MEMBRANE-BOUND (MUC1) AND SECRETORY (MUC2, MUC3, AND MUC4) MUCIN GENE-EXPRESSION IN HUMAN LUNG-CANCER

Abnormalities of mucin-type glycoproteins have been described in lung cancers, but their molecular basis is unknown. In this study, mucin-co re-peptide-specific antibodies and cDNA probes were used to determine the relative expression of mucin genes corresponding to one membrane-b ound mucin (MUC1), two intestinal mucins (MUC2 and MUC3), and one trac heobronchial mucin (MUC4) in normal (nonneoplastic) lung, and in lung neoplasms. Normal lung tissues exhibited a distinct pattern of mucin g ene expression, with high levels of MUC1 and MUC4 mRNA and low to abse nt levels of MUC2 and MUC3 mucin immunoreactivity and mRNA. In contras t, lung adenocarcinomas, especially well-differentiated cancers, exhib ited increased MUC1, MUC3, and MUC4 mRNA levels. Lung squamous-cell, a denosquamous, and large-cell carcinomas were characterized by increase d levels of MUC4 mucin only. We conclude that the expression of one me mbrane-bound and several secretory-type mucins is independently regula ted and markedly altered in lung neoplasms. The frequent occurrence of increased MUC4 transcripts in a variety of non-small-cell lung cancer s indicates the potential importance of this type of mucin in lung can cer biology.