MicroRNA profiling and identification of let-7a as a target to prevent chemotherapy-induced primordial follicles apoptosis in mouse ovaries

Abstract

Cancer treatments as cyclophosphamide and its active metabolites are highly gonadotoxic leading to follicle apoptosis and depletion. Considering the risk of subsequent infertility, fertility preservation is recommended. Beside the germ cells and gametes cryopreservation options, ovarian pharmacological protection during treatment appears to be very attractive. Meanwhile, the advances in the field of oncology have brought microRNAs into spotlight as a potential feature of cancer treatment. Herein, we investigated miRNAs expressions in response to chemotherapy using postnatal-day-3 (PND3) mouse ovaries. Our results revealed that several miRNAs are differently expressed during chemotherapy exposure. Amongst them, let-7a was the most profoundly downregulated and targets genes involved in crucial cellular processes including apoptosis. Thus we developed a liposome-based system to deliver the let-7a mimic in whole PND3 ovaries in vitro . We showed that let-7a mimic prevented the upregulation of genes involved in cell death and reduced the chemotherapy-induced ovarian apoptosis, suggesting that it can be an interesting target to preserve ovarian function. However, its impact on subsequent follicular development has to be further elucidated in vivo using an appropriate delivery system. In this study, we demonstrated that miRNA replacement approaches can be a useful tool to reduce chemotherapy-induced ovarian damage in the future.

Answer to Controversy: miR-10a Replacement Approaches Do Not Offer Protection against Chemotherapy-Induced Gonadotoxicity in Mouse Model

“…In our previous study, we showed that miRNAs can alter their expression profile due to chemotherapy exposure, and this change can be observed after short exposure during 1 h at 20 µM (1 h/4-HC/20 µM) or long exposure during 24 h (24 h/4-HC/20 µM) (Figure 1a) [32]. Amongst the most affected miRNAs, which changed their expression levels after 1 h of exposure to 4-HC in mouse postnatal-day 3 (PND3) ovaries, the miR-10a was one of the most downregulated.…”

“…The transfection of PND3 ovaries in vitro was performed using Lipofectamine RNAiMAX, a liposome-based delivery system (Figure 2a). In our previous study, a transfection protocol was developed after testing different concentrations of the Lipofectamine and the mimic miRNA molecules, while the transfection’s efficiency was verified by a fluorescent label dsRNA [32]. After 48 h in culture with the transfection mix (Lipofectamine + Alexafluor labeled dsRNA), the fluorescent signal was detected in every ovarian section, indicating that the transfection is successful (data is not shown).…”

Crosstalk between PTEN/PI3K/Akt Signalling and DNA Damage in the Oocyte: Implications for Primordial Follicle Activation, Oocyte Quality and Ageing

“…MiRNAs can be effective techniques as their expression can be adjusted with their microenvironment during chemotherapy treatment, thus minimising off-target toxicity. Lethal 7 (let-7a) mimic is an example of a new miRNA based therapeutic to minimise follicle injury following chemotherapy treatment [170]. However, this work is at an early stage, with challenges including how to deliver miRNAs to a specific target organ with minimum side effects.…”

Exposure to Chemotherapy During Childhood or Adulthood and Consequences on Spermatogenesis and Male Fertility

“…These data may pave the way for future studies aimed to optimise the conditions for in vitro maturation of frozen-thawed testicular tissue for future use in fertility preservation strategies. Alternatively, less invasive methods are also in the experimental phase of development such as the administration of cytoprotective agent concomitantly to cancer treatment regimen or the miRNA replacement approaches to prevent chemotherapeutic damages [57,92,[166][167][168][169].…”