+ Resolve Article
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter

+ Translate
+ Subscribe to Site Feed
GeoScience Most Shared ContentMost Shared Content

A novel mutant topoisomerase II-alpha present in VP-16-resistant human melanoma cell lines has a deletion of alanine 429

, : A novel mutant topoisomerase II-alpha present in VP-16-resistant human melanoma cell lines has a deletion of alanine 429. Biochemistry. 33(37): 11327-11332

The human melanoma cell line FEM-X was selected in multiple steps with VP-16 (etoposide) and an inhibitor of P-glycoprotein (Campain et al., 1993). The resulting clones, FVP1b and FVP3, are highly resistant to the nonintercalative epipodophyllotoxins and exhibit moderate levels of resistance to doxorubicin. The topoisomerase II activity present in crude nuclear extracts from mutant and wild-type cells is similar in amount and equally sensitive to VP-16. However, in live cells, the topoisomerase II from FVP lb and FVP3 is much less susceptible to drug-induced cleavable complex formation than is that from FEM-X. Using reverse transcription followed by the polymerase chain reaction (RT-PCR), we have cloned and sequenced the entire cDNA for topoisomerase II-alpha from FEM-X and FVP3. The only sequence change unique to the cDNA from drug-resistant cells is a 3 hp deletion of nucleotide 1320-1322, resulting in a deletion of Ala429. Three FEM-X sublines of increasing resistance were tested, and the prevalence of the mutant RNA over wild-type increases in these cells in parallel with their resistance to VP-16. In FVP3, the most highly resistant line, expression of the wild-type allele is barely detectable. Analysis of genomic DNA shows that FEM-X is homozygous for the wild-type topoisomerase II-alpha sequence and that each of the drug-resistant clones possesses both wild-type and mutant alleles. Although not definitive, these genetic results suggest that the deletion of Ala429 from topoisomerase II-alpha makes the enzyme less susceptible to drug-induced cleavable complex formation and confers a growth advantage upon cells in the presence of VP-16. Since topoisomerase II-alpha activity in extracts from these drug-resistant FEM-X lines is normally sensitive to drugs, the deletion of an Ala at residue 429 may alter intracellular localization of the enzyme or change its interaction with other factors, which could then decrease the DNA-topoisomerase II-alpha complexes trapped in the presence of VP-16. However, proof that the mutant topoisomerase II-alpha is responsible for drug resistance requires its successful expression in drug-sensitive cells.


PMID: 7727383

DOI: 10.1021/bi00203a030

Other references

Ranatunge, A.S.; Farrington, J.; Abeysekera, W.A.T., 1981: Some issues confronting the rehabilitation of major irrigation schemes -- a report arising from pre-investment surveys of conditions at the Tank Irrigation Modernization Project Five Tanks. The paper draws together some of the main agrarian themes emerging from a base line study of the Tank Irrigation Modernization Project in Sri Lanka. Issues are highlighted in terms of their benefits and for their broader significance in dry zone a...

Pinhas Hamiel, O.; Alfaro, M.P.t; Staniford, D.; Dolan, L.M.; Zeitler, P., 1998: Risk factors for diabetes among family members of adolescents with type 2 diabetes. Pediatric Research 43(4 PART 2): 5A, April

Huynh Thi Kim Hoi,.; Nguyen Duc Anh,, 2003: Gop phan nghien cuu giun dat va cac nhom mesofauna khac o dat doi rung Bang ta, Ba vi, Ha tay. A total of 12 earthworm species belonging to 5 genera, 4 families, have been firstly recorded in Bangta hilly area, Camlinh village, Bavi district, Hatay province. Among them, the genus Pheretima with the highest number of species (8 species) acco...

Hersteinsson P., 1989: Population genetics and ecology of different color morphs of arctic foxes alopex lagopus in iceland. Both the white and the blue colour morphs of arctic foxes occur in Iceland. The blue morph is more common, constituting almost one-third of the population. There is considerable variation in the distribution frequency of the two phenotypes, the pr...

Hösl, M.; Berneburg, M., 2008: Vitamin D and the skin. Along with other organs like prostate, bones and kidney, skin is capable of vitamin D synthesis. Primarily keratinocytes but also macrophages and fibroblasts synthesize active vitamin D from cholesterol precursors by photochemical activation. The...

Soliman K.F.A.; Kolta M.G.; Okonmah A.D., 1980: Epinephrine stimulates cortico sterone synthesis and release in the regenerating adrenal gland in vitro. Federation Proceedings 39(3): ABSTRACT 4231

Miller, J.M.; Ashton Miller, J.A.; Delancey, J.O.L., 1998: Quantification of cough-related urine loss using the paper towel test. Objective: To develop and test a simple and rapid method for quantifying the urine loss resulting from three deep coughs using an ordinary brown paper towel. Methods: A brown paper towel is held lightly against the perineum during three single cou...

Srivastava, S.; Singh, N., 2011: The probability analysis of opening of DNA. We have studied the separation of a double stranded DNA (dsDNA), which is driven by either the temperature or force. By monitoring the probability of opening of entire base pairs along the chain, we show that the opening of a dsDNA depends not onl...

Ishunin, GI.; Ishadov, NI., 1976: Distribution and habitat of the central Asian otter in the Amudarya Basin. Uzbekskii Biologicheskii Zhurnal, 1: 52-54

Borsetti, AM.; Loik, L.; Colantoni, P., 1986: Variazioni nella sedimentazione al passaggio glaciale-postglaciale e olocene in alcuni bacini nord-Tirrenici evidenziate dal contenuto microfaunistico. Memorie della Societa Geologica Italiana. 1984 ; 27: 323-332