway presents a novel strategy to combat drug resistance in HCC.
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