hnRNP A2/B1 has been suggested as a useful early detection marker for lung
carcinoma.
hnRNP A2/B1 is a member of a large family of
heterogeneous nuclear ribonucleoproteins (
hnRNP proteins) involved in a variety of functions, including regulation of transcription,
mRNA metabolism, and translation. In
lung cancer, we have evaluated the expression and cellular localization of several members of the
hnRNP family,
hnRNP A1, A2, B1, C1, C2 and K. 16 cell lines (SCLC and NSCLC) and biopsies from 32
lung cancer patients were analyzed. Our results suggest that, besides
hnRNP A2/B1, the expression of other members of the
hnRNP family is altered both in SCLC and NSCLC. In the biopsies, negative or low expression of the
hnRNP proteins analyzed was observed in normal epithelial cells whereas
lung cancer cells showed highly intense nuclear or cytoplasmic immunolocalization. In all the
lung cancer cell lines, the
mRNA for all the
hnRNP proteins was detected. In general, higher levels of
hnRNP mRNAs were found in SCLC as compared with NSCLC. Our results also suggest that the expression and processing of each
hnRNP protein in
lung cancer is independently regulated and is not exclusively related to proliferation status. In SCLC cell lines,
hnRNP A1 protein expression correlated with that of Bcl-x(L). In the
lung cancer cell lines,
hnRNP K protein localization varied with the cellular confluence.