engleski

Comparative analysis of apoptotic activity in teratocarcinoma and the experimental mouse teratocarcinoma model

Incidence of testicular germ cell tumors (TGCT) has been continuously rising (1-5% per year), (1). In Croatia the incidence of TGCT is increasing at the highest rate in the world. Croatia also has a high rate of mortality compared to other countries (2). Germ cell neoplasia in situ (GCNIS) is a precursor lesion of TGCT’s which makes up to 95% of all testicular tumors. TGCT are divided into pure seminomatous tumors and mixed germ cell tumors (non-seminomas). GCNIS is considered to be driven by an interplay of genetic, epigenetic and micro-environmental factors that lead up to an arrest of gonocyte differentiation (3, 4). GCNIS is reprogrammed in the development of non- seminomas into embryonal carcinoma (EC) cells, which make up the pluripotent core of the nonseminomas (3). EC cells are highly similar to embryonic stem cells, expressing the same pluripotency markers OCT4, SOX2 and NANOG. EC cells differentiate into teratoma tissue, or retain their pluripotency and high malignancy as in teratocarcinoma (5). The well-known and established experimental mouse model for teratocarcinoma, at the Biology Department of Zagreb’s School of Medicine, has been described based on histological/histochemical methods and its molecular signature has not yet been studied (6). The aim of this study was to compare the rate of apoptotic activity in the experimental mouse model as well as in human teratocarcinomas.Caspase-3 is the most important apoptotic executioner caspase in apoptosis and is activated by both intrinsic and extrinsic pathways. Some authors consider that Caspase-3 plays a critical role in ES cell differentiation by negatively regulating the self-renewal machinery of these stem cells, in part by cleaving Nanog (7, 8). Formalin-fixed paraffin-embedded tissue from 10 testicular teratocarcinoma from the Ljudevit Jurak Pathology and Cytology Department Archive and 10 animal model tumors from the Biology Department of Zagreb’s School of Medicine were used for immunohistochemical detection of Caspase-3. Slides were analyzed semi- quantitatively, at the area of strongest reaction, by two pathologist (S.M. and M.U.), on a scale from 0-3, depending on the percentage of reactive cells. The data were analyzed in GraphPad Prism using the Mann-Whitney test. The results have shown a statistically significant difference in the rate of apoptosis between the human teratocarcinomas and the experimental mouse model, with the mouse model showing a higher rate (more than 25% of positive cells) in 64% of tumors compared to 30% of human tumors with highest reaction. The difference could be in part attributed to the fact that the study was a pilot with a relatively small sample pool, and the difference in biological development and “age” between the human and mouse model teratocarcinomas which was obtained uniformly. Western Blot analysis of Caspase-3 activity should be done to verify the results and a bigger cohort should be studied (Figure 1).

TGCT ; mouse model ; apoptosis ; caspase-3

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