Alterations in the tissue inhibitor of metalloproteinase-3 (TIMP-3) are found frequently in human colorectal tumours displaying either microsatellite stability (MSS) or instability (MSI)

Drug delivery approaches for HuR-targeted therapy for lung cancer

Lung cancer (LC) is often diagnosed at an advanced stage and conventional treatments for disease management have limitations associated with them. Novel therapeutic targets are thus avidly sought for the effective management of LC. RNA binding proteins (RBPs) have been convincingly established as key players in tumorigenesis, and their dysregulation is linked to multiple cancers, including LC. In this context, we review the role of Human antigen R (HuR), an RBP that is overexpressed in LC, and further associated with various aspects of LC tumor growth and response to therapy. Herein, we describe the role of HuR in LC progression and outline the evidences supporting various pharmacologic and biologic approaches for inhibiting HuR expression and function. These approaches, including use of small molecule inhibitors, siRNAs and shRNAs, have demonstrated favorable results in reducing tumor cell growth, invasion and migration, angiogenesis and metastasis. Hence, HuR has significant potential as a key therapeutic target in LC. Use of siRNA-based approaches, however, have certain limitations that prevent their maximal exploitation as cancer therapies. To address this, in the conclusion of this review, we provide a list of nanomedicine-based HuR targeting approaches currently being employed for siRNA and shRNA delivery, and provide a rationale for the immense potential therapeutic benefits offered by nanocarrier-based HuR targeting and its promise for treating patients with LC.

Tissue inhibitor of matrix metalloproteinase-3 has both anti-metastatic and anti-tumourigenic properties

TIMP-3 is one of four tissue inhibitors of matrix metalloproteinases, the endogenous inhibitors of the matrix metalloproteinase enzymes. These enzymes have an important role in metastasis, in the invasion of cancer cells through the basement membrane and extracellular matrix. TIMP-1, -2 and -4 both promote and inhibit tumour development, in a context-dependent manner, however TIMP-3 is consistently anti-tumourigenic. TIMP-3 is also the only insoluble member of the family, being either bound to the extracellular matrix or the low density lipoprotein-related protein-1, through which it can be endocytosed. Levels of TIMP-3 have also been shown to be regulated by micro RNAs and promoter hypermethylation, resulting in frequent silencing in many tumour types, to the extent that its expression has been suggested as a prognostic marker in some tumours, being associated with lower levels of metastasis, or better response to treatment. TIMP-3 has been shown to have anti-metastatic effects, both through inhibition of matrix metalloproteinases and ADAM family members and downregulation of angiogenesis. This occurs via interactions with receptors including VEGF, via modulation of signaling pathways and due to protease inhibition. TIMP-3 has also been shown to reduce tumour growth rate, most often by inducing apoptosis by stabilisation of death receptors. A number of successful mechanisms of delivery of TIMP-3 to tumour or inflammatory sites have been investigated in vitro or in animal studies. It may therefore be worthwhile further exploring the use of TIMP-3 as a potential anti-metastatic or anti-tumorigenic therapy for many tumour types.

Gene methylation in rectal cancer: predictive marker of response to chemoradiotherapy?

Although numerous studies have focused on the link between CpG island methylator phenotypes and the development of colorectal cancer, few studies have dealt specifically with methylation profiling in rectal cancer and its role in predicting response to neoadjuvant chemoradiotherapy (NCRT). We characterized methylation profiles in normal and neoplastic tissue samples from patients with rectal cancer and assessed the role of this molecular profile in predicting chemoradioactivity. We evaluated 74 pretreatment tumor samples and 16 apparently normal tissue biopsies from rectal cancer patients submitted to NCRT. The methylation profile of 24 different tumor suppressor genes was analyzed from FFPE samples by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA). Methylation status was studied in relation to tissue type and clinical pathological parameters, in particular, pathological response evaluated by tumor regression grade (TRG). ESR1, CDH13, RARB, IGSF4, and APC genes showed high methylation levels in tumor samples (range 18.92-49.77) with respect to normal tissue. Methylation levels of the remaining genes were low and similar in both normal (range 1.91-14.56) and tumor tissue (range 1.84-11). Analysis of the association between methylation and response to therapy in tumor samples showed that only TIMP3 methylation status differed significantly within the four TRG classes (ANOVA, P < 0.05). Results from the present explorative study suggest that quantitative epigenetic classification of rectal cancer by MS-MLPA clearly distinguishes tumor tissue from apparently normal mucosa. Conversely, with the exception of TIMP3 gene, the methylation of selected genes does not seem to correlate with response to NCRT.

Detection of TIMP3 promoter hypermethylation in salivary rinse as an independent predictor of local recurrence-free survival in head and neck cancer

PURPOSE

To validate a panel of methylation-based salivary rinse biomarkers (P16, CCNA1, DCC, TIMP3, MGMT, DAPK, and MINT31) previously shown to be independently associated with poor overall survival and local recurrence in a larger, separate cohort of patients with head and neck squamous cell carcinoma (HNSCC).

EXPERIMENTAL DESIGN

One hundred ninety-seven patients were included. All pretreatment saliva DNA samples were evaluated for the methylation status of the gene promoters by quantitative methylation-specific PCR. The main outcome measures were overall survival, local recurrence-free survival, and disease-free survival.

RESULTS

In univariate analyses, the detection of hypermethylation of CCNA1, MGMT, and MINT31 was significantly associated with poor overall survival; the detection of hypermethylation of TIMP3 was significantly associated with local recurrence-free survival; and the detection of hypermethylation of MINT31 was significantly associated with poor disease-free survival. In multivariate analyses, detection of hypermethylation at any single marker was not predictive of overall survival in patients with HNSCC; detection of hypermethylation of TIMP3 in salivary rinse had an independent, significant association with local recurrence-free survival (HR = 2.51; 95% CI: 1.10-5.68); and none of the studied markers was significantly associated with disease-free survival.

CONCLUSION

The detection of promoter hypermethylation of the seven genes in salivary rinse as an independent prognostic indicator of overall survival in patients with HNSCC was not validated. Detection of promoter hypermethylation of TIMP3 in pretreatment salivary rinse is independently associated with local recurrence-free survival in patients with HNSCC and may be a valuable salivary rinse biomarker for HNSCC recurrence.

DNA methylation in patients with colorectal cancer--correlation with some clinical and morphological features and with local tumour invasion

AIM

To study quantitatively the promoter methylation of hMLH1, p16INK, TIMP3 and TPEF genes in patients with colorectal cancer and synchronous polyps, and correlate it with some clinicomorphological features.

METHODS

DNA was extracted from all studied tumours and the corresponding normal mucosa. Microsatellite instability was analysed using two mononucleotide (BAT 25 and BAT 26) and three dinucleotide markers (D2S123, D5S356, D17S250) and automated DNA sequencing. Quantitative analysis of methylation was performed using DNA bisulfite modification, PCR with biotinylated primers, visualisation by 2% agarose gel electrophoresis and pyrosequencing.

RESULTS

High methylation levels of hMLH1 and p16INK were found in elderly patients (mean age 73.8 +/- 9.5 years and 65.7 +/- 16.6 years, p < 0.03, t-test). Proximal tumours were more often associated with microsatellite instability (p < 0.05, Fisher's test) and higher level of methylation of hMLH1, p16INK and TIMP3 (p < 0.02, Kruskal-Wallis test), while tumours with poor differentiation tended to have higher methylation of the p16INK gene (p < 0.02, Kruskal-Wallis test). Local tumour invasion was correlated with the level of methylation of hMLH1, TIMP3 and the CpG island methylator phenotype (CIMP) status. Tumours with liver metastases showed a lower level of TIMP3 methylation than tumours with no systemic invasion (p < 0.05, Kruskal-Wallis test). We found concordance of methylation in 56% of the cases with colonic cancer and synchronous adenomas; the remaining 44% were discordant.

CONCLUSIONS

Tumours with microsatellite instability, high level methylation and CIMP have distinctive clinical and morphological features. The level of hMLH1 and TIMP3 methylation and CIMP status can be correlated with the local tumour invasion. Different mechanisms, even for one and the same patient, can be responsible for the development of more than one third of the synchronous polyps and carcinomas.

Expression of the PAX8/PPARγ Fusion Protein Is Associated with Decreased Neovascularization In Vivo: Impact on Tumorigenesis and Disease Prognosis

The PAX8/PPARγ fusion protein (PPFP) occurs in 36% of human follicular thyroid carcinoma (FTC) and is associated with favorable prognosis. To elucidate the function of PPFP in FTC, we analyzed the consequences of PPFP expression in immortalized thyrocytes in vitro and in vivo via xenograft tumorigenesis. While PPFP-expressing cells exhibited oncogenic hallmarks, including increased growth and decreased apoptosis, in vitro, xenograft tumors were initiated but not sustained in vivo. PPFP xenograft tumors exhibited reduced CD31 staining and VEGF expression, suggesting that PPFP modulates neovascularization. Microarray analysis demonstrated increased expression of tissue inhibitor of metalloproteinase (TIMP-3), an inhibitor of angiogenesis, in PPFP cells and tumors, a finding confirmed by quantitative PCR and immunohistochemistry. Immunohistochemical staining of archival human thyroid tumors demonstrates a significant decrease in CD31 staining in all adenomas and carcinomas containing the PAX8/PPARγ rearrangement. Decreased angiogenesis in PPFP-containing tumors is directly correlated with our observations in the xenograft model and provides evidence for the first time that PPFP may impact FTC tumorigenesis by modulating angiogenesis in vivo.

Impact of genomic methylation on radiation sensitivity of colorectal carcinoma

PURPOSE

To investigate the influence of demethylation with 5-aza-cytidine (AZA) on radiation sensitivity and to define the intrinsic radiation sensitivity of methylation deficient colorectal carcinoma cells.

METHODS AND MATERIALS

Radiation sensitizing effects of AZA were investigated in four colorectal carcinoma cell lines (HCT116, SW480, L174 T, Co115), defining influence of AZA on proliferation, clonogenic survival, and cell cycling with or without ionizing radiation. The methylation status for cancer or DNA damage response-related genes silenced by promoter methylation was determined. The effect of deletion of the potential target genes (DNMT1, DNMT3b, and double mutants) on radiation sensitivity was analyzed.

RESULTS

AZA showed radiation sensitizing properties at >or=1 micromol/l, a concentration that does not interfere with the cell cycle by itself, in all four tested cell lines with a sensitivity-enhancing ratio (SER) of 1.6 to 2.1 (confidence interval [CI] 0.9-3.3). AZA successfully demethylated promoters of p16 and hMLH1, genes associated with ionizing radiation response. Prolonged exposure to low-dose AZA resulted in sustained radiosensitivity if associated with persistent genomic hypomethylation after recovery from AZA. Compared with maternal HCT116 cells, DNMT3b-defcient deficient cells were more sensitive to radiation with a SER of 2.0 (CI 0.9-2.1; p = 0.03), and DNMT3b/DNMT1-/- double-deficient cells showed a SER of 1.6 (CI 0.5-2.7; p = 0.09).

CONCLUSIONS

AZA-induced genomic hypomethylation results in enhanced radiation sensitivity in colorectal carcinoma. The mediators leading to sensitization remain unknown. Defining the specific factors associated with radiation sensitization after genomic demethylation may open the way to better targeting for the purpose of radiation sensitization.

Loss of expression of TIMP3 in clear cell renal cell carcinoma

AIMS

In clear cell renal cell carcinoma (CCRCC), vascular endothelial growth factor (VEGF) represents the central positive mediator of tumour angiogenesis while VEGF receptor (VEGFR) is the primary target of anti-angiogenic therapies. TIMP3 is a physiological VEGFR-2 antagonist and thus could be considered as an anti-angiogenic factor. We therefore determined the status of this physiological inhibitor in CCRCC.

PATIENTS AND METHODS

Archival tumour from 105 patients was studied. TIMP3 expression was analysed using immuno-histochemistry and real-time RT-PCR. Results were correlated with clinicopathological variables. To analyse the mechanisms of gene silencing involved, we performed Multiplex Ligation-dependent Probe Amplification (MLPA) and methylation-specific MLPA (MS-MLPA). At last, we evaluated the main upstream pathway described implicating TGFbetaRII, which induces TIMP3 expression.

RESULTS

A down-expression of TIMP3, determined by immunohistochemistry, affected 100/105 renal cancers (95.2%). TIMP3 mRNA levels were significantly lower in high-grade tumours. Loss of heterozygosity of the TIMP3 gene was observed in 8 tumours (7.6%) and the 5'CpG island of the TIMP3 promoter was found to be methylated in 25 tumours (23.8%). A down-expression of TGFbetaRII was found in 85/105 CCRCCs (80.9%). A significant correlation was found between TIMP3 expression and TGFbetaRII expression.

CONCLUSIONS

This is the first demonstration that the loss of TIMP3 expression is observed in almost all CCRCCs. This loss of expression is a common molecular event in CCRCC. It may be an important initiation step for tumour development in a complex process implicating loss of heterozygosity on chromosome 22q, promoter hyper-methylation and inactivation of the TGFbetaRII pathway.

Positive correlation of tissue inhibitor of metalloproteinase-3 and death-associated protein kinase hypermethylation in head and neck squamous cell carcinoma

OBJECTIVES/HYPOTHESIS

Promoter hypermethylation of tumor suppressor genes is common in head and neck cancer as well as other primary cancers resulting in epigenetic gene silencing. Tissue inhibitor of metalloproteinase-3 (TIMP-3) has been shown to have promoter hypermethylation in several solid tumors, but has not been identified in head and neck squamous cell carcinoma (HNSCC). Our objective was to determine if TIMP-3 promoter was hypermethylated in HNSCC, if there was any correlation with death associated protein kinase (DAPK), a tumor suppressor whose promoter has been hypermethylated at high levels in HNSCC, and if any clinical factors influence hypermethylation of either of these genes.

STUDY DESIGN

Prospective study.

METHODS

Tumor samples from 124 patients with HNSCC were evaluated for promoter hypermethylation for TIMP-3 and DAPK using quantitative methylation specific polymerase chain reaction (qMSP). We compared both TIMP-3 and DAPK hypermethylation in HNSCC with each other as well as with other clinical variables.

RESULTS

We found that TIMP-3 was hypermethylated in approximately 71.8% of the tumor samples and DAPK was hypermethylated in 74.2%. The presence of TIMP-3 and DAPK promoter hypermethylation was significantly higher than in control specimens. More importantly, TIMP-3 and DAPK hypermethylations in these samples were highly correlated with a concordance of 78% (P < .001). DAPK was also correlated with current alcohol consumption (P < .028), but neither TIMP-3 nor DAPK hypermethylation was significantly correlated with other clinical variables or with survival.

CONCLUSION

TIMP-3 promoter hypermethylation is elevated in HNSCC and is highly correlated with DAPK hypermethylation, implying a functional relationship between these genes.

Gene methylation in thyroid tumorigenesis

Aberrant gene methylation plays an important role in human tumorigenesis, including thyroid tumorigenesis. Many tumor suppressor genes are aberrantly methylated in thyroid cancer, and some even in benign thyroid tumors, suggesting a role of this epigenetic event in early thyroid tumorigenesis. Methylation of some of these genes tends to occur in certain types of thyroid cancer and is related to specific signaling pathways. For example, methylation of PTEN and RASSF1A genes occurs mostly in follicular thyroid cancer, and its tumorigenic role may be related to the phosphatidylinositol 3-kinase/Akt signaling pathway, whereas methylation of genes for tissue inhibitor of metalloproteinase-3, SLC5A8, and death-associated protein kinase occurs in papillary thyroid cancer and is related to the BRAF/MAPK kinase/MAPK pathway. Methylation of thyroid-specific genes, such as those for sodium/iodide symporter and thyroid-stimulating hormone receptor, is also common in thyroid cancer. Although its tumorigenic role is not clear, methylation, and hence silencing, of these thyroid-specific genes is a cause for the failure of clinical radioiodine treatment of thyroid cancer. Unlike gene methylation, histone modifications have been relatively poorly investigated in thyroid tumors. Future studies need to emphasize the mechanistic aspects of these two types of epigenetic alterations to uncover new molecular mechanisms in thyroid tumorigenesis and to provide novel therapeutic targets for thyroid cancer.

[Role of transcription factor AP-1 in integration of cellular signalling systems]

Transcription factor AP-1 is a dimer complex composed by DNA-binding proteins of Jun, Fos, and ATF families. AP-1 mediates cell response on growth factors, cytokines, neurotransmitters and other intercellular signaling molecules. AP-1 activity is mediated by G-proteins, adapter proteins, MAP kinases and other elements of cellular signaling systems. AP-1 dependent genes play a pivotal role in regulation of cell proliferation, morphogenesis, apoptosis, and differentiation.

Association of aberrant methylation of tumor suppressor genes with tumor aggressiveness and BRAF mutation in papillary thyroid cancer

The role of aberrant tumor suppressor gene methylation in the aggressiveness of papillary thyroid cancer (PTC) has not been documented. By showing promoter methylation-induced gene silencing in PTC-derived cell lines, we first demonstrated the functional consequence of methylation of several recently identified tumor suppressor genes, including those for tissue inhibitor of metalloproteinase-3 (TIMP3), SLC5A8, death-associated protein kinase (DAPK) and retinoic acid receptor beta2 (RARbeta2). We then investigated the role of methylation of these genes in the aggressiveness of PTC by examining the relationship of their aberrant methylation to clinicopathological characteristics and BRAF mutation in 231 primary PTC tumors. Methylation of TIMP3, SLC5A8 and DAPK was significantly associated with several aggressive features of PTC, including extrathyroidal invasion, lymph node metastasis, multifocality and advanced tumor stages. Methylation of these genes was also significantly associated with BRAF mutation in PTC, either individually or collectively in various combinations. Methylation of these genes, either individually or collectively, occurred more frequently in more aggressive classical and tall-cell PTC subtypes than in less aggressive follicular-variant PTC, with the latter known to infrequently harbor BRAF mutation. Several other tumor suppressor genes investigated were not methylated. These results suggest that aberrant methylation and hence silencing of TIMP3, SLC5A8, DAPK and RARbeta2, in association with BRAF mutation, may be an important step in PTC tumorigenesis and progression.

Methylation and repeats in silent and nonsense mutations of p53

All exonic CG sequences in p53 are methylated; this epigenetic modification is correlated with frequent G:C-->A:T transitions in p53. Recent reports reveal the presence in p53 of non-CG methylation in CC and CCC sequences, complementary to sites of selective guanosine adduct formation (GG and GGG), and the association of genetic instability with methylation at repetitive sequences. We presently investigated the distribution of methylation sites and repetitive elements in silent and nonsense p53 mutations (2051) among the IARC's TP53 somatic mutation database for exons 5-8. Silent mutations are nonrandom, but mostly involve G:C-->A:T transitions (62%); in particular C-->T mutations (39% of all silent mutations) are mostly correlated with CC and CCC sequences, while G-->A mutations with GG sequences. Sequence analysis of all non-G:C-->A:T silent mutations reveals the frequent formation of new methylation sites (CG), new CCC and GGG sequences in the resulting sequence, refinement of symmetry elements at interrupted microsatellite-like sequences and formation of small repeats (55.3%). The G:C-->A:T silent mutations characterize cancers associated with cigarette smoking (e.g. bladder or lung and bronchus cancer versus colorectal cancer); on the contrary, non-G:C-->A:T silent mutations have similar frequencies in most cancers. Nonsense mutations in exons 5-8, all resulting in mutants lacking amino acids 307-393, which are crucial for p53 activity, were also analyzed. The frequency of nonsense mutations is higher at methylated sites or repeats 1-2 nucleotides removed from methylation sites. Frameshift mutations are also more frequent at repeated sequences. The frequent G:C-->A:T silent mutations could indicate that CC and CCC sequences of exons 5-8 are occasionally targets of non-CpG methylation of cytosine. This process of de novo methylation in the presence of microsatellite-like sequences and small repeats might influence the genetic stability of a variety of genes.