Why pesticides could be a common cause of prostate and breast cancers in the French Caribbean Island, Martinique. An overview on key mechanisms of pesticide-induced cancer.

Prostate and breast cancers have become very frequent in Martinique. We previously conducted a multifactorial analysis in the French Caribbean Island, Martinique, in order to elucidate the aetiology of prostate cancer. Using a linear regression analysis, we found that the growth curves of incidence rates for Martinique and metropolitan France have been significantly diverging since 1983. Although a Caribbean genetic susceptibility factor may be involved in prostate carcinogenesis: this factor, because it could not have changed during the observation period, cannot per se account for the growing incidence of this cancer in the island. We therefore suggested that among possible environmental factors, the intensive and prolonged exposure to Carcinogenic, Mutagenic and/or Reprotoxic (CMR) or presumed CMR pesticides may account for the observed growing incidence of prostate cancer and thus may be involved in prostate carcinogenesis. In this study, we further attempt to show that due to their carcinogenic properties, pesticides and especially organochlorine pesticides may in fact be causally implicated in the growing incidence of prostate cancer in Martinique. Also, we suggest that CMR or presumed CMR pesticides may be causally involved in the growing incidence of breast cancer through a common endocrine disruption mechanism. We therefore propose that protective medical recommendations should be immediately set up and carried out by general practitioners, paediatricians, obstetricians, gynaecologists and urologists; and that public health measures of primary precaution and prevention should be urgently taken in close collaboration with health professionals in order to protect population, more especially pregnant women and children, with the final objective perhaps that these medical recommendations and public health measures will stop Martinique's cancer epidemic.

Ex vivo study of incorporation into adipocytes and lipolysis-inhibition effect of polycyclic aromatic hydrocarbons.

We have previously shown that benzo[a]pyrene (B[a]P) administrated at extremely low dose can cause weight gain in mice and that the increase in adipose tissue mass is due to inhibition of beta-adrenergic stimulation of lipolysis. Moreover we have suggested that in addition to its endocrine properties, adipose tissue act as a reservoir for many chemical carcinogens including Polycyclic Aromatic Hydrocarbons (PAHs). In this paper we show that B[a]P as well as the two C4 PAHs, pyrene and phenanthrene can bioaccumulate into adipocytes in a similar manner, but that at the difference of B[a]P, have no impact on epinephrine-induced lipolysis. On the basis of this ex vivo study, we therefore suggest that B[a]P may play a central role in carcinogenesis not only by inducing cancer through its mutagenic properties, but also by increasing the bioaccumulation capacity of the adipose tissue mass.

Prostate cancer as an environmental disease: an ecological study in the French Caribbean islands, Martinique and Guadeloupe.

Using a transdisciplinary methodological approach we have conducted a multifactorial analysis in Martinique and Guadeloupe in order to elucidate the aetiology of prostate cancer. In 2002, world age standardized rates of prostate cancer were 152 new cases per 100,000 person-years in the two islands; one of the highest worldwide rates and much higher than those reported for other Caribbean islands and metropolitan France. Using a linear regression analysis, we found that the growth curves of incidence rates for Martinique and metropolitan France have been significantly diverging since 1983. That these curves are not parallel suggests that although a Caribbean genetic susceptibility factor may be involved in carcinogenesis, this factor cannot per se account for the observed growing incidence. On the basis of mapping analysis of soil pollution, we further showed that water contamination by pesticides originates from banana plantations. Moreover, we have established retrospectively that general population subjects investigated in 1972 in Martinique for the presence of organochlorinated pesticides in their adipose tissue had been contaminated by extremely high levels of DDT, DDE, alpha, beta and gammaHCH, aldrin and dieldrin. Our study leads to the conclusion that the growing incidence of prostate cancer cannot be related either to a modification of ethnographic factors nor to a change in lifestyle and therefore suggests that environmental factors such as the intensive and prolonged exposure to carcinogenic, mutagenic and reproductive toxin pesticides may cause prostate cancer.

Lifestyle-related factors and environmental agents causing cancer: an overview.

The increasing incidence of a variety of cancers after the Second World War confronts scientists with the question of their origin. In Western countries, expansion and ageing of the population as well as progress in cancer detection using new diagnostic and screening tests cannot fully account for the observed growing incidence of cancer. Our hypothesis is that environmental factors play a more important role in cancer genesis than it is usually agreed. (1) Over the last 2-3 decades, alcohol consumption and tobacco smoking in men have significantly decreased in Western Europe and North America. (2) Obesity is increasing in many countries, but the growing incidence of cancer also concerns cancers not related to obesity nor to other known lifestyle-related factors. (3) There is evidence that the environment has changed over the time period preceding the recent rise in cancer incidence, and that this change, still continuing, included the accumulation of many new carcinogenic factors in the environment. (4) Genetic susceptibility to cancer due to genetic polymorphism cannot have changed over one generation and actually favours the role of exogenous factors through gene-environment interactions. (5) Age is not the unique factor to be considered since the rising incidence of cancers is seen across all age categories, including children, and adolescents. (6) The fetus is specifically vulnerable to exogenous factors. A fetal exposure during a critical time window may explain why current epidemiological studies may still be negative in adults. We therefore propose that the involuntary exposure to many carcinogens in the environment, including microorganisms (viruses, bacteria and parasites), radiations (radioactivity, UV and pulsed electromagnetic fields) and many xenochemicals, may account for the recent growing incidence of cancer and therefore that the risk attributable to environmental carcinogen may be far higher than it is usually agreed. Of major concern are: outdoor air pollution by carbon particles associated with polycyclic aromatic hydrocarbons; indoor air pollution by environmental tobacco smoke, formaldehyde and volatile organic compounds such as benzene and 1,3 butadiene, which may particularly affect children and food contamination by food additives and by carcinogenic contaminants such as nitrates, pesticides, dioxins and other organochlorines. In addition, carcinogenic metals and metalloids, pharmaceutical medicines and some ingredients and contaminants in cosmetics may be involved. Although the risk fraction attributable to environmental factors is still unknown, this long list of carcinogenic and especially mutagenic factors supports our working hypothesis according to which numerous cancers may in fact be caused by the recent modification of our environment.

Overweight/obesity and cancer genesis: more than a biological link.

The classical view according to which overweight/obesity is related to cancer considers adipose tissue as an active and metabolic "organ", acting through endocrine, autocrine and paracrine processes. Consequently, it has been hypothesized, that genesis and progression of cancer may be caused by different biological factors acting through diverse mechanisms including changes in the synthesis and bioavailability of sex hormones, insulin resistance, release of growth factors and/or proinflammatory cytokines and abnormal energetic disposal and expenditure. We have shown that overweight/obesity can be experimentally induced by benzo[a]pyrene, a universal well characterized chemical pollutant and that overweight/obesity may in fact be caused by several types of chemical pollutants. In this paper we propose that in addition to the above hypothetical biological mechanisms, adipose tissue acts as a reservoir for lipophilic, liposoluble environmental carcinogens, so that chemical pollution may in fact generate both overweight/obesity and cancer. More precisely, we propose that many carcinogens, be they mutagens or promotors can be stored in the adipose tissue, be released at convenient dose in the blood circulation and therefore target peripheral tissues to induce carcinogenesis. Such carcinogens mainly include organochlorine pesticides and PCBs. Their association with an increased risk of cancer seems to be demonstrated for breast and prostate carcinoma, as well as for lymphoma, not only in obese patients, but also in normal weight or even leaner patients suggesting that the adipose tissue may act as a reservoir for environmental carcinogens in obese as well as in non-obese patients.

The multitude and diversity of environmental carcinogens.

We have recently proposed that lifestyle-related factors, screening and aging cannot fully account for the present overall growing incidence of cancer. In order to propose the concept that in addition to lifestyle related factors, exogenous environmental factors may play a more important role in carcinogenesis than it is expected, and may therefore account for the growing incidence of cancer, we overview herein environmental factors, rated as certainly or potentially carcinogenic by the International Agency for Research on Cancer (IARC). We thus analyze the carcinogenic effect of microorganisms (including viruses), radiations (including radioactivity, UV and pulsed electromagnetic fields) and xenochemicals. Chemicals related to environmental pollution appear to be of critical importance, since they can induce occupational cancers as well as other cancers. Of major concerns are: outdoor air pollution by carbon particles associated with polycyclic aromatic hydrocarbons; indoor air pollution by environmental tobacco smoke, formaldehyde and volatile organic compounds such as benzene and 1,3 butadiene, which may particularly affect children, and food pollution by food additives and by carcinogenic contaminants such as nitrates, pesticides, dioxins and other organochlorines. In addition, carcinogenic metals and metalloids, pharmaceutical medicines and cosmetics may be involved. Although the risk fraction attributable to environmental factors is still unknown, this long list of carcinogenic and especially mutagenic factors supports our working hypothesis according to which numerous cancers may in fact be caused by the recent modification of our environment.

The growing incidence of cancer: role of lifestyle and screening detection (Review).

The increasing incidence of a variety of cancers after the Second World War confronts scientists with the question of their origin. In Western countries, expansion and ageing of the population, as well as progress in cancer detection using new diagnostic and screening tests cannot fully account for the observed growing incidence of cancer. Our hypothesis is that environmental factors play a more important role in cancer genesis than it is usually agreed: i) over the last 2-3 decades, alcohol consumption and tobacco smoking in men have significantly decreased; ii) obesity is increasing in many countries, but the growing incidence of cancer also concerns cancers not related to obesity nor to other lifestyle-related factors; iii) there is evidence that the environment has changed over the same time scale as the recent rise in cancer incidence, and that this change included the accumulation of many new carcinogenic factors in the environment; iv) genetic susceptibility to cancer due to genetic polymorphism cannot have changed over one generation and actually favours the role of exogenous factors through gene-environment interactions; v) age is not the unique factor to be considered since the rising incidence of cancers is seen across all age categories, including children; vi) the fetus is specifically vulnerable to exogenous factors. A fetal exposure during a critical window period may explain why current epidemiological studies may be negative in adults. We therefore propose that the involuntary exposure to many carcinogens in the environment contributes to the rising trend in cancer incidence.

[The contribution of the physico-chemical environment to the genesis of cancer: what extent and how to measure it?]. / La part de l'environnement physico-chimique dans la genèse des cancers: quelle amplitude et comment la mesurer?

The growing incidence of cancers for the last 20 years in France and in Europe confronts scientists with the problem of their origin. Apart from standard factors such as addiction to smoking, alcoholism and overweight due to inadequate diets, the hypothesis that other environmental causes have recently appeared, is formulated. The author aims at reinforcing this hypothesis based on epidemiological, biological and toxicological arguments. Addiction to smoking and alcoholism have significantly decreased for the last 20 to 30 years and the incidence rise concerns cancers that are not related to these factors. Endogenous factors of genetic susceptibility can hardly have changed over one generation and actually can favour interaction with exogenous factors involving either our life style or the environment. The role of biological factors associated with ageing to explain the increase in cancer rate according to age is worth discussing. Many factors (radiation and chemical molecules) present in the environment, factors that international organizations have proven to be certainly, probably or possibly cancer-inducing, are considered. Some acting as mutagenic, others as promoters can add their cancer-inducing effects to smoking or other factors associated with our lifestyle. However, with the exception of smoking, most of the factors associated with our lifestyle are not mutagenic, an observation which leads to consider mutagenic factors from the environment, because any cancer implies the occurrence of mutations at its initiation step. The magnitude of the risk related to environmental factors is not yet known, therefore implying the need for new research aiming at assessing them accurately. Although, as far as public health is concerned, fighting addiction to smoking, alcoholism and unhealthy eating habits needs to be pursued, evidence regarding these new environmental factors of physico-chemical nature poses the problem of their prevention.

Gemcitabine combined with cisplatin as first-line treatment in patients with epithelial ovarian cancer: a phase II study.

OBJECTIVE: This phase II study was performed to evaluate the activity and toxicity of gemcitabine plus cisplatin as first-line treatment of advanced epithelial ovarian cancer. METHODS: Chemonaive patients with histologically or cytologically confirmed FIGO stage III or IV epithelial ovarian carcinoma were enrolled. Patients received cisplatin 75 mg/m(2) on Day 1 and gemcitabine 1250 mg/m(2) on Days 1 (after cisplatin) and 8 of a 21-day cycle. RESULTS: Of the 42 female patients (median age 60 years) enrolled, 81% had a Zubrod performance status of 0 or 1. Among the 37 response-evaluable patients, there were 5 (13.5%) pathological complete responses (CRs), 16 (43.2%) pathological partial responses (PRs), and 3 (8.1%) clinical PRs, for an overall response rate of 64.9% (95% CI: 47.4-79.8%) and a pathological response rate of 56.8%. Per an intent-to-treat analysis, the overall response rate was 57.1% (95% CI: 41.0-72.3%). After a median follow-up time of 15.8 months, the median survival was 24.0 months and median progression-free survival was 13.4 months. Grade 3/4 neutropenia and thrombocytopenia occurred in 69.0 and 33.3% of patients, respectively, with no febrile neutropenia or hemorrhage. Grade 3/4 nausea and vomiting occurred in 35.7% and grade 3 alopecia in 21.4% of the patients. One patient died due to a toxicity-related death (dyspnea). CONCLUSIONS: Gemcitabine plus cisplatin is active and feasible as first-line treatment of advanced epithelial ovarian cancer. Further clinical trials adding gemcitabine to first-line treatment seem warranted.

Result of two randomized trials comparing nolatrexed (Thymitaq) versus methotrexate in patients with recurrent head and neck cancer.

We report on two randomized trials performed in the USA and Europe, which compared methotrexate and nolatrexed as treatment for patients with recurrent head and neck cancer. Eligibility criteria included: histologically confirmed squamous-cell carcinoma, measurable disease, adequate hematological, renal and hepatic functions, failure of a first-line chemotherapy, and informed consent. Methotrexate 40 mg/m2 was weekly given by short infusion, and nolatrexed 725 mg/m2 per day was administered as a five-day continuous infusion, every three weeks. A total of 139 patients (63 in the USA. 76 in Europe) were randomized based on a ratio of 2/1: 93 and 46 received nolatrexed and methotrexate, respectively. Patient characteristics included 115 males and 24 females; median age 60 years. In the nolatrexed arm, the following grade 3-4 toxicities occurred: neutropenia (29.9%) with 3.1% of febrile neutropenia, mucositis (33.3%), and vomiting (10.3%). In the MTX arm, the grade 3-4 toxicities were neutropenia (7.1%) and mucositis (6.9%). There was no difference in activity between the nolatrexed and the methotrexate treatment: 3.3% and 10.8% of objective responses, 1.9 versus 1.5 months of disease-free progression and 3.5 versus 3.7 months of overall survival, respectively. Nolatrexed has demonstrated a similar activity to methotrexate.

Verapamil increases the survival of patients with anthracycline-resistant metastatic breast carcinoma.

BACKGROUND: Verapamil (VER), a potent calcium channel blocker, has been found to overcome P-gp-mediated multi-drug resistance (MDR) and to increase sensitivity to cytotoxic anticancer drugs in refractory myeloma and non-Hodgkin lymphoma. The value of VER for treating solid tumors is still a matter for debate. PATIENTS AND METHODS: We performed a prospective study in 99 patients with anthracycline-resistant metastatic breast carcinoma (MBC), to assess the clinical effect of oral VER given in association with chemotherapy. Instead of retreating patients with anthracycline, we used a partially noncross-resistant regimen (VF), combining vindesine (VDS) and 5-fluorouracil given as a continuous infusion (5-FU CI). Patients were randomly assigned to two cohorts. One cohort (47 patients) was treated in 28-day cycles, each involving the administration of VDS (3 mg/m2 i.v. bolus on days 1 and 10) and 5-FU CI, (400 mg/m2/day i.v. from day 1 to day 10). The other cohort (52 patients) received the same VDS and 5-FU treatment and an additional oral VER treatment (240 mg/day divided in 2 doses), from day 1 to day 28 of each cycle. Patients were treated until progression. RESULTS: The treatment was well tolerated and no side effects that could be attributed to VER were detected. Patients treated with VER had longer overall survival (OS) (median OS: 323 vs. 209 days, P = 0.036) and a higher response rate (27% vs. 11%, P = 0.04) than those not given VER. Progression-free survival (PFS) was also longer but the difference was not statistically significant (median PFS: 4.6 and 2.7 months for the VER and non-VER groups respectively, P = 0.6). CONCLUSIONS: This clinical trial demonstrates that a chemosensitizer, such as VER, can increase the survival of MBC patients with acquired anthracycline resistance.

Amifostine pretreatment for protection against cyclophosphamide-induced and cisplatin-induced toxicities: results of a randomized control trial in patients with advanced ovarian cancer.

PURPOSE: Serious cumulative toxicity is a well-recognized consequence of chemotherapy. Amifostine, an organic thiophosphate, has demonstrated the ability to protect selectively a broad range of normal, but not neoplastic, tissues from the cytotoxic effects of chemotherapy and radiotherapy. This study was designed to determine if amifostine could reduce the serious toxicities associated with cyclophosphamide and cisplatin (CP), without reducing antitumor efficacy in patients with ovarian cancer. PATIENTS AND METHODS: Two hundred forty-two patients with advanced ovarian cancer were randomized to receive six cycles of cyclophosphamide (1,000 mg/m2) and cisplatin (100 mg/m2) with or without amifostine (910 mg/m2) every 3 weeks for six cycles. The occurrence of hematologic, renal, neurologic, and ototoxicity was evaluated. Antitumor efficacy was assessed by pathologic tumor response and survival. RESULTS: Pretreatment with amifostine before each cycle of chemotherapy resulted in a reduction of cumulative toxicities. Hematologic toxicity consisted of grade 4 neutropenia associated with fever and/or infection that required antibiotic therapy (P = .005), days in hospital (P = .019), and days on antibiotics (P = .031). Platinum-specific toxicities consisted of protracted serum creatinine elevations (P = 0.004), > or = 40% reduction from baseline in creatinine clearance (P = .001), and severity of neurologic toxicity (P = .029). Twenty-four percent of CP patients compared with 9% of amifostine plus CP patients discontinued therapy because of protocol-specified toxicity (P = .002). Pathologic tumor response rates were 37% with amifostine and 28% in controls, with comparable median survival times of 31 months. Amifostine was generally well tolerated; the principal side effects were emesis and a transient decrease in blood pressure. CONCLUSION: Pretreatment with amifostine reduces the cumulative hematologic, renal, and neurologic toxicities associated with the CP regimen, with no reduction in antitumor efficacy.

Adjuvant treatment of node-positive breast cancer with cyclophosphamide, doxorubicin, fluorouracil, and vincristine versus cyclophosphamide, methotrexate, and fluorouracil: final report after a 16-year median follow-up duration.

PURPOSE: To determine the long-term impact on disease-free survival (DFS) and overall survival (OS) of adjuvant anthracycline-based chemotherapy, when prospectively compared by random allocation with standard cyclophosphamide, methotrexate, and fluorouracil (CMF) in node-positive (N+) breast cancer patients. PATIENTS AND METHODS: Two hundred forty-nine patients with N+ breast cancer, recruited from eight French cancer centers, were randomized to receive 12 monthly cycles of adjuvant chemotherapy, either CMF (n = 112) or doxorubicin, vincristine, cyclophosphamide, and fluorouracil (AVCF) (n = 136). All had a negative metastatic work-up before inclusion, which was stratified by accrual center, tumor stage (International Union Against Cancer [UICC]), and menopausal status. RESULTS: No severe adverse effect related to grade 4 (World Health Organization [WHO]) toxicity was observed. There was no difference in second primary tumor incidence between the two arms. The treatment given was 88% of planned for AVCF and 75% for CMF in both premenopausal and menopausal patients. With a median follow-up time of 16 years (range, 13 to 17), the OS and DFS rates are significantly longer in the AVCF arm (56% v 41% [P = .01] for OS, and 53% v 36% [P = .006] for DFS). These differences are significant, irrespective of tumor stage (T1 to T2 v T3 to T4), and remain positive in patients with or without postoperative locoregional radiotherapy (55% of cohort). When analyzed according to menopausal status, the differences remain significant only for premenopausal patients. CONCLUSION: This set of mature controlled data confirms the added value of anthracycline-based combination adjuvant therapy for N+ breast cancer patients when compared with CMF, with both regimens given for 1 year.

[Cancers of the base of the tongue and hypopharynx: results of a multicenter randomized trial of chemotherapy prior to locoregional treatment]. / Cancers de la base de langue et de l'hypopharynx: résultats d'un essai multicentrique randomisé de chimiothérapie avant traitement locorégional.

The authors report the results of a multicentric randomised trial assessing the effects on survival of neoadjuvant chemotherapy with cisplatin (100 mg/m2, D1) and fluorouracil (1 g/m2, D2-4) delivered before regional treatment in patients with squamous cell carcinoma of hypopharynx and base of tongue. 133 patients were enrolled in the study, and 121 were included in the analysis, 64 in group A (regional treatment alone) and 27 in group B (chemotherapy followed by regional treatment). Despite a high objective response rate to chemotherapy (primary tumour: 85%, 24% complete; nodes: 63%), overall survival was not significantly higher in group B than in group A.

Adjuvant radiotherapy versus combined sequential chemotherapy followed by radiotherapy in the treatment of resected nonsmall cell lung carcinoma. A randomized trial of 267 patients. GETCB (Groupe d'Etude et de Traitement des Cancers Bronchiques).

BACKGROUND: The effect of adjuvant chemotherapy after resection of nonsmall cell lung cancer (NSCLC) remains an unresolved question. METHODS: From October, 1982, to November, 1986, 267 patients with resected NSCLC were included in a randomized trial. The adjuvant allocated treatments were either postoperative radiotherapy, 60 Gy in 6 weeks (radiotherapy group = 129 patients), or three courses of postoperative COPAC (cyclophosphamide, doxorubicin, cisplatin, vincristine, lomustine) chemotherapy followed by a similar radiotherapy schedule (chemotherapy/radiotherapy group = 138 patients). RESULTS: The sex ratio (M:F) was 19/1; mean age was 57 +/- 9 years. According to postoperative staging, 8 patients were Stage I, 70 were Stage II, and 189 were Stage III. The histologic type was squamous cell carcinoma in 175 patients, adenocarcinoma in 57, and large cell carcinoma in 35. The minimum follow-up was 6 years. Four patients were lost to follow-up. Death was recorded in 233 patients. No significant difference was observed in terms of disease free interval (P = 0.47, log-rank test), or overall survival (P = 0.68, log-rank test). With respect to the first site of relapse, distant metastasis occurred more frequently in the radiotherapy group (P = 0.09, log-rank test) whereas local relapse occurred similarly in both groups (P = 0.27). An interaction was observed between lymph node involvement and treatment in terms of overall survival. CONCLUSIONS: The COPAC chemotherapy as postoperative treatment failed to improve overall survival in patients with resected NSCLC receiving postoperative radiotherapy but decreased the pattern of metastatic progression, mainly in the N2 patients.

Selective induction of apoptosis in myeloid leukemic cell lines by monoacetone glucose-3 butyrate.

Butyric acid is a potent cell growth inhibitor and differentiation inducer. Our previous studies have shown that MAG=3but, a monosaccharide ester of butyric acid, used at 1 mM, induces apoptosis in the HL-60 cell line. We report here that this drug can also induce apoptosis in the U-937 leukemic cell lines whereas the myeloblastic KG1 and the NB4 promyelocytic leukemic cell lines were refractory to induction of apoptosis. In order to determine what can trigger cells to undergo apoptosis, cell cycle analysis, induction of differentiation and p53, c-myc and Bcl-2 expression was studied. Apoptosis was correlated to an arrest of cell growth in the G1 phase of the cell cycle and to an induction of differentiation through the monocytic pathway in HL-60 and U-937 cells. Time course studies demonstrated DNA fragmentation after few hours incubation with the drug, while morphological signs appeared later (days 2 or 3). Northern blot analysis and flow cytometric studies have shown that cell death induced by MAG=3but was not associated to an overexpression of c-myc and p53. However, in the HL-60 cells, BCL-2 protein expression was decreased after MAG=3but treatment, corroborating the apoptosis observed.

Butyric acid and its monosaccharide ester induce apoptosis in the HL-60 cell line.

Butyric acid is a potent cell growth inhibitor and differentiation inducer (1-4). However, the short plasma half-life of this fatty acid limits its potential therapeutic use (5,6). The recent synthesis of several monosaccharide esters of butyric sodium salt (BuONa) with a prolonged plasma half-life and similar biological properties as the sodium salt opens new perspectives (7-12). We report here that the human myeloid HL-60 cell line can be induced to apoptosis when cultured with one of these esters, monoacetone glucose 3-butyrate (MAG = 3but) or BuONa. Cytospin slide preparations and flow cytometric studies showed that HL-60 cells treated with 1 mM MAG = 3but or BuONa exhibited a reduction in cell volume and condensation of nuclear structure characteristic of apoptosis, associated with monocytic differentiation. Time course studies demonstrated that DNA fragmentation, as determined by agarose gel electrophoresis, was detected 4 hours after incubation with the drugs, while morphologic signs appeared at day 3. Apoptotic cells increased with culture time and reached a maximum at day 6 of 20 +/- 5% with BuONa, 25 +/- 5% with MAG = 3but, and only 5 +/- 2% in controls. These findings suggest that these drugs may exert their actions, at least in part, through induction of apoptosis.