Journal
MOLECULAR CANCER THERAPEUTICS
Volume 4, Issue 7, Pages 1096-1104Publisher
AMER ASSOC CANCER RESEARCH
DOI: 10.1158/1535-7163.MCT-05-0081
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Funding
- NCI NIH HHS [P30 CA046592, CA83087, P30 CA46592, P50 CA97248, P50 CA097248] Funding Source: Medline
- NIDCD NIH HHS [P30 DC005188, P30 DC05188, T32 DC00011] Funding Source: Medline
- NIDCR NIH HHS [DE13346] Funding Source: Medline
- NIGMS NIH HHS [GM07767] Funding Source: Medline
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Organ preservation protocols in head and neck squamous cell carcinoma (HNSCC) are limited by tumors that fail to respond. We observed that larynx preservation and response to chemotherapy is significantly associated with p53 overexpression, and that most HNSCC cell lines with mutant p53 are more sensitive to cisplatin than those with wild-type p53. To investigate cisplatin resistance, we studied two HNSCC cell lines, UM-SCC-5 and UM-SCC-10B, and two resistant sublines developed by cultivation in gradually increasing concentrations of cisplatin. The cisplatin-selected cell lines, UM-SCC-5PT and UM-SCC-10BPT, are 8 and 1.5 times more resistant to cisplatin than the respective parental cell lines, respectively. The parental lines overexpress p53 and contain p53 mutations but the cisplatin-resistant cell lines do not, indicating that cells containing mutant p53 were eliminated during selection. Bcl-x(L) expression increased in the cisplatin-resistant lines relative to the parental lines, whereas Bcl-2 expression was high in the parental lines and decreased in the cisplatin-resistant lines. Thus, cisplatin selected for wild-type p53 and high Bcl-x(L) expression in these cells. We tested a small-molecule BH3 mimetic, (-)-gossypol, which binds to the BH3 domain of Bcl-2 and Bcl-x(L), for activity against the parental and cisplatin-resistant cell lines. At physiologically attainable levels, (-)-gossypol induces apoptosis in 70% to 80% of the cisplatin-resistant cells but only in 25% to 40% of the parental cells. Thus, cisplatin-resistant cells seem to depend on wild-type p53 and Bcl-x(L) for survival and BH3 mimetic agents, such as (-)-gossypol, may be useful adjuncts to overcome cisplatin resistance in HNSCC.
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