p53 immunostaining pattern is a useful surrogate marker for TP53 gene mutations

Abstract

Background: TP53 is the most frequently mutated gene in the human cancer, and the awareness of its mutational status is useful in the diagnosis and treatment of cancer patients. In the present study, we investigated the association between TP53 gene mutations and p53 immunohistochemical staining (IHC) patterns and non-genetic effect of MDM2 as a negative regulator of p53.

Methods: A total of 135 solid cancer cases with next generation sequencing data were subjected to p53 IHC and classified as overexpression, null type or usual pattern.

Results: TP53 mutation was observed in 104 out of 135 cases (77.0%). When the TP53 mutations were annotated into DISRUPTED (truncations, frameshifts, splice site mutations, and deep deletions) and IF-DBD (in-frame mutations in the DNA binding domain), the null type p53 IHC pattern was associated with DISRUPTED mutations (sensitivity 86.2%, specificity 97.2%) while the overexpression pattern was associated with IF-DBD mutations (sensitivity 100%, specificity 81.7%). The specificity of p53 IHC usual pattern predicting wild type TP53 was also as high as 100%. Regardless of MDM2 amplification, p53 IHC pattern showed a perfect association with TP53 mutation pattern.

Conclusions: p53 IHC pattern (overexpression, null type, usual) reasonably predicted TP53 mutational status (DISRUPTED, IF-DBD), and MDM2 amplification status did not have any impact on the p53 IHC pattern.

Keywords: Association; Immunohistochemistry; Mutation; TP53 gene; p53 protein.

Fig. 1

Representative figures for three p53 immunohistochemistry patterns. A Invasive ductal carcinoma of the breast harboring TP53 H193R mutation (Hematoxylin & Eosin, × 1.25 objective lens). B Diffuse strong immunoreactivity for p53, that is overexpression pattern (p53 immunohistochemistry, × 1.25 objective lens). C Low grade papillary serous carcinoma of the ovary without any oncogenic TP53 mutation (Hematoxylin & Eosin, × 10 objective lens) D Approximately a half of the tumor cells express p53 in the nuclei, that is usual pattern (p53 immunohistochemistry, × 10 objective lens). E Adenocarcinoma of the colon harboring TP53 H214Qfs*2 mutation (Hematoxylin & Eosin, × 4 objective lens). F Tumor cells are completely negative for p53 protein expression. Adjacent non-neoplastic cells showing p53 expression serves as an internal positive control. This pattern is classified as null pattern (p53 immunohistochemistry, × 4 objective lens)

Fig. 2

Mucinous adenocarcinoma of the colon that experienced neo-adjuvant chemoradiation therapy but did not show any TP53 mutation. A Several strips or clusters of tumor cells are floating in the mucin pool (Hematoxylin & Eosin, × 10 objective lens). B TP53 overexpression pattern is noted (p53 immunohistochemistry, × 10 objective lens)

Fig. 3

Representative case with discrepancy between TP53 mutation and p53 IHC pattern. A&B Tumor area from which DNA was extracted for NGS analysis. Tumor cell purity is in acceptable range (Hematoxylin & Eosin, A: X4, B: X10 objective lens, respectively). C Null type pattern of p53 immunostaining is observed. No TP53 mutation was detected in this case (p53 immunohistochemistry, × 10 objective lens). D, E Adenocarcinoma of the cecum with comedo-type necrosis. Area from which DNA has been extracted is shown in E (Hematoxylin & Eosin, D: X1.25, and E: X4 objective lens, respectively). F Overexpression pattern of p53 immunostaining is noted in the absence of detectable TP53 mutation (p53 immunohistochemistry, × 4 objective lens). G, H Moderately differentiated adenocarcinoma of the rectum. DNA has been extracted from the area shown in G (Hematoxylin & Eosin, G: X4, and H: X10 objective lens, respectively). I Overexpression pattern of p53 immunostaining is noted in the absence of detectable TP53 mutation. This patient did not receive neoadjuvant chemoradiation therapy (p53 immunohistochemistry, × 10 objective lens)