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Marked reduction of type I keratin (K14) in cisplatin-resistant human lung squamous-carcinoma cell lines
M Katabami1, H Fujita, K Honke
1Laboratory of Molecular Genetics, Cancer Institute, Sapporo, Japan.
Abstract:
We have established two cisplatin-resistant human lung squamous-carcinoma cell lines, PC10-B3 and PC10-E5, from their original cell line PC10. To discover which proteins are associated with cisplatin resistance, we carried out a two-dimensional gel electrophoresis to analyze differences in protein alteration between PC10, PC10-B3 and PC10-E5. A protein spot M(r) 50 kDa, pI5.3, was reduced markedly and a spot M(r) 50 kDa, pI4.9 was increased when PC10-B3 and PC10-E5 were compared with PC10. A spot M(r) 58 kDa, pI5.8 newly appeared only in PC10-E5. Cell fractionation showed that the M(r) 50 kDa, pI5.3 (p50-5.3) and the M(r) 50 kDa, pI4.9 fell within the nuclear fraction, while the M(r) 58 kDa, pI5.8 was found among the cytosol and microsomal fractions. Microsequencing after in situ digestion of the dramatically reduced spot p50-5.3 revealed that it was identical to 50 kDa, type I keratin (K14). Moreover, a retinoic acid-mediated K14 reduction was concomitant with a 4.0-fold increase in cisplatin resistance in PC10. Our report is the first to suggest the possible association of marked K14 reduction and cisplatin resistance in PC10-B3 and PC10-E5.
Insights
Researchers identified a significant reduction in keratin 14 (K14) protein levels in cisplatin-resistant lung cancer cells. This K14 reduction is linked to increased resistance to cisplatin chemotherapy, offering new insights into drug resistance mechanisms.
Area of Science:
- Biochemistry
- Molecular Biology
- Oncology
Background:
- Cisplatin is a cornerstone chemotherapy agent for lung cancer.
- Mechanisms underlying cisplatin resistance in lung squamous carcinoma are not fully understood.
- Identifying specific protein alterations can elucidate resistance pathways.
Purpose of the Study:
- To investigate proteomic differences between cisplatin-sensitive and cisplatin-resistant human lung squamous carcinoma cell lines.
- To identify proteins associated with acquired cisplatin resistance.
- To explore the role of keratin 14 (K14) in cisplatin resistance.
Main Methods:
- Establishment of cisplatin-resistant cell lines (PC10-B3, PC10-E5) from a parental line (PC10).
- Comparative proteomic analysis using two-dimensional gel electrophoresis.
- Cellular fractionation to localize protein expression.
- Protein identification via microsequencing.
Main Results:
- A significant reduction in a 50 kDa, pI 5.3 protein (later identified as keratin 14, K14) was observed in resistant cell lines.
- An increase in a 50 kDa, pI 4.9 protein and the appearance of a 58 kDa, pI 5.8 protein were noted in resistant cells.
- K14 was localized to the nuclear fraction, while other altered proteins were found in cytosol and microsomal fractions.
- Retinoic acid treatment reduced K14 levels and increased cisplatin resistance 4-fold in PC10 cells.
Conclusions:
- Marked reduction of keratin 14 (K14) is associated with cisplatin resistance in human lung squamous carcinoma cells.
- This study provides the first evidence suggesting a link between K14 downregulation and cisplatin resistance.
- Further research into K14's role could reveal novel therapeutic targets for overcoming cisplatin resistance.