Onco, Volume 4, Issue 2 (June 2024) – 3 articles

Although pancreatic neuroendocrine neoplasms (panNENs) are much less common and have a better prognosis than exocrine pancreatic cancers, their recurrence rate is not low, even in Grade 1 (World Health Organization classification) panNEN. Recently, there have been several reports that the progression-free survival in patients with unresectable panNEN could be improved by an antidiabetic drug, metformin, with the co-treatment of everolimus or a somatostatin analog. In this study, we aimed to evaluate the effects of metformin on cell metabolism and viability using the panNEN cell line, QGP-1, and RIN-m in culture. We observed an inhibitory effect of metformin on QGP-1 cell proliferation in a dose-dependent manner. Metformin was found to decrease the oxygen consumption rate in QGP-1 and RIN-m cells after metformin 48 h treatment and immediately after exposure. Cell proliferation was suppressed after metformin treatment. Phosphorylated adenosine monophosphate-activated protein kinase (AMPK) expression was increased, and cyclin D1 expression was decreased in RIN-m cells 24 h after metformin treatment by Western blotting in a dose-dependent manner. In conclusion, suppressive mitochondrial respiration and AMPK activation by metformin are, thus, suggested to inhibit panNEN cell viability and cell survival. Full article

Synthetic peptides derived from antigen sequences are essential reagents for the detection of CD8⁺ cytotoxic T lymphocytes (CTLs), in assays such as ELISPOT/ImmunoSpot^®. Indeed, the combination of peptides and ImmunoSpot^® has been widely used for immune monitoring in numerous vaccine trials. Target antigens in pathogens or cancers may be large in size and multiple in number, often seemingly necessitating in silico peptide epitope predictions using algorithms and programs for certain HLA alleles to narrow down the numbers of required peptides. In this commentary, we discuss our data in the context of immune responses to viral and cancer antigens, concluding that systematic high-throughput immune monitoring of CD8⁺ T cells will provide more reliable insights on the host’s response to cancer than the reliance on select CD8⁺ T cell epitopes, no matter whether these are in silico predicted or even if they had been empirically established. We show the feasibility of large scale, high-throughput systematic CD8⁺ T cell epitope testing towards this goal. Full article

Introduction: DNA damage repair gene deficiency defines a subgroup of prostate cancer patients with early metastatic progression and unfavorable disease outcome. Whether deficiency in DNA damage repair genes directly promotes metastatic dissemination is not completely understood. Methods: The migratory behavior of prostate cancer cells was analyzed after siRNA-mediated knockdown of DNA damage repair and checkpoint proteins, including BRCA2, ATM, and others, using transwell migration assays, scratch assays and staining for F-actin to ascertain cell circularity. Cells deficient in BRCA2 or ATM were tested for oxidative stress by measuring reactive oxygen species (ROS). The effects of ROS inhibition on cell migration were analyzed using the antioxidant N-acetylcysteine (NAC). The correlation between BRCA2 deficiency and oxidative stress was ascertained via immunohistochemistry for methylglyoxal (MG)-modified proteins in 15 genetically defined primary prostate cancers. Results: Prostate cancer cells showed a significantly increased migratory activity after the knockdown of BRCA2 or ATM. There was a significant increase in ROS production in LNCaP cells after BRCA2 knockdown and in PC-3 cells after BRCA2 or ATM knockdown. Remarkably, the ROS scavenger NAC abolished the enhanced motility of prostate cancer cells after the knockdown of BRCA2 or ATM. Primary prostate cancers harboring genetic alterations in BRCA2 showed a significant increase in MG-modified proteins, indicating enhanced oxidative stress in vivo. Conclusions: Our results indicate that DNA damage repair gene deficiency may contribute to the metastatic dissemination of prostate cancer through enhanced tumor cell migration involving oxidative stress. Full article