Epigenetic inactivation of RASSF1A in lung and breast cancers and malignant phenotype suppression

David G. Burbee, Eva Forgacs, Sabine Zöchbauer-Müller, Latha Shivakumar, Kwun Fong, Boning Gao, Dwight Randle, Masashi Kondo, Arvind Virmani, Scott Bader, Yoshitaka Sekido, Farida Latif, Sara Milchgrub, Shinichi Toyooka, Adi F. Gazdar, Michael I. Lerman, Eugene Zabarovsky, Michael White, John D. Minna

Research output: Contribution to journalArticlepeer-review

732 Citations (Scopus)


Background: The recently identified RASSF1 locus is located within a 120-kilobase region of chromosome 3p21.3 that frequently undergoes allele loss in lung and breast cancers. We explored the hypothesis that RASSF1 encodes a tumor suppressor gene for lung and breast cancers. Methods: We assessed expression of two RASSF1 gene products, RASSF1A and RASSF1C, and the methylation status of their respective promoters in 27 non-small-cell lung cancer (NSCLC) cell lines, in 107 resected NSCLCs, in 47 small-cell lung cancer (SCLC) cell lines, in 22 breast cancer cell lines, in 39 resected breast cancers, in 104 nonmalignant lung samples, and in three breast and lung epithelial cultures. We also transfected a lung cancer cell line that lacks RASSF1A expression with vectors containing RASSF1A complementary DNA to determine whether exogenous expression of RASSF1A would affect in vitro growth and in vivo tumorigenicity of this cell line. All statistical tests were two-sided. Results: RASSF1A messenger RNA was expressed in nonmalignant epithelial cultures but not in 100% of the SCLC, in 65% of the NSCLC, or in 60% of the breast cancer lines. By contrast, RASSF1C was expressed in all nonmalignant cell cultures and in nearly all cancer cell lines. RASSF1A promoter hypermethylation was detected in 100% of SCLC, in 63% of NSCLC, in 64% of breast cancer lines, in 30% of primary NSCLCs, and in 49% of primary breast tumors but in none of the nonmalignant lung tissues. RASSF1A promoter hypermethylation in resected NSCLCs was associated with impaired patient survival (P = .046). Exogenous expression of RASSF1A in a cell line lacking expression decreased in vitro colony formation and in vivo tumorigenicity. Conclusion: RASSF1A is a potential tumor suppressor gene that undergoes epigenetic inactivation in lung and breast cancers through hypermethylation of its promoter region.

Original languageEnglish
Pages (from-to)691-699
Number of pages9
JournalJournal of the National Cancer Institute
Issue number9
Publication statusPublished - 02-05-2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


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