Knecht Hans, Brüderlein Silke, Wegener Silke, Lichtensztejn Daniel, Lichtensztejn Zelda, Lemieux Bruno, Möller Peter, Mai Sabine
CHUS, Université de Sherbrooke, Québec, Canada.
BMC Cell Biol. 2010 Dec 14;11:99. doi: 10.1186/1471-2121-11-99.
In cancer cells the three-dimensional (3D) telomere organization of interphase nuclei into a telomeric disk is heavily distorted and aggregates are found. In Hodgkin's lymphoma quantitative FISH (3D Q-FISH) reveals a major impact of nuclear telomere dynamics during the transition form mononuclear Hodgkin (H) to diagnostic multinuclear Reed-Sternberg (RS) cells. In vitro and in vivo formation of RS-cells is associated with the increase of very short telomeres including "t-stumps", telomere loss, telomeric aggregate formation and the generation of "ghost nuclei".
Here we analyze the 3D telomere dynamics by Q-FISH in the novel Hodgkin cell line U-HO1 and its non-receptor protein-tyrosine phosphatase N1 (PTPN1) stable transfectant U-HO1-PTPN1, derived from a primary refractory Hodgkin's lymphoma. Both cell lines show equally high telomerase activity but U-HO1-PTPN differs from U-HO1 by a three times longer doubling time, low STAT5A expression, accumulation of RS-cells (p < 0.0001) and a fourfold increased number of apoptotic cells.As expected, multinuclear U-HO1-RS-cells and multinuclear U-HO1-PTPN1-RS-cells differ from their mononuclear H-precursors by their nuclear volume (p < 0.0001), the number of telomeres (p < 0.0001) and the increase in telomere aggregates (p < 0.003). Surprisingly, U-HO1-RS cells differ from U-HO1-PTPN1-RS-cells by a highly significant increase of very short telomeres including "t-stumps" (p < 0.0001).
Abundant RS-cells without additional very short telomeres including "t-stumps", high rate of apoptosis, but low STAT5A expression, are hallmarks of the U-HO1-PTPN1 cell line. These characteristics are independent of telomerase activity. Thus, PTPN1 induced dephosphorylation of STAT5 with consecutive lack of Akt/PKB activation and cellular arrest in G₂, promoting induction of apoptosis, appears as a possible pathogenetic mechanism deserving further experimental investigation.
在癌细胞中，间期细胞核的三维（3D）端粒组织形成端粒盘的过程严重扭曲，且会出现聚集现象。在霍奇金淋巴瘤中，定量荧光原位杂交（3D Q-FISH）揭示了从单核霍奇金（H）细胞向诊断性多核里德-斯特恩伯格（RS）细胞转变过程中核端粒动力学的重大影响。RS细胞在体外和体内的形成与包括“t-残端”在内的极短端粒的增加、端粒丢失、端粒聚集形成以及“幽灵核”的产生有关。
在此，我们通过Q-FISH分析了新型霍奇金细胞系U-HO1及其非受体蛋白酪氨酸磷酸酶N1（PTPN）稳定转染体U-HO1-PTPN1中的3D端粒动力学，这两种细胞系源自原发性难治性霍奇金淋巴瘤。两种细胞系均显示出同样高的端粒酶活性，但U-HO1-PTPN与U-HO1的不同之处在于其倍增时间长三倍、STAT5A表达低、RS细胞积累（p < 0.0001）以及凋亡细胞数量增加四倍。正如预期的那样，多核U-HO1-RS细胞和多核U-HO1-PTPN1-RS细胞与其单核H前体细胞在核体积（p < 0.0001）、端粒数量（p < 0.0001）和端粒聚集增加（p < 0.003）方面存在差异。令人惊讶的是，U-HO1-RS细胞与U-HO1-PTPN1-RS细胞的不同之处在于包括“t-残端”在内的极短端粒显著增加（p < 0.0001）。
大量不含包括“t-残端”在内的额外极短端粒的RS细胞、高凋亡率但低STAT5A表达，是U-HO1-PTPN1细胞系的特征。这些特征与端粒酶活性无关。因此，PTPN1诱导STAT5去磷酸化，随后缺乏Akt/PKB激活并使细胞停滞在G₂期，从而促进凋亡诱导，这似乎是一种值得进一步实验研究的可能发病机制。
