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Modulation of cellular chemoresistance in keratinocytes by activation of different oncogenes
R Sanchez-Prieto1, J A Vargas, A Carnero
1Department of Pathology, Clínica Puerta de Hierro, Universidad Autónoma de Madrid, Spain.
Abstract:
Response to chemotherapeutic agents in malignant tumors depends on many factors, most of which are as yet unknown. We investigated the correlation between the activation of different oncogenes and protein-kinase-C (PKC) modulation, and the cytotoxicity of some of the most widely used anti-cancer drugs. We transformed the murine keratinocyte cell line PAM 212, with different oncogenes (v-H-ras, v-myc and adenovirus E1a) and a mutant p53 suppressor gene (mp53). The cytotoxic effect of cisplatin (CDDP), doxorubicin (DOX) and vincristine (VCR), together with the concomitant action of modulators of PKC, TPA and staurosporine were evaluated by the crystal-violet method, thymidine incorporation and flow cytometry. We report that (a) the oncogene v-H-ras induces resistance to CDDP (> 50%), DOX (> 25%) and VCR (> 20%); (b) the E1a oncogene induces only resistance to VCR (> 40%) and marked sensitivity to CDDP and DOX; (c) the mp53 oncogene induces more resistance to VCR and insignificant resistance to the other drugs; and (d) activation of PKC by TPA increases the resistance to VCR and DOX in cells transformed by the v-H-ras, while it significantly increases the lethality with CDDP of the E1a-transformed cells. Staurosporine increases the cytoxicity of all the drugs, especially in the E1a-transformed keratinocytes. In the flow-cytometry analysis, the percentage of BUdR incorporation was related to sensitivity to anti-cancer drugs.
Insights
Oncogene activation significantly impacts cancer drug response. Certain oncogenes like v-H-ras confer resistance, while others, like E1a, increase sensitivity to chemotherapy, influencing treatment outcomes.
Area of Science:
- Oncology
- Molecular Biology
- Cancer Research
Background:
- Chemotherapeutic drug response in tumors is complex and not fully understood.
- Investigating oncogene activation and protein-kinase-C (PKC) modulation is crucial for understanding drug resistance.
Purpose of the Study:
- To explore the relationship between oncogene activation (v-H-ras, v-myc, adenovirus E1a, mp53) and protein-kinase-C (PKC) modulation on the cytotoxicity of cisplatin (CDDP), doxorubicin (DOX), and vincristine (VCR).
Main Methods:
- Murine keratinocyte cell line (PAM 212) was transformed with oncogenes and a mutant p53 suppressor gene.
- Cytotoxicity was assessed using crystal-violet, thymidine incorporation, and flow cytometry.
- Effects of PKC modulators (TPA, staurosporine) were evaluated concurrently.
Main Results:
- v-H-ras oncogene induced resistance to CDDP, DOX, and VCR.
- E1a oncogene conferred VCR resistance but increased sensitivity to CDDP and DOX.
- mp53 oncogene primarily increased VCR resistance.
- PKC activation by TPA modulated drug resistance/sensitivity differently based on the oncogene.
- Staurosporine generally enhanced drug cytotoxicity, particularly in E1a-transformed cells.
Conclusions:
- Oncogene activation profoundly influences cellular response to common chemotherapeutic agents.
- Targeting PKC pathways presents a potential strategy for overcoming drug resistance or enhancing drug efficacy.
- Further research into oncogene-PKC interactions is vital for personalized cancer therapy.