The Biological Role Of HMGB1 In Colorectal Cancer

Objective Colorectal cancer(CRC) is a common malignant tumor of digestive tract, and its morbidity and mortality rate increased year by year. The invasion and distant metastasis of CRC can affect significantly the prognosis of patients with CRC. In recent years, scholars have found that high mobility group protein B1 is a kind of protein with very rich, evolution highly conserved and almost 100% exists in eukaryotic cells. HMGB1 is named after the deep rapidly migration in the polyacrylamide gel electrophoresis. Studies have found that HMGB1 play the role of tumor promoting genes, and participate in the occurrence and development of tumor, invasion, and metastasis. HMGB1 could express highly in human malignant tumors, and is closely connected with the tumor growth, invasion and metastasis. The main purpose of this study is that we silence HMGB1 gene expression by small inference RNA and observe the colorectal cancer cell line Lovo cells growth, proliferation, invasion and metastasis and related biological effects of inhibition.Methods HMGB1 gene expression was silenced by lentivirus-mediated si RNA, WB method is used to detect expression of HMGB1 protein after silenced,reverse transcription polymerase chain reaction was used todetect HMGB1 m RNA expression level in lovo cells. MTT method, flow cytometry, Transwell and scratched cells and nude mice experiment to analysis respectively colorectal cancer Lovo cell growth, proliferation, invasion and metastasisafter HMGB1 gene silencing.Results Colorectal cancer cell line Lovo were successful transfection by lentivirus-mediated si RNA. HMGB1 m RNA in HMGB1-si RNA Lovo cell transfection group was 0.24±0.04, the relative expression level was lower than that HMGB1 m RNA 0.82±0.13 in the negative control group and HMGB1 m RNA was 0.93 ± 0.15 in the blank control group(P<0.05). Similarly, HMGB1 protein HMGB1-si RNA Lovo cell transfection group was 0.21±0.03, the relative expression level significantly lower than HMGB1 protein 1.15±0.18 in the negative control group and HMGB1 protein 1.21±in the blank control group(P < 0.05). In terms of cell growth,MTT method shows that HMGB1-si RNA transfection group Lovo cell growth rate was decreased when compared with negative control group and blank control group(P < 0.05). In terms of cell proliferation index(PI),Flow cytometry showed that HMGB1-si RNA Lovo cell transfection group was 38.27 ± 1.32, significantly lower than 54.66±1.74 in the negative control group and 57.43±1.29 in blank control group(P < 0.05). Transwell experiments show that HMGB1-si RNA transfection group was(14.0± 3.5)/high power field of vision, significantly lower than the negative control group [(51.0±6.7)/high power field of vision and the blank control group [(68.0 ± 5.3)/high power field of vision, P<0.05). Cell scratch experiments have shown that 48 h after training, the migration distance in HMGB1-si RNA Lovo cell transfection group is(83.61±23.21) microns, significantly lower than the negative control group [(202.86 ±46.46) um] and blank control group [(214.58±57.38)um, P < 0.05). In the nude mice tumor experiment we found that the experiment after 21 d, tumor volume(521±34) mm3, significantly less than the negative control group [(763±46) mm3] and [(802±51) mm3, blank control group(P < 0.05).Conclusion HMGB1 gene expression in colorectal cancer Lovo cell can effectively be silenced bylentivirus-mediated si RNA.When HMGB1 gene expression was silenced by si RNA, it can effectively reduce colorectal cancer cell growth rate, prolong the proliferation cycle, decrease cell invasion and migration ability. At the same time in nude mice in vivo can effectively inhibit the growth of nude mouse transplantation tumor.