Novel function of PERP-428 variants impacts lung cancer risk through the differential regulation of PTEN/MDM2/p53-mediated antioxidant activity

A self-amplifying loop of TP53INP1 and P53 drives oxidative stress-induced apoptosis of bone marrow mesenchymal stem cells

Bone marrow mesenchymal stem cell (BMSC) transplantation is a promising regenerative therapy; however, the survival rate of BMSCs after transplantation is low. Oxidative stress is one of the main reasons for the high apoptosis rate of BMSCs after transplantation, so there is an urgent need to explore the mechanism of oxidative stress-induced apoptosis of BMSCs. Our previous transcriptome sequencing results suggested that the expression of P53-induced nuclear protein 1 (TP53INP1) and the tumor suppressor P53 (P53) was significantly upregulated during the process of oxidative stress-induced apoptosis of BMSCs. The present study further revealed the role and mechanism of TP53INP1 and P53 in oxidative stress-induced apoptosis in BMSCs. Overexpression of TP53INP1 induced apoptosis of BMSCs, knockdown of TP53INP1 alleviated oxidative stress apoptosis of BMSCs. Under oxidative stress conditions, P53 is regulated by TP53INP1, while P53 can positively regulate the expression of TP53INP1, so the two form a positive feedback loop. To clarify the mechanism of feedback loop formation. We found that TP53INP1 inhibited the ubiquitination and degradation of P53 by increasing the phosphorylation level of P53, leading to the accumulation of P53 protein. P53 can act on the promoter of the TP53INP1 gene and increase the expression of TP53INP1 through transcriptional activation. This is the first report on a positive feedback loop formed by TP53INP1 and P53 under oxidative stress. The present study clarified the formation mechanism of the positive feedback loop. The TP53INP1-P53 positive feedback loop may serve as a potential target for inhibiting oxidative stress-induced apoptosis in BMSCs.

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

PERP May Affect the Prognosis of Lung Adenocarcinoma by Inhibiting Apoptosis

Background

PERP, a member of the peripheral myelin protein gene family, is a new therapeutic target in cancer. The relationships between PERP and immune cell infiltration in lung cancer have not been studied. Therefore, the role of PERP in the tumour microenvironment (TME) of lung cancer needs to be further explored.

Methods

In this study, we explored the association between PERP expression and clinical characteristics by analysing data from the TCGA database. Cox regression and Kaplan‒Meier methods were used to investigate the relationship between the expression of PERP and overall survival in patients with lung adenocarcinoma (LUAD). The relationship between PERP expression and the degree of infiltration of specific immune cell subsets in LUAD was evaluated using the TIMER database and GEPIA. We also performed GO enrichment analysis and KEGG enrichment analysis to reveal genes coexpressed with PERP using the Coexpedia database. Finally, we verified the expression and function of PERP in LUAD tissues and the A549 cell line by RT‒PCR, Western blot, CCK-8, IHC, and wound healing assays. The mouse model was used to study the in vivo effects of PERP.

Results

According to our results, PERP expression was significantly higher in LUAD tissues and associated with the clinical characteristics of the disease. Survival was independently associated with PERP in LUAD patients. We further verified that PERP might regulate B-cell infiltration in LUAD to affect the prognosis of LUAD. To identify PERP-related signalling pathways in LUAD, we performed a genome-aggregation analysis (GSEA) between low and high PERP expression datasets. LUAD cells express higher levels of PERP than paracarcinoma cells, and PERP inhibits the proliferation and metastasis of A549 cells through apoptosis.

Conclusion

PERP may affect the prognosis of lung adenocarcinoma by inhibiting apoptosis and is associated with immune cell infiltration.

Protective effect of Peucedanum praeruptorum Dunn extract on oxidative damage of LLC‑PK1 cells induced by H2O2

Peucedanum praeruptorum Dunn extract (PPDE) is a well-known treatment used in traditional Chinese medicines, where it is most commonly used to treat coughs and symptoms such as headaches and fever. In the present study, the antioxidant capacity of PPDE in vitro was determined by scavenging experiments using DPPH, ABTS+·, ·OH, and ·O2-. The cell survival rate was determined by MTT assay. The MDA, SOD, CAT, GSH, and GSH-Px content were determined by colorimetry assays. The expression levels of antioxidant genes SOD, CAT, GSH, and GSH-Px were assessed by reverse transcription-quantitative PCR. HPLC was used to identify the PPDE components. The results suggested that PPDE had scavenging effects on DPPH, ABTS, hydroxyl, and superoxide anion radicals in a concentration-dependent manner; H2O2 treatment resulted in oxidative stress in LLC-PK1 cells, and the degree of injury of LLC-PK1 cells following PPDE treatment was improved, which was positively correlated with its concentration. Peucedanum praeruptorum Dunn extract treatment reduced the content of MDA and increased the content of CAT, SOD1, GSH, and GSH-Px. The mRNA expression levels of antioxidant genes detected by quantitative PCR were consistent with changes in CAT, SOD, GSS, and GSH-Px. Additionally, the trend in CAT, SOD1, GSH, and GSS protein expression levels was also consistent at the mRNA level. PPDE was found to consist of isochlorogenic acid C, myricetin, baicalin, luteolin, and kaempferol. Therefore, PPDE, which was formed of products derived from natural substances, functioned in the inhibition of oxidative damage. The present study aimed to obtain a better understanding of the traditional Chinese medicine Peucedanum praeruptorum Dunn and preliminarily elucidate its antioxidant mechanism at the cellular level. Further animal or human experiments are required to verify the antioxidant effects of PPDE for further development and utilization.

Effects of NAC and Gallic Acid on the Proliferation Inhibition and Induced Death of Lung Cancer Cells with Different Antioxidant Capacities

N-acetylcysteine (NAC) is a recognized antioxidant in culture studies and treatments for oxidative stress-related diseases, but in some cases, NAC is a pro-oxidant. To study the effect of NAC on cell proliferation in the presence or absence of ROS stress, we used the stable ROS generator gallic acid (GA) to treat CL1-0 lung cancer cell models with different antioxidant activities. Different antioxidant activities were achieved through the ectopic expression of different PERP-428 single nucleotide polymorphisms. GA increased ROS levels in CL1-0/PERP-428C cells and caused cell death but had no effect on CL1-0/PERP-428G cells within 24 h. We found that 0.1 mM NAC eliminated GA-induced growth inhibition, but 0.5 mM NAC enhanced GA-induced CL1-0/PERP-428C cell death. However, in the absence of GA, NAC exceeding 2 mM inhibited the growth of CL1-0/PERP-428G cells more significantly than that of CL1-0/PERP-428C cells. Without GA, NAC has an antioxidant effect. Under GA-induced ROS stress, NAC may have pro-oxidant effects. Each cell type has a unique range of ROS levels for survival. The levels of ROS in the cell determines the sensitivity of the cell to an antioxidant or pro-oxidant. Cells with different antioxidant capacities were used to show that the intracellular ROS level affects NAC function and provides valuable information for the adjuvant clinical application of NAC.