Amifostine protection against mitomycin-induced chromosomal breakage in fanconi anaemia lymphocytes

Heterozygous FMN2 missense variant found in a family case of premature ovarian insufficiency

Background

Premature ovarian insufficiency (POI) plagues 1% of women under 40, while quite a few remain an unknown cause. The development of sequencing has helped find pathogenic genes and reveal the relationship between DNA repair and ovarian reserve. Through the exome sequencing, our study targets screening out the possible POI pathogenic gene and variants in a Chinese family and 20 sporadic POI patients, preliminarily exploring the functional impact and finding out potential linkages between the gene and POI.

Results

The whole exome sequencing suggested a novel FMN2 heterozygous variant c.1949C > T (p.Ser650Leu) carried by all three patients in a Chinese family and another c.1967G > A(p.Arg656His) variant in a sporadic case. Since no FMN2 missense mutation is reported for causing human POI, we preliminarily assessed p.Ser650Leu variant via cross-species alignment and 3D modeling and found it possibly deleterious. A series of functional evidence was consistent with our hypothesis. We proved the expression of FMN2 in different stages of oocytes and observed a statistical difference of chromosomal breakages between the POI patient carrying p.Arg656His variant and the health control (p = 0.0013). Western Blot also suggested a decrease in FMN2 and P21 in the mutant type and an associated increase in H2AX. The p.Arg656His variant with an extremely low frequency also indicated that the gene FMN2 might play an essential role in the genetic etiology of POI. To the best of our knowledge, this is the first POI report on missense variants of FMN2.

Conclusion

This finding indicates a novel gene possibly related to POI and sheds lights on the study of FMN2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13048-022-00960-y.

Lymphopenia and intratumoral lymphocytic balance in the era of cancer immuno-radiotherapy

INTRODUCTION

The immune response has been recognized as a major tumor-eradication component of radiotherapy.

OBJECTIVE

This review studies, under a clinical perspective, two contrasting effects of radiotherapy, namely immunosuppression and radiovaccination.

MATERIALS AND METHODS

We critically reviewed the available clinical and experimental experience on radiotherapy-induced lymphopenia.

RESULTS

Radiation-induced tumor damage promotes radio-vaccination, enhances cytotoxic immune responses, and potentiates immunotherapy. Nevertheless, radiotherapy induces systemic and intratumoral lymphopenia. The above effects are directly related to radiotherapy fractionation and field size/location, and tumor characteristics.

DISCUSSION

Hypofractionated stereotactic and accelerated irradiation better promotes radio-vaccination and produces less severe lymphopenia. Adopting cytoprotective policies and combining lympho-stimulatory agents or agents blocking regulatory lymphocyte activity are awaited to unmask the radio-vaccination effect, enhancing the efficacy immuno-radiotherapy.

CONCLUSION

Radiation-induced lymphopenia and immunosuppression are important issues that should be considered in the design of immuno-radiotherapy clinical trials.

Diagnosis of Fanconi Anaemia by ionising radiation- or mitomycin C-induced micronuclei

Fanconi Anaemia (FA) is an autosomal recessive disorder characterised by defects in DNA repair, associated with chromosomal instability and cellular hypersensitivity to DNA cross-linking agents such as mitomycin C (MMC). The FA repair pathway involves complex DNA repair mechanisms crucial for genomic stability. Deficiencies in DNA repair genes give rise to chromosomal radiosensitivity. FA patients have shown increased clinical radiosensitivity by exhibiting adverse normal tissue side-effects. The study aimed to investigate chromosomal radiosensitivity of homozygous and heterozygous carriers of FA mutations using three micronucleus (MN) assays. The G0 and S/G2MN assays are cytogenetic assays to evaluate DNA damage induced by ionising radiation in different phases of the cell cycle. The MMC MN assay detects DNA damage induced by a crosslinking agent in the G0 phase. Patients with a clinical diagnosis of FA and their parents were screened for the complete coding region of 20 FA genes. Blood samples of all FA patients and parents were exposed to ionising radiation of 2 and 4Gy. Chromosomal radiosensitivity was evaluated in the G0 and S/G2 phase. Most of our patients were homozygous for the founder mutation FANCG c.637_643delTACCGCC; p.(Tyr213Lysfs*6) while one patient was compound heterozygous for FANCG c.637_643delTACCGCC and FANCG c.1379G > A, p.(Gly460Asp), a novel missense mutation. Another patient was compound heterozygous for two deleterious FANCA mutations. In FA patients, the G0- and S/G2-MN assays show significantly increased chromosomal radiosensitivity and genomic instability. Moreover, chromosomal damage was significantly elevated in MMC treated FA cells. We also observed an increase in chromosomal radiosensitivity and genomic instability in the parents using 3 assays. The effect was significant using the MMC MN assay. The MMC MN assay is advantageous as it is less labour intense, time effective and has potential as a reliable alternative method for detecting FA patients from parents and controls.

Two New Faces of Amifostine: Protector from DNA Damage in Normal Cells and Inhibitor of DNA Repair in Cancer Cells

Amifostine protects normal cells from DNA damage induction by ionizing radiation or chemotherapeutics, whereas cancer cells typically remain uninfluenced. While confirming this phenomenon, we have revealed by comet assay and currently the most sensitive method of DNA double strand break (DSB) quantification (based on γH2AX/53BP1 high-resolution immunofluorescence microscopy) that amifostine treatment supports DSB repair in γ-irradiated normal NHDF fibroblasts but alters it in MCF7 carcinoma cells. These effects follow from the significantly lower activity of alkaline phosphatase measured in MCF7 cells and their supernatants as compared with NHDF fibroblasts. Liquid chromatography-mass spectrometry confirmed that the amifostine conversion to WR-1065 was significantly more intensive in normal NHDF cells than in tumor MCF cells. In conclusion, due to common differences between normal and cancer cells in their abilities to convert amifostine to its active metabolite WR-1065, amifostine may not only protect in multiple ways normal cells from radiation-induced DNA damage but also make cancer cells suffer from DSB repair alteration.

Synthesis of novel tetrahydrobenzazepine derivatives and their cytoprotective effect on human lymphocytes

Cytoprotective compounds such as amifostine play an important role in chemo- and radiotherapy due to their ability to reduce the side effects of these treatments. Our work was initiated with the intention to design, synthesise and test a new class of heterocyclic compounds that would have an antioxidative profile with the potential to be further developed as cytoprotective agents. The design was based on the privileged tetrahydrobenzazepine scaffold found in many natural products with a wide range of biological properties. This structure was further functionalised with moieties known to possess antioxidative features such as tertiary amine and styrene double bond. A series of eight tetrahydrobenzazepine derivatives of isoquinoline, 3,4-dihydro-β-carboline and pyridine were synthesised employing the Heck reaction as a key transformation. Some of the prepared compounds were tested for their in vitro effects on chromosome aberrations in peripheral human lymphocytes using the cytochalasin-B blocked micronucleus (MN) assay. Three tetrahydrobenzoazepine derivatives showed significant cytoprotective properties, comparable or even better to those of the radioprotective agent amifostine.

The influence of amifostine administration prior to cyclophosphamide on in vitro maturation of mouse oocytes

PURPOSE

The protective effect of amifostine against cyclophosphamide (CP) was evaluated on mouse oocytes.

MATERIALS AND METHODS

Female mice were divided into four groups as follows: group1: cyclophosphamide (CP) (75 mg/kg, i.p) injection, group2: amifostine (250 mg/kg, i.p) injection, group3: amifostine (250 mg/kg, i.p) administered prior to CP (75 mg/kg, i.p) injection, Control group with injection of saline. About 21 days after injection, in vitro maturation (IVM) of oocytes was recorded. Furthermore the percentage of aneuploid oocytes was determined.

RESULTS

In the CP group IVM rate was significantly decreased and aneploidy rate was significantly increased when compared to other groups (p < 0.05). With the administration of Amifostine prior to CP injection IVM rate was increased and aneploidy rate was decreased.

DISCUSSION

Depletion in IVM rate with administration of CP is due its adverse effects on oocyte quality. Amifostine administration prior to CP injection appears to modulate deleterious effects of CP on oocytes.

Do reactive oxygen species play a role in myeloid leukemias?

Reactive oxygen species (ROS) are a heterogeneous group of molecules that are generated by mature myeloid cells during innate immune responses, and are also implicated in normal intracellular signaling. Excessive production of ROS (and/or a deficiency in antioxidant pathways) can lead to oxidative stress, a state that has been observed in several hematopoietic malignancies including acute and chronic myeloid leukemias (AML and CML). Currently it is unclear what the cause of oxidative stress might be and whether oxidative stress contributes to the development, progression, or maintenance of these diseases. This article reviews the current evidence suggesting a role for ROS both in normal hematopoiesis and in myeloid leukemogenesis, and discusses the usefulness of therapeutically targeting oxidative stress in myeloid malignancy.