SLC38A1 Promotes Proliferation and Migration of Human Colorectal Cancer Cells

Current studies have demonstrated that SLC38A1 proteins play a causal role in neoplastic cell transformation. The twofold aim of this study was to provide insight into whether a variance in the expression of SLC38A1 exists between human colorectal cancer and healthy human tissues and to determine how silencing or overexpressing the SLC38A1 gene could affect the proliferation, viability and migration of colorectal cancer cells. Immunohistochemical staining was used to analyze the expression of SLC38A1 in colorectal cancer tissues and adjacent normal mucosa in 77 patients who underwent surgical resection. The expression of SLC38A1 in colorectal cancer tissues and cell lines was detected using RT-PCR and Western blotting. Two colorectal cancer cell lines SW480 and HCT116 were used to examine whether silencing SLC38A1 with si RNA and overexpressing SLC38A1 with sh RNA could affect cell viability and migration. As a result, the SLC38A1 protein was very low or undetectable in the normal colon mucosa. In contrast, strong staining of SLC38A1 protein was found in the cytoplasm in 79.2% colorectal cancer samples. More pronounced SLC38A1 expression in colorectal cancer tissues was significantly associated with tumor node metastasis（TNM） stage. Inhibition of SLC38A1 reduced tumour growth and suppressed proliferation and migration of SW480 cells. In contrast, overexpression of SLC38A1 had the opposite effects on HCT116 cells. SLC38A1 is overexpressed in colorectal cancer, which suggests that it is associated with tumour progression. These results encourage the exploration of SLC38A1 as a target for intervention in colorectal cancer.

Knockdown of GRHL3 Inhibits Activities and Induces Cell Cycle Arrest and Apoptosis of Human Colorectal Cancer Cells

The Grainyhead-like 3（GRHL3） is involved in epidermal barrier formation, neural tube closure and wound repair. Previous studies have suggested that GRHL3 has been linked to many different types of cancers. However, to date, its effects on human colorectal cancer（CRC） has not been clarified yet. Our microarray analysis has indicated predominant GRHL3 expression in CRC. The purpose of this study was to investigate the expression and significance of GRHL3 in CRC tumorigenesis using CRC tissues and paired paracancerous tissues, as well as using distinct CRC cell lines（HT29 and DLD1）. We observed increased GRHL3 expression at both m RNA and protein levels in CRC tissues and CRC cell lines using quantitative real-time polymerase chain reaction（q RT-PCR） and Western blotting. Moreover, silencing GRHL3 with si RNA could suppress CRC cell proliferation, viability and migration in vitro. We also found that knockdown of GRHL3 could promote cell cycle arrest at G0/G1 phase in HT29 cells and DLD1 cells, and induce cell apoptosis in HT29 cells. Together, our study revealed the down-regulation of GRHL3 in vitro could inhibit CRC cell activity and trigger cell cycle arrest at G0/G1 phase and apoptosis.

Scutellaria barbata D.Don Inhibits Colorectal Cancer Growth via Suppression of Wnt/β-Catenin Signaling Pathway

Objective： To investigate the effect of the ethanol extract of Scutellaria barbata D. Don（EESB） on colorectal cancer（CRC） growth and Wnt/β-catenin signaling pathway in vivo and in vitro. Methods： In vivoexperiment, CRC xenograft mouse model was constructed with injection of HT-29 cells. Following xenograft implantation, twenty mice were randomly divided into EESB-treated group（n=10） and control group（n=10） by a random number table, and were given with intra-gastric administration of 2 g/kg EESB or saline, 5 days a week for 16 days, respectively. At the end of experiment, tumors were removed and weighed by electronic scales. The proliferation biomarker Ki-67 of tumor was evaluated by immunohistochemistry（IHC） assay. In vitro study, HT-29 cells were treated with 0, 0.5, 1.5, 2.5 mg/m L EESB for 24 h. At the end of the treatment, the viability and survival of HT-29 cells were determined by methylthiazolyldiphenyl-tetrazolium bromide（MTT） assay and colony formation assay, respectively. The m RNA expression of c-Myc, Survivin and adenomatous polyposis coli（APC） was examined by reverse transcription-polymerase chain reaction（RT-PCR） both in tumor tissues of CRC xenograft mice and HT-29 cells. Protein expression of c-Myc, Survivin, APC, and β-catenin as well as β-catenin phosphorylation level were evaluated by IHC assay or Western blotting. Results： EESB significantly reduced tumor weight in CRC xenografts mice, compared with the control group（P〈0.05）. IHC assay showed that EESB significantly inhibited protein expression of Ki-67 in tumor tissues（P〈0.05）. MTT assay showed that EESB significantly reduced HT-29 cell viability in a dose-dependent manner（P〈0.05）. Colony formation assay showed that EESB dose-dependently decreased the survival of HT-29 cells（P〈0.05）. In addition, RT-PCR assay showed that EESB decreased the m RNA expression of c-Myc and Survivin and increased APC expression, both in tumor tissues of CRC xenograft mice and HT-29 cells（P〈0.05）. IHC assay or Western blotting showed that EESB decreased protein expression of β-catenin, c-Myc and Survivin, as well as increased APC expression and β-catenin phosphorylation in tumor tissues or HT-29 cells（P〈0.05）. Conclusions： EESB significantly reduced tumor growth in CRC xenografts mice, and inhibited the viability and survival of HT-29 cells. EESB could suppress the activation of the Wnt/β-catenin pathway, which might be one of the mechanisms whereby Scutellaria barbata D. Don exerts its anticancer activity.