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PubMed1985

Gonadal toxicity after combination chemotherapy for Hodgkin's disease. Comparative results of MOPP vs ABVD.

The comparative gonadal toxicity following two equally effective and non-cross-resistant regimens (MOPP and ABVD) was prospectively evaluated in 53 males with Hodgkin's disease. The median age was 29 yr (range 16-45). MOPP produced azoospermia in 28/29 patients (97%) while ABVD induced oligoazoospermia in 13/24 patients (54%). Follicle-stimulating hormone levels were consistently and significantly increased after MOPP while their median value remained within normal range after ABVD. Sperm count was repeated in 34 patients. Recovery of spermatogenesis occurred in 3/21 cases treated with MOPP and in all 13 cases given ABVD. Present findings confirm that the two alkylating agents, mechlorethamine and procarbazine, included in the MOPP regimen cause sterility in most patients while the drugs included in ABVD are not associated with permanent gonadal dysfunction.

Adolescent↗
PubMed1983

Combined moderate dose electron beam radiotherapy and topical chemotherapy for cutaneous T-Cell lymphoma.

Between October, 1978 and June, 1979, nine patients with biopsy-proven cutaneous T-Cell lymphoma were treated with combined total-skin electron beam radiation (TSEB) and topical chemotherapy. TSEB was administered using 3.8 MeV electron and dual exposure technique. All patients received skin dose of 400 rad once weekly to a total dose of 2000 to 2400 rad followed by topical chemotherapy with mechlorethamine hydrochloride (HN2) two to four weeks after completion of radiation. A complete response followed TSEB in seven of nine patients, but a relapse of disease activity has subsequently occurred within the first year for all the patients despite adjunct therapy, except for one patient who remains disease free for more than 21 months. Generalized severe erythema developed during or shortly after completion of radiation in six of nine patients, with blistering at the overlapping treatment fields and body folds in four patients. In addition four patients developed diffuse permanent telangiectasia of skin and one patient developed linear sclerosis, telangiectasis and painful ischemic ulceration on the fingertips two years after completion of electron beam therapy. Most patients had evidence of mild depression of lymphocyte responsiveness to Phytohemagglutinin after TSEB. Our conclusion is that the short-term benefits and convenience of this particular technique do not justify the acute and chronic toxicity encountered.

Administration, Topical↗
PubMed1989

Total lymphoid irradiation, high-dose chemotherapy and autologous bone marrow transplantation for chemotherapy-resistant Hodgkin's disease.

Seventeen patients with advanced stage Hodgkin's disease who relapsed or failed to respond to multiple regimens of combination chemotherapy (mostly Mechlorethamine, Vincristine, Procarbarzine, Prednisone and Adriamycin, Bleomycin, Vinblastine, Dacarbazine) were treated with accelerated hyperfractionated total lymphoid irradiation (TLI) and high-dose chemotherapy followed by autologous bone marrow transplantation (AuBMT). Candidates for the protocol did not have prior radiation therapy and had no evidence of bone marrow involvement. Their bone marrow was initially harvested and cryopreserved. The treatment protocol consisted of reinduction with conventional doses of combination chemotherapy followed by boost local field irradiation to areas of residual disease (1500 cGy within 5 days) and total lymphoid irradiation (2004 cGy given in 12 fractions of 167 cGy each t.i.d. delivered within 4 days). The patients were treated with Etoposide (250 mg/m2/day I.V. X 3 days) and high-dose Cyclophosphamide (60 mg/kg/day I.V. X 2 days). Cryopreserved (unpurged) autologous bone marrow was infused 48 hr after completion of chemotherapy. Of the 17 patients treated, four were in relapse and 13 refractory to multiple regimens of combination chemotherapy. Four patients died during the immediate peritransplant period (2--septicemia, 2--pulmonary complications). Of the 13 surviving patients, 12 entered a complete remission and one had a partial remission and died of disease 6 months later. One patient relapsed 5 months after treatment and is currently alive with disease. Eleven patients (65%) are alive with no evidence of disease 4-35 months (median 20 months) following completion of therapy. Treatment with this protocol results in a high rate of complete remission and a potential for long-term disease-free survival in previously unirradiated patients with advanced stage refractory or relapsed Hodgkin's disease who have exhausted conventional modes of chemotherapy.

Adult↗
PubMed1993

Combined chemotherapy-radiotherapy in advanced Hodgkin's disease: results of a prospective clinical trial with 70 stage IIIB-IV patients.

PURPOSE: To evaluate two regimens of chemotherapy followed by high dose total or subtotal nodal irradiation in advanced Stages of Hodgkin's disease. METHODS AND MATERIALS: From October 1980 to September 1985, 70 patients with Hodgkin's disease, with clinical Stages IIIB (35 cases) and IV (35 cases) were treated with combined modality therapy. Patients were randomly assigned to receive four cycles of chemotherapy, mechlorethamine, vincristine, procarbazine and prednisone (MOPP) versus the same regimen alternating with adriamycin, bleomycin, vinblastine and dacarbazine, ABVD-derived regimen, followed by high-dose (40 Gy) total or subtotal nodal irradiation. Because of partial response, 13 patients (18.5%) got additional chemotherapy (1-4 cycles). RESULTS: After chemotherapy, 49 patients (70%) achieved complete remission or good partial response and 15 patients (21.5%) partial response. Five primary failures (7%) and one death (1.5%) occurred. After combined modality therapy, 59 patients (84%) achieved complete remission, one patient partial response (1.5%) and eight patients (11.5%) failed to primary treatment. Two toxic deaths (3%) were observed during initial treatment. There was no significant difference in response rates between MOPP/radiotherapy and MOPP/ABVD/radiotherapy. Nine patients relapsed (15%). A total of 21 patients died, 13 because of Hodgkin's disease and eight from other causes. High dose total or subtotal nodal irradiation following four courses of chemotherapy was feasible, although hematological toxicity grade > or = 2 (World Health Organization) was observed in one-third of the patients, particularly in patients aged over 40. The median duration of follow-up was 75 months. Actuarial survival curves indicate a 8 years disease-free survival and survival of 70% and 65% respectively, without any significant difference between the two regimens. Because of hematological toxicity, the percentage of planned full treatment was lower in MOPP/radiotherapy regimen. CONCLUSION: These results lead to recommend the alternating regimen. Patients restaged as poor responders after initial chemotherapy did not survive for long. More intensive treatment is now proposed for this subgroup of patients.

Adolescent↗
PubMed1992

Early stage Hodgkin's disease: ten-year results of a non-randomised study with radiotherapy alone or combined with MOPP.

From September 1976 to June 1982, 201 consecutive patients with stage I (A and B)-IIA Hodgkin's disease were stratified in two groups according to prognostic factors. The F group included 116 patients with favourable presentation: they were staged with laparotomy and treated with subtotal or total nodal radiotherapy alone. The U group included 85 cases with unfavourable presentation who were staged by laparoscopy and treated with 3MOPP (mechlorethamine, vincristine, procarbazine, prednisone)-radiotherapy-3MOPP. At 10 years the F group showed a freedom from progression (FFP) of 71% with significant difference between stage I and II (85% vs. 59%; P = 0.003) and an overall survival of 84%. The results of the U group were: FFP 83%, overall survival 74%, and the findings were not influenced by stage. FFP in patients with bulky vs. not bulky lymphoma was 70% vs. 87% (P = 0.04). No secondary acute non-lymphocytic leukaemia developed among patients treated with radiotherapy and in continuous complete remission, while acute leukaemia occurred in the F group patients who received salvage chemotherapy (4 of 31 cases) and in the U group (3 of 85 cases). Present results confirm the usefulness of radiotherapy alone in favourable pathological stage IA. All other disease stages will require a different strategy that should consist of radiotherapy combined with short-term effective regimens, such as ABVD (doxorubicin, bleomycin, vinblastine and decarbazine) or VBM (vinblastine, bleomycin and methotrexate) to reduce the incidence of MOPP-associated gonadal dysfunction and leukaemogenesis.

Adolescent↗
PubMed2004

Combination chemotherapy plus low-dose involved-field radiotherapy for early clinical stage Hodgkin's lymphoma.

PURPOSE: To present our long-term experience regarding the use of chemotherapy plus low-dose involved-field radiotherapy (IFRT) for clinical Stage I-IIA Hodgkin's lymphoma. METHODS AND MATERIALS: We analyzed the data of 368 patients. Of these, 66 received mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) and 302 received doxorubicin (or epirubicin), bleomycin, vinblastine, and dacarbazine [A(E)BVD]. Patients with complete remission or very good partial remission were scheduled for low-dose IFRT (< or =3200 cGy). RESULTS: The 10-year failure-free survival (FFS) and overall survival (OS) rate was 85% and 86%, respectively. A(E)BVD-treated patients had superior 10-year FFS and OS rates compared with MOPP-treated patients (87% vs. 75%, p = 0.009; and 93% vs. 71%, p = 0.0004, respectively). Only 10 of 41 relapses had any infield (irradiated) component. Of the complete responders/very good partial responders treated with low-dose IFRT, those who received <2800 cGy had inferior FFS but similar OS as those who received 2800-3200 cGy. Adverse prognostic factors for FFS included age > or =45 years, leukocytosis > or =10 x 10(9)/L, and extranodal extension. Secondary acute leukemia developed after MOPP with or without salvage therapy (n = 6) or after ABVD plus salvage therapy (n = 2). None of the nine secondary solid tumors developed within the RT fields. CONCLUSION: IFRT at a dose of 2800-3000 cGy is highly effective in clinical Stage I-IIA HL patients who achieved a complete response or very good partial response with A(E)BVD. The long-term toxicity with respect to secondary malignancies appears to be acceptable.

Adolescent↗
PubMed2005

Quality control of involved-field radiotherapy in patients with advanced Hodgkin's lymphoma (EORTC 20884).

PURPOSE: To evaluate the impact of the quality of involved-field radiotherapy (IFRT) on clinical outcome in patients with advanced Hodgkin's lymphoma (HL) in complete remission (CR) after six to eight cycles of mechlorethamine, vincristine, procarbazine, prednisone-doxorubicin, bleomycin, and vinblastine (MOPP-ABV) chemotherapy. METHODS AND MATERIALS: A retrospective review of clinical and radiologic data, radiation charts, simulator films, and megavoltage (MV) photographs was performed. IFRT consisted of 24 Gy to all initially involved nodal areas and 16-24 Gy to all initially involved extranodal sites. Major violations were defined as no or only partial irradiation of an originally involved area, or a total dose <90% of the prescribed dose. RESULTS: Of the 739 patients who were enrolled in the trial between 1989 and 2000, 57% achieved a CR; 152 of 172 patients randomized to IFRT actually received radiotherapy; and in 135 patients, quality control was performed. The overall major violation rate was 47%, predominantly concerning target volumes. The total dose was correct in 81% of the patients. After a median follow-up of 6.5 years, there was no difference in cumulative failure rate between patients with or without major violations. There was no relationship between incidence or site of relapse and major protocol violations. CONCLUSION: In advanced-stage HL patients in complete remission after six to eight cycles of MOPP-ABV, the outcome was not influenced by violation of the radiotherapy protocol.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2005

S100P is selectively upregulated in tumor cell lines challenged with DNA cross-linking agents.

Bifunctional alkylating agents that cross-link DNA are implicated in the pathogenesis of therapy related myelodysplastic syndromes (MDS) and MDS related acute myeloid leukemia (MDR-AML). We exposed HL60 cells to the highest level of bifunctional alkylating nitrogen mustard mechlorethamine (HN2) that was consistent with recovery following suppressed growth. Microarray analyses showed minor changes in transcripts in HN2 treated cells. A moderate up-regulation of S100P mRNA was consistently observed after 1 day of exposure to bifunctional alkylating agents and expression was not induced with monofunctional agents. Elevated S100P protein/antigen was not detected until days later in a subset of non-mitotic G2 cells. Elevated S100P protein persisted over the course of a delayed recovery phase. The results confirm recent reports indicating that S100P is a survival factor. In addition, our results indicate that S100P has a specific role in G2 cell function associated with a prolonged phase of recovery after exposure to bifunctional alkylating agents.

Alkylating Agents↗
PubMed2005

Nitrogen mustard- and half-mustard-induced damage in Escherichia coli requires different DNA repair pathways.

Bifunctional alkylating agents are used in tumor chemotherapy to induce the death of malignant cells through blockage of DNA replication. Nitrogen mustards are commonly used chemotherapeutic agents that can bind mono- or bifunctionally to guanines in DNA. Mustard HN1 is considered a monofunctional analog of bifunctional mustard HN2 (mechlorethamine). Escherichia coli K12 mutant strains deficient in nucleotide excision repair (NER) or base excision repair (BER) were submitted to increasing concentrations of HN2 or HN1, and the results revealed that damage induced by each chemical demands different DNA repair pathways. Damage induced by HN2 demands the activity of NER with a minor requirement of the BER pathway, while HN1 damage repair depends on BER action, without any requirement of NER function. Taken together, our data suggest that HN1 and HN2 seem to induce different types of damage, since their repair depends on distinct pathways in E. coli.

DNA Repair↗
PubMedDate not supplied

A chick model for the mechanisms of mustard gas neurobehavioral teratogenicity.

The chemical warfare blistering agent, sulfur mustard (SM), is a powerful mutagen and carcinogen. Due to its similarity to the related chemotherapy agents nitrogen mustard (mechlorethamine), it is expected to act as a developmental neurotoxicant. The present study was designed to establish a chick model for the mechanisms of SM on neurobehavioral teratogenicity, free of confounds related to mammalian maternal effects. Chicken eggs were injected with SM at a dose range of 0.0017-17.0 microg/kg of egg, which is below the threshold for dysmorphology, on incubation days (ID) 2 and 7, and then tests were conducted posthatching. Exposure to SM elicited significant deficits in the intermedial part of the hyperstriatum ventrale (IMHV)-related imprinting behavior. Parallel decreases were found in the level of membrane PKCgamma in the IMHV, while eliciting no net change in cytosolic PKCgamma. The chick, thus, provides a suitable model for the rapid evaluation of SM behavioral teratogenicity and elucidation of the mechanisms underlying behavioral anomalies. The results obtained, using a model that controls for confounding maternal effects, may be replicated in the mammalian model and provide the groundwork for studies designed to offset or reverse the SM-induced neurobehavioral defects in both avian and mammals.

Analysis of Variance↗
PubMed1991

Topical nitrogen mustard: an effective treatment for cutaneous Langerhans cell histiocytosis.

In 16 children with multisystem Langerhans cell histiocytosis (mean age 22 months, range 5 to 36 months) severe symptomatic skin involvement was treated with topical nitrogen mustard (mechlorethamine hydrochloride). In each case, rapid clinical improvement occurred within 10 days; subsequent complete healing was observed in 14 children, and partial healing in 2 others in whom treatment was a component of palliative care. Mean duration of treatment was 3.5 months (range 2 to 6 months). Systemic treatment was averted in 11 patients because response to topical therapy was so favorable, but bone marrow or respiratory failure led to a fatal outcome in 5 other patients. Adverse effects were minimal. One patient developed contact allergy to topical nitrogen mustard after 2 years of intermittent therapy, but was successfully desensitized and was then able to continue treatment. We conclude that the topical application of nitrogen mustard is an effective treatment for cutaneous Langerhans cell histiocytosis. Although adverse effects were minimal in the short term, there remains concern about the possibility of long-term cutaneous carcinogenicity.

Administration, Topical↗
PubMed1994

Vancouver hybrid: preliminary experience in the treatment of Hodgkin's disease in childhood and adolescence.

OBJECTIVE: To describe our preliminary experience with 19 young patients with newly diagnosed Hodgkin's disease who received the Vancouver hybrid chemotherapeutic regimen. DESIGN: We summarized the characteristics of our 19 study patients, the treatment administered (between June 1988 and June 1992), and the outcome. RESULTS: The Vancouver hybrid, which consists of mechlorethamine, vincristine sulfate (Oncovin), procarbazine hydrochloride, prednisone, doxorubicin hydrochloride (Adriamycin), bleomycin, and vinblastine sulfate (MOPP/ABV), was based on the hypothesis of preventing drug resistance by early introduction and alternation of all active agents and was aimed at decreasing the severity and frequency of treatment-related complications. Of our 19 patients with Hodgkin's disease (age range, 6 to 20 years) treated with this regimen, 2 had clinical stage I disease, 10 had stage II, 6 had stage III, and 1 had stage IV. Only two patients had systemic symptoms, and nodular sclerosis was the most common histologic feature. Patients were given four to eight cycles of chemotherapy, depending on the clinical stage of disease. In addition, 10 patients received irradiation, including 6 of 9 patients with bulky disease. In all patients, complete remission was achieved. After a median follow-up of 3.3 years, only two patients had had a relapse; both underwent autologous bone marrow transplantation and were alive and well with no evidence of disease at last follow-up. The treatment was well tolerated, and delivery of treatment was excellent. The only severe toxicity was myelosuppression; 8 patients experienced a total of 15 episodes of fever and neutropenia that necessitated hospitalization and antibiotic therapy, but no systemic infections were confirmed during 104 cycles of therapy. CONCLUSION: The MOPP/ABV hybrid is an effective and well-tolerated therapy in most young patients with Hodgkin's disease. Long-term monitoring is needed to evaluate late effects.

Adolescent↗
PubMed2001

Genetic damage by bifunctional agents in repair-active pre-meiotic stages of Drosophila males.

Most of our understanding of germline mutagenesis in Drosophila is based on the DNA repair-inactive, haploid post-meiotic stages. The diploid, repair-active pre-meiotic stages are more relevant to the situation encountered in somatic cells. DNA mono-adducts induced by agents like methyl methanesulphonate (MMS) and ethylene oxide (EO) are well repaired in the pre-meiotic cell stages, and these agents show therefore, no or considerable lower mutagenic activity in these stages. In contrast, in this study the two bifunctional nitrogen mustards chlorambucil (CAB) and mechlorethamine (MEC) show significantly elevated mutant frequencies of both post- and pre-meiotic germ cells. Results were similar for the X-chromosomal and the autosomal (2nd) recessive lethal (RL) test. CAB and MEC were also active in stem cells, but in comparison with post-stem cell stages they seem to be better protected. The germ cell specific response in post- and pre-meiotic cell stages was for both nitrogen mustards comparable to mutagenic activity patterns observed in the specific locus test in the mouse. It was reported that for diepoxybutane (DEB), another cross-linking agent, the ratio of the RL frequency for the 2nd- and the X-chromosome was increased from 2.1 for post-meiotic stages to 9.5 for pre-meiotic stages. In own experiments aiming to confirm this observation, a high ratio was indeed found. The induction of large deletions by DEB could be the reason for this difference, since such lesions might include both a sex-linked lethal and a vital gene required for the development of spermatocytes into mature sperm. Similar differences were expected for CAB and MEC since they are also inducers of large deletions. But unexpectedly, no differences in 2nd/X RL ratio between post- and pre-meiotic cell stages were found for the nitrogen mustards. Possible causes such as distinct proportions of multi-locus deletions (MLDs), mitotic recombination and the formation of persistent lesions, are discussed.

Animals↗
PubMed2000

Hypopigmented mycosis fungoides: treatment and a 6(1/2)-year follow-up of 9 patients.

BACKGROUND: The clinical course of hypopigmented mycosis fungoides has not been well described. OBJECTIVE AND METHODS: We sought to review the management and follow-up of patients with hypopigmented mycosis fungoides evaluated between January 1990 and August 1998. RESULTS: There were 7 African American and 2 Asian patients (5 male and 4 female patients); 8 had stage Ia and 1 had stage Ib disease. The mean age at diagnosis was 34.4 years, the mean latent period was 9.2 years, and the mean follow-up period after diagnosis was 6.5 years. Treatment modalities used included psoralen UVA, UVB, and topical mechlorethamine. Eight had complete clinical responses, and another had a partial response. The remission period ranged from 2 months to 3 years. In all but one patient, lesions recurred; all responded rapidly to another course of therapy. CONCLUSION: Hypopigmented mycosis fungoides is characterized by early onset, occurrence in dark-skinned individuals, and good response to therapy. Recurrences are common. In most, it has a biologically benign course.

Adolescent↗
PubMed1986

Cutaneous malignancies and metastatic squamous cell carcinoma following topical therapies for mycosis fungoides.

Specific treatments for mycosis fungoides, including electron beam irradiation, topical mechlorethamine, and psoralen plus ultraviolet A (PUVA) may be associated with the development of skin cancers after a variable latency period. Because these treatments are often not curative, topical therapies for mycosis fungoides, administered sequentially or concomitantly, are being used increasingly in order to control recurrent disease. This report documents the development of multiple cutaneous tumors, including squamous cell carcinoma, basal cell carcinoma, actinic keratoses, keratoacanthomas, and one case of lentigo maligna, in seven patients who received topical therapies for mycosis fungoides. In contrast to the usual latency period between ionizing radiation therapy and the development of skin cancer, two of our patients who had received prior PUVA therapy developed multiple skin tumors upon completion of electron beam irradiation. The development of metastatic squamous cell carcinoma in two of the other seven patients with multiple cutaneous neoplasms suggests that this potential hazard must be considered in the evaluation and treatment of patients with mycosis fungoides.

Administration, Topical↗
PubMed2000

The activity of the DNA-dependent protein kinase (DNA-PK) complex is determinant in the cellular response to nitrogen mustards.

The DNA-dependent protein kinase plays a critical role in mammalian DNA double strand break (DSB) repair and in specialized recombination, such as lymphoid V(D)J recombination. Its regulatory subunit Ku (dimer of the Ku70 and Ku80 protein) binds to DNA and recruits the kinase catalytic sub-unit, DNA-PKcs. We show here that three different strains deficient in either the Ku80 (xrs-6) or DNA-PKcs (V-3, scid) component of DNA-PK are markedly sensitive (3.5- to 5-fold) to a group of DNA cross-linking agents, the nitrogen mustards (NMs) (melphalan and mechlorethamine) as compared to their parental cell line. Importantly, the level of hypersensitivity to these drugs was close to the level of hypersensitivity observed for radiomimetic agents that create DSBs in DNA (bleomycin and neocarzinostatin). In addition, sensitivity to NMs was restored to the parental level in the xrs-6 cell line stably transfected with the human Ku80 gene (xrs-6/Ku80), showing unequivocally that DNA-PK is involved in this phenotype. These results indicate that a function of the whole DNA-PK protein complex is involved in the cellular response to NMs and suggest that the repair of DNA interstrand cross-links induced in DNA by NMs involved a DNA-PK dependent pathway that shares common features with DNA DSBs repair.

Animals↗
PubMed2003

Analysis of treatment results in advanced Hodgkin's disease: the case for adjuvant radiotherapy.

PURPOSE: To assess the treatment results in patients with advanced Hodgkin's disease in a single center and to evaluate the clinical and therapeutic prognostic factors, including verification of the significance of the prognostic score. METHODS AND MATERIALS: Treatment results were analyzed in 133 patients with newly diagnosed Stage IIIB and IV Hodgkin's disease. Treatment consisted of six courses of hybrid chemotherapy (mechlorethamine, vincristine, procarbazine, and prednisone [MOPP]/doxorubicin (adriamycin), bleomycin, and vincristine [ABV]) followed by irradiation (RT) in patients with an indication for RT (84 patients). Chemotherapy was then continued for another two cycles. The indications for consolidation RT included bulky disease and/or partial response after six cycles of chemotherapy. In 31 patients, extended-field RT was performed, and in 53, limited fields were irradiated. The median radiation dose was 39 Gy. RESULTS: The median follow-up was 78 months. Complete remission after whole treatment was achieved in 88.7% of patients. The actuarial overall survival rate was 78% and 71%, and relapse-free survival rate was 73% and 65% at 5 and 10 years, respectively. The independent adverse prognostic factors in multivariate analysis appeared to be older age, low serum albumin, low serum gammaglobulin, lower number of chemotherapy cycles, and no RT. The value of the prognostic score was confirmed; the higher the prognostic score, the worse the survival. CONCLUSION: In patients with advanced Hodgkin's disease, consolidation RT improved survival. The best results were achieved with the use of large-volume RT.

Adolescent↗
PubMed1999

The effect of the Saccharomyces cerevisiae endo-exonuclease NUD1 gene expression on the resistance of HeLa cells to DNA-damaging agents.

HeLa cells transiently transfected with a mammalian expression DNA vector expressing the Saccharomyces cerevisiae endo-exonuclease (EE) NUD1 gene have exhibited changes in cell survival frequencies after treatment with different DNA-damaging agents as compared to HeLa cells transfected with a control plasmid. The NUD1-transfected cells showed a dose-dependent increase in sensitivity to UV irradiation resulting in up to 58% decrease in cell survival. In response to gamma-irradiation NUD1 transfected cells featured an increased survival at doses equal to and greater than 2.0 Gy, reaching a maximum enhancement in survival frequency of 17%. At the same time, the NUD1-transfectants featured an increase in resistance to 0.25 microM-0.5 microM cis-platin (up to 58% increase in cell survival) and 1.0 mM EMS (11% increase). At higher concentrations of EMS NUD1 expression resulted in a decreased cell survival of the transfected cells (17% decrease for 2.5 mM EMS). No difference in cell survival frequencies between the NUD1-transfectants and the controls was observed after treatment with different concentrations of chlorambucil and mechlorethamine. These results suggest possible roles played by EEs in different DNA repair pathways--being stimulatory for the repair of certain types of DNA lesions, such as double strand breaks (DSBs), and interfering with the endogenous DNA repair systems for the repair of other types of lesions. Furthermore, these results also provide additional indirect evidence for the role of EEs in homologous recombination.

Alkylating Agents↗