Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Jun;21(3):266-273.
doi: 10.1007/s11102-018-0862-x.

MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals

Alexander S G Micko  1   2 , Romana Höftberger  2 , Adelheid Wöhrer  2 , Matthias Millesi  1 , Engelbert Knosp  3 , Stefan Wolfsberger  1
Affiliations

MGMT assessment in pituitary adenomas: comparison of different immunohistochemistry fixation chemicals

Alexander S G Micko et al. Pituitary. 2018 Jun.

Abstract

Purpose: Despite the established role of O6-methyl-guanine-DNA methyltransferase (MGMT) as a marker for temozolomide response, consensus of the most reliable method to assess MGMT expression in pituitary adenomas is still missing. Currently, immunohistochemistry (IHC) assessment of formaldehyde fixed tissue samples is most widely used in a semiquantitative description. As formaldehyde fails to completely preserve nucleic acids, RCL2, an alcohol-based formaldehyde-free fixative, has been proposed as a more reliable alternative in terms of cell stability. Furthermore, as the current method of IHC is semiquantitative and observer-dependent, pyrosequencing, an objective tool to evaluate the methylation status of the MGMT promoter, has emerged as a reliable and accurate alternative. The aim of this study was to validate the current IHC method for assessment of MGMT protein expression in pituitary adenomas.

Methods: The tissue samples of 8 macroadenomas with positive IHC MGMT expression (> 50%) were investigated: first, we compared the time dependent stability of MGMT protein expression after pituitary adenoma removal between formaldehyde vs. RCL2. Then, we compared positive IHC MGMT expression with methylated promoter status using pyrosequencing.

Results: In the first 12 h after adenoma removal, tissue samples remained MGMT positive in significantly more samples when fixated with formaldehyde than with RCL2, respectively (96 vs. 81%, p = 0.025).

Conclusion: Our data confirm that the current method using formaldehyde tissue fixation and IHC reveals stable and reliable results of MGMT assessment in pituitary adenomas.

Keywords: MGMT; Pituitary adenoma; Promoter methylation; Time dependent.

PubMed Disclaimer

Conflict of interest statement

All authors have no financial interest/arrangement or affiliation with one or more organizations that could be perceived as a real or apparent conflict of interest in the context of the article.

Figures

Fig. 1
Fig. 1
Boxplots of assessed time dependent MGMT expression in formaldehyde fixed tissue samples x—demonstrating the respective MGMT expression to the defined time point red line—demonstrating values above and below 50% MGMT Expression
Fig. 2
Fig. 2
Boxplots of assessed time dependent MGMT expression in RCL2 fixed tissue sample x—demonstrating the respective MGMT expression to the defined time point red line—demonstrating values above and below 50% MGMT expression
Fig. 3
Fig. 3
Time dependent MGMT pyrosequencing results bold red line—demonstrating values above and below 8% MGMT promotor methylation
Fig. 4
Fig. 4
Case 2: time dependent MGMT expression, ×40 magnification (a, b) time point = 0 min after tumour removal (a formalin > 75%; b RCL2 0–10%), c, d time point = 30 min after tumour removal (c formalin 50–75%; d RCL2 10–25%), e, f time point = 1 h after tumour removal (e formalin 50–75%; f RCL2 10–25%), g, h time point = 2 h after tumour removal (g formalin > 75%; h RCL2 10–25%), i, j time point = 6 h after tumour removal (i formalin > 75%; j RCL2 25–50%), k, l time point = 12 h after tumour removal (k formalin 50–75%; l RCL2 25–50%)
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Middleton MR, Grob JJ, Aaronson N, Fierlbeck G, Tilgen W, Seiter S, Gore M, Aamdal S, Cebon J, Coates A, Dreno B, Henz M, Schadendorf D, Kapp A, Weiss J, Fraass U, Statkevich P, Muller M, Thatcher N. Randomized phase III study of temozolomide versus dacarbazine in the treatment of patients with advanced metastatic malignant melanoma. J Clin Oncol. 2000;18(1):158–166. doi: 10.1200/JCO.2000.18.1.158. - DOI - PubMed
    1. Stupp R, Mason WP, van den Bent MJ, Weller M, Fisher B, Taphoorn MJ, Belanger K, Brandes AA, Marosi C, Bogdahn U, Curschmann J, Janzer RC, Ludwin SK, Gorlia T, Allgeier A, Lacombe D, Cairncross JG, Eisenhauer E, Mirimanoff RO, European Organisation for R, Treatment of Cancer Brain., Radiotherapy T, G., National Cancer Institute of Canada Clinical Trials, G Radiotherapy plus concomitant and adjuvant temozolomide for glioblastoma. New Engl J Med. 2005;352(10):987–996. doi: 10.1056/NEJMoa043330. - DOI - PubMed
    1. Augustine CK, Yoo JS, Potti A, Yoshimoto Y, Zipfel PA, Friedman HS, Nevins JR, Ali-Osman F, Tyler DS. Genomic and molecular profiling predicts response to temozolomide in melanoma. Clin Cancer Res. 2009;15(2):502–510. doi: 10.1158/1078-0432.CCR-08-1916. - DOI - PubMed
    1. Neyns B, Tosoni A, Hwu WJ, Reardon DA. Dose-dense temozolomide regimens: antitumor activity, toxicity, and immunomodulatory effects. Cancer. 2010;116(12):2868–2877. doi: 10.1002/cncr.25035. - DOI - PubMed
    1. Bengtsson D, Schroder HD, Andersen M, Maiter D, Berinder K, Feldt Rasmussen U, Rasmussen AK, Johannsson G, Hoybye C, van der Lely AJ, Petersson M, Ragnarsson O, Burman P. Long-term outcome and MGMT as a predictive marker in 24 patients with atypical pituitary adenomas and pituitary carcinomas given treatment with temozolomide. J Clin Endocrinol Metab. 2015;100(4):1689–1698. doi: 10.1210/jc.2014-4350. - DOI - PubMed

Substances