Effect Of Baicalin On Signaling Transduction Pathway Of JAK-STAT3 In SMMC-7721 Cell Line

Objective: Hepatocellular carcinoma (HCC) is a common tumor of digestive tract with poor prognosis and high mortality rate. It is a serious threat to human health and life. The early surgery is still the best current treatment of the hepatocellular carcinoma. But 95% of the patients lost the chance of operation when they get the time of diagnosis. At this time the most of patients with poor liver function and physical condition. Then they have been difficult to tolerate the radiofrequency ablation treatment. Most patients with liver cancer also depend on the treatment of chemical drugs. However, the chemotherapy drugs also caused serious side effects in patients .It is the great challenge to discover and develop the new antitumor drugs which can control the progression of the disease, improve the quality of life and prolong survival.In recent years, with the development of the molecular oncology and the molecular pharmacology, the comprehensive treatment based on blocking abnormal signalling pathways has become a new target for anticancer drug research. These new antitumor drugs can kill cancer cells but have little effect on normal cells, lessen the injury to normal tissue, prolong the patients life span .the drugs retrieve the shortage of traditional chemotherapeutics. The therapy target to cell receptor, key gene, controlling molecule is called targeted therapy. Targeted therapy is popular on the treatment of anti-tumor. Recently there are researches about varieties abnormal signal transduction pathway, the most popular is Janus protein tyrosine kinase / signal transducer and activator of transcription (JAK/STAT). As one of the stat family, STAT3 is a important signal factor to JAK-STAT, P-STAT3 is its active form. The normal signal transduction of STAT3 activation is quick and short, abnormal signal transduction of JAK-STAT has closely relation with the occurrence, development, invasion, diversion and prognosis of tumor. STAT3 persist activation was found in the process of tumor formation. People are focus on the effect of STAT3 on the occurrence and development of malignant tumor. It will be the effective intervention therapy.Baicalin, one of the main active compounds of scutellaria baicalensis, molecular formula :C₂₁H₁₈O₁₁, molecular weight: 446.36 , possesses anti-inflammatory, anti-allergy,antioxidant and antitumor properties Recent studies have shown that certain concentration of baicalin can inhibit proliferation of the liver cancer cell. In this study, we treat HCC cell line of SMMC-7721 cell with Chinese herbal baicalin, JAK-STAT signaling transduction way inhibitor AG490 to study their effect on signaling way changes so as to HCC cell outcome.Methods:1 The cells were divided into 4 groups:(1)blank control group ; (2) AG490 group ;(3) baicalin group ; (4) baicalin+AG490 group.2 The mRNA expressional levels of STAT3 in SMMC-7721 cells were measured by RT-PCR.3 The protein expression levels of STAT3 and P-STAT3 in SMMC-7721 cells were measured by Western blotting.Result:1 After treated with baicalin, the expressional levels of STAT3 mRNA in SMMC-7721 cells were significantly lower than those in control group (P<0.05). After treated with AG490, the expressional levels of STAT3mRNA in SMMC-7721 cells show no difference compared with control group. After treated with baicalin+AG490, the expressional levels of STAT3 mRNA in SMMC-7721 cells were significantly lower than control group (P<0.05). Compared with baicalin group, there were no significant differences of the STAT3 mRNA expressional levels after treated with baicalin +AG490. Compared with AG490 group, the expressional levels of STAT3 mRNA were significantly lower in baicalin +AG490 group (P<0.05).2 After treated with baicalin, the protein expressional levels of STAT3 in SMMC-7721 cells were significantly lower than those in control group(P<0.05) After treated with AG490, the protein expressional levels of STAT3 in SMMC-7721 cells show no difference compared with control group. After treated with baicalin+AG490, the protein expressional levels of STAT3 in SMMC-7721 cells were significantly lower than control group (P<0.05). Compared with baicalin group, there were no significant differences of the protein expressional levels of STAT3 after treated with baicalin +AG490. Compared with AG490 group, the protein expressional levels of STAT3 were significantly lower in baicalin +AG490 group (P<0.05).3 After treated with baicalin, the protein expressional levels of P-STAT3 in SMMC-7721 cells were significantly lower than those in control group (P<0.05). After treated with AG490,the protein expressional levels of p-stat3 in SMMC-7721 cells were significantly lower than those in control group(P<0.05) After treated with baicalin+AG490,the protein expressional levels of P-STAT3 in SMMC-7721 cells were significantly lower than those in control group(P<0.05). Compared with baicalin group, the protein expressional levels of P-STAT3 in SMMC-7721 cells were significantly decreased after treated with baicalin+AG490. Compared with AG490 group, the protein expressional levels of P-STAT3 were significantly lower after treated with baicalin +AG490 group (P<0.05).Conclusion:1 Baicalin could significantly down-regulate the mRNA expressional levels of STAT3 in SMMC-7721 cells.2 Baicalin could significantly down-regulate the protein expressional levels of STAT3 and P- STAT3 in SMMC-7721 cells.3 Baicalin could significantly inhibit the activation of STAT3 protein. Baicalin could enhance the inhibition ratios of SMMC-7721 cells treated with AG490 and increase their effect.4 Baicalin and AG490 both could inhibit the proliferation of SMMC-7721 cells. Different from the AG490, Baicalin could not only inhibit JAK-STAT signaling transduction pathway through blocking of the activation of STAT3, but also down-regulate the mRNA expressional levels of STAT3 from the gene level in SMMC-7721 cells.