Potential biological role of poly (ADP-ribose) polymerase (PARP) in male gametes

Maintaining the integrity of sperm DNA is vital to reproduction and male fertility. Sperm contain a number of molecules and pathways for the repair of base excision, base mismatches and DNA strand breaks. The presence of Poly (ADP-ribose) polymerase (PARP), a DNA repair enzyme, and its homologues has recently been shown in male germ cells, specifically during stage VII of spermatogenesis. High PARP expression has been reported in mature spermatozoa and in proven fertile men. Whenever there are strand breaks in sperm DNA due to oxidative stress, chromatin remodeling or cell death, PARP is activated. However, the cleavage of PARP by caspase-3 inactivates it and inhibits PARP's DNA-repairing abilities. Therefore, cleaved PARP (cPARP) may be considered a marker of apoptosis. The presence of higher levels of cPARP in sperm of infertile men adds a new proof for the correlation between apoptosis and male infertility. This review describes the possible biological significance of PARP in mammalian cells with the focus on male reproduction. The review elaborates on the role played by PARP during spermatogenesis, sperm maturation in ejaculated spermatozoa and the potential role of PARP as new marker of sperm damage. PARP could provide new strategies to preserve fertility in cancer patients subjected to genotoxic stresses and may be a key to better male reproductive health

Lazarus-Type Tumour Response to Therapy with Nivolumab for Sarcomatoid Carcinomas of the Lung

Pulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small-cell lung carcinoma with a poor prognosis and poor response to chemotherapy and radiotherapy. A previous study reported that psc expresses high levels of PD-L1, suggesting the potential efficacy of immune checkpoint inhibitors in these tumours. We report 2 cases of patients with a lung sarcomatoid carcinoma. Both patients initially underwent curative lung resection, but developed early recurrent disease. Because PD-L1 was highly expressed in the tumour cells, we initiated therapy with nivolumab, which showed good efficacy, almost complete radiologic tumour remission, and a remarkable improvement in the condition of those patients. Immune checkpoint inhibitors targeting PD-1 might be a valuable therapy option for PSCS