Related Experiment Videos
Differential Na+,K(+)-ATPase activity and cisplatin sensitivity between transformants induced by H-ras and those
1Department of Urology, Hokkaido University School of Medicine, Sapporo, Japan.
Abstract:
We examined the differential effects of the H-ras oncogene and the K-ras oncogene on cisplatin sensitivity in murine NIH/3T3 cells transfected with these oncogenes. Although the NIH/3T3 cells transformed with H-ras oncogenes (EJ-NIH/3T3 and Ha8-21) showed an increased resistance to cisplatin compared to the parental NIH/3T3, the cell lines transformed with K-ras oncogenes (DT and 1,8DNP2-2-5) did not. Compared with NIH/3T3, the 2 H-ras transformants reduced both the accumulation of cisplatin and the Na+,K(+)-ATPase activity in the membrane fraction. On the other hand, we observed no significant difference in cellular accumulation of cisplatin or in Na+,K(+)-ATPase activity between parental NIH/3T3 and the K-ras transformants. Since these ras transformants did not affect the cellular metallothionein content, transcriptional level of DNA polymerase beta or activity of glutathione-S-transferase which is not associated with cisplatin sensitivity, these results suggest that cisplatin resistance is brought about by the H-ras oncogene, but not by K-ras, and that induction of cisplatin resistance by H-ras is mainly due to a reduction of cisplatin accumulation and an impairment of Na+,K(+)-ATPase activity in the membrane fraction.
Insights
The H-ras oncogene increases cisplatin resistance in NIH/3T3 cells by reducing drug accumulation and Na+,K+-ATPase activity. In contrast, K-ras oncogenes do not affect cisplatin sensitivity or these cellular mechanisms.
Area of Science:
- Molecular Biology
- Oncology
- Cell Biology
Background:
- Ras oncogenes are frequently activated in human cancers.
- Cisplatin is a widely used chemotherapy drug.
- Understanding mechanisms of drug resistance is crucial for effective cancer treatment.
Purpose of the Study:
- To investigate the differential roles of H-ras and K-ras oncogenes in conferring cisplatin resistance.
- To elucidate the cellular mechanisms underlying ras-mediated cisplatin resistance.
Main Methods:
- Transfection of murine NIH/3T3 cells with H-ras and K-ras oncogenes.
- Assessment of cisplatin sensitivity using cell viability assays.
- Measurement of intracellular cisplatin accumulation.
- Quantification of Na+,K+-ATPase activity in cell membrane fractions.
Main Results:
- H-ras transformed cells (EJ-NIH/3T3, Ha8-21) exhibited increased cisplatin resistance compared to parental NIH/3T3 cells.
- K-ras transformed cells (DT, 1,8DNP2-2-5) did not show altered cisplatin sensitivity.
- H-ras transformants displayed reduced cisplatin accumulation and impaired Na+,K+-ATPase activity.
- No significant changes in cisplatin accumulation or Na+,K+-ATPase activity were observed in K-ras transformants.
Conclusions:
- H-ras oncogene induces cisplatin resistance, while K-ras does not.
- H-ras-mediated cisplatin resistance is primarily attributed to decreased cisplatin uptake and compromised Na+,K+-ATPase function.
- These findings highlight distinct roles of H-ras and K-ras in chemotherapy response.