| In tumor cells and immortalizing cells, with the balance between the positive regulation of telomerase and the negative regulation of TRF1, the length of telomere is maintained in a certain range. Recently, scientists discoved a novel telomerase regulating enzyme, tankyrasel, which co-localizes with TRF1 at the ends of human chromosomes in metaphase. In vitro poly(ADP-ribosyl)ation by tankyrasel inhibits TRF1 binding to telomeric DNA, which is of great benefit for telomerase elongating the length of telomere . Since the function of tankyrasel has already been definite in the process of telomere replication, our experiment was aimed at investigating the TANKl-ASODN's potential effect on the proliferation of human lung cancer cell line CALU.Objective: To observe the suppressing effect of antisense oligodeoxynucleotides of Tankyrasel ( TANK1-ASODN ) on murine tumor growth following intratumoral injection , and discuss the possibility of using it in clinical treatment of lung cancer.Methods: After human lung cancer cell line CALU had been inoculated subcutaneously to BALB/c nude mice and grew to tumor nodules , we grouped these mice randomly into three parts: Four mice in saline treatd group served as control group, and five in the other two groups respectively. Then mutiple direct intratumoral injection of synthesized TANK1-ASODN was given continously into tumor nodles for 15 days, compared with sense oligodeoxynucleotides of tankyrase (TANK1-SODN) and saline contral groups. During the experiment we measured the tumor volume every five days with vernier caliper, observed the histopathological characteristics of tumor tissues under microscope and went further to research the wispy changing of ultrastructure of lung cancer cells by electron microscope. Immunohistochemistry was used to detect the expression levels of Ki67 and hTERT4protein in three different tissue groups by SABC immunohistrochemical method. We also measured the lung cancer cells' hTERT mRNA expressing level by hybridization in situ (ISH) in the same groups. Results:1. The suppressing effect of TANKl-ASODN on murine tumor growthAfter 15 days of continuous injection, the suppressing rate of tumor growth in TANKl-ASODN treated group was 69.32%, significantly higher than that of the saline treated group (the tumors' volume was progressively getting bigger), and that of the TANK-SODN treated group (the suppressing rate of tumor growth was less than 40%). There was no significant difference in tumor volume among the three groups(P > 0.05) on the first and the fifth treating day. Whereas on the tenth treating day, the tumor volume of control group was significantly bigger than that of TANKl-ASODN (PO.01) and TANKl-SODN treated group (PO.01). There was also significant difference in tumor volume between control group and TANKl-SODN group (P<0.05). After 15 days' injection treatment had been completed, a significant difference in tumor volume was found between TANKl-ASODN group and control group (PO.01), the same between TANKl-ASODN group and TANKl-SODN group (PO.01). But there was no significant difference in volume between control group and TANKl-SODN group (P > 0.05).2. The changing of histopathological characteristics and ultrscrostructure of tumor tissues in tree different groupsUnder microscope quite a lot tumor cell degeneration and necrosis were observed in tumor nodules given TANKl-ASODN. The results of electron microscope showed that the TANKl-ASODN had the obvious killing effects on lung cancer cell line CALU through various paths, such as necrosis, apoptosis, oncosis and so on. Whereas the TANKl-SODN had a certain degree of promoting the canser cells to5proliferate and invade the normal tissues around, but this influence was only for a kind of tendency. Necrosis and apoptosis hadn't been seen in TANK1-SODN treated cancer cells. The matched control cancer cells treated with saline reported the prosperous growth without necrosis and apoptosis. 3. The expressing levels of Ki67 and hTERT protein in there differ...
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