Complex phenotypic heterogeneity of combined hepatocellular-cholangiocarcinoma with a homogenous TERT promoter mutation

Sumie Ohni; Hiromi Yamaguchi; Yukari Hirotani; Yoko Nakanishi; Yutaka Midorikawa; Masahiko Sugitani; Tomohiro Nakayama; Makoto Makishima; Mariko Esumi

doi:10.62347/CQJW7490

Complex phenotypic heterogeneity of combined hepatocellular-cholangiocarcinoma with a homogenous TERT promoter mutation

Am J Transl Res. 2024 Feb 25;16(2):690-699. doi: 10.62347/CQJW7490. eCollection 2024.

Authors

Sumie Ohni¹, Hiromi Yamaguchi², Yukari Hirotani¹, Yoko Nakanishi¹, Yutaka Midorikawa³, Masahiko Sugitani⁴, Tomohiro Nakayama⁵, Makoto Makishima², Mariko Esumi²

Affiliations

¹ Division of Oncologic Pathology, Department of Pathology and Microbiology, Nihon University School of Medicine Tokyo, Japan.
² Division of Biochemistry, Department of Biomedical Sciences, Nihon University School of Medicine Tokyo, Japan.
³ Department of Surgery, Nihon University School of Medicine Tokyo, Japan.
⁴ Division of Human Pathology, Department of Pathology and Microbiology, Nihon University School of Medicine Tokyo, Japan.
⁵ Division of Clinical Laboratory Medicine, Department of Pathology and Microbiology, Nihon University School of Medicine Tokyo, Japan.

Abstract

To clarify the mechanism underlying the development and poor prognosis of combined hepatocellular-cholangiocarcinoma (cHCC-CCA), we characterized liver cancer driver mutations and poor prognostic markers in both the HCC and intrahepatic CCA (iCCA) components of a cHCC-CCA tumor. The telomerase reverse transcriptase (TERT) promoter mutation C228T was quantified by digital polymerase chain reaction using DNA from multiple microdissected cancer components of a single cHCC-CCA nodule. The protein expression of cancer-related markers, including TERT, was examined by serial thin-section immunohistochemistry and double-staining immunofluorescence. TERT promoter mutation and TERT protein expression were detected in all cancer components but not in noncancer regions. TERT promoter mutation frequencies were similar among components; those of TERT protein-positive cancer cells were higher in iCCA and mixed components than in HCC. The frequencies of Ki67- and p53-positive cells were similarly higher in iCCA and mixed components than in HCC. However, double-positive cells for the three proteins were unexpectedly rare; single-positive cells dominated, indicating phenotypic microheterogeneity in cancer cells within a component. Interestingly, HCC and CCA marker protein immunohistochemistry suggested dedifferentiation of HCC and transdifferentiation from HCC to iCCA in HCC and iCCA components, respectively. Such phenotypic intercomponent heterogeneity and intracomponent microheterogeneity were detected in a tumor nodule of cHCC-CCA uniformly carrying the early HCC driver mutation. Moreover, poor prognostic markers were randomly expressed without a regular pattern, consistent with the poor prognosis.

Keywords: Combined hepatocellular-cholangiocarcinoma; Ki67; TERT promoter mutation; TERT protein; dedifferentiation; digital PCR; immunohistochemistry; p53; phenotypic heterogeneity; transdifferentiation.