Downregulation of peroxiredoxin II suppresses the proliferation and metastasis of gastric cancer cells

The beginning of GPX2 and 30 years later

We published the first paper to characterize GPX2 (aka GSHPx-GI) as a selenoenzyme with glutathione peroxidase activity in 1993. Among the four Se-GPX isozymes, GPX1-4, GPX1 and GPX2 are closely related in terms of structure, substrate specificities, and subcellular localization. What sets them apart are distinct patterns of gene regulation, tissue distribution and response to selenium. While we identified the digestive tract epithelium as the main site of GPX2 expression, later work has shown GPX2 is found more widely in epithelial tissues with concentration of expression in stem cell and proliferative compartments. GPX2 expression is regulated over a wide range of levels by many pathways, including NRF2, WNT, p53, RARE and this often results in attaching undue significance to GPX2 as GPX2 is only a part of a system of hydroperoxidase activities, including GPX1, peroxiredoxins and catalase. These other activities may play equal or greater roles, particularly in cell lines cultured without selenium supplementation and often with very low GPX2 levels. This could be assessed by examining levels of mRNA and protein among these various peroxidases at the outset of studies. As an example, it was found that GPX1 responds to the absence of GPX2 in mouse ileum and colon epithelium with higher expression. As such, both Gpx1 and Gpx2 had to be knocked out in mice to produce ileocolitis. However, we note that the actual role of GPX1 and GPX2 in relation to peroxiredoxin function is unclear. There may be an interdependence that requires only low amounts of GPX1 and/or GPX2 in a supporting role to maintain proper peroxiredoxin function. GPX2 levels may be prognostic for cancer progression in colon, breast, prostate and liver, however, there is no consistent trend for higher or lower levels to be favorable.

Endoplasmic Reticulum Stress and Impairment of Ribosome Biogenesis Mediate the Apoptosis Induced by Ocimum x africanum Essential Oil in a Human Gastric Cancer Cell Line

Background and Objectives: Gastric cancer remains a major unmet clinical problem worldwide. Although conventional medical treatments are available, their curative effects are generally unsatisfactory. Consequently, it remains necessary to search natural products for potential alternatives in treating gastric cancer patients. Ocimum x africanum Lour. is a culinary herb that has been used in folk medicine for various diseases, but little is known regarding its anti-cancer activity against gastric cancer cells. In the current study, we focus on the anti-cancer mechanisms of O. x africanum essential oil (OAEO) in the AGS human gastric cancer cell line. Materials and Methods: After OAEO treatment, AGS cell viability was evaluated by MTT assay. Cell migration and apoptotic nuclear morphology were determined by wound-healing assay and DAPI staining, respectively. Gene expression levels of apoptosis-related genes were quantified by qRT–PCR. Differential protein expression was determined with an LC–MS/MS-based proteomics approach to identify the key proteins that may be important in the anti-cancer mechanisms of OAEO on AGS cells. The chemical constituents of OAEO were identified by GC–MS analysis. Results: We found OAEO to exhibit a potent growth-inhibiting effect on AGS cells, with an IC₅₀ value of 42.73 µg/mL. After OAEO treatment for 24 h, AGS cell migration was significantly decreased relative to the untreated control. OAEO-treated AGS cells exhibited common features of apoptotic cell death, including cell shrinkage, membrane blebbing, chromatin condensation, and nuclear fragmentation. Apoptotic cell death was confirmed by qRT–PCR for apoptosis-related genes, revealing that OAEO decreased the expression of anti-apoptotic genes (BCL2 and BCL-xL) and activated pro-apoptotic genes and apoptotic caspase genes (TP53, BAX, CASP9, CASP12, and CASP3). Moreover, expression of CASP8 was not changed after treatment. Proteomic analysis revealed that OAEO may produce a signature effect on protein clusters relating to unfolded protein accumulation, thereby inducing severe ER stress and also impairing ribosome synthesis. STRING analysis revealed seven up-regulated and 11 down-regulated proteins, which were significantly associated with protein folding and ribosome biogenesis, respectively. Using GC–MS analysis, 6-methyl-5-hepten-2-one, citral, neral, and linalool were found to be the major chemical constituents in OAEO. Conclusions: Taken together, these results indicate that OAEO has a potential anti-proliferative effect on AGS cells. Our molecular findings show evidence supporting an important role of ER stress and ribosome biogenesis impairment in mediating the induction of cell death by OAEO through the mitochondrial-apoptotic pathway. This study, therefore, provides fundamental knowledge for future applications using OAEO as an alternative therapy in gastric cancer management.

SNHG3 Knockdown Suppresses Proliferation, Migration and Invasion, and Promotes Apoptosis in Non-Small Cell Lung Cancer Through Regulating miR-216a/ZEB1 Axis

Background

Tumour growth and development are dependent on many factors including long noncoding RNAs (lncRNAs). However, limited information is available on the involvement of lncRNAs in non-small cell lung cancer (NSCLC) and the molecular mechanisms have not been defined. Here, we examined the expression of small nucleolar RNA host gene 3 (SNHG3) and its contribution to the development of NSCLC.

Methods

We detected SNHG3, miR-216a, and ZEB1 expression in tissues from NSCLC patients and lung adenocarcinoma cell lines using quantitative real-time polymerase chain reaction. Proliferation, migrations, invasion, and apoptosis of tumour cells were assessed using cell counting kit-8, transwell experiments, and flow cytometry after SNHG3 knockdown by small interfering RNAs. Bioinformatics and luciferase reporter assays were employed for analysing the interactions between SNHG3, miR-216a, and ZEB1.

Results

We found highly upregulated SNHG3 in tissues and cells from NSCLC patients, which was linked to poor prognosis. SNHG3 silencing diminished the ability of NSCLC cells to proliferate, migrate, and invade and promoted apoptosis. Furthermore, SNHG3 competed with endogenous RNA and enhanced the expression of ZEB1 by interfering with miR-216a. ZEB1 overexpression or miR-216a blockade reversed SNHG3-induced tumour inhibition. Similar effects were observed in vivo where SNHG3 knockdown inhibited NSCLC tumour growth by reducing expression of miR-216a while increasing that of ZEB1.

Conclusion

Knockdown of SNHG3 inhibits NSCLC tumour development and progression by upregulation of ZEB1 and interference with miR-216a, revealing an attractive alternative target for patients with NSCLC.

Demethylation of the Cosmc Promoter Alleviates the Progression of Breast Cancer Through Downregulation of the Tn and Sialyl-Tn Antigens

Background

Aberrant gene methylation in breast cancer is associated with an unfavorable prognosis. Besides, abnormal Cosmc can induce the expression of Tn and STn antigens. The present study aimed to investigate the roles of Cosmc promoter methylation in breast cancer through the regulation of Tn and STn antigens.

Methods

The expression patterns of Cosmc and the Tn and STn antigens in breast cancer cell lines were determined. Cosmc was overexpressed to explore the effects of Cosmc on cell behavior, including the growth, migration, invasion, and apoptosis of breast cancer cells and tumor growth with in vitro and in vivo experiments. Afterwards, a methyltransferase and a methyltransferase inhibitor were used to alter the methylation status of Cosmc to explore the mechanisms related to Cosmc promoter methylation.

Results

Cosmc was poorly expressed in breast cancer cells. Cosmc overexpression inhibited cell growth, migration, and invasion while promoting apoptosis in breast cancer cells in vitro and restraining tumor growth in vivo. Cosmc promoter methylation was found to decrease the levels of Cosmc and increased the expression of the Tn and STn antigens in breast cancer.

Conclusion

In conclusion, the demethylation of Cosmc mitigates breast cancer progression through the repression of the Tn and STn antigens, which provides evidence for therapeutic considerations for a novel target against breast cancer.

LncRNA GAS5 facilitates nasopharyngeal carcinoma progression through epigenetically silencing PTEN via EZH2

Increasing evidence demonstrated that long non-coding RNA growth-arrest-specific transcript 5 (GAS5) serves as a critical regulator in cancer development and progression. However, its function and mechanism in nasopharyngeal carcinoma (NPC) is still not well elucidated. In this study, we investigate the functional role as well as the molecular mechanism of GAS5 in NPC progression. Our results indicated that GAS5 expression was elevated in NPC tissues and cells. High GAS5 expression was correlated with poor prognosis of NPC patients. GAS5 knockdown suppressed proliferation, migration and invasion, and induced apoptosis in NPC cells. Moreover, GAS5 could epigenetically suppress PTEN expression via recruiting enhancer of zeste homolog 2 (EZH2). PTEN knockdown could reverse the inhibitory effect of GAS5 inhibition on NPC progression. Furthermore, GAS5 knockdown suppressed the tumor growth in vivo. In summary, knockdown of GAS5 repressed proliferation, migration and invasion, and promoted apoptosis in NPC through epigenetically silencing PTEN via recruiting EZH2.

The lncRNA TDRG1 promotes cell proliferation, migration and invasion by targeting miR-326 to regulate MAPK1 expression in cervical cancer

BACKGROUND

Recently, lncRNA-Testis developmental related gene 1 (TDRG1) was proved to be a key modulator in reproductive organ-related cancers. The biological role of TDRG1 in cervical cancer (CC) progression remains largely unknown.

METHOD

Real-time PCR (qRT-PCR) examined the expression level of TDRG1, microRNA (miR)-326 and MAPK1 mRNA. OS tissues and corresponding relative normal tissues, as well as CC cell lines and normal cell line Ect1/E6E7 were collected to determine the expression of TDRG1 in CC. MTT, colony formation, wound-healing, transwell and flow cytometer assay detected the influence of TDRG1 and miR-326 on CC cells growth, metastasis and apoptosis. Western blot examined proteins level. Bioinformatics, RNA pull-down assay, RNA immunoprecipitation and dual-luciferase reporter assays detected the molecular mechanism of TDRG1 in CC. Xenograft tumour model was established to determine the role of TDRG1 in vivo.

RESULTS

The expression of TDRG1 was significantly increased in CC tissues and cell lines compared with normal tissue and normal cell line respectively and its expression was associated with clinicopathological characteristics of CC patients. Knockdown of TDRG1 inhibited the cell proliferation, migration and invasion in Hela and SIHA cells. Moreover, TDRG1 directly interacted with miR-326, and the inhibition effect on cell growth and metastasis induced by TDRG1 siRNA can be abrogated by miR-326 silencing by its inhibitor in Hela and SIHA cells. Further, MAPK1 was proved to be a direct target of miR-326, and its expression was negatively regulated by miR-326 while positively modulated by TDRG1.

CONCLUSION

TDRG1 acts as a competing endogenous lncRNA (ceRNA) to modulate MAPK1 by sponging miR-326 in CC, shedding new light on TDRG1-directed diagnostics and therapeutics in CC.