Topoisomerase I, II alpha and II beta mRNA expression in peripheral blood mononuclear cells of patients with solid tumor: preliminary results.
BACKGROUND
The pyrimidine antimetabolite Gemcitabine (G) (2',2'-difluorodeoxycytidine) is used against several malignancies G exerts its antitumour effect mainly by incorporation of its triphosphate metabolite (dFdCTP) into DNA. Subsequently, DNA polymerase adds one additional deoxynucleotide and DNA synthesis is interrupted. The nuclear enzymes topoisomerase I and II (TPs) are critical for DNA function and cell survival; they control, maintain and modify DNA topology during both replication and translation of genetic materials. These enzymes induce cuts in one or both strands of DNA, allowing strands to pass through the nick and then rejoining the nicked strand of DNA. Anti-topoisomerase (TPs-inhibitors) drugs exist and are largely used in chemotherapy, however, most often blindly of the cancer TPs status.


OBJECTIVE
To understand the best association between G and TPs-inhibitors, we studied: (a) Topoisomerases I, II alpha and II beta mRNA expression in Peripheral Mononuclear Blood Cells (PBMCs) of patients with solid tumor, after 1, 2, 3, 4, 5, 6 h after treatment with Gemcitabine (G); b) in vivo expression of TPs genes after administration of Gemcitabine (a topoisomerases up-regulating drug) combined with the TPs inhibitors drugs (TID) Topotecan (T) and Etoposide (E), added to the culture beneath 1 h after TPD treatment. TPs mRNA expression was measured by quantitative real-time RT-PCR in PBMCs.


RESULTS
The administration of 1-h infused G is followed by a fast rise of TPs expression (P > 0.0001 Student's t test, paired data, each patient control of himself); TPs inhibitors, sequentially given after G, highly reduced the TPs rising (P > 0.0001).


CONCLUSIONS
G induces a TPs increase. A rationale might be available for combination chemotherapy (G plus TPs inhibitors). The study is ongoing to enroll further patients.
Cartei
G
G
UOC Medical Oncology, 1 Floor, National Cancer Institute IOV-IRCSS, University of Padova, Padova, Italy.
Trestin
A
A
Colombrino
E
E
Nadai
M
M
Richter
S N
SN
Barzon
L
L
Palù
G
G
Palumbo
M
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000235:genetics* / Q000378:metabolism; D000964:Antimetabolites, Antineoplastic / Q000008:administration & dosage / Q000494:pharmacology; D004264:DNA Topoisomerases, Type I / Q000235:genetics* / Q000378:metabolism; D004250:DNA Topoisomerases, Type II / Q000235:genetics* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D003841:Deoxycytidine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000008:administration & dosage; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007963:Leukocytes, Mononuclear / Q000378:metabolism; D008875:Middle Aged; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D000093542:Gemcitabine
D000951:Antigens, Neoplasm; D000964:Antimetabolites, Antineoplastic; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D059004:Topoisomerase I Inhibitors; D059005:Topoisomerase II Inhibitors; D003841:Deoxycytidine; D004264:DNA Topoisomerases, Type I; D004250:DNA Topoisomerases, Type II; D000093542:Gemcitabine