Affiliations: Institute of Biochemistry, Polytechnic University of
the Marche, Ancona, Italy
Note: [] Adress for correspondence: Francesca Bruge, Institute of
Biochemistry, Polytechnic University of the Marche, 60121 Ancona, Italy.
E-mail: [email protected]
Abstract: Two-electron reduction of quinones catalyzed by NAD(P)H:quinone
oxidoreductase (NQO1) protects cells against oxidative stress and toxic
quinones. In fact, low level of NQO1 activity is often associated with
increased risk of developing different types of tumours and with toxic effects
linked to environmental quinones. In a previous report we analyzed the
relationship between the oxidative stress induced by UV radiation and
CoQ_{10} content in Burkitt's lymphoma cell lines compared
to HL-60. The basal content of CoQ_{10} in Raji cells was
slightly higher compared to HL-60. Moreover, after irradiation or ubiquinone
supplementation in the medium, reduced CoQ_{10} levels were
higher in Raji and Daudi cells compared to HL-60. In the present work, in order
to inquire if NQO1 plays a role in the CoQ reducing capacity observed in the
lymphoblastoid cell lines, we analyzed the transcription and translation
products of this gene in Raji and Daudi cells, compared to cell lines
possessing low and high NQO1 activity. The amount of transcripts of this gene in lymphoblastoid cells was
comparable to that observed in HL-60 cells (low activity), as well as the level
of two alternatively spliced mRNAs; one of which is described for the first
time in this work. From the genotype analysis of polymorphisms C609T and C465T
we observed that HL-60, Raji and Daudi cells were all heterozygous.
Furthermore, NQO1 enzyme activity and protein synthesis in the cytosol of Raji
and Daudi cells were undetectable. Therefore in Burkitt's lymphoma cell lines
the NQO1 gene is not efficiently translated and this effect is not related to
(C609T) polymorphism. Further studies will be necessary to find the enzyme
responsible for CoQ_{10} reducing activity observed in
lymphoma cell lines. On the other hand, this result suggests a careful
re-evaluation of data concerning loss of NQO1 activity and polymorphisms in
tumour cells.
Keywords: Burkitt's lymphoma, coenzyme Q oxidoreductase, polymorphism, alternative splicing
Journal: BioFactors, vol. 32, no. 1-4, pp. 71-81, 2008
