Phospholipase C delta 1 inhibits WNT/ß-catenin and EGFR-FAK-ERK signaling and is disrupted by promoter CpG methylation in renal cell carcinoma.

BACKGROUND: PLCD1, located at 3p22, encodes an enzyme that mediates cellular metabolism and homeostasis, intracellular signal transduction and movement. PLCD1 plays a pivotal role in tumor suppression of several types of cancers; however, its expression and underlying molecular mechanisms in renal cell carcinoma (RCC) pathogenesis remain elusive. METHODS: RT-PCR and Western blot were used to detect PLCD1 expression in RCC cell lines and normal tissues. Bisulfite treatment, MSP and BGS were utilized to explore the CpG methylation status of PLCD1 promoter. Online databases were analyzed for the association between PLCD1 expression/methylation and patient survival. In vitro experiments including CCK8, colony formation, wound-healing, transwell migration and invasion, immunofluorescence and flow cytometry assays were performed to evaluate tumor cell behavior. Luciferase assay and Western blot were used to examine effect of PLCD1 on WNT/ß-catenin and EGFR-FAK-ERK signaling. RESULTS: We found that PLCD1 was widely expressed in multiple adult normal tissues including kidney, but frequently downregulated or silenced in RCC due to its promoter CpG methylation. Restoration of PLCD1 expression inhibited the viability, migration and induced G2/M cell cycle arrest and apoptosis in RCC cells. PLCD1 restoration led to the inhibition of signaling activation of WNT/ß-catenin and EGFR-FAK-ERK pathways, and the EMT program of RCC cells. CONCLUSIONS: Our results demonstrate that PLCD1 is a potent tumor suppressor frequently inactivated by promoter methylation in RCC and exerts its tumor suppressive functions via suppressing WNT/ß-catenin and EGFR-FAK-ERK signaling. These findings establish PLCD1 as a promising prognostic biomarker and treatment target for RCC.

Evolutions in the management of non-small cell lung cancer: A bibliometric study from the 100 most impactful articles in the field.

Objective: The study was designed to explore the evolution of non-small cell lung cancer (NSCLC) management in the last 20 years. Methods: The top 100 most-cited papers on NSCLC treatment were retrieved from the Web of Science Core Collection database. R and VOSviewer were used to extract bibliographic information, including the year of publication, countries/regions, institutions, authors, journals, keywords, impact factor, and total citations. The topic and type of papers were checked independently by authors. Bibliometric analysis was conducted and visualized with R, CiteSpace, Excel and VOSviewer to identify output dynamics, research forces, topics, hotspots, and frontiers in the field. Results: The average citation of each retrieved top 100 most-cited NSCLC management papers was 1,725 (range: 615-7,340). Fifty-seven corresponding authors were from the United States. This country contributed the most papers (n=76), followed by Germany (n=34), France (n=33), and South Korea (n=32). The top contributors were Paz-Ares L. (n=12) and Reck M. (n=12). The Memorial Sloan Kettering Cancer Center published the largest number of papers (n=20). There were two significant citation paths, indicating publications in medicine/medical/clinical journals primarily cited journals in molecular/biology/genetics fields, partly cited health/nursing/medicine fields. Top-cited papers mainly came from the New England Journal of Medicine (n=33, citations=80,427), followed closely by the Journal of Clinical Oncology (n=28, citations=32,408). "Chemotherapy" (n=36) was the keyword with the greatest frequency of co-occurrence. "Open-label" was the keyword with the strongest burst strength (=4.01), followed by "nivolumab" (=3.85), "blockade" (=2.86), and "efficacy" (=2.85). Conclusions: The United States as a nation and the Memorial Sloan Kettering Cancer Center as an institute contributed the most to this field. The New England Journal of Medicine is the most eye-catching journal. Hotspots of NSCLC management have almost undergone an evolution from chemotherapy and radiotherapy to targeted therapy to immunotherapy. Molecular/biological/genetic fields become the main research base for NSCLC treatment. Immunotherapy and combination therapy are research frontiers.