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BackgroundLung cancer is among the most common malignant tumors. Because of the lack of clear pathogenesis of lung cancer, this disease still can not be diagnosed early and treated specifically, both of which lead to its poor prognosis. Previous researches have found that there is an abnormal high level of hnRNP B1 and PKM2 in lung cancerous tissue and both of them relate to cell proliferation. As isoenzyme of PKM1 which participate in aerobic oxidation, PKM2 has the same source and similar structure as PKM1 but correlates with acrobic glycolysis, which maintain the balance of energe metabolism and mass synthesis in proliferating cells. PKM2 and PKM1 are different products of the same pre-mRNA under alternatively splicing. As an important part of RNA binding protein in the cell, hnRNP B1 plays a role in pre-mRNA splicing. We want to know the relationship between hnRNP B1 and PKM and their influence to cell proliferation.MethodsWe construct hnRNP B1-specific siRNA on plasmid, then use it to transfect A549 cells. The continuous expression of siRNA could inhibit the expression of hnRNP B1 which may influence level of PKM2 and PKM1 and cell proliferation. We use fluorescent quantitation PCR to detect the levels of the genes and MTT to observe the rate of cell proliferation.ResμLtsWe construct successfully hnRNP B1-specific recombinant plasmid. After transient transfection, the levels of hnRNP B1 in recombinant group A,B,C,D decrease. Their inhibitory efficiency are 42.54%,35.64%,45.38%,34.58% respectively (P<0.05), compared with untransfected group F. There is no inhibitory efficiency of recombinant group E (P>0.05). The ratio of PKM1/PKM2 mRNA of group A-F are 1.8857±0.5467,1.7771±0.7229,1.8400±0.7745,2.5231±1.2323, 1.2700±0.4855,1, respectively. However, the figures show no statistical difference (P>0.05). The levels of hnRNP B1 in positive polyclones pA-pD are dramatically decreased, the inhibitory efficiency are 86.9%,60%,73%,68.8%, respectively. For pE, it is 27.2%. The ratio of PKM1/PKM2 are all above 1.0 in group pA-pD, while under 1.0 in group pE. The results of MTT show no statistical difference in proliferating rate between group pA, pE and F (P>0.05). While the rate of group pC is less than group pE and F(P<0.05).ConclusionsThe recombinant plasmid which could express hnRNP B1-specific siRNA indeed inhibit the expression of hnRNP B1 in A549 cells and decrease the rate of cell proliferation. When expression of hnRNP B1 is inhibited, the ratio of PKM1/PKM2 mRNA changes and has a tendency to go up. It suggests that hnRNP B1 may change the levels of different isoenzymes of PKM, which could influence cell proliferation.
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