title: Comparison of beta-tubulin mRNA and protein levels in 12 human cancer cell lines.
abstract: Antimitotic drugs are chemotherapeutic agents that bind tubulin and microtubules. Resistance to these drugs is a major clinical problem. One hypothesis is that the cellular composition of tubulin isotypes may predict the sensitivity of a tumor to antimitotics. Reliable and sensitive methods for measuring tubulin isotype levels in cells and tissues are needed to address this hypothesis. Quantitative measurements of tubulin isotypes have frequently relied upon inferring protein amounts from mRNA levels. To determine whether this approach is justified, protein and mRNA levels of beta-tubulin isotypes from 12 human cancer cell lines were measured. This work focused on only beta-tubulin isotypes because we had readily available monoclonal antibodies for quantitative immunoblots. The percentage of beta-tubulin isotype classes I, II, III, and IVa + IVb mRNA and protein were compared. For beta-tubulin class I that comprises >50% of the beta-tubulin protein in 10 of the 12 cell lines, there was good agreement between mRNA and protein percentages. Agreement between mRNA and protein was also found for beta-tubulin class III. For beta-tubulin classes IVa + IVb, we observed higher protein levels compared to mRNA levels.Beta-tubulin class II protein was found in only four cell lines and in very low abundance. We conclude that quantitative Western blotting is a reliable method for measuring tubulin isotype levels in human cancer cell lines. Inferring protein amounts from mRNA levels should be done with caution, since the correspondence is not one-to-one for all tubulin isotypes.
authors.affiliation: School of Nursing, University of Mississippi Medical Center, Jackson, MS 39216, USA.
authors.forename: Laree
authors.initials: L
authors.lastname: Hiser
authors.forename: Ashish
authors.initials: A
authors.lastname: Aggarwal
authors.forename: Rebekah
authors.initials: R
authors.lastname: Young
authors.forename: Anthony
authors.initials: A
authors.lastname: Frankfurter
authors.forename: Anthony
authors.initials: A
authors.lastname: Spano
authors.forename: John J
authors.initials: JJ
authors.lastname: Correia
authors.forename: Sharon
authors.initials: S
authors.lastname: Lobert
mesh_terms: D000595:Amino Acid Sequence; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects*; D006801:Humans; D015151:Immunoblotting / Q000379:methods; D008969:Molecular Sequence Data; D017239:Paclitaxel / Q000494:pharmacology*; D020033:Protein Isoforms / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D014404:Tubulin / Q000378:metabolism*; D014747:Vinblastine / Q000494:pharmacology*
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D014404:Tubulin; D014747:Vinblastine; D017239:Paclitaxel