Relative amounts of antagonistic splicing factors, hnRNP A1 and ASF/SF2, change during neoplastic lung growth: implications for pre-mRNA processing.
Pre-mRNA processing is an important mechanism for globally modifying cellular protein composition during tumorigenesis. To understand this process during lung cancer, expression of two key pre-mRNA alternative splicing factors was compared in a mouse model of early lung carcinogenesis and during regenerative growth following reversible lung injury. Heterogeneous nuclear ribonucleoprotein (hnRNP) A1 and alternative splicing factor/splicing factor 2 (ASF/SF2) act antagonistically to modulate splice site selection. Both hnRNP A1 and ASF/SF2 contents rose in adenomas and during injury-induced hyperplasia compared to control lungs, as measured by immunoblotting. While both proteins increased similarly during compensatory hyperplasia, hnRNP A1 increased to a much greater extent than ASF/SF2 in tumors, resulting in a 6-fold increase of the hnRNP A1 to ASF/SF2 ratio. Immunohistochemical analysis showed that hnRNP A1 localized exclusively within tumor nuclei, while ASF/SF2 appeared in cytoplasm and/or nuclei, depending on the growth pattern of the tumor cells. We also demonstrated cancer-associated changes in the pre-mRNA alternative splicing of CD44, a membrane glycoprotein involved in cell-cell and cell-extracellular matrix interactions. hnRNP A1 and ASF/SF2 expression is thus differentially altered in neoplastic lung cells by mechanisms that do not strictly arise from increased cell division. These changes are influenced by tumor histology and may be associated with production of variant CD44 mRNA isoforms.
Zerbe
Laura K
LK
Department of Pharmaceutical Sciences, University of Colorado Health Sciences Center, Denver, Colorado 802262, USA.
Pino
Irene
I
Pio
Ruben
R
Cosper
Pippa F
PF
Dwyer-Nield
Lori D
LD
Meyer
Amy M
AM
Port
J David
JD
Montuenga
Luis M
LM
Malkinson
Alvin M
AM
D017398:Alternative Splicing / Q000235:genetics; D000818:Animals; D002084:Butylated Hydroxytoluene / Q000494:pharmacology; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced; D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B / Q000378:metabolism*; D018960:Hyaluronan Receptors / Q000235:genetics; D006965:Hyperplasia / Q000139:chemically induced / Q000378:metabolism; D008175:Lung Neoplasms / Q000139:chemically induced / Q000235:genetics* / Q000473:pathology*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009367:Neoplasm Staging; D020033:Protein Isoforms / Q000235:genetics; D021381:Protein Transport; D012322:RNA Precursors / Q000235:genetics / Q000378:metabolism*; D012326:RNA Splicing / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000378:metabolism*; D000068103:Serine-Arginine Splicing Factors
D000076245:Heterogeneous Nuclear Ribonucleoprotein A1; D034481:Heterogeneous-Nuclear Ribonucleoprotein Group A-B; D018960:Hyaluronan Receptors; D020033:Protein Isoforms; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; C494908:Srsf1 protein, mouse; D000068103:Serine-Arginine Splicing Factors; D002084:Butylated Hydroxytoluene