Cell-in-cell structures are more potent predictors of outcome than senescence or apoptosis in head and neck squamous cell carcinomas

Hannah Schenker,Rainer Fietkau,Maike Büttner-Herold,Luitpold V Distel

doi:10.1186/s13014-016-0746-z

Hannah Schenker, Rainer Fietkau + Show 2 more

Open Access

https://doi.org/10.1186/s13014-016-0746-z

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Abstract

BackgroundThis study sheds light on cell inactivating processes with focus on the phenomenon of cell-in-cell (CIC). Cell-in-cell describes a cell process where one cell is being engulfed by another non-professional phagocyte. We determined frequency and prognostic impact of CIC structures (CICs) as well as of senescent and apoptotic cells in head and neck squamous cell carcinomas (HNSCC).MethodsThese different forms of cell inactivation as well as the proportion of proliferating and tumor cells were assessed in 169 pre-radiochemotherapy biopsies and 32 post-therapy tumor resections by immunohistochemistry of tissue microarrays. Four consecutive cancer sections were stained with antibodies specific for E-cadherin for CIC detection, cleaved caspase-3 for apoptosis, H3K9Me for senescence and Ki67 as a proliferation marker. Positive events were quantified in corresponding tumor areas.ResultsCICs were found in 55.5%, senescent cells in 67.1% and apoptotic cells in 93.3% of samples. While no prognostic impact of apoptotic and senescent cells was observed, CICs turned out to significantly influence overall-survival (p = 0.016) with a lack of CICs being prognostically beneficial. There was no correlation between CICs and apoptosis and 98.9% of CICs were negative for cleaved caspase-3.ConclusionCIC formation is a frequent event in HNSCC and a superior predictive marker compared to senescence and apoptosis. Independence of CIC and apoptosis and the adverse prognosis associated with numerous CICs lead to the assumption that CICs might take up necrotic rather than apoptotic cells preventing an adequate antitumoral immune response that would otherwise be initiated by necrotic cells through damage-associated molecular pattern molecules.

Highlights

This study sheds light on cell inactivating processes with focus on the phenomenon of cell-in-cell (CIC)
Four consecutive cancer sections were stained with E-cadherin for CIC structures (CICs) detection (Fig. 1a), anti-cleaved caspase-3 for detection of apoptosis (Fig. 1b), anti-H3K9Me for detection of senescence (Fig. 1c) and anti-Ki67 for identification of proliferating cells (Fig. 1d)
Senescence and proliferation were assessed in positive cells morphologically consistent with carcinoma cells, whereas other cells like stromal or inflammatory cells were not included in the analysis

Summary

Introduction

This study sheds light on cell inactivating processes with focus on the phenomenon of cell-in-cell (CIC). According to the NCCD the phenomena of apoptosis and necrosis can be further defined as follows: apoptosis is characterized by cytoplasmic shrinkage, chromatin condensation (marginalization), nuclear fragmentation (karyorrhexis), so called blebbing and apoptotic bodies and is considered a “regulated cell death”, generally referred to as “programmed cell death”. Necrosis presents generalized swelling of the cytoplasm and organelles (oncosis), alteration of chromatin (condensation) and the nuclear membrane (dilatation) and is regarded as “accidental cell death” [1]. Apart from these morphological features there was no reliable marker for detection of necrosis available

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