title: DNA damage and repair in peripheral blood lymphocytes from healthy individuals and cancer patients: a pilot study on the implications in the clinical response to chemotherapy.
abstract: Drug resistance is considered the main impediment to successful cancer chemotherapy. The quest for a method useful to predict individual responses to chemotherapy prior to treatment is highly desired. This study was designed to determine the individual influences of doxorubicin and cisplatin on the degree of DNA damage, DNA repair and hMSH2 and the hMLH1 protein expression in peripheral blood lymphocytes (PBL) and their correlations with the clinical response. PBL were obtained from 25 cancer patients (pre- and post-chemotherapy) and from 10 healthy persons, cultured and exposed to doxorubicin or cisplatin. Cells were collected at T0 (immediately after drug treatment) and 24h after damage (T24). The alkaline comet assay was employed to assess the DNA damage and repair function, and immunocytochemistry to study hMLH1 and hMSH2 expression. Clinical response was evaluated after three cycles of chemotherapy. Pre-chemotherapy PBL from cancer patients showed significantly higher levels of basal DNA damage than healthy persons, with appreciable interindividual variations between them. The in vivo administration of antineoplasic drugs was accompanied by significant DNA damage, and an increased in the number of apoptotic cells. Cancer patients with complete response showed a high number of apoptotic cells. The DNA migration increased at T0 and at T24 in cisplatin-treated patients, reflecting a decreased rate of cisplatin adducts repair than that observed in healthy individuals. The ability to repair DNA lesions in doxorubicin-damaged cells was very similar between healthy individuals and cancer patients. Cisplatin-treated patients that died by the disease showed lower DNA migration than the mean value. The expression of hMLH1 and hMSH2 was practically identical between healthy individuals and cancer patients. Nevertheless, chemotherapy induced a depletion mostly of hMLH1. In 83% of cisplatin-treated patients with CR the hMLH1 and hMSH2 expression at T24 was higher than the mean. In this pilot study the alkaline comet assay offered information about the amount of DNA damage and the DNA repair status in PBL from individual patients and this seems useful in predicting the response to chemotherapy.
authors.affiliation: Oncology Laboratory, Institute of Experimental Medicine and Biology of Cuyo, Regional Center for Scientific and Technological Research, C.C.855, C.P. 5500 Mendoza, Argentina.
authors.forename: Silvina Beatriz
authors.initials: SB
authors.lastname: Nadin
authors.forename: Laura M
authors.initials: LM
authors.lastname: Vargas-Roig
authors.forename: Gisela
authors.initials: G
authors.lastname: Drago
authors.forename: Jorge
authors.initials: J
authors.lastname: Ibarra
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Ciocca
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D002352:Carrier Proteins / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D002945:Cisplatin / Q000494:pharmacology; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects*; D004260:DNA Repair / Q000187:drug effects*; D004317:Doxorubicin / Q000494:pharmacology; D005260:Female; D006801:Humans; D007223:Infant; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein / Q000378:metabolism; D009369:Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010865:Pilot Projects
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000903:Antibiotics, Antineoplastic; D000970:Antineoplastic Agents; D002352:Carrier Proteins; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D004317:Doxorubicin; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D002945:Cisplatin