Elsevier

Translational Oncology

Volume 9, Issue 5, October 2016, Pages 411-418
Translational Oncology

Minichromosome Maintenance Expression Defines Slow-Growing Gastroenteropancreatic Neuroendocrine Neoplasms1

https://doi.org/10.1016/j.tranon.2016.07.006Get rights and content
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Abstract

BACKGROUND: Small intestinal neuroendocrine neoplasm (SI-NEN) proliferation is quantified by Ki67 measurements which capture G1-G2M phases of the cell cycle. G0 and early G1 phases, typical of slow-growing cells, can be detected by minichromosome maintenance protein (MCM) expression. We hypothesized that these replication licensing markers may provide clinically relevant information to augment Ki67 in low-grade neuroendocrine neoplasia. METHODS: Immunohistochemical staining (IHC), Western blot analysis, quantitative polymerase chain reaction, and copy number variations of MCM2, MCM3, and Ki67 were undertaken in SI-NENs (n = 22). MCM and Ki67 expression was compared by Kaplan-Meier survival analysis (tissue microarray, independent set [n = 55]). Forty-three pancreatic NENs and 14 normal tissues were included as controls. RESULTS: In SI-NENs, MCM2 (mean: 21.2%: range: 16%-25%) and MCM3 (28.7%: 22%-34%) were detected in significantly more cells than Ki67 (2.3%: 0%-7%, P < .01). MCM2 mRNA correlated with Ki67 IHC (P < .05). MCM3 protein expression was higher in metastases (38-fold) than in normal small intestine (P = .06) and was largely absent in normal neuroendocrine cells. There was considerable variation at the MCM copy number level (0-4 copies). MCM3 expression in proliferating cells significantly predicted overall survival (P < .002). Combinations of Ki67 and MCM2/3 in algorithms differentiated low and higher proliferative lesions (overall survival: 12 vs 6.1 years, P = .06). MCM expression was not informative in pancreatic NENs. CONCLUSION: MCMs are expressed in a higher proportion of NEN cells than Ki67 in slow-growing small intestinal lesions and correlate with survival. Assessment can be used to augment Ki67 to improve prognostic classification in these low-grade tumors.

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1

S. S. was supported by the Deutsche Forschungsgemeinschaft: SCHI 1177/1-1. B. L. was partially supported by the Murray Jackson Clinical Fellowship from the Genesis Oncology Trust Auckland, New Zealand.