Metastasis suppressor genes in clinical practice: are they druggable?

Since the identification of NM23 (now called NME1) as the first metastasis suppressor gene (MSG), a small number of other gene products and non-coding RNAs have been identified that suppress specific parameters of the metastatic cascade, yet which have little or no ability to regulate primary tumor initiation or maintenance. MSG can regulate various pathways or cell biological functions such as those controlling mitogen-activated protein kinase pathway mediators, cell-cell and cell-extracellular matrix protein adhesion, cytoskeletal architecture, G-protein-coupled receptors, apoptosis, and transcriptional complexes. One defining facet of this gene class is that their expression is typically downregulated, not mutated, in metastasis, such that any effective therapeutic intervention would involve their re-expression. This review will address the therapeutic targeting of MSG, once thought to be a daunting task only facilitated by ectopically re-expressing MSG in metastatic cells in vivo. Examples will be cited of attempts to identify actionable oncogenic pathways that might suppress the formation or progression of metastases through the re-expression of specific metastasis suppressors.

Evaluation of Metastasis Suppressor Genes Expression and In Vitro Anti-Cancer Effects of Zinc Oxide Nanoparticles in Human Breast Cancer Cell Lines MCF-7 and T47D

Background:

Metallic nanoparticles are useful materials to be applied in biomedical research. In this study, the possible apoptotic and anti-metastatic activity of Zinc Oxide Nanoparticles (ZnONPs) was assessed in breast cancer cells.

Methods:

First, in vitro cell viability was investigated by MTT assay in two human breast cancer cells (MCF-7 and T47D) and normal Human Embryonic Kidney (HEK293) cells at 37°C overnight. Apoptosis induced by ZnONPs was evaluated by annexin V/PI staining, cell cycle analysis and caspase assay in cancerous cells. Moreover, quantitative real-time PCR was employed for the detection of two metastasis suppressor genes (KAI-1 and NM23) expression in cancerous cells.

Results:

Data demonstrated that ZnONPs exert a dose-dependent inhibitory effect on the viability of T47D and MCF-7 cells, while no cytotoxic effect was observed on normal HEK293 cells. The mRNA expression levels of KAI-1 and non-metastatic protein (NM23) genes were up-regulated in ZnONP-exposed cancerous cells. ZnONPs were also found to enhance the apoptosis properties of cells by annexin V/PI staining, and caspase assay in cancerous cells. Furthermore, ZnONPs can increase sub-G1 population as compared to negative control.

Conclusion:

Our findings showed that ZnONPs induce apoptotic activity and can modulate metastasis by up-regulating of KAI-1 and NM23 gene expression in two breast cancer (MCF-7 and T47D) cells.

Effect of methotrexate on embryonal implantation: an experimental rat model

The aim of this study is to investigate the methotrexate (MTX) in rat embryonal implantation and its association with Glycodelin A (GdA) and Mucin-1 (MUC-1) expression. For this purpose, 32 pregnant rats were divided into four equal groups: non-pregnant rats in group I (n = 8, control) and pregnant rats in group III (n = 8) were injected intraperitoneal with single dose of normal saline, non-pregnant rats in group II (n = 8) and pregnant rats in group IV (n = 8) were given 0.2 mg i.m. injection of MTX before three months of pregnancy. The dams were killed on 5th day of gestation and uterine horn samples were removed. Following dissection and routine histological preparation, immunohistochemical analysis was carried out. During immunohistochemical examination of the tissue samples prepared from the control and experimental groups, a statistically significant difference was observed between the groups in the luminal-glandular-decidualized epithelium of the uterus with GdA and MUC-1. Finally, in light of our findings, MTX adversely affected the expression of two molecules in Wistar Albino rats embryonal implantation model.

Effect of single-dose depot leuprolide acetate on embryonal implantation: an experimental rat model

The objective of this article is to investigate the effect of single-dose depot leuprolide acetate in rat embryonal implantation and its association with glycodelin A, mucin-1 and leukemia inhibitory factor expression. Thirty-two pregnant Wistar Albino rats were divided into four equal groups: untreated control rats in group I (n = 8) and untreated pregnant rats in group II (n = 8) were injected intraperitoneally with single dose of normal saline, treated rats in group III (n = 8) and treated pregnant rats in group IV (n = 8) were given single 1 mg/kg subcutaneous injection of leuprolide acetate at day 8 of pregnancy. The dams were sacrificed on the 15th day of gestation, uterine horn samples were removed. Immunohistochemical examination of the tissue samples prepared from the control and experimental groups, a statistically significant difference was observed between the groups in the luminal-glandular-decidualized epithelium of the uterus with glycodelin A, mucin-1 and leukemia inhibitory factor. A statistically significant difference was observed between the groups for the concentration of glycodelin A but no statistically significant difference was found for the other two molecules. In light of our findings, leuprolide acetate adversely affected expression and concentration of all three molecules in embryonal implantation model.

Nm23-H1 was involved in regulation of KAI1 expression in high-metastatic lung cancer cells L9981

BACKGROUND

The tetraspanin KAI1/CD82 was identified as a tumor metastasis suppressor that down-regulated in malignant progression of lung cancer. However, the underlying mechanism of anti-metastasis role of KAI1 in lung cancer is hardly known. In this paper, we sought to study the function and regulatory mechanism of KAI1 in high metastasis lung cancer cell line.

METHODS

KAI1 expression was detected in high/low metastatic large lung cancer cell line L9981/NL9980 by quantitative real-time polymerase chain reaction (qRT-PCR). The tumor suppressor function of KAI1 was determined by wound healing assay after over-expression or knockdown of KAI1 in L9981 or NL9980 cells. Invasion assay was performed to detect the invasion ability of L9981 by transfection of KAI1. The effect of tumor suppressor p53 on KAI1 expression was measured by western blot and luciferase assay. Then the regulation of KAI1 due to over-expression of metastasis suppressor nm23-H1 was monitored by qRT-PCR, western blot and reporter gene assay. The progression of L9981 cells after p53 and nm23-H1 expression was detected by invasion assay. Also, methylation status of KAI1 promoter in NL9980 and L9981 cells were examined by bisulfite sequencing and methylation-specific PCR.

RESULTS

We found that KAI1 is down-regulated in high metastatic L9981 cells compare with NL9980 cells. The migration and invasion of L9981 cells were remarkably suppressed in vitro by KAI1 transfection. The migration ability of NL9980 was enhanced by inhibition of KAI1. Furthermore, KAI1 expression was induced after over-expression of p53 or nm23-H1, while cell invasion was inhibited in L9981 cells. The results of reporter analysis indicated that KAI1 promoter region between -922 to -846 could response to nm23-H1. In addition, we discovered only slight methylation of KAI1 promoter, which showed that loss expression of KAI1 in L9981 cells may not due to promoter methylation.

CONCLUSIONS

The results suggested that nm23-H1 was involved in the KAI1-regulated inhibition of metastasis in lung cancer cells. More insights into the relationship between KAI1 and other metastasis suppressors will pave the way for the elucidation of anti-metastasis mechanism in lung cancer.

Metastasis suppressor proteins in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinomas (cSCCs) are common human carcinomas. Despite having metastasizing capacities, they usually show less aggressive progression compared to squamous cell carcinoma (SCC) of other organs. Metastasis suppressor proteins (MSPs) are a group of proteins that control and slow-down the metastatic process. In this study, we established the importance of seven well-defined MSPs including NDRG1, NM23-H1, RhoGDI2, E-cadherin, CD82/KAI1, MKK4, and AKAP12 in cSCCs. Protein expression levels of the selected MSPs were detected in 32 cSCCs, 6 in situ SCCs, and two skin cell lines (HaCaT, A-431) by immunohistochemistry. The results were evaluated semi-quantitatively using the HSCORE system. In addition, mRNA expression levels were detected by qRT-PCR in the cell lines. The HSCOREs of NM23-H1 were similar in cSCCs and normal skin tissues, while RGHOGDI2, E-cadherin and AKAP12 were significantly downregulated in cSCCs compared to normal skin. The levels of MKK4, NDRG1 and CD82 were partially conserved in cSCCs. In stage I SCCs, nuclear staining of NM23-H1 (NM23-H1nuc) was significantly lower than in stage II/III SCCs. Only nuclear staining of MKK4 (MKK4nuc) showed significantly higher scores in in situ carcinomas compared to invasive SCCs. In conclusion, similar to other human tumors, we have demonstrated complex differential expression patterns for the MSPs in in-situ and invasive cSCCs. This complex MSP signature warrants further biological and experimental pathway research.

Effect of vitamin C on collagen structure of cardinal and uterosacral ligaments during pregnancy

OBJECTIVE

This study aimed to investigate changes in collagen structure in the cardinal and uterosacral ligaments of rats that were administered vitamin C during pregnancy.

STUDY DESIGN

Eighteen female rats were divided into three groups: six pregnant rats administered 1.25mg/ml/day of vitamin C during pregnancy (Group A); six non-pregnant rats that were not administered vitamin C (Group B); and six pregnant rats that were not administered vitamin C during pregnancy (Group C). Fifteen days after delivery, the uteruses of all rats were removed. The intensity of staining (mild, moderate or severe) and the extent of positive staining areas (%) of type I and type III collagen H scores for types I and III collagen, and intensity of elastin fibres in the cardinal and uterosacral ligaments were investigated immunohistochemically. Differences between groups were analysed using Kruskal-Wallis and independent samples tests.

RESULTS

The intensity and extent of type I and type III collagen, the H scores for type I and type III collagen, and the ratio of type III collagen H score: type I collagen H score differed significantly between groups. Pregnant rats administered vitamin C (Group A) had significantly higher values compared with non-pregnant rats (Group B): intensity of type I collagen (p=0.001), extent of type I collagen (p≤0.001), H score for type I collagen (p≤0.001), intensity for type III collagen (p=0.002), extent of type IV collagen (p=0.007), H score for type III collagen (p=0.017), type III collagen H score: type I collagen H score (p=0.039) and intensity of elastin fibres (p=0.097). A significant difference in the ratio of type III collagen H score: type I collagen H score was found between pregnant rats administered vitamin C (Group A) and pregnant rats not administered vitamin C (Group C) (p=0.002).

CONCLUSIONS

The administration of vitamin C to rats during pregnancy had a favourable impact on collagen structure in the cardinal and uterosacral ligaments, suggesting that vitamin C supplementation during pregnancy may help to prevent pelvic organ prolapse and stress urinary incontinence.