NAIF1 inhibits gastric cancer cells migration and invasion via the MAPK pathways.

PURPOSE: Nuclear apoptosis-inducing factor 1 (NAIF1) could induce apoptosis in gastric cancer cells. Previously, we have reported that the expression of NAIF1 protein is down-regulated in gastric cancer tissues compared with the adjacent normal tissues. However, the role of NAIF1 in gastric cancer cells is not fully understood. METHODS: The effects of NAIF1 on cell viability were evaluated by MTT and colony formation assays. The ability of cellular migration and invasion were analyzed by transwell assays. The expression levels of targeted proteins were determined by western blot. The relative RNA expression levels were analyzed using quantitative polymerase chain reaction assays. Xenograft experiment was employed to determine the anti-tumor ability of NAIF1 in vivo. RESULTS: The study demonstrates that transient transfection of NAIF1 in gastric cancer cells BGC823 and MKN45 could inhibit the cell proliferation, migration, and invasion of the two gastric cancer cell lines. The tumor size is smaller in NAIF1-overexpressed MKN45 cell xenograft mice than in unexpressed group. Further in-depth analysis reveals that NAIF1 reduces the expression of MMP2 as well as MMP9, and inhibits the activation of FAK, all of which are key molecules involved in regulating cell migration and invasion. In addition, NAIF1 inhibits the expression of c-Jun N-terminal kinase (JNK) by accelerating its degradation through ubiquitin-proteasome pathway. Meanwhile, NAIF1 reduces the mRNA and protein expression of ERK1/2. CONCLUSIONS: Our study revealed that NAIF1 plays a role in regulating cellular migration and invasion through the MAPK pathways. It could be a therapeutic target for gastric cancer.

[Research advances on microchimerism].

The microchimerism is a status of the microcell or DNA of an individual in another one with genetic differences. Taking an overall view about the discovery and research of the microchimerism, it was found that although the study of the microchimerism emphasizes the formation, origin, distribution, type, relationship to disease and several other aspects, the objects of the study are always the microchimerism that obtained naturally. As it is known to all, the microchimerism can also be produced in some clinical treatment, such as in the transplant and transfusion, but compared with the microchimerism gained naturally, obviously, the study for the iatrogenic microchimerism formed in the treatment is not elaborate enough. The curative effect of micro transplantation, a new technique for leukemia treatment, is obvious, but its mechanism is unclear, whether that is related to microchimerism still needs further research. This review summarizes the study history and perspective of the microchimerism so as to provide some ideas for studying the action mechanism of microchimerism in micro transplantation.

Protein phosphatase Pph3 and its regulatory subunit Psy2 regulate Rad53 dephosphorylation and cell morphogenesis during recovery from DNA damage in Candida albicans.

The ability of the pathogenic fungus Candida albicans to switch cellular morphologies is important for infection and virulence. Recent studies have revealed that C. albicans yeast cells can switch to filamentous growth under genotoxic stress in a manner dependent on the DNA replication/damage checkpoint. Here, we have investigated the functions of Pph3 (orf19.4378) and Psy2 (orf19.3685), whose orthologues in Saccharomyces cerevisiae mediate the dephosphorylation of the DNA damage checkpoint kinase Rad53 and the histone variant H2AX during recovery from DNA damage. Deleting PPH3 or PSY2 causes hypersensitivity to DNA-damaging agents, including cisplatin, methylmethane sulfonate (MMS), and UV light. In addition, pph3Δ and psy2Δ cells exhibit strong filamentous growth under genotoxic stress. Flow cytometry analysis shows that the mutant cells have lost the ability to adapt to genotoxic stress and remain arrested even after the stress is withdrawn. Furthermore, we show that Pph3 and Psy2 are required for the dephosphorylation of Rad53, but not H2AX, during DNA damage recovery. Taken together, these results show that C. albicans Pph3 and Psy2 have important roles in mediating genotoxin-induced filamentous growth and regulating Rad53 dephosphorylation.

The F-box protein Grr1 regulates the stability of Ccn1, Cln3 and Hof1 and cell morphogenesis in Candida albicans.

Both G1 and mitotic cyclins have been implicated in regulating Candida albicans filamentous growth. We have investigated the functions of Grr1 whose orthologue in Saccharomyces cerevisiae is known to mediate ubiquitin-dependent degradation of the G1 cyclins Cln1 and Cln2. Here, we report that deleting C. albicans GRR1 causes significant stabilization of two G1 cyclins Ccn1 and Cln3 and pseudohyphal growth. grr1Delta cells are highly heterogeneous in length and many of them fail to separate after cytokinesis. Interestingly, some isolated rod-like G1 cells of similar sizes are present in the grr1Delta culture. Time-lapse microscopy revealed that the rod-shaped G1 cells first grew exclusively in width before budding and then the bud grew exclusively by apical extension until after cytokinesis, yielding rod-like daughter cells. Consistently, actin patches persistently localize to the bud tip until around the time of cytokinesis. Despite the pseudohyphal phenotype, grr1Delta cells respond normally to hyphal induction. Hyperphosphorylated Cln3 isoforms accumulate in grr1Delta cells, indicating that Grr1 selectively mediates their degradation in wild-type cells. grr1Delta pseudohyphal growth requires neither Hgc1 nor Swel, two important regulators of cell morphogenesis. Furthermore, the cellular level of Hof1, a protein having a role in cytokinesis, is also significantly increased in grr1Delta cells.

[Antisense to CDK4 inhibits the growth of human colon cancer cells HT29].

OBJECTIVE: Antisense CDK4 was transfected into human colorectal cancer cells HT29 to examine the effect of it on the growth and proliferation of HT29 cells. METHODS: Antisense CDK4 transfected the HT29 cells with lipofectamine. The transfected effects were verified by the Northern blot, Western blot, morphological method, flow cell measure, etc. RESULTS: The transformant cells showed the expression of exogenous antisense CDK4 mRNA, and downmodulation of endogenous CDK4 mRNA expression and inhibition of its protein synthesis. The transformant cells exhibited the partial reversion of the malignant phenotype and behavior, and that the cell growth and the ability of colony formation in soft agar were inhibited. The arrest of G1 phase was also revealed. the apoptosis rate is higher in HT29-asCDK4. CONCLUSION: The antisense CDK4 gene can inhibited the cell growth and proliferation, and induce the cell apoptosis. It might provide a new way to gene therapy of the colorectal carcinoma.

[Coordination inhibition of the proliferation of MCF-7 by enhancing expression of p53,p21 and decreasing expression of c-myc].

To study the coordination inhibition of the proliferation of breast cancer cell line MCF-7 by enhancing expression of p53,p21 and decreasing expression of c-myc, as well as the relationship among these genes when they express in the cells, eukaryotic expression plasmids of sense p53,p21 and antisense c-myc were constructed first, different concentrations of three plasmids were determined and the combinations were designed according to factorial design. Cells were transfected by the combination plasimids, then the inhibition rate of proliferation of the transfected cells were tested. The results were analyzed using the methods of statistics including Jin's Q-test, Least significant difference (LSD), cluster analysis. It was shown that all of them (Sense p21,p53, antisense c-myc) could inhibit the proliferation of MCF-7 in different levels of concentration, while the degrees of inhibition were different among them. In the aspect of coordination inhibition, the proliferation of MCF-7 was inhibited much strongly by p21 coordination with antisense c-myc and p53 coordination with antisense c-myc, but p53 coordination with p21 did not show inhibition effect. Rusults of cluster analysis showed that the first combination of three genes showed the best coordination, the ninth combination had the highest rate of inhibition. In conclusion, we suppose that when p53 as a cancer suppressor gene and p21 as a CDK suppressor gene express highly, and the expression of c-myc as a cancer gene is inhibited meantime could obviously enhance the inhibition on the proliferation of MCF-7 cells by coordination effect.

Identification of a lens-specific cis-acting element within the basal promoter of the human lens intrinsic membrane protein MP19 gene (LIM2).

Using overlapping and mutant oligonucleotides as probes, gel mobility assays and competition experiments identified a sequence from -47 to -32 bp upstream of the LIM2 CAP site, which a lens protein complex bound with high affinity which appeared to bind only to the "sense" strand of the double-stranded DNA molecule. This sequence consisted of a string of four guanine residues followed by seven other nucleotides (AACCTAA) and followed by another four guanines, i.e. GGGGAACCTAAGGGG, called the Hsu element. Promoter-CAT constructs containing this sequence or mutations of the sequence indicated that the Hsu element is located within the basal promoter, and is essential for expression of the LIM2 gene. The trans factors binding to the Hsu element are present throughout development, and appear to be lens-specific. Since the LIM2 gene promoter does not contain a classic TATA box, the Hsu element may serve as the site for binding the RNA polymerase complex.