DNA damage levels in peripheral blood mononuclear cells before and after first cycle of chemotherapy have comparable prognostic values in germ cell tumor patients.

Background: Germ cell tumors (GCTs) represent the most frequent solid malignancy in young men. This malignancy is highly curable by cisplatin (CDDP)-based chemotherapy. However, there is a proportion of patients having a poor prognosis due to refractory disease or its relapse. No reliable biomarkers being able to timely and accurately stratify poor prognosis GCT patients are currently available. Previously, we have shown that chemotherapy-naïve GCT patients with higher DNA damage levels in peripheral blood mononuclear cells (PBMCs) have significantly worse prognosis compared to patients with lower DNA damage levels. Methods: DNA damage levels in PBMCs of both chemotherapy-naïve and first cycle chemotherapy-treated GCT patients have been assessed by standard alkaline comet assay and its styrene oxide (SO)-modified version. These levels were correlated with clinico-pathological characteristics. Results: We re-confirm prognostic value of DNA damage level in chemotherapy-naïve GCT patients and reveal that this prognosticator is equally effective in GCT patients after first cycle of CDDP-based chemotherapy. Furthermore, we demonstrate that SO-modified comet assay is comparably sensitive as standard alkaline comet assay in case of patients who underwent first cycle of CDDP-based chemotherapy, although it appears more suitable to detect DNA cross-links. Conclusion: We propose that DNA damage levels in PBMCs before and after first cycle of CCDP-based chemotherapy are comparable independent prognosticators for progression-free and overall survivals in GCT patients. Therefore, their clinical use is highly advised to stratify GCT patients to identify those who are most at risk of developing disease recurrence or relapse, allowing tailoring therapeutic interventions to poor prognosis individuals, and optimizing their care management and treatment regimen.

Unraveling the complexity: A comprehensive analysis of the PP2A in cancer and its potential for novel targeted therapies.

Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase considered a potent tumor suppressor that critically regulates diverse cellular processes, including cell cycle progression, apoptosis, or DNA repair. PP2A is typically downregulated in cancers but mechanisms for its inactivation in human cancers are poorly understood. PP2A represents a family of more than 60 phosphatases. According to cellular context, each heterotrimeric PP2A holoenzyme exerts a unique role in cancer, and PP2A isoforms can act either as tumor suppressors or as promoters. Due to wide structural diversity, PP2A has been considered undruggable. However, increasing knowledge predisposes PP2A diversity to therapeutical targeting for the treatment of a broad range of cancer pathologies, including drug resistance or cloaking immune surveillance. In this review, we discuss the regulatory role of PP2A in cancer, its regulation by microRNA and hypoxia, its contribution to therapy resistance development, and the therapeutic potential of direct and indirect targeting, or combinatory administration with other anti-cancer drugs to improve cancer treatment outcomes.