Post-transcriptional regulation of P-glycoprotein expression in cancer cell lines.
The present study of inhibitors shows that the histone deacetylase-induced increase in P-glycoprotein (Pgp) mRNA (MDR1 mRNA) does not parallel either an increase in Pgp protein or an increase in Pgp activity in several colon carcinoma cell lines. Furthermore, studying the polysome profile distribution, we show a translational control of Pgp in these cell lines. In addition, we show that the MDR1 mRNA produced in these cell lines is shorter in its 5' end that the MDR1 mRNA produced in the MCF-7/Adr (human breast carcinoma) and K562/Adr (human erythroleukemia) cell lines, both of them expressing Pgp. The different size of the MDR1 mRNA is due to the use of alternative promoters. Our data suggest that the translational blockade of MDR1 mRNA in the colon carcinoma cell lines and in wild-type K562 cells could be overcome by alterations in the 5' end of the MDR1 mRNA in the resistant variant of these cell lines, as in the case of the K562/Adr cell line. This is, to our knowledge, the first report demonstrating that the presence of an additional 5' untranslated fragment in the MDR1 mRNA improves the translational efficiency of this mRNA.
Gómez-Martínez
Angeles
A
Instituto de Biología Molecular y Celular, Ed. Torregaitan, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain.
García-Morales
Pilar
P
Carrato
Alfredo
A
Castro-Galache
María D
MD
Soto
José L
JL
Carrasco-García
Estefanía
E
García-Bautista
Miriam
M
Guaraz
Patricia
P
Ferragut
José A
JA
Saceda
Miguel
M
D020121:5' Untranslated Regions; D018435:ATP Binding Cassette Transporter, Subfamily B / Q000096:biosynthesis*; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic; D056572:Histone Deacetylase Inhibitors; D006801:Humans; D020014:K562 Cells; D008957:Models, Genetic; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism
D020121:5' Untranslated Regions; D018435:ATP Binding Cassette Transporter, Subfamily B; D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D004791:Enzyme Inhibitors; D056572:Histone Deacetylase Inhibitors; D012333:RNA, Messenger