Pu Xia

The nuclear to cytoplasmic shift of ING5 protein during colorectal carcinogenesis with their distinct links to pathologic behaviors of carcinomas

Inhibitor of growth 5, a tumor suppressor protein, can interact with p53, thereby inhibiting cell growth and inducing apoptosis. Inhibitor of growth 5 overexpression results in a reduction in colony-forming efficiency and cell population in S phase. To clarify the roles of inhibitor of growth 5 in tumorigenesis and progression of colorectal carcinomas, we examined inhibitor of growth 5 expression by immunohistochemistry on a tissue microarray containing colorectal carcinomas (n = 306), adenomas (n = 69), and nonneoplastic mucosa (n = 288) and compared this with clinicopathologic parameters of the carcinomas. In addition, inhibitor of growth 5 expression in colorectal carcinoma tissues and cell lines (DLD-1, HCT-15, SW480, and WiDr) was analyzed by Western blot and reverse transcriptase-polymerase chain reaction. It was found that the inhibitor of growth 5 protein was localized to the nuclei of colon carcinoma cells with no differences at mRNA levels. Among 18 frozen samples of colorectal carcinoma, significantly increased expression of inhibitor of growth 5 protein was observed in the carcinoma in comparison with adjacent mucosa in 14 cases (77.8%; P < .05), and 71.4% (10/14) of carcinoma cases exhibited up-regulated inhibitor of growth 5 mRNA expression. Decreased inhibitor of growth 5 expression was detected by immunohistochemistry in colorectal carcinoma, compared with non-neoplastic mucosa and adenoma (P < .05). Nuclear inhibitor of growth 5 expression was negatively correlated with tumor size, depth of invasion, degree of dedifferentiation, and Union Internationale Contre le Cancer staging (P < .05). In contrast, cytoplasmic inhibitor of growth 5 expression was positively correlated with depth of invasion, lymphatic invasion, and Union Internationale Contre le Cancer staging (P < .05). It was suggested that aberrant inhibitor of growth 5 expression may contribute to pathogenesis, growth, and invasion of colorectal carcinomas and could be considered as a promising marker to gauge aggressiveness of colorectal carcinomas.

Involvement of inactive GSK3β overexpression in tumorigenesis and progression of gastric carcinomas

Glycogen synthase kinase 3beta is reported to repress Wnt/beta-catenin pathway and regulate the balance between cellular proliferation and apoptosis. Its inactivation by ser(9) phosphorylation might play a critical role in the tumorigenesis and development of malignancies. Here, the expression of phosphorylated glycogen synthase kinase 3beta at ser(9) was examined in gastric carcinoma and adjacent non-neoplastic mucosa by immunohistochemistry and Western blot, and compared with the clinicopathological parameters of carcinomas, including the expression of vascular endothelial growth factor, extracellular matrix metalloproteinase inducer and beta-catenin, and microvessel density labeled by CD34, as well as survival data. Gastric carcinoma cell lines (MKN28, MKN45, AGS, GT-3 TKB, KATO-III and HGC-27) were studied for the phosphorylated kinase by Western blot and for its encoding mRNA by RT-PCR, followed by sequencing. All carcinoma cell lines showed strong expression of the phosphorylated kinase and its encoding mRNA.There were two isoforms of glycogen synthase kinase 3beta in all carcinoma cell lines and a synonymous mutation in HGC-27 carcinoma cell line at codon 65(GGA-->GGT: Gly). The phosphorylated kinase was localized in the cytoplasm of gastric carcinoma cell lines or carcinomas. It was more expressed in gastric carcinomas than that in non-neoplastic mucosa (P < .05) in line with the data of Western blot. There was a higher expression of the phosphorylated kinase in men carcinoma patients than that in women (P < .05). Its expression was positively correlated with depth of invasion, lymphatic and venous invasion, lymph node metastasis, Union Internationale le Contre Cancer staging, expression of vascular endothelial growth factor and extracellular matrix metalloproteinase inducer in gastric carcinoma (P < .05). Survival analysis indicated the phosphorylated kinase expression to be positively linked to poor prognosis (P< 05), but not independent (P>.05). Three independent prognostic factors, depth of invasion, lymphatic and venous invasion, concordantly influenced its relationship with prognosis (P < .05). Our study indicated that up-regulated expression of phosphorylated glycogen synthase kinase 3beta at ser(9) was closely linked to gastric carcinogenesis and subsequent progression, and could be employed as a good indicator of aggressive behaviors and prognosis of gastric carcinoma.

Distinct Radiosensitivity of Lung Carcinoma Stem-Like Side Population and Main Population Cells

PURPOSE Lung cancer is a leading cause of cancer death worldwide. Efficacy of radiation therapy on lung cancer is hindered by many factors. Among these, both cancer stem-like side population (SP) and main population (MP) cells may contribute to tumorigenesis and resistance to radiation therapy. However, the detailed mechanism responsible for this effect remains unknown. MATERIALS AND METHODS The SP and MP cells were obtained from lewis lung carcinoma cells and analyzed the DNA dye (Hoechst 33342) method and flow cytometry. The levels of ABCG2 and CD133 markers were examined by reverse transcription polymerase chain reaction, Western blot, and immunofluorescence. The effects of ionizing radiation (IR) on the growth and apoptosis of SP and MP cells were determined by 3-(4, 5-dimethylthiazol-2-y)-2, 5-diphenylterazolium bromide (MTT), colony formation, and apoptosis assays. Mitochondrial membrane potential and intracellular reactive oxygen species production were measured by flow cytometry. Finally, the expression of Bax, Bcl-xL, Bcl-2, activated caspase-3 and caspase-9 proteins were examined by Western Blot. RESULTS IR decreased proliferation, increased apoptosis and mitochondria damage in MP, but not in SP cells. Protein levels of Bcl-2 and Bcl-xl were decreased, while Bax expression was increased in MP cells following IR exposure. In addition, increased activation of caspase-3 and caspase-9 were detected after IR exposure in MP cells, but not in SP cells. CONCLUSIONS Our results show that IR decreases proliferation, increases apoptosis, and induces mitochondria damage in MP cells, but not in SP cells, through increased Bax and decreased Bcl-2 and Bcl-xl protein expression. This protein expression pattern induces activation of caspase-3 and caspase-9. This study suggests that IR exposure targets MP cells through a mitochondrial apoptosis pathway. However, more work is required to further confirm these results using in vivo xenograft models. More importantly, further studies are warranted to elucidate the radioresistant mechanisms of SP cells.

The roles of REIC gene and its encoding product in gastric carcinoma.

REIC is downregulated in immortalized cell lines compared with the parental normal counterparts. It may inhibit colony formation, tumor growth and induce apoptosis. Here, gastric carcinoma or epithelial cells transfected with REIC-expressing plasmid, its siRNA or treated with recombinant REIC were subjected to the phenotypes’ measurement or related molecules’ detection. REIC expression was examined in gastric carcinomas by RT-PCR, western blot and immunohistochemistry. REIC overexpression or treatment resulted in a low karyoplasmic ratio and proliferation, G1 arrest, high apoptosis, low migration, invasion or lamellipodia formation in AGS cells. REIC knockdown caused the opposite in GES-1 cells. Anti-REIC antibody blocked the effects of REIC overexpression on proliferation, G1/S progression and apoptosis. Ectopic REIC expression downregulated the expression of β-catenin, phosphorylated S6K (Thr389), phosphorylated Akt1/2/3 (Ser473), cyclin D2 and E, WAVE2 and upregulated phosphorylated mTOR (Ser2448) expression and the mRNA level of Akt1, Akt2, mTOR, Raptor and Rictor in AGS cells. REIC expression was negatively associated with tumor size, lymph node metastasis, dedifferentiation or poor prognosis of carcinoma. The serum REIC level was significantly higher in healthy individuals than the carcinoma patients and inversely linked to tumor size by ELISA. The possible mechanisms underlying the forced REIC overexpression or recombinant REIC mediated the reversal of the aggressive phenotypes of gastric carcinoma cells are to downregulate β-catenin and WAVE2 expression and to alter other related target proteins. Downregulated REIC expression was closely linked to aggressive behaviors and poor prognosis of gastric carcinoma.

Prognostic value of DKK2 from the Dickkopf family in human breast cancer

Breast cancer is one of the most frequently diagnosed types of cancer with a high mortality and malignancy rate in women worldwide. The Dickkopf (DKK) protein family, as a canonical Wnt/β-catenin pathway antagonist, has been implicated in both physiological and pathological processes. This study aimed to comprehensively characterize the prognostic value and elucidate the mechanisms of DKKs in breast cancer and its subtypes. Firstly, DKK mRNA expression and corresponding outcome were analyzed by means of the Gene Expression-Based Outcome for Breast Cancer Online (GOBO) platform based on PAM50 intrinsic breast cancer subtypes. Subsequently, we extracted breast cancer datasets from the Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) to validate the expression profile and prognostic values from the GOBO platform. Moreover, a protein-protein network was created and functional enrichment was conducted to explore the underlying mechanisms of action of the DKKs. In addition, we uncovered the genetic and epigenetic alterations of DKK2 in breast cancer. The main finding of this study was the differential roles of DKKs in the PAM50 subtypes of breast cancer analyzed. The overall trend was that a high level of DKK2 was associated with a good survival in breast cancer, although it played an opposite role in the Normal-like subtype. We also found that DKK2 carried out its functions through multiple signaling pathways, not limited to the Wnt/β-catenin cascade in breast cancer. Finally, we used our own data to validate the bioinformatics analysis data for DKK2 by RT-qPCR. Taken together, our findings suggest that DKK2 may be a potential prognostic biomarker for the Normal-like subtype of breast cancer. However, the prognostic role of DKKs in the subtypes of breast cancer still requires validation by larger sample studies in the future.