Classification of Cell-in-Cell Structures: Different Phenomena with Similar Appearance

Area of Science:

• Cell Biology
• Cancer Research
• Molecular Mechanisms

Background:

• Cell-in-cell (CIC) is a phenomenon known for over a century, now experiencing a resurgence due to advanced cell visualization techniques.
• Increasing evidence suggests CICs hold prognostic and diagnostic value for cancer patients, moving them from an esoteric topic to a clinically relevant area.
• Despite growing interest, challenges in studying CICs and limitations of current molecular techniques leave many questions unresolved.

Purpose of the Study:

• To review and distinguish the five known forms of cell-in-cell phenomena: cell cannibalism, phagoptosis, enclysis, entosis, and emperipolesis.
• To highlight the unique features, characteristics, and underlying molecular mechanisms of each CIC type.
• To provide a comprehensive overview of the current understanding of CIC formation and its potential implications in cancer.

Main Methods:

• Literature review of cell-in-cell phenomena.
• Analysis of modern cell visualization techniques applied to CIC studies.
• Examination of molecular mechanisms and signaling pathways involved in CIC formation.

Main Results:

• Distinction of five distinct CIC types: cell cannibalism, phagoptosis, enclysis, entosis, and emperipolesis.
• Elucidation of the dynamic cell-cell interaction, including adhesion, cytoskeleton activation, and membrane deformation, leading to CIC formation.
• Identification of potential roles for both homotypic and heterotypic cell engulfment in initiating the process.

Conclusions:

• Cell-in-cell phenomena represent a complex cellular process with diverse forms and underlying molecular mechanisms.
• Understanding the distinct types of CICs is crucial for exploring their potential diagnostic and prognostic applications in oncology.
• Further research is needed to overcome current technical limitations and fully elucidate the biological significance of CICs in health and disease.