Potential transmission of the cytogenetic toxic effects of methotrexate in the male germline cells of Swiss mice

A systematic overview of the spermatotoxic and genotoxic effects of methotrexate, ganciclovir and mycophenolate mofetil

INTRODUCTION

Immunosuppressant drugs are increasingly being used in the reproductive years. Theoretically, such medications could affect fetal health either through changes in the sperm DNA or through fetal exposure caused by a presence in the seminal fluid. This systematic overview summarizes existing literature on the spermatotoxic and genotoxic potentials of methotrexate (MTX), a drug widely used to treat rheumatic and dermatologic diseases, and mycophenolate mofetil (MMF), which alone or supplemented with ganciclovir (GCV) may be crucial for the survival of organ transplants.

MATERIAL AND METHODS

The systematic overview was performed in accordance with the PRISMA guidelines: A systematic literature search of the MEDLINE and Embase databases was done using a combination of relevant terms to search for studies on spermatotoxic or genotoxic changes related to treatment with MTX, GCV or MMF. The search was restricted to English language literature, and to in vivo animal studies (mammalian species) and clinical human studies.

RESULTS

A total of 102 studies were identified, hereof 25 human and 77 animal studies. For MTX, human studies of immunosuppressive dosages show transient effect on sperm quality parameters, which return to reference values within 3 months. No human studies have investigated the sperm DNA damaging effect of MTX, but in other organs the genotoxic effects of immunosuppressive doses of MTX are fluctuating. In animals, immunosuppressive and cytotoxic doses of MTX adversely affect sperm quality parameters and show widespread genotoxic damages in various organs. Cytotoxic doses transiently change the DNA material in all cell stages of spermatogenesis in rodents. For GCV and MMF, data are limited and the results are indeterminate, for which reason spermatotoxic and genotoxic potentials cannot be excluded.

CONCLUSIONS

Data from human and animal studies indicate transient spermatotoxic and genotoxic potentials of immunosuppressive and cytotoxic doses of MTX. There are a limited number of studies investigating GCV and MMF.

Ameliorating effect of kisspeptin-10 on methotrexate-induced sperm damages and testicular oxidative stress in rats

The purpose of this study was to determine the kisspeptin-10 (Kiss) administration on the damages in testicular oxidant-antioxidant system, reproductive organ weights and some spermatological characteristics resulted from methotrexate (MTX) exposure. Group 1 (n:6) received saline only; group 2 (n:6) received 50 nmol/kg kisspeptin-10 for 10 days; group 3 (n:10) received single-dose methotrexate 20 mg/kg; and group 4 (n:10) received MTX 20 mg/kg single dose and, after 3 days, received kisspeptin-10, 50 nmol/kg, lasted for 10 days by intraperitoneal injection. At the end of the study, malondialdehyde levels were found to have increased following the application of MTX while showing a significant reduction in group 4 with Kiss administration. With respect to the spermatological parameters, administering MTX decreased motility and increased the rates of abnormal spermatozoa in group 2, while improvements were observed in group 4 in the form of increased motility in the spermatozoa and fewer abnormal spermatozoa. In addition, Kiss treatment provided statistically significant increases in the absolute weight of the seminal vesicles and the relative weights of the right cauda epididymis and seminal vesicles resulting from MTX administration. MTX administration damaged some spermatological parameters and increased oxidative stress when compared to the control group. However, Kiss treatment was observed to mitigate these adverse effects as demonstrated by the improvements in coadministration of Kiss and MTX when compared to the MTX group. It is concluded that Kiss treatment may reduce MTX-induced reproductive toxicity as a potential antioxidant compound.

The Influence of Methotrexate Treatment on Male Fertility and Pregnancy Outcome After Paternal Exposure

BACKGROUND

Inflammatory bowel disease incidence peaks during the reproductive years. Methotrexate (MTX) is frequently used for inflammatory bowel disease, but its use during pregnancy is contraindicated in women because of teratogenic effects. The aim of this review is to investigate the influence of MTX on male fertility and pregnancy outcomes after paternal MTX exposure.

METHODS

A systematic literature search was performed by applying 2 focus areas, "methotrexate" and "male fertility or pregnancy outcome." Terms and keywords were used both as MeSH terms and free-text searches. Pertinent articles were searched for additional relevant references.

RESULTS

In animal studies, MTX induces aberrations in sperm DNA that have not been identified in humans. The effects of MTX on human sperm quality have only been described in case reports. A transient adverse effect on sperm quality with low-dose MTX has been reported, but several other cases have not found harmful effects of MTX. MTX has not been measured in human sperm ejaculates; yet, the risk of a direct toxic effect on the fetus through MTX-contaminated seminal plasma seems negligible. Until now, 284 pregnancies with paternal MTX exposure have been reported. The outcomes were 248 live births and a total of 13 malformations, with no overt indication of MTX embryopathy.

CONCLUSIONS

This review reveals the lack of studies on the safety of MTX with regard to male reproduction. It is not clear whether MTX transiently influences male fertility and sperm DNA integrity, and more studies are needed. Comparative cohort studies found no increased risk of adverse pregnancy outcomes.

Immunosuppressants and Male Reproduction

Prolonged use of immunosuppressant medications is occasionally seen in infertile men with chronic inflammatory conditions; autoimmune disorders; or an organ or hematopoietic stem cell transplant. Chronic inflammation impacts negatively on male reproductive endpoints, so immunosuppressant therapy can produce improvements. Corticosteroids have been used to treat antisperm antibodies and even as an empirical treatment for male infertility in general. Trials of these methods have provided mixed results on semen quality and fertility, with improvement, no change and negative effects reported by different investigators. In a substantial number of observational studies, patients on long-term therapy with prednisone for chronic inflammatory disease, testosterone levels were lower compared to untreated controls, though randomized controlled trials have not been conducted. Similarly decreases in testosterone have been reported in men receiving corticosteroids to minimize transplant rejection; however, most were treated with multiple immunosuppressive medications that may have contributed to this effect. A large number of trials of healthy men treated with corticosteroids have shown some disruption in reproductive hormone levels, but other studies reported no effect. Studies in monkeys, rats (at human equivalent dose), cattle, sheep, and horses have shown endocrine disruption, including low testosterone with dexamethasone treatment. Of the cytostatic immunosuppressives, which have high potential for cellular damage, cyclophosphamide has received the most attention, sometimes lowering sperm counts significantly. Methotrexate may decrease sperm numbers in humans and has significant negative impacts in rodents. Other chemotherapeutic drugs used as immunosuppressants are likely to impact negatively on male fertility endpoints, but few data have been collected. The TNF-α Inhibitors have also received little experimental attention. There is some evidence that the immunophilin modulators: cyclosporine, sirolimus, and everolimus cause endocrine disruption and semen quality impairment. As we review in this chapter, results in experimental species are concerning, and well-designed studies are lacking for the effects of these medications on reproductive endpoints in men.

Genotoxicity of pemetrexed in human peripheral blood lymphocytes

Pemetrexed (PMX) is an antineoplastic antifolate used in the treatment of non-small cell lung cancer, mesothelioma and several types of neoplasms. Its toxicity in tumor cells has been linked with the potent inhibition of thymidylate synthase, dihydrofolate reductase and glycinamide ribonucleotide formyl transferase, and subsequent depletion of both purine and pyrimidine nucleotides. However, cytogenetic toxicity of PMX in non-diseased cells has not been adequately studied; despite the increasing data on the DNA-damaging potential of antineoplastic agents on normal cells. In the present study, the genotoxic potential of PMX was evaluated in peripheral blood lymphocytes obtained from healthy human subjects using chromosome aberration (CA), sister chromatid exchange (SCE) and micronucleus (MN) assays as the cytogenetic damage markers. Human peripheral blood lymphocytes were exposed to four different concentrations (25, 50, 75 and 100 μg/mL) of PMX for 24- and 48-h treatment periods. PMX significantly increased the formation of CA in 24-h treatment, but not in 48-h treatment. PMX did not increase the mean SCE frequency in 24- and 48-h treatment periods; however, there was a striking increase (although not statistically significant, p > 0.05) in the number of SCEs at 25 μg/mL (24- and 48-h treatment) and 50 μg/mL (24-h treatment) due to an increase of SCE at the single-cell level. Interestingly, PMX did not induce MN formation in either 24- or 48-h treatment periods. PMX strongly decreased the mitotic index (MI), proliferation index (PI) and nuclear division index (NDI) in 24- and 48-h treatment periods. Our results suggest that PMX has a potent cytotoxic effect against human peripheral blood lymphocytes at concentrations which are reached in vivo in the blood plasma.

Protective role of taurine against genotoxic damage in mice treated with methotrexate and tamoxfine

The genotoxic actions of anti-neoplastic drugs can lead to the development of secondary cancers in patients in extended remission. One of the most attractive approaches to disease prevention involves the use of natural antioxidants to protect tissue against toxic injury. We investigated the modulatory effects of exogenously administered taurine, on the genotoxicity of two well known anti-neoplastic drugs methotrexate (MTX) and tamoxifen (TAM) in Swiss albino mice. The animals were randomly divided into six groups consisting of ten mice each. Two groups were received single intraperitoneal injection of MTX (10 mg/kgb.wt.) and TAM (50 mg/kgb.wt.) to induce genotoxicity. Two other groups were treated orally with taurine (100 mg/kgb.wt.) for nine days prior to MTX and TAM administration. A vehicle treated control group and taurine control groups were also included. The protective effects of taurine were monitored by apoptosis assays and level of reduced glutathione (GSH), a key antioxidant, in liver, chromosomal aberrations in somatic and germ cells as well as sperm count, motility and morphology. The results indicated that taurine pre-treatment showed significant increment in the levels of GSH content, reduction in DNA fragmentation and ladder formation in hepatic tissue, suggesting the antioxidant activity of taurine may reduce the toxic effects of MTX and TAM. Treatment with taurine showed also significant reduction in the frequency of chromosomal aberrations in both somatic and germ cells. Moreover, it increases sperm count and motility, and decreases the incidence of sperm abnormalities. In conclusion, it appears that taurine protects against anti-neoplastic drugs-induced genotoxicity in somatic and germ tissues and may be of therapeutic potential in alleviating the risk of secondary tumors in chemotherapy.

Methotrexate-induced cytotoxicity and genotoxicity in germ cells of mice: intervention of folic and folinic acid

Methotrexate (MTX) is an anti-metabolite widely used in the treatment of neoplastic disorders, rheumatoid arthritis and psoriasis. The basis for its therapeutic efficacy is the inhibition of dihydrofolate reductase (DHFR), a key enzyme in the folic acid (FA) metabolism. FA is a water-soluble vitamin which is involved in the synthesis of purines and pyrimidines, the essential precursors of DNA. Folinic acid (FNA) is the reduced form of FA that circumvents the inhibition of DHFR. Folate supplementation during MTX therapy for psoriasis and inflammatory arthritis reduces both toxicity and side effects without compromising the efficacy. Further, FNA supplementation reduces the common side effects of MTX in the treatment of juvenile idiopathic arthritis. FA and FNA are reported to have protective effects on MTX-induced genotoxicity in the somatic cells; however their protective effects on the germ cells have not been much explored. Previously, we evaluated the cytotoxic and genotoxic effects of MTX in the germ cells of mice. In the present study, we have intervened FA and FNA for the protection of germ cell toxicity induced by MTX in male swiss mice. The animals were pre-treated with FA at the doses of 50, 100 and 200 microg/kg for 4 consecutive days per week and on day five; MTX was administered at the dose of 20mg/kg once. FNA was administered at the doses of 2.5, 5 and 10 mg/kg, 6 h (h) after single administration of MTX at the dose of 20 mg/kg. The dosing regimen was continued up to 10 weeks. The germ cell toxicity was evaluated using testes weight (wt), sperm count, sperm head morphology, sperm comet assay, histology, TUNEL and halo assay in testis. The results clearly demonstrate that prior administration of FA and post-treatment with FNA reduces the germ cell toxicity induced by MTX as evident from the decreased sperm head abnormalities, seminiferous tubule damage, sperm DNA damage, TUNEL positive cells and increased sperm counts. In the present study, we report that FA and FNA ameliorate the germ cell toxicity of MTX in mice.

Modulation of methotrexate-induced cytogenotoxicity in mouse spermatogonia and its transmission in the male germline by caffeine

Apart from its own controversial cytogenotoxic effects, caffeine (CAF), one of the most commonly consumed alkaloids worldwide, is found potentiative to and so also protective from the cytogenotoxic effects of numerous chemical and physical mutagens. It also has modulated the actions of several antineoplastic agents. Additionally, it has been tested as a chemopreventive of cancer and is reportedly associated inversely with different cancer risks. Therefore, in the present study, three different sub-lethal doses of CAF, 25, 50 and 100mg/kg, were tested in mouse to assess their cytogenotoxic effects on dividing spermatogonia at 24h post-treatment, and transmission of such effects in the male germline from the primary spermatocytes and sperm at week 4 and week 8 post-treatment, respectively. CAF was found to be weakly clastogenic to mouse spermatogonia and the effects were also found transmitted in the male germline. Interestingly, such induced effects were quantitatively related to the dose of CAF tested. On the other hand, methotrexate (MTX), an antifolate antimetabolite, is prescribed frequently for the treatment of various types of cancers. However, MTX is reportedly clastogenic. Modulation of the said three different pre-treated doses of CAF on MTX 10mg/kg-induced cytogenotoxic effects, tested in the same experimental protocol, indicated that CAF pre-treatment was decreasing the MTX-induced clastogenicity in spermatogonia, and was lowering the concurrent transmission of such effects in the male germline of mice, significantly. Such decreases were related to the dose of CAF tested, i.e. higher the dose of CAF more was the decrease in the MTX-induced cytogenotoxic effects and in their transmission. The possible mechanisms that might have caused the manifestation of a weak clastogenic action of CAF on spermatogonia and in its transmission in the male germline, and the CAF modulation of MTX-induced cytogenotoxic effects in spermatogonia and in their transmission have been discussed.

Etoposide-induced cytogenotoxicity in mouse spermatogonia and its potential transmission

As cancer chemotherapeutic agents are cytogenotoxic but not target-specific during systemic treatment, they affect all the encountered cells including the non-cancerous ones and consequently lead to the recurrence of second malignancy in post-chemotherapeutic cancer survivors. The effects would be persistent if the stem cells were affected. These drugs also may affect germline cells during therapeutic treatments. There is every chance that the effects are transmitted through the germline cells to the gametes and to the next generation if the gonadal mother cells are affected. Such transmission of effects from the post-chemotherapeutic childhood cancer survivors is of serious concern but very little attention has been given so far to such studies. Etoposide (VP-16)--a semi-synthetic epipodophyllotoxin derivative, a DNA non-intercalating agent and a topoisomerase II inhibitor--is prescribed frequently for the treatment of various types of cancers. It is a potent clastogen inducing chromosomal damage both in vitro and in vivo. Its clastogenic effect is indirect through inhibition of the catalytic activity of topoisomerase II enzymes, which maintain the topology of DNA during replication, recombination, transcription, etc. by forming a 'cleavable complex' and facilitate the cleaving and re-ligation of the cleaved DNA to relieve the torsional stress during such events. Transient stabilization of the cleavable complex by etoposide leads to illegitimate ligation of the cleaved DNA. Consequently, single- and double-strand breaks occur. In the present study, the clastogenic potential of three different doses of etoposide (10, 15 and 20 mg kg(-1)) in the male germline of mice was assessed from the dividing spermatogonia after a single exposure for one cell cycle duration at 24 h post-treatment. Transmission of such effects was assessed from the frequency of aberrant primary spermatocytes at week 4 post-treatment and of abnormal sperm at week 8 post-treatment. All three doses of etoposide were found to be clastogenic to the dividing spermatogonia of mice, and mostly chromatid breaks were induced. The effects also were transmitted through the male germline of mice, which was evident from the prevalence of statistically significant increased percentages of aberrant primary spermatocytes at week 4 posttreatment and the higher percentages of abnormal sperm at week 8 post-treatment. Thus, there is every chance that the cytogenotoxic effects of etoposide are transmitted to the next generation through the male germline of post-chemotherapeutic cancer survivors, therefore it is essential to make etoposide target-specific or modulate its effects.