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Published on: February 6, 2015
Cryptotanshinone Reverses Cisplatin Resistance of Human Lung Carcinoma A549 Cells through Down-Regulating Nrf2
Chen Xia1, Xupeng Bai, Xiangyu Hou
1School of Pharmaceutical Sciences, Sun Yat-sen University, Guangzhou, China.
Background/Aims:
To explore whether Nrf2 was associated with drug-resistance in cisplatin resistant A549 (A549/DDP) cells, and if cryptotanshinone (CTS), one of the bioactive compounds isolated from the roots of Salvia miltiorrhiza Bunge (Danshen), could enhance the sensitivity in A549/DDP cells towards cisplatin.
Methods:
A549 and A549/DDP cells were subjected to various treatments, and then Sulforhodamine B (SRB) assay, flow cytometry analysis and western immunoblotting analysis were applied to determine IC50, apoptotic status and expressions of Nrf2 and its downstream genes.
Results:
The endogenous expression levels of Nrf2 as well as its target genes including GCLC, GCLM, HO-1, NQO1 and MRP1 were much higher in A549/DDP cells than those of A549 cells and the susceptibility of A549/DDP cells to cisplatin was partially restored by silencing Nrf2. The combination of CTS and cisplatin led to cell death and apoptosis through sensitizing A549/DDP cells towards cisplatin compared with cisplatin mono-treatment, however, this reversal role could be abolished by Nrf2 knockdown. Specifically, CTS obviously diminished Nrf2 expression, thus contributing to the decrease of Nrf2-target genes expression levels. Meanwhile, we also discovered that CTS triggered several other signals involving in chemoresistance such as MAPKs, Akt and STAT3 pathway.
Conclusion:
Our data indicated CTS may be developed as a potential sensitizer cooperating with anticancer drugs to combat chemoresistant carcinoma through the inhibition of the Nrf2 pathway.
Insights
Cryptotanshinone (CTS) combats cisplatin resistance in lung cancer cells by inhibiting the Nrf2 pathway. This compound enhances cisplatin sensitivity, offering potential for combination cancer therapy.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Drug resistance is a major challenge in cancer chemotherapy.
- The Nrf2 pathway plays a critical role in cellular defense mechanisms and chemoresistance.
- Cisplatin is a widely used chemotherapeutic agent, but resistance limits its efficacy.
Purpose of the Study:
- To investigate the association between Nrf2 and cisplatin resistance in A549/DDP lung cancer cells.
- To determine if cryptotanshinone (CTS) can overcome cisplatin resistance.
- To elucidate the mechanism by which CTS affects chemoresistance.
Main Methods:
- Cell culture of A549 and cisplatin-resistant A549/DDP cells.
- Sulforhodamine B (SRB) assay to determine cell viability (IC50).
- Flow cytometry for apoptosis analysis.
- Western immunoblotting to assess protein expression (Nrf2 and downstream targets).
Main Results:
- Nrf2 and its target genes (GCLC, GCLM, HO-1, NQO1, MRP1) were upregulated in A549/DDP cells.
- Silencing Nrf2 partially restored cisplatin sensitivity.
- CTS combined with cisplatin induced cell death and apoptosis, sensitizing A549/DDP cells.
- CTS diminished Nrf2 expression and its downstream targets, an effect abolished by Nrf2 knockdown.
- CTS also modulated other chemoresistance pathways (MAPKs, Akt, STAT3).
Conclusions:
- Nrf2 is implicated in cisplatin resistance in lung cancer.
- Cryptotanshinone (CTS) acts as a sensitizer, enhancing cisplatin efficacy.
- CTS inhibits the Nrf2 pathway, offering a potential strategy to overcome chemoresistance.
- CTS may be developed as a co-treatment agent for chemoresistant carcinomas.
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