Therapeutic effects of signal transducer and activator of transcription 3 siRNA on human breast cancer in xenograft mice / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Signal transducer and activator of transcription 3 (STAT3) is usually constitutively activated in a variety of malignancies. It directly contributes to tumorigenesis, invasion, and metastasis. The surgical treatment of breast cancer has made no breakthroughs in terms of treatment effect, in spite of its long history. Current biotherapies bring a note of optimism to breast cancer treatment. To explore the possibility of a siRNA targeted STAT3 blocking treatment for over-activated tumor cells, we evaluated the efficacy of a STAT3 siRNA on human breast cancer cells in vitro and in vivo.</p><p><b>METHODS</b>Three MCF-7 human breast cancer cell lines were tested: control MCF-7 cells, non-specific siRNA transfected MCF-7 cells and STAT3 siRNA transfected MCF-7 cells. Expression of STAT3 in MCF-7 cells was inhibited by RNA interference (RNAi). The STAT3 mRNA and protein levels were detected by semi-quantity RT-PCR and Western blotting. Cell proliferation and apoptosis were determined by MTT method and flow cytometry. The three groups of MCF-7 cells mentioned above were transplanted subcutanuously into nude mice and their tumorgenic ability observed. The STAT3 mRNA and protein levels of the samples from tumors in different groups were determined by semi-quantity RT-PCR and Western blotting and compared.</p><p><b>RESULTS</b>In STAT3 siRNA transfected MCF-7 cells, the expressions (STAT3/β-actin) of STAT3 mRNA (0.327 ± 0.020) and protein (0.153 ± 0.006) were significantly lower than that in control MCF-7 cells (mRNA 1.093 ± 0.018, protein 1.374 ± 0.022) and non-specific siRNA transfected MCF-7 cells (mRNA 1.035 ± 0.050, protein 1.320 ± 0.033) (P < 0.05). MTT showed that cell proliferation was significantly reduced and the cell growth inhibition ratio in the STAT3-siRNA group was (44.00 ± 5.10)%, significantly higher than that in non-specific siRNA transfected MCF-7 cells ((16.10 ± 1.05)%, P < 0.05). Flow cytometry results showed that more apoptosis was observed in the STAT3-siRNA group. The rate of apoptosis was (14.79 ± 0.22)%, much higher than in control MCF-7 cells (7.06 ± 0.71) and non-specific siRNA transfected MCF-7 cells (8.45 ± 0.43) (P < 0.05). The tumor growth in the STAT3 siRNA transfected MCF-7 cells was significantly slower than in the two control groups. On the 22th day after transplantation the tumor weight ((21.40 ± 10.57) mg) and volume ((41.15 ± 12.17) mm(3)) in the STAT3 siRNA transfected group were significantly lower than in control group (weight (88.60 ± 12.16) mg, volume (118.45 ± 24.68) mm(3)) and non-specific siRNA transfected group (weight (57.20 ± 21.86) mg, volume (101.36 ± 21.90) mm(3)) (P < 0.05). Both the STAT3 mRNA and protein levels in the tumors from the STAT3 siRNA transfected group were significantly lower than in the tumors from the two control groups.</p><p><b>CONCLUSIONS</b>STAT3 siRNA can effectively silence the STAT3 gene in vitro and in vivo, increase cell apoptosis rate and significantly decrease cell proliferation, which inhibits the growth of breast cancer cell in vitro. Tumor growth of xenograft mice is significantly inhibited. The results obtained in vivo are in consistency with those in vitro. STAT3 may be a novel therapeutic target for breast cancer and RNA interference has potential clinical application.</p>

Growth inhibition of breast cancer cells in vitro and in vivo by siRNA targeting signal transducers and activators of transcription 3 / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To observe the effect of signal transducers and activators of transcription 3 (STAT3) gene silence on the growth of breast cancer cell line MCF7 in vitro and in vivo and discuss the feasibility and effectiveness of STAT3 used as gene therapeutic target for breast cancer.</p><p><b>METHODS</b>Human breast cancer cell line MCF7 cells were divided into 3 groups: mock control group, control group transfected with scrambled sequence siRNA, and experimental group transfectod with STAT3 siRNA. The STAT3 mRNA and protein levels were detected by semi-quantity RT-PCR and Western blotting, respectively. The cell proliferation and apoptosis were examined by MTT method and flow cytometry. MCF7 cells treated with STAT3-siRNA were transplanted subcutaneously in nude mice and their tumorgenic ability was observed. The STAT3 mRNA and protein levels of the samples from nude mice of different groups were detected by semi-quantity RT-PCR and Western blotting and compared.</p><p><b>RESULTS</b>After treatment with STAT3-siRNA, STAT3 mRNA (0.327 ± 0.020 vs. 1.035 ± 0.050, 1.093 ± 0.018) and ptotein (0.153 ± 0.006 vs. 1.320 ± 0.033, 1.374 ± 0.022) levels in the MCF7 cells transfected with STAT3-siRNA were significantly lower than that in the two control groups (P < 0.05). MTT assay showed that after transfection of the STAT3-siRNA into MCF7 cells, cell proliferation was significantly reduced and the cell growth inhibition ratio in the STAT3-siRNA group was (44.00 ± 5.10)%, significantly higher than that in the control group (16.1 ± 1.05)% (P < 0.05). Flow cytometry results suggested that more apoptosis was observed in the STAT3-siRNA group. The apoptosis rate was (14.79 ± 0.22)%, much higher than that in the control group [(7.06 ± 0.71)%, (8.45 ± 0.43)%, P < 0.05]. The tumor growth in the experimental group was significantly slower than that in the two control groups. 0n the 22th day after transplantation, the tumor weight [(21.4 ± 10.6) mg vs. (88.6 ± 12.2) mg, (57.2 ± 21.9) mg] and volume [(41.15 ± 12.17) mm³ vs. (118.45 ± 24.68) mm³, (101.36 ± 21.90) mm³] in the experimental group were significantly lower than that in the two control groups (P < 0.05). The STAT3 mRNA and protein levels of the samples from nude mice in the experimental group were significantly lower than that in the two control groups.</p><p><b>CONCLUSION</b>siRNA targeting STAT3 can inhibit the proliferation of MCF7 cells in vitro and in vivo. STAT3 may become a novel therapeutic target for breast cancer.</p>

Clinical significance of micrometastasis in lymph nodes and microinvasion in primary lesion in submucosal gastric cancer / 中华外科杂志

<p><b>OBJECTIVE</b>To clarify the clinicopathologic characteristics of micrometastasis in lymph nodes and microinvasion in primary lesion for the treatment options with regard to submucosal gastric cancer.</p><p><b>METHODS</b>1945 lymph nodes and 68 primary tumors resected from 79 patients with submucosal gastric cancer were examined. Two consecutive sections were prepared for simultaneous staining with HE and immunostaining with anti-cytokeratin antibody (CAM 5.2), respectively.</p><p><b>RESULTS</b>The incidence of nodal involvement in 79 patients with submucosal gastric cancer was increased from 13% (10/79 patients) by HE staining to 34% (27/79 patients) by cytokeratin immunostaining. Micrometastasis in the lymph nodes were found in 17 of 69 patients (25%) with cancer-free nodes examined by HE staining. Microinvasion to the muscularis properia was found in 11 of 68 patients (16%) who were histologically diagnosed as submucosal gastric cancer. Survival analysis demonstrated a worse 5-year survival in the patients with micrometastasis in lymph nodes (82%) and with microinvasion to muscularis properia (73%). A higher incidence of nodal involvement was found in submucosal cancers of large size (> 2 cm; 43%), a depressed type (48%), lymphatic invasion (73%), and deeper submucosal invasion (submucosal 3; 53%). A higher incidence of microinvasion was found with the diffused-type carcinoma (33%).</p><p><b>CONCLUSIONS</b>Cytokeratin immunostaining is useful for detecting micrometastasis and microinvasion in submucosal gastric cancer. Tumor size, microscopic type, lymphatic invasion, and the depth of submucosal invasion are strongly associated with lymph node involvement. Micrometastasis in lymph nodes and microinvasion in primary lesion indicate an unfavorable outcome of the patients with submucosal gastric cancer.</p>