Cell cannibalism in oral cancer: A sign of aggressiveness, de-evolution, and retroversion of multicellularity.

Abstract

According to Darwin's theory of evolution, complex creatures evolve from more simplistic ancestors. Dollo's law of irreversibility states that evolution is irreversible. However, cancer cells tend to follow anti-Dollo's law. Unfavorable conditions such as hypoxia, acidic pH and low nutrients cause the cancer cells to switch their lifestyle atavistically in order to survive. They start behaving like a unicellular organism. There is a switch from normal metabolism to Warburg effect and finally cannibalism. Cannibalism is a cell eating cell phenomenon. It is defined as a large cell enclosing a smaller one within its cytoplasm and is known by odd names such as "bird's eye cells" or "signet ring cells." Smaller tumor cells are found in the cytoplasm of larger tumor cells with crescent-shaped nucleus. Cannibalistic cells (CCs) are a feature of aggressive tumors. These cell types are vulnerable to metastasis. The aim of this study is to identify CCs in various histological grades of oral squamous cell carcinoma (OSCC) and to relate them with the pattern of invasion, lymphocytic response (LR), and mitotic figures (Mfs). The purpose of the article is to establish it as a marker of aggressiveness and metastasis and as an evidence of de-evolution and retroversion of multicellularity. Sixty-five histologically confirmed cases of OSCC were studied. Pattern of invasion, LR, number of CCs, and Mfs were recorded on 5 μ hematoxylin and eosin-stained tissue sections. ANOVA and t-test were applied; P < 0.05 was considered statistically significant. CCs were more in sections with patchy LR, increased Mfs, and grade IV pattern of invasion. With increase in dedifferentiation, tumor cells start behaving like unicellular organisms with cell eating cell characteristics.