Suppression of transforming growth factor-beta signaling enhances spermatogonial proliferation and spermatogenesis recovery following chemotherapy

Abstract

STUDY QUESTION Could small molecules (SM) which target (or modify) signaling pathways lead to increased proliferation of undifferentiated spermatogonia following chemotherapy? SUMMARY ANSWER Inhibition of transforming growth factor-beta (TGFb) signaling by SM can enhance the proliferation of undifferentiated spermatogonia and spermatogenesis recovery following chemotherapy. WHAT IS KNOWN ALREADY Spermatogonial stem cells (SSCs) hold great promise for fertility preservation in prepubertal boys diagnosed with cancer. However, the low number of SSCs limits their clinical applications. SM are chemically synthesized molecules that diffuse across the cell membrane to specifically target proteins involved in signaling pathways, and studies have reported their ability to increase the proliferation or differentiation of germ cells. STUDY DESIGN, SIZE, DURATION In our experimental study, spermatogonia were collected from four brain-dead individuals and used for SM screening in vitro. For in vivo assessments, busulfan-treated mice were treated with the selected SM (or vehicle, the control) and assayed after 2 (three mice per group) and 5 weeks (two mice per group). PARTICIPANTS/MATERIALS, SETTING, METHODS We investigated the effect of six SM on the proliferation of human undifferentiated spermatogonia in vitro using a top–bottom approach for screening. We used histological, hormonal and gene-expression analyses to assess the effect of selected SM on mouse spermatogenesis. All experiments were performed at least in triplicate and were statistically evaluated by Student’s t-test and/or one-way ANOVA followed by Scheffe’s or Tukey’s post-hoc. MAIN RESULTS AND THE ROLE OF CHANCE We found that administration of SB431542, as a specific inhibitor of the TGFb1 receptor (TGFbR1), leads to a two-fold increase in mouse and human undifferentiated spermatogonia proliferation. Furthermore, injection of SB to busulfan-treated mice accelerated spermatogenesis recovery as revealed by increased testicular size, weight and serum level of inhibin B. Moreover, SB administration accelerated both the onset and completion of spermatogenesis. We demonstrated that SB promotes proliferation in testicular tissue by regulating the cyclin-dependent kinase (CDK) inhibitors 4Ebp1 and P57 (proliferation inhibitor genes) and up-regulating Cdc25a and Cdk4 (cell cycle promoting genes). LIMITATIONS, REASONS FOR CAUTION The availability of human testis was the main limitation in this study. WIDER IMPLICATIONS OF THE FINDINGS This is the first study to report acceleration of spermatogenesis recovery following chemotherapy by administration of a single SM. Our findings suggest that SB is a promising SM and should be assessed in future clinical trials for preservation of fertility in men diagnosed with cancer or in certain infertility cases (e.g. oligospermia). STUDY FUNDING/COMPETING INTEREST(S) This study was supported by Royan Institute and National Institute for Medical Research Development (NIMAD, grant no 963337) granted to H.B. The authors have no conflict of interest to report.

Evidence that activin A directly modulates early human male germline differentiation status

“…The INHBA subunit is detectable in fetal Leydig cells, as are receptor proteins in human gonocytes, indicating that human germline cells can respond directly to locally produced TGFβ superfamily ligands (Anderson et al 2002). Furthermore, human gonocyte and spermatogonial stem cell behaviors are affected by specific ligand inhibitors in testis cultures, demonstrating germline responsiveness within the testicular milieu (Jorgensen et al 2018, Moraveji et al 2019.…”

TCF3 Regulates the Proliferation and Apoptosis of Human Spermatogonial Stem Cells by Targeting PODXL

“…Given that TGFB3 stimulates adipocyte progenitor proliferation (Petrus et al, 2018), it is possible that TGFB3 may also affect spermatogenesis by regulating the proliferation of SSCs. Interestingly, it has been shown that the suppression of the TGFB1 receptor enhances spermatogonial proliferation and spermatogenesis (Moraveji et al, 2019). WNT2B is a ligand of the frizzled family and functions in the canonical Wnt/beta-catenin signaling pathway (Goss et al, 2009), the effect of WNT2B deletion was not as obvious as that of PODXL (data not shown).…”

miR-301a-5p Regulates TGFB2 during Chicken Spermatogenesis

“…Furthermore, using target gene prediction in three databases, we found that TGFB2 was among the target genes of miR-301a-5p. Previous studies on the TGFb signaling system in mice have shown the TGFb negative regulator of germ cell proliferation in fetal and newborn animals and to reduce gonocyte proliferation in [47,48]. TGFb, on the other hand, controls the proliferation of germ line stem cells and spermatogonia in Drosophila testis [49].…”