A signature for induced pluripotent stem cell-associated genes in colorectal cancer.

Genes associated with induced pluripotent stem cells (iPS genes) are several pivotal transcriptional factors, which are used to induce pluripotent stem cells from some adult somatic cells. The roles of these iPS genes and especially the signature for these iPS genes in colorectal cancer (CRC) are still unclear. Overexpressed Oct4 and Lin28 but down-regulated Nanog were found in tumor tissues compared with that in their paired normal counterparts of CRC patients. Interestingly, we found that Oct4, Lin28 and Nanog were highly overexpressed in some patients. And the signature for iPS genes was correlated with tumor site (P = 0.012), lymph node status (P = 0.033), Dukes classification (P = 0.033) of CRC patients. Moreover, an independent public expression profiling data showed signature for the four iPS genes could successfully be used to predict the survival of CRC patients with Dukes stages B and C. Immunofluorescent staining of fresh CRC tissues from patients showed that strong co-expressions of Oct4 and Nanog proteins or Sox2 and Lin28 were present in some CRC cells. Then, CRC cell subclone with four iPS genes overexpression were establish by a mixed retroviral system. We found that iPS genes promote sphere-formation, proliferation, colony formation, migration of human CRC cells in vitro and tumor growth in vivo. Our study first shows the clinical significance of iPS signature in CRC patients.

Characterization of microRNAs expression profiling in one group of Chinese urothelial cell carcinoma identified by Solexa sequencing.

OBJECTIVE: The goal of this study was to extend the known repertoire of microRNAs (miRNAs) expressed in urothelial bladder cancer (BCa) of the Chinese population and further understand the molecular events of miRNAs underlying urothelial bladder tumorigenesis at the global genome level. MATERIALS AND METHODS: We separated well-characterized epithelial tumor cells from 20 moderately differentiated or poorly differentiated BCa specimens by laser capture microdissection (LCM) and pooled these cells of interest prior to RNA analysis. Ten normal bladder epithelia (NBE) samples were pooled as the control. After preparation of small RNAs library, the 2 samples were sequenced simultaneously by the next generation high through-put Solexa sequencing technology. RESULTS: We employed the next generation high through-put Solexa sequencing technology to clone and identify miRNAs in BCa and NBE, and generated 11,146,610, and 10,263,845 high quality sequence reads, respectively. According to the analysis of size distribution, 22 nt class was the most abundant group of small RNAs in the BCa. Likewise, the 20 and 22 nt sequences were significantly greater than shorter or longer sequences, and accounted for 59.55% of the total sequence number of NBE library. The whole-genome-scale data mining suggested that BCa and NBE libraries both contained multiple and heterogeneous small RNA species. On further analysis, the sequencing data revealed that different miRNAs showed clearly in-house differential expression levels in BCa and NBE and 74 miRNAs aberrantly expressed between BCa and NBE at the global genome level. We also predicted 13 novel miRNAs in both BCa and NBE libraries. CONCLUSIONS: Our results suggest that BCa miRNAs include a large proportion of conserved miRNAs and a set of non-conserved miRNAs with low expression levels. These known and newly identified miRNAs at the population level significantly enhance our knowledge of BCa miRNAs expression profiling and provide insights into miRNAs oncogenesis and oncotherapy in BCa. Further studies are necessary to elucidate the roles of miRNAs in urothelial bladder tumorigenesis and determine the potential of miRNAs as diagnostic and prognostic tools or therapeutic targets for BCa in the future.

Snail as a key regulator of PRL-3 gene in colorectal cancer.

The regulators of a key metastasis gene PRL-3 in colorectal cancer (CRC) are still largely unknown. We found three potential binding sites of Snail, a key transcriptional factor involved in the epithelial-mesenchymal transition (EMT), in the region of PRL-3 promoter (located at -642 to -383). Moreover, our results showed that one of the Snail binding sites (located at -624 to -619) was the key element to maintain promoter activity of human PRL-3 gene. The transcriptional activity of PRL-3 promoter was abolished after the Snail binding site (located at -624 to -619) was mutated. Both promoter activity and protein expression of PRL-3 in CRC cell lines could be regulated by Snail. In clinical samples of CRC and metastatic lymph node of CRC, expression of PRL-3 protein was correlated with expression of Snail protein. Functional studies using gene over-expression and knockdown methods indicated that Snail promoted proliferation, cell adhesion and migration of human CRC cells. In SW480 cells with PRL-3 stable knockdown, cell proliferation increased after Snail was up-regulated. Our data first reveal transcriptional factor Snail as a key regulator of PRL-3 in CRC. The link between Snail and PRL-3 suggests a new potential mechanism of Snail contributing to progression and metastasis of CRC.

Stathmin, a new target of PRL-3 identified by proteomic methods, plays a key role in progression and metastasis of colorectal cancer.

To better understand the role of PRL-3 in progression and metastasis of colorectal cancer (CRC), we searched for PRL-3 associated proteins using proteomic methods. We identified 39 PRL-3 associated proteins based on proteomic strategy. Stathmin, a key oncoprotein, was proved to be a new PRL-3 associated protein. Notably, co-immunoprecipitation assays in both endogenous CRC cell lines and CRC tissues indicated that PRL-3 could interact with stathmin. And, both stathmin and PRL-3 contributed to microtubule (MT) destabilization of CRC cells. Moreover, gain-of-function and loss-of-function analyses revealed that stathmin promoted proliferation, cell adhesion, and migration of human CRC cells. Immunohistochemical analysis of 149 colorectal tumor samples showed that overexpression of stathmin was strongly correlated with tumor differentiation (P = 0.035), tumor invasion (P = 0.024), lymph node status (P < 0.001), Dukes classification (P < 0.001), and TNM staging (P < 0.001) of CRC patients. Univariate and multivariate survival analyses further supported that overexpression of stathmin protein was a potential independent poor prognostic factor for CRC. Our results reveal many PRL-3 associated proteins for the first time. The oncoprotein stathmin plays a key role in CRC as a new target of PRL-3. Interaction between PRL-3 and stathmin leads to MT destabilization of CRC cells, which contributes to progression and metastasis of CRC.

[Brain impairment induced by oral intake of lead and its effects on expression of Hoxa9 Gen in Rats].

OBJECTIVE: To observe effects of oral intake of lead on the expression of Hoxa9 gen and the ability of learning and memory and explore the the toxic molecular mechanisms of lead. METHODS: Thirty male Wistar rats were chosen and randomly divided into the low lead dosage group, the high lead dosage group and the control group, 10 rats in each group. The low lead dosage group and the high lead dosage group were given respectively 0.06%, 0.2% lead acetate orally while the control group was given distilled water orally. The Y-maze test was used to measure the ability of learning and memory, the graphite heat atomic absorption spectrum method to determine the lead concentration in blood and brain, and the in situ hybridization (ISH) method to determine the expression of Hoxa9 mRNA in brain. RESULTS: (1) The number of electric shocks of the lead poisoned rats were significantly increased over time. The number of electric shocks of the lead poisoning rats was much higher than that of the control group (P < 0.01) (at the end of the experiment, the low lead dosage group: 31.8 +/- 2.26; the high lead dosage group: 37.3 +/- 1.70; the control group: 18.4 +/- 1.51). (2) The brain of the lead poisoned rats including the hippocampus, the cerebellum and the cerebral cortex were significantly atrophic and the apoptosis and necrosis occurred in the cells of the brain. Purkinje's cells in the cerebellum showed significant necrosis and disappearance. The structure of brain in rats of the control group demonstrated no atrophy. (3) The expression of Hoxa9 mRNA in the lead poisoned rats was significantly decreased compared with the control group. There were few Hoxa9 positive cells in the brain of the lead poisoned rats, but many of them were observed in the control group. CONCLUSION: Lead may inhibit the expression of Hoxa9 and induce atrophy and necrosis of brain, which gives rise to a damage of learning and memory.