H HERG's Expression In Different Classificatory Bone Tumors And Its Effect On The Proliferation Of Osteosacoma Cell Lines

Background: Human ether-à-gò-gò-related gene (HERG)was first discovered in guineapig's cardiac muscle cell, and then was discovered in many kinds of cardiac muscle cells. HERG (human EAG related gene) encodes a particular type of K+ channel who belongs to an evolutionary conserved multigene family of voltage-activated, outward rectifying K+ channels, the EAG (etherà-gò-gò) family. Many research have shown that HERG expressed selectively in several tumors of different histolocical origins, and widely affected the biological behavior of tumors. It is relevant to the proliferation; apoptosis; differentiation and invasion. But it is not seen in nomal cells. This selective expressing maybe stand for a potentially advantage of the development of tumors. Currently, it is a hot spot for study on the proliferation of tumor cells when block the potassium channels on their membrane. It has been revealed thatα-subunit of the delayed rectifier potassium channel, encoded by HERG gene participated in processes such as aggressive as well as growth and death of tumor cells. However, the mechanism of how HERG affact the regulation and invasiveness of cell proliferation is not fully understood till now. HERG's expression is scarely reported within common bone tumors as well as its lack of enough study.Objective: This study is to explore the protein expression levels of HERG in various common malignant bone tumor tissues, and in 3 osteosarcoma cell lines: MG-63; SOSP-9607; Saos-2. To analyze the association between HERG gene in bone tumors and tumor patients'clinicopathological characteristics, and to explore the relationship between tumor differentiation and the degree of malignancy. Meanwhile we discovered the effect on proliferation of these cell lines by several blocker of K+ channels. This study is to give a guiding role with a view for future clinical cancer treatment, especially chemotherapy.Method: 1 Agreed by the consent of medical council and patients, according to common 60 cases of clinical bone tumor tissue were selected and assorted. 2 Immunohistochemical stained with uniform cases of histological sections, and observed under microscopic. 3 mRNA were extracted from various specimens RT-PCR used to observe their herg's mRNA expression levels. 4 Total protein were extracted from tissue specimens, western blot was used to observe the HERG protein expressions. 5 Anabiosis and culture osteosarcoma cell lines MG-63;SOSP-9607;Saos-2, extract Mrna, observed the expression level of herg by RT-PCR too. 6 Blocker of potassium Ion channels 4-AP; E-4031were used on the three cell lines; and MTT were carried on to observed the effect on proliferation of the cell lines.Results: 1 The 60 clinical specimens which were gathered from 2007 to 2009 were separated into two groups by sum up and sorting. Benign: 25 cases; malignant: 35 cases. Detail information in the text. 2 Immunohistochemical staining showed that HERG is differently expressed in different malignant tumors. Both the level and position. It is not express in normal bone tissue. 3 RT-PCR results showed that the mRNA level of HERG was related to the origin of tumor and the degree of malignancy. 4 Western Blot shows that protein expression was affected by the degree of malignant. 5 RT-PCR results showed that herg were highly expressed in the osteosarcoma cell lines MG63; SOSP-9607;Saos-2. 6 Different concentration of blockers were utendus in the culture media of cell lines, MTT method were used to observe the changing of value of A of each groups after cultured of 48h. The conclusion is that blocker E-4031 can not markedly inhibit the proliferation of osteosarcoma cell lines. But 4-AP in the concentrations of 3 mmol/L and 5 mmol/L can apparently inhibit their proliferation.Conclusion: HERG was involved in the evolution of various bone tumors. The expression level of HERG was distinguishing in different origin and different malignance of tumors. Many malignant bone tumors are potential targets of HERG expression. HERG was not expressed or lowly expressed in the benign or low malignant tumors, but highly expressed in malignant tumors. It also highly expressed in osteosarcoma cell lines MG63; SOSP-9607 and Saos-2.Some blockers of potassium ion channels can apparently inhibit their proliferation. These proved that HERG is closely related with the origin; proliferation; malignancy.