Epigenetic inactivation of laminin-5-encoding genes in lung cancers

Ubaradka G. Sathyanarayana, Shinichi Toyooka, Asha Padar, Takashi Takahashi, Elizabeth Brambilla, John D. Minna, Adi F. Gazdar

Research output: Contribution to journalArticlepeer-review

43 Citations (Scopus)


Purpose: We investigated the loss of expression of three laminin-5 (LN5)-encoding genes in lung cancer cell lines and elucidated the mechanism of inactivation of the genes in lung cancer cell lines and tumors. Experimental Design: We examined the expression of LN5-encoding genes by reverse transcription-PCR in 49 lung cancer cell lines. To elucidate the mechanism of gene silencing, we treated expression-negative cell lines (two for each gene) with a demethylating agent and examined the restoration of expression by reverse transcription-PCR. We dissected out the methylation patterns of CpG sites unique to the promoter regions of LN5-encoding genes by bisulfite genomic sequencing of expression-negative cell lines. We designed methylation-specific primers and validated the methylation status of the promoter regions in lung cancer cell lines using methylation-specific PCR. We further studied the methylation patterns of primary non-small cell lung cancer [NSCLC (n = 36)], small cell lung cancer [SCLC (n = 26)], and carcinoids (n = 24) tumors. Results: We observed frequent losses of expression in NSCLC (20-60%) and SCLC (65-86%) cell lines. Expression of one or more genes was lost in 90% of SCLC cell lines and 65% of NSCLC cell lines. Treatment of expression-negative cell lines with demethylating agent restored expression in all of the cases. Methylation of LN5-encoding genes was present more frequently in SCLC cell lines (60-80%) than in NSCLC cell lines (15-60%), and at least one gene was methylated in 95% of SCLC and 60% of NSCLC cell lines. The concordances between loss of expression and methylation in 40 lung cancer cell lines for the three genes (90-95%) were statistically significant. Methylation was more frequent in SCLC tumors (58-77%) than in NSCLC tumors (22-42%) and carcinoids (13-33%), and at least one gene was methylated in 92% of SCLC tumors, 47% of NSCLC tumors, and 33% of carcinoids. Conclusions: Our results demonstrate frequent epigenetic inactivation of LN5-encoding genes in lung cancers, and these findings are of biological interest and are potentially of clinical importance.

Original languageEnglish
Pages (from-to)2665-2672
Number of pages8
JournalClinical Cancer Research
Issue number7
Publication statusPublished - Jul 1 2003
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


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