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Carcinogen induced DNA damage in isolated rat liver nuclei.

Alkali-labile DNA lesions were detected by a hydroxylapatite batch assay following incubation of isolated rat liver nuclei with direct and indirect-acting alkylating agents. N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG) (20-200 microM) produced a steep, concentration-related decrease in double stranded DNA. In contrast, only minimal effects on DNA integrity were observed with methylmethane sulfonate (200 microM). The bifunctional alkylating agent, mechlorethamine produced an apparent increase in double-stranded DNA in accord with its ability to induce interstrand DNA crosslinks. The indirect-acting alkylating agent, dimethylnitrosamine (DMN) induced DNA damage only when an NADPH generating system was included in the incubation mixture. These results suggest that isolated rat liver nuclei may be a useful model for studying the effects of mutagenic and carcinogenic chemicals on the integrity of chromosomal DNA.

Animals↗

The radiation therapy of early stage cutaneous T-cell lymphoma.

Results of different radiotherapy schedules used for early stage (T1-2, N0-1, M0) cutaneous T-cell lymphoma (CTCL) are compared in a series of 45 patients (22 patients treated with high dose total skin electron beam therapy (TSEB) with curative intent, 18 patients treated with palliative radiotherapy, and 5 patients treated with high dose local electron beam). At 3, 5, and 10 years after diagnosis the high dose TSEB treatment group had a probability of overall survival of 91%, 86%, and 75%, respectively, compared with 94%, 88%, and 88% for the palliative treatment group. The complete response (CR) rate for the high dose TSEB treatment group was 82% (18/22), compared with a 57% (4/7) complete response rate for seven patients in the palliative group who received low dose TSEB (less than 25 Gy in 6-7 weeks) followed by daily application of topical mechlorethamine hydrochloride (HN2). However, the probability of continued remission at 3, 5, and 10 years was 44%, 44%, and 33%, respectively, for the high dose TSEB group and 25%, 25%, and 0%, respectively, for the low dose TSEB + HN2 group. The median disease-free survival was 17.5 months for the high dose TSEB group versus 5.5 months for the low dose TSEB + HN2 group. The five patients who were treated with high doses of local electrons to a single local field had an overall survival rate of 80%, a median survival rate of 64 months, and a median length of continued remission of 31 months. These results indicate that high-dose electron beam can result in long-term disease-free survival in patients with localized and limited extent skin involvement with cutaneous T-cell lymphoma.

Adult↗

Enhanced host cell reactivation capacity and expression of DNA repair genes in human breast cancer cells resistant to bi-functional alkylating agents.

Human breast carcinoma (MCF7-MLNr) cells resistant to the bifunctional drugs L-phenylalanine mustard (L-PAM, 5-fold resistance), mechlorethamine (9-fold), cisplatin (3-fold), and BCNU (3-fold) were used to investigate the role of DNA repair in the development of resistance to alkylating agents. We have previously shown that neither L-PAM transport and metabolism nor glutathione-associated enzymes were altered in MCF7-MLNr cells, compared to the sensitive cells MCF7-WT. This study shows that treatment of pRSV-CAT plasmid with L-PAM at concentrations up to 1 microM proportionally inhibit the expression of chloramphenicol acetyl transferase (CAT) activity, while higher concentrations abolished CAT activity. pRSV-CAT reactivation was significantly increased when plasmid was transfected into MCF7-MLNr cells, compared to MCF7-WT cells. This indicates that resistant cells have more efficient capacity to recognize and repair L-PAM induced DNA damage. The mRNA expression of DNA nucleotide excision repair genes ERCC1, XPD (ERCC2), XPB (ERCC3), and polymerase beta was found to be similar in both the MCF7-WT and MCF7-MLNr cells. Western blot analysis also reveals no difference in the expression of ERCC1, AP endonuclease, poly (ADP-ribose) polymerase, and alkyl-N-purine-DNA glycosylase proteins. The lack of correlation between enhanced host cell reactivation capacity in resistant cells, and the expression of these specific DNA repair genes suggests that proteins encoded by these genes are not rate limiting steps for resistance to bi-functional alkylating drugs in human breast cancer cells.

Adenocarcinoma↗

Procarbazine in haematology: an old drug with a new life?

Procarbazine (PCB) was developed in the 1960s and was rapidly recognised as an active agent in lymphoid malignancies. PCB was one of the four drugs combined in mechlorethamine, vincristine, PCB, prednisolone (MOPP), one of the first combination chemotherapy regimens to show that advanced-stage disease could be cured in humans. During the last few decades, comprehensive studies have clarified cellular pathways involved in the modes of action of PCB and its drug resistance mechanisms. However, late toxicities, especially secondary leukaemias and sterility, led to its withdrawal from combination regimens used to treat Hodgkin's lymphomas (HLs). PCB was recently reintroduced in dose-intensified regimens and yielded impressive results. These new regimens (bleomycin, etoposide, doxorubicin, vincristine, PCB, and prednisone (BEACOPP) or escalated BEACOPP) are now being investigated versus the classic ABVD (doxorubicin, bleomycin, vinblastine, dacarbazine) or ABVD-like combination chemotherapy regimens in the treatment of HLs.

Antineoplastic Agents↗

Diagnostic challenge posed by the clinical presentation of foot drop in a patient with Hodgkin's lymphoma.

We report the case of a 56-year-old male with Hodgkin's disease who was being treated with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) and who presented with paresthesias, bilateral leg weakness, and foot drop. MRI revealed a paravertebral abscess with intraspinal extension that was drained and treated with vancomycin. Foot drop was persistent after the treatment. The objective of this case report is to highlight the diagnostic challenge posed by the clinical presentation of foot drop in a medical patient with multiple co-morbidities.

Journal Article↗

Inhibition of nucleotide excision repair and sensitisation of cells to DNA cross-linking anticancer drugs by F 11782, a novel fluorinated epipodophylloid.

F 11782, or 2',3'-bis-pentafluorophenoxyacetyl-4',6'-ethylidene-beta-D-glucoside of 4'-phosphate-4'-dimethylepipodophyllotoxin 2-N-methyl glucamine salt, a novel dual catalytic inhibitor of topoisomerases I and II, was identified as a potent inhibitor of nucleotide excision repair (NER) by screening procedures using the in vitro 3D (DNA damage detection) assay. F 11782 was then shown predominantly to inhibit the incision rather than the repair synthesis step, using two new methodologies derived from this 3D assay, effectively ruling out any inhibition of polymerases delta/var epsilon. Moreover, data from two other in vitro assays showed an absence of any effect of F 11782 on: (i) the DNA damage binding of the XPA-RPA complex, and (ii) on SV40 large T-antigen helicase activity. Therefore, the inhibitory activity of F 11782 on NER may involve an inhibition of the ERCC1-XPF or XPG endonuclease activity. Moreover, inhibition of DNA repair by F 11782 was confirmed in human A549 cells by monitoring unscheduled DNA synthesis following mechlorethamine treatment. Such an inhibition provides an explanation for the highly synergistic cytotoxicity observed against cultured A549 lung tumour cells, when F 11782 was combined with cross-linking agents, such as cisplatin or mitomycin C. These results emphasise the unique mode of action of this novel molecule in inhibiting NER and provide a basis for its evaluation in clinical trials in combination with DNA cross-linking agents.

Antineoplastic Agents↗

The modulation of the DNA-damaging effect of polycyclic aromatic agents by xanthines. Part I. Reduction of cytostatic effects of quinacrine mustard by caffeine.

Recently, accumulated statistical data indicate the protective effect of caffeine consumption against several types of cancer diseases. There are also reports about protective effect of caffeine and other xanthines against tumors induced by polycyclic aromatic hydrocarbons. One of the explanations is based on biological activation of such carcinogens by cytochromes that are also known for metabolism of caffeine. However, there is also numerous data indicating reverse effect on cytotoxicity of anticancer drugs that inhibit the action of topoisomerase I (e.g. Camptothecin or Topotecan) and topoisomerase II inhibitors (e.g. Doxorubicin, Mitoxantrone or mAMSA). In this work we tested the hypothesis that the caffeine protective effect is the result of sequestering of aromatic mutagens by formation of stacking (pi-pi) complexes. As the models for the study we have chosen two well-known mutagens, that do not require metabolical activation: quinacrine mustard(QM, aromatic, heterocyclic nitrogen mustard) and mechlorethamine (NM2, aliphatic nitrogen mustard). The flow cytometry study of these agents' action on the cell cycle of HL-60 cells indicated that caffeine prevents the cytotoxic action of QM, but not that of NM2. The formations of stacking complexes of QM with caffeine were confirmed by light absorption, calorimetric measurements and by molecular modeling calculation. Using the statistical thermodynamics calculations we calculated the "neighborhood" association constant (K(AC)=59+/-2M(-1)) and enthalpy change (DeltaH(0')=-116cal mol(-1)); the favorable entropy change of complex formation (DeltaS(0')=7.72cal mol(-1)K(-1), due to release of several water molecules, associated with components in the process of complex formation). The Gibbs' free energy change of QM-CAF formation is DeltaG(0')=-2.41kcal mol(-1). We were unable to detect any interaction between NM2 and caffeine either by spectroscopic or calorimetric measurement. In order to establish, whether the intercalation of QM plays any role in cytotoxic effect we tested, as a control, non-alkylatiatig, but also intercalating QM derivative-quinacrine (Q). The later had no cytostatic effect on HL-60 cell even at there order of higher concentration than QM or NM2 but, similar to QM forms (which we demonstrated) stacking complexes with caffeine (K(AC)=75+/-3M(-1)). These results strongly indicate, that the attenuating effect of caffeine on cytotoxic or mutagenic effects of some mutagens, is not the results of metabolic processes in the cells, but simply the physicochemical process of sequestering of aromatic molecules (potential carcinogens or mutagens) by formation of stacking complexes with them. The caffeine may then act as the "interceptor" of potential carcinogens (especially in the upper part of digesting track where its concentration can reach the concentration of mM level). There is, however, no indication either in the literature or in our experiments that xanthines can reverse the damage to nucleic acids when the damage to DNA has already occurred.

Antineoplastic Agents↗

Involvement of phosphatidylinositol-3-kinase in membrane ruffling induced by P-glycoprotein substrates in multidrug-resistant carcinoma cells.

P-glycoprotein (P-gp) is a transmembrane protein that transports a variety of structurally and functionally diverse drugs. We recently found that the interaction of drugs with P-gp promoted invasion and metastasis. In this study, we sought to determine the mechanism by which the interaction of P-gp with its substrates leads to the earliest membrane changes associated with cellular invasion, i.e., membrane ruffling. We focused on the activation of phosphatidylinositol-3-kinase (PI-3-kinase), a lipid kinase that regulates actin cytoskeletal organization and cell movement. Sensitive or multidrug-resistant (MDR) MCF-7 (human breast cancer) or KB (human oral carcinoma) cells were treated with drugs or vehicle, and then were stained with phalloidin-tetramethyl-rhodamine isothiocyanate. Membrane ruffles were visualized using a fluorescence microscope. PI-3-kinase activity was determined by an in vitro immune-complex kinase assay and thin-layer chromatography. Drugs transported by P-gp, vinblastine and trans-flupenthixol, increased membrane ruffling and PI-3-kinase activity in the MDR cell lines, MCF-7/AdrR and KBV-1, which overexpress P-gp. This effect was not seen with mechlorethamine, a drug that is not transported by P-gp, and was not detected in sensitive parental cell lines that do not express P-gp. A similar effect was also observed in the MDR1 transfectant, MCF-7/BC-19. Wortmannin, an inhibitor of PI-3-kinase, blocked the effect of VBL and tFPT on membrane ruffling and the activity of PI-3-kinase in MDR cells. These results indicate that drugs transported by P-gp induce membrane ruffling, an early indicator of cellular motility and metastatic potential, in cancer cells overexpressing P-gp and that this effect may be mediated through activation of PI-3-kinase.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

Acrolein-induced cell death: a caspase-influenced decision between apoptosis and oncosis/necrosis.

Due to the dominating roles that caspases play in the apoptotic cascade, their activities appear to be a primary factor in the death pathway (apoptosis versus oncosis/necrosis) decision. In murine FL5.12 proB lymphocytes, the cellular consequences of acrolein treatment included a lack of typical apoptotic features in preference to oncosis/necrosis. Oncosis/necrosis was apparent by detection of a reduction in intracellular ATP concentration, increased plasma membrane leakage (measured by LDH release and flow cytometric detection of propidium iodide uptake) and morphological criteria. Analysis of acrolein-treated cell lysates or recombinant caspase enzymes showed overall dose-dependent decreases in caspase-3, -8 and -9 activities. In addition to acrolein's effect on intracellular caspases, it was also able to alter caspase-dependent apoptosis induced by secondary treatment with etoposide or following cytokine withdrawal. Acrolein at doses > or =20 microM circumvented etoposide or interleukin-3 withdrawal induced apoptosis. When acrolein was combined with mechlorethamine, another alkylating agent not dependent on caspases for its cell death signaling, necrosis was increased in a dose-dependent manner. Overall, these data suggest that caspase inhibition plays an important role in the cell death pathway decision, particularly with treatments dependent on the caspase cascade to induce apoptosis.

Acrolein↗

Active sperm production after cancer chemotherapy with doxorubicin.

The sperm production of 14 cancer patients who received doxorubicin was examined after cessation of therapy. Doxorubicin was used in several multiple-drug protocols for the treatment of various malignancies. Seven patients also received radiotherapy to different sites. Total cumulative doses of doxorubicin ranged from 145 to 625 mg./m.2. Sperm concentration, motility, morphology and the frequency of quinacrine-stained sperm with 2 fluorescent bodies (2F sperm) were measured 7 to 79 months after discontinuation of doxorubicin. Of the patients 6 remained azoospermic, 3 were oligospermic and 5 were normospermic. Sperm motility among the 8 patients with sperm ranged from 20 to 80 per cent. Morphology and 2F sperm distributions were not significantly different from controls. We conclude that, in contrast with the mechlorethamine, vincristine, procarbazine and prednisone protocol, active sperm production within relatively short recovery times is possible after treatment with protocols that include doxorubicin.

Adult↗

Phenotypes of Drosophila homologs of human XPF and XPG to chemically-induced DNA modifications.

DmXPF (mei9) and DmXPG (mus201) mutants are Drosophila homologs of the mammalian XPF and XPG genes, respectively. For Drosophila germ cells, causal correlations exist between the magnitude of a potentiating effect of a deficiency in these functions, measured as the M(NER-)/M(NER+) mutability ratio, and the type of DNA modification. M(NER-)/M(NER+) mutability ratios may vary with time interval between DNA adduct formation and repair, mutagen dose and depend also on the genetic endpoint measured. For forward mutations, there is no indication of any differential response of DmXPF compared to DmXPG. Subtle features appeared from a class-by-class comparison: (i) Methylating agents always produce higher M(NER-)/M(NER+) ratios than their ethylating analogs; (ii) M(NER-)/M(NER+) mutability ratios are significantly enhanced for cross-linking N-mustards, aziridine and di-epoxide compounds, but not for cross-linking nitrosoureas. The low hypermutability effects with bifunctional nitrogen mustards, aziridine and epoxide compounds are attributed to unrepaired mono-alkyl adducts; (iii) The efficient repair of mono-alkyl-adducts at ring nitrogens in wild-type germ cells is evident from the absence of a dose-response relationship for ethylene oxide, propylene imine and methyl methanesulfonate (MMS). These chemicals become powerful germline mutagens when the NER system is disrupted. Systematic studies of the type performed on germ cells are not available for somatic cells of Drosophila. The sparse data available show large differences in the response of germ cells and somatic cells. The bifunctional agent mechlorethamine (MEC) but not the monofunctional MMS or 2-chloroethylamine cause in NER(-) XXfemale symbol the highest potentiating effect on mitotic recombination. The causes of the discrepancy between the extraordinarily high activity of MEC in mus201 somatic cells and its low potentiating effect in germ cells is unknown at present.

Animals↗

Alleviation of mutagenic effects of polycyclic aromatic agents (quinacrine mustard, ICR-191 and ICR-170) by caffeine and pentoxifylline.

Previous studies performed by others indicated that apart from its other biological effects, caffeine (CAF) may have a role in protection of organisms against cancer. However, biological mechanism of this phenomenon remained unknown. Recent studies suggested that caffeine can form stacking (pi-pi) complexes with polycyclic aromatic chemicals. Therefore, one might speculate that effective concentrations of polycyclic aromatic mutagens could be reduced in the presence of caffeine. Here we demonstrate that caffeine and another xanthine, pentoxifylline (PTX), effectively alleviate mutagenic action of polycyclic aromatic agents (exemplified by quinacrine mustard (QM), 2-methoxy-6-chloro-9-(3-(2-chloroethyl)aminopropylamino)acridine.2HCl (ICR-191) and 1,3,7-propanediamine-N-(2-chloroethyl)-N'-(6-chloro-2-methoxy-9-acridinyl)-N-ethyl.2HCl (ICR-170)), but not of aliphatic mutagens (exemplified by mechlorethamine), in the recently developed mutagenicity test based on bacterium Vibrio harveyi. Biophysical studies indicated that caffeine and pentoxifylline can form stacking complexes with the aromatic agents mentioned above. Molecular modeling also confirmed a possibility of stacking interactions between examined molecules.

Aminacrine↗

The naevoid basal-cell carcinoma syndrome (Gorlin syndrome) is a chromosomal instability syndrome.

The Gorlin syndrome, or naevoid basal-cell carcinoma syndrome (NBCS) is an autosomal dominant cancer prone disease (at risk of multiple basal cell carcinomas, and other malignant or benign proliferations). We have previously reported data from peripheral blood lymphocytes of patients with this condition, showing a significant level of spontaneous chromatid and chromosome rearrangements and an overall lengthening of the cell cycle. In this paper, we confirm this disease to be a chromosome instability syndrome from studies on fibroblasts of 5 patients. Spontaneous chromosomal rearrangements, an increased frequency of sister chromatid exchanges and a slowing of the cell cycle were found, compared to age-matched control material. There was also an increased sensitivity to aberration production by mechlorethamine in patient fibroblasts. The chromosome instability we found was not restricted to a given cell lineage, but appears to be part of the general condition of this syndrome. The recently discovered gene responsible for Gorlin syndrome, PTC (or PTCH), encodes a transmembrane protein with yet poorly known functions. However, the demonstration of Gorlin syndrome as a chromosome instability syndrome suggests that this protein has a role in DNA maintenance, repair and/or replication.

Basal Cell Nevus Syndrome↗

Toxicity of sea nettle toxin to human hepatocytes and the protective effects of phosphorylating and alkylating agents.

The sea nettle jellyfish toxin (SNTX), which contains several polypeptides, was highly toxic to human hepatocytes. The Cytosensor microphysiometer was used continuously to monitor cell media acidification rate as an index of cellular metabolic activity. Cells exposed to > 1 microg SNTX protein/ml media exhibited a transient increase in metabolic activity, followed by a sharp decrease and cell death within minutes. The kinetics of the transient increase and subsequent decline increased with higher concentrations of SNTX. The biphasic and time-dependent response of hepatocytes to SNTX suggests that more than one mechanism may be involved in the toxicity of its different polypeptides. SNTX-induced cytotoxicity of hepatocytes was reduced by the presence of high titer antibodies against a heterologous jellyfish. Phenobarbital-induced cells became more vulnerable to SNTX, suggesting that some toxin component(s) require(s) bioactivation. Short-term exposure (1-2 h) to 10 microg/ml of the calcium ionophore calcimycin, or the non-selective monovalent cation ionophore gramicidin, had no effect on metabolic activity. However, 165 microg/ml gramicidin or 53 microg/ml calcimycin produced slight transient activation followed by steady decline in metabolic activity, while 20 h exposure to either ionophore produced total cell death. Exposure to even a 10-fold lower concentration of either ionophore killed 88% and 75%, respectively. This contrasts with the toxicity of SNTX which is detectable in minutes with as little as 3 microg/ml. Since pre-exposure to the organophosphate anticholinesterases VX and paraoxon, or the chemotherapeutic alkylating agents cyclophosphamide and mechlorethamine reduced the cytotoxic effects of SNTX, it suggests that phosphorylation or alkylation of cell protein(s) interferes with SNTX toxicity.

Alkylating Agents↗

False-positive serum prostate-specific antigen values in a patient with non-Hodgkin lymphoma of the kidney.

Prostate-specific antigen (PSA) is the clinically most useful tumor marker for prostate cancer. Although false-positive elevations have been reported due to disease processes outside the prostate gland with the use of the polyclonal assay, such false-positive test results have been exceedingly rare with the use of the monoclonal assay. We report the case of a patient diagnosed with a B-cell lymphoma of the kidney and a significant elevation of serum PSA levels by monoclonal assay in the absence of either inflammatory or malignant prostate disease. PSA returned to normal during lymphoma-specific chemotherapy with a cyclophosphamide, mechlorethamine, vincristine, procarbazine, prednisone regimen. Possible explanations and clinical implications are discussed.

Antineoplastic Combined Chemotherapy Protocols↗

[Hypopigmented mycosis fungoides].

INTRODUCTION: Hypopigmented mycosis fungoides is a rare clinical form of the disease, first described in 1978. Since then, only a hundred odd cases have been documented. CASE REPORT: A young 19 year-old African woman had presented with hypochromatic macules since the age of 9 and for which the diagnostic enquiry had finally concluded in hypopigmented mycosis fungoides. DISCUSSION: The particularities of this form of mycosis fungoides, grade I according to the TNM classification, are principally its onset in black-skinned persons or of Asian origin, and the age of early onset with a predominance of pediatric cases. Its course is indolent for several years and thus source of delayed diagnosis. The differential diagnoses to be evoked are basically vitiligo, achromate eczematides and parapsoriasisis. The post-inflammatory depigmentation, frequent in black-skinned subjects, is only an eliminating diagnosis. Its treatment is that of classical Grade I mycosis fungoides: topical mechlorethamine, phototherapy and topical corticosteroids.

Adult↗

Mycosis fungoides presenting as areas of hypopigmentation: a report of three cases.

In three patients with histologically documented mycosis fungoides, all or most of the lesions were hypopigmented. Unsuspected microscopic foci of mycosis fungoides were found in a purely macular hypopigmented area in one of these patients who had been treated with vitiligo 15 years earlier. Two of the patients were black, and one was Latin American. Repigmentation in all patients followed treatment with carmustine (BCNU) and mechlorethamine.

Adult↗

Radiotherapy for unilesional mycosis fungoides.

PURPOSE: To evaluate the treatment outcome and natural history of patients with the diagnosis of unilesional mycosis fungoides, treated according to a prospective radiotherapy protocol in our institution since July 1975. METHODS AND MATERIALS: A total of 325 patients with the diagnosis of mycosis fungoides have been referred to the Department of Radiation Oncology at Allegheny University of Health Sciences from July 1975 through September 1996. Of these, 18 patients (5%) were classified as having unilesional mycosis fungoides and were irradiated with a curative intent using local electron fields. One patient received 22 Gy; 1 patient received 40 Gy, and the rest of the patients 30.6 Gy. Daily fractions ranged from 1.8 to 2.0 Gy. Treatments prior to radiation consisted of topical steroids and/or antifungal creams in the majority of patients, with temporary partial responses. One patient had received 2 years of topical mechlorethamine (HN2) and another patient had received topical carmustine solution (BCNU) without response prior to irradiation. RESULTS: The responses were measured clinically; posttreatment skin biopsy was not performed routinely unless there was clinical evidence of disease persistence. Complete response rate was 100%; all treated lesions cleared completely within 4 to 8 weeks after the completion of radiation. With a median follow-up of 43 months (range 12 to 240 months), 2 relapses have occurred, 2 and 71 months after the completion of radiation. Both relapses were confined to the skin and were remote from the original site. Both relapses responded to topical application of HN2. There have been no recurrences in the irradiated field nor systemic dissemination. No long-term side effects were found related to treatment, and all the patients are currently alive and without evidence of disease. Actuarial relapse-free and overall survival at 10 years are, respectively, 86.2% and 100%. CONCLUSION: Unilesional mycosis fungoides has a long natural history, is possibly the earliest manifestation of a malignant process, and local treatments, including local radiotherapy, result in long-term disease-free intervals and, possibly, cure. Total skin electron beam radiotherapy is not indicated for this disease entity.

Adult↗