Variation rs2235503 C \> A Within the Promoter of MSLN Affects Transcriptional Rate of Mesothelin and Plasmatic Levels of the Soluble Mesothelin-Related Peptide

Our plain-English summary of Variation rs2235503 C > A Within the Promoter of MSLN Affects Transcriptional Rate of Mesothelin and Plasmatic Levels of the Soluble Mesothelin-Related Peptide, by R. Silvestri, P. Pucci, C. De Santi, et al (Frontiers in Genetics, 2020).

The study

• Authors: R. Silvestri, P. Pucci, C. De Santi, I. Dell'Anno, S. Miglietta, A. Corrado, V. Nicolí, D. Marolda, M. Cipollini, E. Pellegrino, M. Evangelista, A. Bonotti, R. Foddis, A. Cristaudo, S. Landi, F. Gemignani
• Journal: Frontiers in Genetics
• Published: 2020;11:975
• Cited by: 4 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Soluble mesothelin-related peptide (SMRP) is a promising biomarker for malignant pleural mesothelioma (MPM), but several confounding factors can reduce SMRP-based test's accuracy. The identification of these confounders could improve the diagnostic performance of SMRP. In this study, we evaluated the sequence of 1,000 base pairs encompassing the minimal promoter region of the MSLN gene to identify expression quantitative trait loci (eQTL) that can affect SMRP. We assessed the association between four MSLN promoter variants and SMRP levels in a cohort of 72 MPM and 677 non-MPM subjects, and we carried out in vitro assays to investigate their functional role. Our results show that rs2235503 is an eQTL for MSLN associated with increased levels of SMRP in non-MPM subjects. Furthermore, we show that this polymorphic site affects the accuracy of SMRP, highlighting the importance of evaluating the individual's genetic background and giving novel insights to refine SMRP specificity as a diagnostic biomarker.

Copyright © 2020 Silvestri, Pucci, De Santi, Dell’Anno, Miglietta, Corrado, Nicolí, Marolda, Cipollini, Pellegrino, Evangelista, Bonotti, Foddis, Cristaudo, Landi and Gemignani.

In plain English

This brief research report from Pisa, Italy, asked whether common genetic variants in the promoter (the switch region) of the MSLN gene, which makes mesothelin, affect blood levels of soluble mesothelin-related peptide (SMRP). SMRP is a proposed blood marker for malignant pleural mesothelioma. Participants came from an occupational surveillance program for workers previously exposed to asbestos. There were 677 people without mesothelioma (371 healthy, 306 with benign respiratory diseases) and 72 with mesothelioma. Among people without mesothelioma, those carrying variant combination (haplotype) #2 or #3 alongside #1 had significantly higher SMRP than those with two copies of #1. No significant difference was seen among mesothelioma patients. In cell experiments, the A form of rs2235503 raised promoter activity 1.35-fold. In people carrying an A, SMRP separated mesothelioma from non-mesothelioma less accurately: the area under the curve, where 1 means perfect, was 0.798, against 0.915 in C/C individuals. The variant was not associated with patient survival (p-value 0.66). The authors concluded that rs2235503 affects MSLN gene transcription and is a genetic factor influencing SMRP levels. They noted that the small number of mesothelioma patients limited statistical power.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Brief research report: genetic association study in an asbestos-exposed surveillance cohort, combined with laboratory (in vitro) fluorescent reporter experiments in cell lines
• Who was studied: 677 people without malignant pleural mesothelioma (371 healthy, 306 with benign respiratory diseases) and 72 patients with malignant pleural mesothelioma, all recruited at the University Hospital of Pisa, Italy, through an occupational surveillance program on workers previously exposed to asbestos. The haplotype association analysis was restricted to carriers of haplotype #1 (H1H2, H1H3, H1H4, with H1H1 as reference), which excluded 19 non-MPM and 6 MPM subjects.
• Exposure: Previous occupational asbestos exposure (fiber types not specified). The factors studied were four genetic variants in the MSLN promoter: rs3764247 A > C, rs3764246 A > G, rs2235503 C > A and rs2235504 A > G
• Main results:
  • Among non-MPM subjects, people carrying haplotype #2 or #3 together with haplotype #1 (H1H2, H1H3) had significantly different SMRP levels from the H1H1 reference group (p-value less than 10 to the minus 5, and 0.0047, respectively). H1H4 people did not.
  • Average SMRP (with standard error) among non-MPM subjects: haplotype #2 carriers 1.30 ± 0.046 nM; haplotype #3 carriers 0.98 ± 0.060 nM; haplotype #1 0.80 ± 0.022 nM; haplotype #4 carriers 0.78 ± 0.047 nM
  • No significant difference in SMRP by haplotype was seen among the MPM patients
  • In cell experiments, the haplotype #2 promoter construct (HR_HAP2) gave a 1.41-fold increase in reporter fluorescence compared with HR_HAP1 (±0.267; p-value 6 × 10 to the minus 4)
  • Of the single-variant constructs, only the one carrying the rs2235503 variant (HR_503) significantly increased reporter fluorescence compared with HR_HAP1 (fold change 1.35 ± 0.164; p-value less than 10 to the minus 5)
  • SMRP's ability to distinguish MPM from non-MPM: area under the ROC curve 0.798 ± 0.055 in rs2235503 C/A + A/A carriers versus 0.915 ± 0.018 in the C/C group
  • The AUC for the C/C group was also higher than for the overall population (0.877 ± 0.019)
  • Optimal SMRP cut-off values differed by genotype: 1.118 (sensitivity 84.31, specificity 82.86) for the C/C group and 3.092 (sensitivity 52.58, specificity 96.69) for the C/A + A/A group
  • Among MPM patients, rs2235503 was not associated with overall survival (p-value 0.66)
• The authors' conclusion: The authors concluded that rs2235503 affects MSLN gene transcription, represents an eQTL (a genetic variant affecting gene activity) for SMRP levels, and can affect the diagnostic performance of SMRP
• Limitations the authors state:
  • The lack of association among MPM patients may reflect limited statistical power, as there were only 72 patients
  • MSLN mRNA expression could not be measured in the study's own volunteers
  • The survival (prognosis) result rests on a small number of MPM patients and needs confirmation in other cohorts

Topics

Medical terms in this study, explained in our Lexicon: Mesothelin, Soluble Mesothelin-Related Peptides (SMRP), Biomarker, Pleural Mesothelioma, Confounding.

Related studies

• Mesothelin promoter variants are associated with increased soluble mesothelin-related peptide levels in asbestos-exposed individuals — C. De Santi, P. Pucci, et al. (2017)
• A common polymorphism within MSLN affects miR-611 binding site and soluble mesothelin levels in healthy people — S. Garritano, C. De Santi, et al. (2014)
• Two novel polymorphisms in 5' flanking region of the mesothelin gene are associated with soluble mesothelin-related peptide (SMRP) levels — A. Cristaudo, R. Foddis, et al. (2011)
• Evaluation of soluble mesothelin-related peptides and MSLN genetic variability in asbestos-related diseases — K. Goricar, V. Kovac, et al. (2020)
• Mesothelin (MSLN) methylation and soluble mesothelin-related protein levels in a Chinese asbestos-exposed population — M. Yu, Y. Zhang, et al. (2015)
• Soluble mesothelin-related peptide level elevation in mesothelioma serum and pleural effusions — H.I. Pass, A. Wali, et al. (2008)

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