Cell-in-Cell: A Century-Old Mystery Comes to the Table

Heterotypic cell-in-cell structures between cancer and NK cells is associated with enhanced anti-cancer drug resistance

The heterotypic CIC structures formed of cancer and immune cells have been observed in tumor tissues. We aimed to assess the feasibility of using heterotypic CICs as a functional biomarker to predict NK susceptibility and drug resistance. The heterotypic CIC-forming cancer cells showed a lower response to NK cytotoxicity and higher proliferative ability than non-CIC cancer cells. After treatment with anticancer drugs, cancer cells that formed heterotypic CICs showed a higher resistance to anticancer drugs than non-CIC cancer cells. We also observed the formation of more CIC structures in cancer cells treated with anticancer drugs than in the non-treated group. Our results confirm the association between heterotypic CIC structures and anticancer drug resistance in CICs formed from NK and cancer cells. These results suggest a mechanism underlying immune evasion in heterotypic CIC cancer cells and provide insights into the anticancer drug resistance of cancer cells.

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Conformation of heterotypic CIC structures formed between cancer and NK cells

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Heterotypic CICs exhibit a higher proliferative ability than non-CIC cells

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Heterotypic CICs are associated with NK susceptibility

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Heterotypic CICs are involved in anticancer drug resistance

Autophagy-Regulating microRNAs and Cancer

Macroautophagy (autophagy herein) is a cellular stress response and a survival pathway that is responsible for the degradation of long-lived proteins, protein aggregates, as well as damaged organelles in order to maintain cellular homeostasis. Consequently, abnormalities of autophagy are associated with a number of diseases, including Alzheimers’s disease, Parkinson’s disease, and cancer. According to the current view, autophagy seems to serve as a tumor suppressor in the early phases of cancer formation, yet in later phases, autophagy may support and/or facilitate tumor growth, spread, and contribute to treatment resistance. Therefore, autophagy is considered as a stage-dependent dual player in cancer. microRNAs (miRNAs) are endogenous non-coding small RNAs that negatively regulate gene expression at a post-transcriptional level. miRNAs control several fundamental biological processes, and autophagy is no exception. Furthermore, accumulating data in the literature indicate that dysregulation of miRNA expression contribute to the mechanisms of cancer formation, invasion, metastasis, and affect responses to chemotherapy or radiotherapy. Therefore, considering the importance of autophagy for cancer biology, study of autophagy-regulating miRNA in cancer will allow a better understanding of malignancies and lead to the development of novel disease markers and therapeutic strategies. The potential to provide study of some of these cancer-related miRNAs were also implicated in autophagy regulation. In this review, we will focus on autophagy, miRNA, and cancer connection, and discuss its implications for cancer biology and cancer treatment.

Mechanisms and consequences of entosis

Multiple mechanisms have emerged where the engulfment of whole live cells, leading to the formation of what are called 'cell-in-cell' structures, induces cell death. Entosis is one such mechanism that drives cell-in-cell formation during carcinogenesis and development. Curiously, entotic cells participate actively in their own engulfment, by invading into their hosts, and are then killed non-cell-autonomously. Here we review the mechanisms of entosis and entotic cell death and the consequences of entosis on cell populations.