Abrogation of USP7 is an alternative strategy to downregulate PD-L1 and sensitize gastric cancer cells to T cells killing

Targeting immune checkpoints such as programmed cell death protein 1 (PD-1) and programmed death ligand-1 (PD-L1) have been approved for treating melanoma, gastric cancer (GC) and bladder cancer with clinical benefit. Nevertheless, many patients failed to respond to anti-PD-1/PD-L1 treatment, so it is necessary to seek an alternative strategy for traditional PD-1/PD-L1 targeting immunotherapy. Here with the data from The Cancer Genome Atlas (TCGA) and our in-house tissue library, PD-L1 expression was found to be positively correlated with the expression of ubiquitin-specific processing protease 7 (USP7) in GC. Furthermore, USP7 directly interacted with PD-L1 in order to stabilize it, while abrogation of USP7 attenuated PD-L1/PD-1 interaction and sensitized cancer cells to T cell killing in vitro and in vivo. Besides, USP7 inhibitor suppressed GC cells proliferation by stabilizing P53 in vitro and in vivo. Collectively, our findings indicate that in addition to inhibiting cancer cells proliferation, USP7 inhibitor can also downregulate PD-L1 expression to enhance anti-tumor immune response simultaneously. Hence, these data posit USP7 inhibitor as an anti-proliferation agent as well as a novel therapeutic agent in PD-L1/PD-1 blockade strategy that can promote the immune response of the tumor.

Fetal Surgery in the Era of SARS-CoV-2 Pandemic: A Single-Institution Review

Objective

To cope with the changing health care services in the era of SARS-CoV-2 pandemic. We share the institutional framework for the management of anomalous fetuses requiring fetal intervention at Mayo Clinic, Rochester, Minnesota. To assess the success of our program during this time, we compare intraoperative outcomes of fetal interventions performed during the pandemic with the previous year.

Patients

We implemented our testing protocol on patients undergoing fetal intervention at our institution between March 1, and May 15, 2020, and we compared it with same period a year before. A total of 17 pregnant patients with anomalous fetuses who met criteria for fetal intervention were included: 8 from 2019 and 9 from 2020.

Methods

Our testing protocol was designed based on our institutional perinatal guidelines, surgical requirements from the infection prevention and control (IPAC) committee, and input from our fetal surgery team, with focus on urgency of procedure and maternal SARS-CoV-2 screening status. We compared the indications, types of procedures, maternal age, gestational age at procedure, type of anesthesia used, and duration of procedure for cases performed at our institution between March 1, 2020, and May 15, 2020, and for the same period in 2019.

Results

There were no statistically significant differences among the number of cases, indications, types of procedures, maternal age, gestational age, types of anesthesia, and duration of procedures (P values were all >.05) between the pre–SARS-CoV-2 pandemic in 2019 and the SARS-CoV-2 pandemic in 2020.

Conclusions

Adoption of new institutional protocols during SARS-CoV-2 pandemic, with appropriate screening and case selection, allows provision of necessary fetal intervention with maximal benefit to mother, fetus, and health care provider.

Differential regulation of MCM7 and its intronic miRNA cluster miR-106b-25 during megakaryopoiesis induced polyploidy

Megakaryocytes exit from mitotic cell cycle and enter a phase of repeated DNA replication without undergoing cell division, in a process termed as endomitosis of which little is known. We studied the expression of a DNA replication licensing factor mini chromosome maintenance protein 7 (MCM7) and its intronic miR-106b-25 cluster during mitotic and endo-mitotic cycles in megakaryocytic cell lines and in vitro cultured megakaryocytes obtained from human cord blood derived CD34(+) cells. Our results show that contrary to mitotic cell cycle, endomitosis proceeds with an un-coupling of the expression of MCM7 and miR-106b-25. This was attributed to the presence of a transcript variant of MCM7 which undergoes nonsense mediated decay (NMD). Additionally, miR-25 which was up regulated during endomitosis was found to promote megakaryopoiesis by inhibiting the expression of PTEN. Our study thus highlights the importance of a transcript variant of MCM7 destined for NMD in the modulation of megakaryopoiesis.

Molecular chaperons and co-chaperons, Hsp90, RAR1, and SGT1 negatively regulate bacterial wilt disease caused by Ralstonia solanacearum in Nicotiana benthamiana

Ralstonia solanacearum is the causal agent of bacterial wilt disease. To better understand the molecular mechanisms involved in interaction between Nicotiana benthamiana and R. solanacearum, we focused on Hsp90, RAR1 and SGT1. Appearances of wilt symptom were significantly suppressed in Hsp90, RAR1 and SGT1-silenced plants compared with control plants. In RAR1-silenced plants, population of R. solanacearum increased in a similar manner to control plants. In contrast, multiplication of R. solanacearum was significantly suppressed in Hsp90 and SGT1-silenced plants. In addition, expression of PR genes were increased in Hsp90 and SGT1-silenced plants challenged with R. solanacearum. Therefore, RAR1 might be required for disease development or suppression of disease tolerance. These results also suggested that Hsp90 and/or SGT1 might play an important role in suppression of plant defenses leading to disease susceptibility and disease development.