Effects of Acute and Chronic Cyclophosphamide Treatment on Meiotic Progression and the Induction of DNA Double-Strand Breaks in Rat Spermatocytes1

Immune-boosting effect of Yookgong-dan against cyclophosphamide-induced immunosuppression in mice

Immune responses must be strictly regulated to prevent autoimmune and infectious diseases and to protect against infectious agents. As people age, their immunity wanes, leading to a decrease in lymphocyte production in bone marrow and thymus and a decline in the efficacy of mature lymphocytes in secondary lymphoid organs. This study explores the immune-boosting potential of Yookgong-dan (YGD) in enhancing the immune system by activating immune cells. In our in vitro experiments, cyclophosphamide (Cy) treatment led to a significant decrease in primary splenocyte viability. However, subsequent treatment with YGD significantly improved cell viability, with doses ranging between 1 and 25 μg/mL in Cy-treated splenocytes. Flow cytometry analysis demonstrated that the Cy group exhibited reduced positivity of CD3+ T cells and CD45+ leukocytes compared to the blank group. In contrast, treatment with YGD led to a notable, dose-responsive increase in these immune cell types. In our in vivo experiments, YGD was orally administered to Cy-induced immunosuppressed mice at 20 and 100 mg/kg doses for 10 days. The results indicated a dose-dependent elevation in immunoglobulin (Ig)G and IgM levels in the serum, emphasizing the immunostimulatory effect of YGD. Furthermore, the Cy-treated group showed decreased T cells, B (CD19+) cells, and leukocytes in the total splenocyte population. Yet, YGD treatment resulted in a dose-dependent reversal of this pattern, suggesting its ability to counter immunosuppression. Notably, YGD was found to effectively stimulate T (CD4+ and CD8+) lymphocyte subsets and natural killer cells, along with enhancing Th1/Th2 cytokines in immunosuppressed conditions. These outcomes correlated with the modulation of BCL-2 and BAX expression, which are critical for apoptosis. In conclusion, YGD has the potential to bolster immune functionality through the activation of immune cells, thereby enhancing the immune system's capacity to combat diseases and improve overall health and wellness.

Research progress on the role and mechanism of DNA damage repair in germ cell development

In the complex and dynamic processes of replication, transcription, and translation of DNA molecules, a large number of replication errors or damage can occur which lead to obstacles in the development process of germ cells and result in a decreased reproductive rate. DNA damage repair has attracted widespread attention due to its important role in the maintenance and regulation of germ cells. This study reports on a systematic review of the role and mechanism of DNA damage repair in germline development. First, the causes, detection methods, and repair methods of DNA damage, and the mechanism of DNA damage repair are summarized. Second, a summary of the causes of abnormal DNA damage repair in germ cells is introduced along with common examples, and the relevant effects of germ cell damage. Third, we introduce the application of drugs related to DNA damage repair in the treatment of reproductive diseases and related surgical treatment of abnormal DNA damage, and summarize various applications of DNA damage repair in germ cells. Finally, a summary and discussion is given of the current deficiencies in DNA damage repair during germ cell development and future research development. The purpose of this paper is to provide researchers engaged in relevant fields with a further systematic understanding of the relevant applications of DNA damage repair in germ cells and to gain inspiration from it to provide new research ideas for related fields.

Hematopoietic Effects of Angelica gigas Nakai Extract on Cyclophosphamide-Induced Myelosuppression

Myelosuppression is a major adverse effect of chemotherapy. With the increasing number of cancer patients worldwide, there is a growing interest in therapeutic approaches that reduce the adverse effects of chemotherapy. Angelica gigas Nakai (AGN) roots have been widely used in oriental medicine to treat blood-related diseases, including cancer. However, the effects of AGN on myelosuppression have not been studied. Here, we investigated the effects of AGN ethanol extract (AGNEX) on cyclophosphamide-induced myelosuppression. AGNEX treatment significantly decreased white blood cell levels while increasing red blood cell and platelet levels in the peripheral blood. It inhibited thymus and spleen atrophy. It also enhanced serum levels of interleukin (IL)-6 and tumor necrosis factor (TNF)-α. qRT-PCR results showed that AGNEX decreased the expression of IL-1b and stem cell factor (SCF) in the bone marrow (BM) while increasing the mRNA expression of IL-3 and IL-6 in the spleen. Although AGNEX did not significantly decrease apoptosis and cell cycle arrest in the BM and splenocytes, AGNEX plays a positive role in cyclophosphamide-induced myelosuppression. AGNEX administration increased BM cells in the femur while decreasing apoptotic BM cells. These findings suggest that AGNEX could be used to treat myelosuppression and as a combination therapy in cancer patients.

Cyclophosphamide-induced GPX4 degradation triggers parthanatos by activating AIFM1

Cyclophosphamide is an alkylating agent used to treat a variety of cancers, including leukemia. Here, we show a previously unrecognized role of cyclophosphamide in triggering the protein degradation of glutathione peroxidase 4 (GPX4), a phospholipid hydroperoxidase that protects cells from oxidative damage. Mechanistically, we found that the ubiquitin-proteasome system, but not autophagy, mediates cyclophosphamide-induced degradation of GPX4 in human leukemia cell lines. Surprisingly, cyclophosphamide-induced degradation of GPX4 leads to caspase-independent parthanatos, but not lipid peroxidation-mediated ferroptosis, through the nuclear translocation of apoptosis-inducing factor mitochondria-associated 1 (AIFM1). Consequently, the overexpression of GPX4 or the knockdown of AIFM1 limits the anticancer activity of cyclophosphamide in vitro and in xenograft tumor models. These findings establish a new framework for understanding the central role of GPX4 in blocking oxidative cell death.

Curcumin nanocrystals attenuate cyclophosphamide-induced testicular toxicity in mice

The cancer therapy using cyclophosphamide (CP) has been associated with adverse effects on the testicular function that raises concerns about the future fertility potential among cancer survivors. Curcumin, a polyphenol, has shown to possess a plethora of biological functions including tissue protective effects. In the present study, we investigated the protective effects of curcumin nanocrystals (NC) in mitigation of CP-induced testicular toxicity. Healthy adult (8-10 week) and prepubertal (2 week) male Swiss albino mice were injected with a single dose of CP (200 mg/kg) intraperitoneally (i.p). NC (4 mg/kg, i.p.) was administered every alternate day, for 35 days in adult mice while, a single dose of NC was injected intraperitoneally to prepubertal mice 1 h prior to CP. Administration of multiple doses of NC ameliorated CP-induced testicular toxicity in adult mice, which was evident from the improved sperm functional competence, sperm chromatin condensation, seminiferous tubule architecture and decreased apoptosis in testicular cells. Further, administration of NC 1 h prior to CP in prepubertal mice modulated the expression of genes pertaining to proliferation, pluripotency, DNA damage and DNA repair in spermatogonial cells at 24 h after the treatment. Overall, these results suggest that NC could be a promising chemoprotective agent, which can have potential application in male fertility preservation.

Evaluation of mutagenic and anti-mutagenic potential of alpha-lipoic acid by chromosomal aberration assay in mice

This study investigated both the mutagenicity and anti-mutagenicity of alpha-lipoic acid (ALA) in the bone marrow cells of mice using a chromosomal aberration assay. Cyclophosphamide (CP) 40 mg/kg was used as a clastogen in the positive control, and a vehicle-treated negative control group was also included. Multiple dose levels (15, 30, and 100 mg/kg of ALA) were given by intraperitoneal injection (IP) alone and in combination with CP (CP was administered 1 h prior to ALA). Bone marrow samples were collected 12 and 24 h after drug administration. The results demonstrated a significant increase in the frequency of chromosomal aberrations (CA) in bone marrow cells with depressions in the mitotic index (MI) of the positive control group of mice. However, in the groups of mice treated with different doses of ALA in the presence of CP, the percentages of CA decreased significantly with increases in mitotic activity. The results also indicate that ALA given alone in different doses had no mutagenic effect on mouse bone marrow cells. ALA has a dose and time-dependent protective effect against the mutagenicity induced by CP.

Genotoxic and mutagenic studies of teratogens in developing rat and mouse

In this review, genotoxic and mutagenic effects of teratogenic chemical agents in both rat and mouse have been reviewed. Of these chemicals, 97 are drugs and 33 are pesticides or belong to other groups. Large literature searches were conducted to determine the effects of chemicals on chromosome abnormalities, sister chromatid exchanges, and micronucleus formation in experimental animals such as rats and mice. In addition, studies that include unscheduled DNA synthesis, DNA adduct formations, and gene mutations, which help to determine the genotoxicity or mutagenicity of chemicals, have been reviewed. It has been estimated that 46.87% of teratogenic drugs and 48.48% of teratogenic pesticides are positive in all tests. So, all of the teratogens involved in this group have genotoxic and mutagenic effects. On the other hand, 36.45% of the drugs and 21.21% of the pesticides have been found to give negative results in at least one test, with the majority of the tests giving positive results. However, only 4.16% of the drugs and 18.18% of the pesticides were determined to give negative results in the majority of the tests. Among tests with major negative results, 12.50% of the teratogenic drugs and 12.12% of the teratogenic pesticides were negative in all conducted tests.

A Potential Adjuvant Agent of Chemotherapy: Sepia Ink Polysaccharides

Sepia ink polysaccharide (SIP) isolated from squid and cuttlefish ink is a kind of acid mucopolysaccharide that has been identified in three types of primary structures from squid (Illex argentinus and Ommastrephes bartrami), cuttlefish Sepiella maindroni, and cuttlefish Sepia esculenta ink. Although SIP has been proved to be multifaceted, most of the reported evidence has illuminated its chemopreventive and antineoplastic activities. As a natural product playing a role in cancer treatment, SIP may be used as chemotherapeutic ancillary agent or functional food. Based on the current findings on SIP, we have summarized four topics in this review, including: chemopreventive, antineoplastic, chemosensitive, and procoagulant and anticoagulant activities, which are correlative closely with the actions of anticancer agents on cancer patients, such as anticancer, toxicity and thrombogenesis, with the latter two actions being common causes of death in cancer cases exposed to chemotherapeutic agents.

Classification of in vitro genotoxicants using a novel multiplexed biomarker assay compared to the flow cytometric micronucleus test

Regulatory in vitro genotoxicity testing exhibits shortcomings in specificity and mode of action (MoA) information. Thus, the aim of this work was to evaluate the performance of the novel MultiFlow^® assay composed of mechanistic biomarkers quantified in TK6 cells after treatment (4 and 24 hr): γH2AX (DNA double strand breaks), phosphorylated H3 (mitotic cells), translocated p53 (genotoxicity), and cleaved PARP1 (apoptosis). A reference dataset of 31 compounds with well-established MoA was studied using the MicroFlow^® micronucleus assay. A positive call was raised following the earlier published criteria from Litron Laboratories. In the light of our data, these evaluation criteria should probably be adjusted since only 8/11 (73%) nongenotoxicants and 18/20 (90%) genotoxicants were correctly identified. Moreover, there is a need for new in vitro tools to delineate the predominant MoA as in the MicroFlow^® assay only 5/9 (56%) aneugens and 4/11 (36%) clastogens were correctly classified. In contrast, the MultiFlow^® assay provides more in-depth information about the MoA and therefore reliably discriminates clastogens, aneugens, and nongenotoxicants. By using a lab-specific, practical threshold for the aforementioned biomarkers, 10/11 (91%) nongenotoxicants and 19/20 genotoxicants (95%), 9/11 (82%) clastogens, and 8/9 (89%) aneugens were correctly categorized, suggesting a clear improvement over the MicroFlow^® . Furthermore, the MultiFlow markers were benchmarked against established methods to assess the validity of the data. Altogether, these findings demonstrated good agreement between the MultiFlow^® assay and the benchmarking methods. Finally, p21 may improve class discrimination given the correct identification of 4/4 (100%) aneugens and 2/5 (40%) clastogens. Environ. Mol. Mutagen. 58:662-677, 2017. © 2017 Wiley Periodicals, Inc.

Inhibition of chemotherapy-induced apoptosis of testicular cells by squid ink polysaccharide

The aim of this study was to determine the mechanisms driving the protective effects of squid ink polysaccharide (SIP) against cyclophosphamide (CP)-induced testicular damage, focusing on germ cells. In the testes of mice exposed to CP and/or SIP, the present study examined the levels of reactive oxygen species (ROS) and malondialdehyde, activity of superoxide dismutase levels, protein expression levels of B-cell lymphoma 2 (Bcl2), Bcl2-associated X protein (Bax), and total Caspase 3, activation of p-p38 and p-Akt proteins, and tissue morphology. The findings indicated that CP induced ROS production and oxidative stress, resulting in testicular damage. However, under administration of SIP, oxidative stress was impaired and the testicular toxicity induced by CP was weakened, which implied that SIP may have an important role in preventing chemotherapeutic damage to the male reproductive system via promoting antioxidant ability. Furthermore, the altered expression levels, including the upregulation of Bax and Caspase 3, downregulation of Bcl-2 and the increased Bax/Bcl-2 ratio, indicated that apoptosis occurred in CP exposed testes of mice; however, the alterations were reversed in mice treated with SIP. Moreover, in CP-exposed testes, p38 and Akt proteins were significantly phosphorylated (P<0.05), whereas in the testes of mice co-treated with SIP and CP, phosphorylation of the two proteins was inhibited, demonstrating that the two signalling pathways participated in the regulative processes of the deleterious effects caused by CP, and the preventive effects SIP mediated.

Zinc Transport Differs in Rat Spermatogenic Cell Types and Is Affected by Treatment with Cyclophosphamide

Adequate zinc levels are required for proper cellular functions and for male germ cell development. Zinc transport is accomplished by two families of zinc transporters, the ZIPs and the ZnTs, that increase and decrease cytosolic zinc levels, respectively. However, very little is known about zinc transport in the testis. Furthermore, whether cytotoxic agents such as cyclophosphamide (CPA), a known male germ cell toxicant, can affect zinc transport and homeostasis is unknown. We examined zinc transporter expression and zinc transport in pachytene spermatocytes (PS) and round spermatids (RS) in a normal state and after exposure to CPA. We observed differences in the expression of members of the ZnT and ZIP families in purified populations of PS and RS. We also observed that RS accumulate more zinc over time than PS. The expression of many zinc binding genes was altered after CPA treatment. Interestingly, we found that the expression levels of ZIP5 and ZIP14 were increased in PS from animals treated daily with 6 mg/kg CPA for 4 wk but not in RS. This up-regulation led to an increase in zinc uptake in PS but not in RS from treated animals compared to controls. These data suggest that CPA treatment may alter zinc homeostasis in male germ cells leading to an increased need for zinc. Altered zinc homeostasis may disrupt proper germ cell development and contribute to infertility and effects on progeny.

Evaluation of lemon fruit extract as an antioxidant agent against histopathological changes induced by cyclophosphamide in the testes of albino mice

Introduction

The aim of this study was to determine the protective effects of lemon fruit extracts (LFE) against histopathological changes induced in the testes of male mice treated with cyclophosphamide (CP).

Methods

Thirty male mice were divided evenly into six groups: 1) group 1: the controls, 2) group 2: treated with LFE (10 ml/kg b wt.), 3) group 3: treated with CP (10 mg/kg b wt.), 4) group 4: treated with CP (20 mg/kg b wt.), 5) group 5: treated with LFE (10 ml/kg) + CP (10 mg/kg), 6) group 6: treated with LFE (10 ml/kg) + CP (20 mg/kg).

Results

Histological examination of the testes of mice treated with CP revealed histopathological changes, such as atrophy, degeneration, incomplete spermatogenic series in most seminiferous tubules, and spermatogenic necrosis with pyknotic nuclei. Advanced degree of improvement was seen in testes of mice treated with LFE co-administered with CP. Most of the seminiferous tubules restored their normal structure and spermatogenic layers appeared semi-normal with complete spermatogenic series.

Conclusion

Lemon fruit extract in conjunction with drug treatment protects the testicular tissue against CP-induced testicular injury in mice.

Evaluating γH2AX in spermatozoa from male infertility patients

OBJECTIVE

To investigate whether γH2AX levels were different in the spermatozoa of healthy men compared with infertility patients, and to assess the possible correlations between γH2AX and conventional semen parameters and double-stranded breaks (DSBs) identified with the use of comet assay.

DESIGN

Prospective study.

SETTING

Clinical laboratory.

PATIENT(S)

Semen from 100 male infertile patients and 100 healthy sperm donors.

INTERVENTION(S)

Human sperm samples were analyzed in terms of World Health Organization parameters. The γH2AX levels were detected by means of flow cytometry. DSBs of sperm were detected by means of comet assay. Morphology slides were made and the sperm morphology assessed according to strict criteria.

MAIN OUTCOME MEASURE(S)

Conventional semen analyses, γH2AX levels in sperm, DNA DSBs in sperm, and correlations among γH2AX, conventional semen analyses, and DSBs.

RESULT(S)

Concentration, viability, motility, and normal sperm morphology were significantly lower in male infertility patients compared with healthy men. Also, γH2AX levels and the number of DSBs were significantly higher in the sperm of infertile subjects compared with healthy men. γH2AX levels correlated negatively with conventional semen parameters and positively with DSBs. A threshold γH2AX level of 18.55% was identified as a cutoff value to discriminate infertile subjects from fertile control subjects with a specificity of 86.0% and a sensitivity of 83.0%. The positive and negative predictive values of the 18.55% γH2AX threshold were high: 87.7% and 85.5%, respectively.

CONCLUSION(S)

γH2AX levels were higher in the sperm of male infertility patients than in healthy men. γH2AX levels in sperm, as evaluated with the use of flow cytometry, might be a useful biomarker for evaluating DSBs in human spermatozoa.

Protective effect of diallyl disulfide on cyclophosphamide-induced testicular toxicity in rats

This study investigated the protective effects of diallyl disulfide (DADS) against cyclophosphamide (CP)-induced testicular toxicity in male rats. DADS was gavaged to rats once daily for 3 days at 100 mg/kg/day. One hour after the final DADS treatment, the rats were given a single intraperitoneal dose of 150 mg/kg CP. All rats were killed and necropsied on day 56 after CP treatment. Parameters of testicular toxicity included reproductive organ weight, testicular sperm head count, epididymal sperm motility and morphology, epididymal index, and histopathologic examinations. The CP treatment caused a decrease in body weight, testicular sperm head count, epididymal sperm motility, and epididymal index. The histopathological examination revealed various morphological alterations, characterized by degeneration of spermatogonia/spermatocytes, vacuolization, and decreased number of spermatids/spermatocytes in the testis, and cell debris and mild oligospermia in the ductus epididymis. In contrast, DADS pretreatment effectively attenuated the testicular toxicity caused by CP, including decreased sperm head count, epididymal sperm motility, and epididymal index and increased histopathological alterations in the testis and epididymis. These results indicate that DADS attenuates testicular toxicity induced by CP in rats.

Effects of multiple doses of cyclophosphamide on mouse testes: accessing the germ cells lost, and the functional damage of stem cells

Spermatogenesis is sensitive to the chemotherapeutic drug cyclophosphamide, which decreases the patients' sperm count. Since the recovery of fertility is dependent on regeneration from stem cells, in the present study we evaluated the ability of cyclophosphamide-exposed stem spermatogonia from mice to regenerate spermatogenesis in situ and after transplantation. When seven doses of cyclophosphamide were given at 4-day intervals, the differentiating germ cells were largely eliminated but ~50% of the undifferentiated type A spermatogonia remained. We monitored the recovery and found that sperm production recovered to 64% of control within the time expected. When the cyclophosphamide-surviving spermatogonia were transplanted into recipient mice, recovery of spermatogenesis from the cyclophosphamide-exposed donor cells was observed, but was reduced when compared to cells from cryptorchid donors. Thus, multidose regimens of cyclophosphamide did not eliminate the stem spermatogonia, but resulted in cell loss and residual damage.

Detection of DNA damage in oocytes of small ovarian follicles following phosphoramide mustard exposures of cultured rodent ovaries in vitro

Healthy oocytes are critical for producing healthy children, but little is known about whether or not oocytes have the capacity to identify and recover from injury. Using a model ovotoxic alkylating drug, cyclophosphamide (CPA), and its active metabolite, phosphoramide mustard (PM), we previously showed that PM (≥3μM) caused significant follicle loss in postnatal day 4 (PND4) mouse ovaries in vitro. We now investigate whether PM induces DNA damage in oocytes, examining histone H2AX phosphorylation (γH2AX), a marker of DNA double-strand breaks (DSBs). Exposure of cultured PND4 mouse ovaries to 3 and 0.1μM PM induced significant losses of primordial and small primary follicles, respectively. PM-induced γH2AX was observed predominantly in oocytes, in which foci of γH2AX staining increased in a concentration-dependent manner and peaked 18-24h after exposure to 3-10μMPM. Numbers of oocytes with ≥5 γH2AX foci were significantly increased both 1 and 8days after exposure to ≥1μMPM compared to controls. Inhibiting the kinases that phosphorylate H2AX significantly increased follicle loss relative to PM alone. In adult mice, CPA also induced follicle loss in vivo. PM also significantly decreased primordial follicle numbers (≥30μM) and increased γH2AX foci (≥3μM) in cultured PND4 Sprague-Dawley rat ovaries. Results suggest oocytes can detect PM-induced damage at or below concentrations which cause significant follicle loss, and there are quantitative species-specific differences in sensitivity. Surviving oocytes with DNA damage may represent an increased risk for fertility problems or unhealthy offspring.

Antiperoxidative and anti-apoptotic effects of lycopene and ellagic acid on cyclophosphamide-induced testicular lipid peroxidation and apoptosis

The present study was conducted to investigate the possible protective effects of lycopene (LC) and ellagic acid (EA) on cyclophosphamide (CP)-induced testicular and spermatozoal toxicity associated with the oxidative stress and apoptosis in male rats. Forty-eight healthy adult male Sprague-Dawley rats were divided into six groups of eight rats each. The control group was treated with placebo; the LC, EA and CP groups were given LC (10 mg kg–1), EA (2 mg kg–1) and CP (15 mg kg–1), respectively, alone; the CP+LC group was treated with a combination of CP (15 mg kg–1) and LC (10 mg kg–1); and the CP+EA group was treated with a combination of CP (15 mg kg–1) and EA (2 mg kg–1). All treatments were maintained for 8 weeks. At the end of the treatment period, bodyweight and the weight of the reproductive organs, sperm concentration and motility, testicular tissue lipid peroxidation, anti-oxidant enzyme activity and apoptosis (i.e. Bax and Bcl-2 proteins) were determined. Administration of CP resulted in significant decreases in epididymal sperm concentration and motility and significant increases in malondialdehyde levels. Although CP significantly increased the number of Bax-positive (apoptotic) cells, it had no effect on the number of Bcl-2-positive (anti-apoptotic) cells compared with the control group. However, combined treatment of rats with LC or EA in addition to CP prevented the development of CP-induced lipid peroxidation and sperm and testicular damage. In conclusion, CP-induced lipid peroxidation leads to structural and functional damage, as well as apoptosis, in spermatogenic cells of rats. Both LC and EA protect against the development of these detrimental effects.

Previous maternal chemotherapy by cyclophosphamide (Cp) causes numerical chromosome abnormalities in preimplantation mouse embryos

This study investigated the consequences of maternal cyclophosphamide treatment on fertilization rate, development and chromosomal integrity of embryos. It also evaluated efficiency of two methods of classic and metaphase induction for chromosomes assessment. Two different groups of NMRI mice 2-3 weeks and 6-7 weeks were injected intraperitonealy with 75 mg cyclophosphamide/kg. Six weeks later, oocytes were recovered, fertilized and incubated for 3 days in 5% CO(2) in air. Eight to 10 cell stage embryos were subjected to chromosomal study. Cyclophosphamide in both experimental groups reduced the oocyte fertilization rate and in the 6-7 weeks group it was significantly lower compared with control group (P<0.01). Also there was a reduction in 8-cell stage embryos formation from 48 to 72 h post-fertilization in both treated groups (P<0.05). Aneuploidy increased in the treatment groups compared with controls, which in the older group was significant (P<0.001). The success rate of the classic method to analyze metaphase plates was 30.1% and the success rate of heterokaryons formation with analyzable chromosomes was 67.8% in the metaphase induction method. In regards to the adverse effects of cyclophosphamide on fertilization rate, embryo development and chromosomal integrity of the mouse embryos, using Preimplantation Genetic Diagnosis in addition to Assisted Reproductive Technique is suggested.

Adriamycin induces H2AX phosphorylation in human spermatozoa

AIM

To investigate whether adriamycin induces DNA damage and the formation of gammaH2AX (the phosphorylated form of histone H2AX) foci in mature spermatozoa.

METHODS

Human spermatozoa were treated with adriamycin at different concentrations. gammaH2AX was analyzed by immunofluorescent staining and flow cytometry and double-strand breaks (DSB) were detected by the comet assay.

RESULTS

The neutral comet assay revealed that the treatment with adriamycin at 2 microg/mL for different times (0.5, 2, 8 and 24 h), or for 8 h at different concentrations (0.4, 2 and 10 microg/mL), induced significant DSB in spermatozoa. Immunofluorent staining and flow cytometry showed that the expression of gH2AX was increased in a dose-dependent and time-dependant manner after the treatment of adriamycin. Adriamycin also induced the concurrent appearance of DNA maintenance/repair proteins RAD50 and 53BP1 with gammaH2AX in spermatozoa. Wortmannin, an inhibitor of the phosphatidylinositol 3-kinase (PI3K) family, abolished the co-appearance of these two proteins with gammaH2AX.

CONCLUSION

Human mature spermatozoa have the same response to DSB-induced H2AX phosphorylation and subsequent recruitment of DNA maintenance/repair proteins as somatic cells.

Dynamic Regulation of Histone H3 Methylation at Lysine 4 in Mammalian Spermatogenesis1

Spermatogenesis is a highly complex cell differentiation process that is governed by unique transcriptional regulation and massive chromatin alterations, which are required for meiosis and postmeiotic maturation. The underlying mechanisms involve alterations to the epigenetic layer, including histone modifications and incorporation of testis-specific nuclear proteins, such as histone variants and protamines. Histones can undergo methylation, acetylation, and phosphorylation among other modifications at their N-terminus, and these modifications can signal changes in chromatin structure. We have identified the temporal and spatial distributions of histone H3 mono-, di-, and trimethylation at lysine 4 (K4), and the lysine-specific histone demethylase AOF2 (amine oxidase flavin-containing domain 2, previously known as LSD1) during mammalian spermatogenesis. Our results reveal tightly regulated distributions of H3-K4 methylation and AOF2, and that H3-K4 methylation is very similar between the mouse and the marmoset. The AOF2 protein levels were found to be higher in the testes than in the somatic tissues. The distribution of AOF2 matched the cell- and stage-specific patterns of H3-K4 methylation. Interaction studies revealed unique epigenetic regulatory complexes associated with H3-K4 methylation in the testis, including the association of AOF2 and methyl-CpG-binding domain protein 2 (MBD2a/b) in a complex with histone deacetylase 1 (HDAC1). These studies enhance our understanding of epigenetic modifications and their roles in chromatin organization during male germ cell differentiation in both normal and pathologic states.

DNA damage recognition in the rat zygote following chronic paternal cyclophosphamide exposure

The detrimental effects of preconceptional paternal exposure to the alkylating anticancer agent, cyclophosphamide, include aberrant epigenetic programming, dysregulated zygotic gene activation, and abnormalities in the offspring that are transmitted to the next generation. The adverse developmental consequences of genomic instabilities transmitted via the spermatozoon emphasize the need to elucidate the mechanisms by which the early embryo recognizes DNA damage in the paternal genome. Little information exists on DNA damage detection in the zygote. We assessed the impact of paternal cyclophosphamide exposure on phosphorylated H2AX (gammaH2AX) and poly(ADP-ribose) polymerase-1(PARP-1), biomarkers of DNA damage, to determine the capacity in the rat zygote to recognize genomic damage and initiate a response to DNA lesions. An amplified biphasic gammaH2AX response was triggered in the paternal pronucleus in zygotes sired by drug-treated males; the maternal genome was not affected. PARP-1 immunoreactivity was substantially elevated in both parental genomes, coincident with the second phase of gammaH2AX induction in embryos sired by cyclophosphamide-exposed spermatozoa. Thus, paternal exposure to a DNA damaging agent rapidly activates signals implemental for DNA damage recognition in the zygote. Inefficient repair of DNA lesions may lead to persistent alterations of the histone code and chromatin integrity, resulting in aberrant embryogenesis. We propose that the response of the early embryo to disturbances in spermatozoal genomic integrity plays a vital role in determining its outcome.

Oxidative stress induces H2AX phosphorylation in human spermatozoa

H2AX phosphorylation occurs following the induction of DNA double strand breaks (DSBs), thus collaborating with many other proteins to mediate important biological functions in somatic cells. In human spermatozoa, the present study showed that H(2)O(2) induced H2AX phosphorylation in a time- and dose-dependent manner. Moreover, such effect could be abolished by the phosphatidylinositol 3-kinase inhibitor wortmannin. Meanwhile, the neutral comet assay also revealed DSBs production in correlation with H2AX phosphorylation assessed by flow cytometry. Besides H2AX phosphorylation, two other collaborating proteins, Rad50 and 53BP1, were also generated in spermatozoa after H(2)O(2) exposure. However, unlike in somatic FL cells, there were no distinctive focuses, but rather a whole nuclei staining pattern of these three proteins in spermatozoa. Additionally, gammaH2AX (the phosphorylated form of H2AX) staining in spermatozoa persisted despite the fact of a decrease in the number of gammaH2AX foci in FL cells after H(2)O(2) removal. Collectively, these results demonstrate that oxidative stress can induce H2AX phosphorylation in human spermatozoa through DSB induction, and that gammaH2AX may be used as a sensitive, novel marker for such DSBs. Moreover, the surveillance system involving gammaH2AX, Rad50, and 53BP1 in human spermatozoa cannot function effectively in DNA repair, but this system may possess other biological functions in response to DSBs.

Cyclophosphamide treatment causes impairment of sperm and its fertilizing ability in mice

This study is focused on the toxicological effect of cyclophosphamide on male mice reproductive system. In the present study, cyclophosphamide was injected intraperitoneally (ip) at the level of 50-200mg/kg body weight into 6-weeks old ICR male mice once in a week for a period of 5 weeks. The animals were sacrificed after 1st and 5th week of last injection. Reduction in weight of testis and epididymis were observed both in 1st and 5th week group mice after administration with increasing concentration of cyclophosphamide. The weight of the body significantly decreased in both 1st and 5th week group in mice treated with 200mg/kg cyclophosphamide. The weight of the testis significantly decreased with all doses of cyclophosphamide in 1st week group, whereas, in 5th week group significant reduction was observed only in 200mg/kg dose of cyclophosphamide. The sperm motility was analyzed with Computer-Assisted Sperm Analysis (CASA). The motility of caudal sperm decreased with increasing concentration of cyclophosphamide in the 1st week group, whereas, it revived after 5th week. The total sperm counts in the epididymis of 1st week group mice declined significantly while significant restoration of the same was observed with mice treated with 50,100 and 150 mg/kg doses in the 5th week group. The intact acrosome was lower with 150 and 200mg/kg doses in both 1st and 5th week group. The live sperm was reduced to 29% in mice treated with 200mg/kg in the 5th week group. The decrease in the pregnancy rate of female mice was 17, 50, 58 and 100% when mated with male mice injected with 50, 100, 150 and 200mg/kg dose, respectively. Seminiferous tubules of mouse testis were severely damaged in the 1st week group. However, reinstate of sperm within the seminiferous tubules was observed in the 5th week group mice. Significant decrease in serum luteinizing hormone (LH) was observed in the 1st week group treated with 50, 100, 150 and 200mg/kg dose of cyclophosphamide. However, no significant difference was observed in the serum follicle-stimulating hormone (FSH), whereas, a decrease of about 98% in serum testosterone level was observed in cyclophosphamide treated mice. The decrease in the mean testosterone levels of cyclophosphamide treated mice served as proof for the damage of testis. These results demonstrate that cyclophosphamide caused temporary interference of normal male reproductive system with low dose treatment, but might be permanent dysfunction in high dose treatment.