Hypermethylation of the large tumor suppressor genes in Japanese lung cancer

m6A methyltransferase METTL3-induced lncRNA SNHG17 promotes lung adenocarcinoma gefitinib resistance by epigenetically repressing LATS2 expression

Gefitinib has been widely applied for the treatment of lung adenocarcinoma (LUAD). However, the long-term application of gefitinib usually leads to acquired drug resistance in tumour patients, resulting in clinical treatment failure. Small nucleolar host gene 17 (SNHG17) has been shown to play a regulatory role in LUAD progression. Nevertheless, the role of SNHG17 in LUAD gefitinib resistance remains elusive. The expression pattern of SNHG17 was examined in tissues and cell lines of gefitinib-sensitive and gefitinib-resistant LUAD, respectively. Gain- and loss-of-function experiments were employed to assess the biological functions of SNHG17 in cell proliferation and apoptosis, as well as aggressive phenotypes of LUAD cells. MeRIP-qPCR and colorimetric quantificational analysis were performed to detect m6A modifications and contents. Fluorescence in situ hybridisation (FISH) and subcellular fractionation analysis were used to reveal the distribution of SNHG17. RIP and ChIP assays were performed to further validate the SNHG17/EZH2/LATS2 regulatory axis. A xenograft tumour growth assay was conducted to evaluate the role of SNHG17 in LUAD gefitinib resistance in vivo. SNHG17 was upregulated in gefitinib-resistant LUAD tissues and cell lines. Functional assays showed that SNHG17 aggravated the malignant phenotypes of gefitinib-resistant LUAD cells. In addition, METTL3-mediated N⁶-methyladenosine modification could induce the upregulation of SNHG17by stabilising its RNA transcript. Mechanistically, SNHG17 epigenetically repressed the expression of LATS2 by recruiting EZH2 to the promoter region of LATS2. The regulatory role of the SNHG17/EZH2/LATS2 axis in LUAD gefitinib resistance was further supported in vivo. Collectively, our findings suggested that SNHG17 induced by METTL3 could promote LUAD gefitinib resistance by epigenetically repressing LATS2 expression.

Promoter Hypermethylation of LATS2 Gene in Oral Squamous Cell Carcinoma (OSCC) Among North Indian Population

Large Tumor Suppressor (LATS2) gene are Tumor Suppressor gene, linked with epigenetic modifications. LATS2 promoter hypermethylation is an important epigenetic silencing mechanism leading to cancer. Cancer is the most common, vicious and dangerously increasing diseases of the world today, associated with high morbidity and mortality. Oral cancers (OC) are the blazing universal dilemma and is the sixth most frequent cancer observed in Indian population. Tobacco consumption is the main cause of the increase in OSCC. The association between LATS2 in the pathogenesis of cancers propose that their combination might be studied as a possible molecular marker for particular subgroups of patients. Therefore, the present study tried to investigate whether LATS2 promoter methylation was associated with oral squamous cell carcinoma (OSCC) in North Indian subjects. DNA methylation quantitative studies of LATS2 Tumor Suppressor genes were performed by methylation-specific polymerase chain reaction (MSP). 38 out of 70 patients (55 %) were found to be methylated for LATS2 gene, a statistically significant result was obtained (p-value < 0.005) for LATS2 genes. The results suggest that epigenetic changes may be related to the down-regulation of LATS2 expression. It can be concluded that LATS2 gene plays a significant role in the diagnosis of cancer and provide a better alternative as a diagnostic biomarker. Our data infer that a low LATS2 expression due to methylation may contribute to the cancer progression and could be useful for the diagnosis of OSCC. Therefore, investigation of promoter methylation in such genes may provide a biomarker which may prove to be useful in early detection of Oral Cancer.

Dysregulation of the Hippo pathway signaling in aging and cancer

Human beings are facing emerging degenerative and cancer diseases, in large part, as a consequence of increased life expectancy. In the near future, researchers will have to put even more effort into fighting these new challenges, one of which will be prevention of cancer while continuing to improve the aging process through this increased life expectancy. In the last few decades, relevance of the Hippo pathway on cancer has become an important study since it is a major regulator of organ size control and proliferation. However, its deregulation can induce tumors throughout the body by regulating cell proliferation, disrupting cell polarity, releasing YAP and TAZ from the Scribble complexes and facilitating survival gene expression via activation of TEAD transcription factors. This pathway is also involved in some of the most important mechanisms that control the aging processes, such as the AMP-activated protein kinase and sirtuin pathways, along with autophagy and oxidative stress response/antioxidant defense. This could be the link between two tightly connected processes that could open a broader range of targeted molecular therapies to fight aging and cancer. Therefore, available knowledge of the processes involved in the Hippo pathway during aging and cancer must necessarily be well understood.

Hypermethylated LATS2 gene with decreased expression in female breast cancer: A case control study from North India

BACKGROUND

LATS2, a presumed tumor suppressor gene located on chromosome 13q11-12 is involved in cell growth related activity like regulation of cell cycle at G1/S. The reduced expression of LATS2 has been reported in many tumors; including tumors of Breast, which is to the best of our knowledge has not been studied in north Indian female breast cancer population.

OBJECTIVE

Here, we looked upon the expression pattern and methylation status of the LATS2 gene in north Indian female breast cancer cases to further strengthen its role as a tumor suppressor gene and more importantly as a cancer biomarker.

METHODS

mRNA expression level was determined by real time PCR in 140 Breast cancer patients, Protein expression was studied by Immunohistochemistry and Promoter methylation was studied by Methylation specific PCR. All findings were correlated with clinicopathological features.

RESULTS

LATS2 mRNA expression was remarkably downregulated in 67.85% (95/140) cases. The expression of Large Associated Tumor Suppressor 2 at protein level was also absent in 67.85% (95/140) cases. The absence of LATS2 protein strongly correlated with promoter hypermethylation where 91 out of a total of 107 hyper methylated cases showed absence of protein (91/107, 85%). The absence of LATS2 protein was strongly significant with HER2 neu status (0.01), TNM staging (0.009) and Molecular subtype (0.024).

CONCLUSION

The decreased expression in breast cancer seems to be associated with hypermethylation of LATS2 promoter regions. Further LATS2 as a tumor suppressor can be recognized as a promising Biomarker in Breast cancer pathogenesis. Though, further studies, targeting larger sets of breast cancer population are required to establish LATS2 as a promising biomarker.

LATS2 promoter hypermethylation and its effect on gene expression in human breast cancer

Tumor-specific promoter hypermethylation of large tumor suppressor, homolog 2 (LATS2), a tumor suppressor gene, has been investigated using methylation-specific polymerase chain reaction (MSP) assays in different types of human cancer producing conflicting results. The aim of the present study was to evaluate the methylation status of the LATS2 promoter region using bisulfite sequencing with a next generation sequencer for breast cancer. In the 11 patients enrolled in the present study, the LATS2 promoter methylation index (MI) was uniformly high in tumor and normal tissues of the breast (median, 84.0 and 87.4%, respectively). The presence of LATS2 promoter hypermethylation was confirmed in isolated tumor cells and normal epithelial cells using the magnetic-activated cell sorting method. In situ hybridization for LATS2 messenger RNA (mRNA) revealed that the mRNA expression of LATS2 was higher in normal epithelial cells, compared with tumor cells, however, it was not significantly associated with LATS2 MI. In 12 breast cancer cell (BCC) lines and two normal breast cell lines, the LATS2 promoter was uniformly hypermethylated with no correlation between the mRNA expression of LATS2 and the LATS2 MI. In addition, treatment of the BCC lines with a demethylating reagent had minimal effect on the mRNA expression of LATS2 in any of these cell lines. These results demonstrated that LATS2 hypermethylation was not involved in silencing the mRNA expression of LATS2 mRNA. The lower mRNA expression level of LATS2 in tumor cells, compared with normal epithelial cells, suggested the possible involvement of downregulation in the mRNA expression of LATS2 in the pathogenesis of breast cancer. Therefore, the conflicting results previously reported for LATS2 promoter methylation in different types of cancer, detected using MSP assays may be attributable to the low fidelity of the MSP assay.

The LATS1 and LATS2 tumor suppressors: beyond the Hippo pathway

Proper cellular functionality and homeostasis are maintained by the convergent integration of various signaling cascades, which enable cells to respond to internal and external changes. The Dbf2-related kinases LATS1 and LATS2 (LATS) have emerged as central regulators of cell fate, by modulating the functions of numerous oncogenic or tumor suppressive effectors, including the canonical Hippo effectors YAP/TAZ, the Aurora mitotic kinase family, estrogen signaling and the tumor suppressive transcription factor p53. While the basic functions of the LATS kinase module are strongly conserved over evolution, the genomic duplication event leading to the emergence of two closely related kinases in higher organisms has increased the complexity of this signaling network. Here, we review the LATS1 and LATS2 intrinsic features as well as their reported cellular activities, emphasizing unique characteristics of each kinase. While differential activities between the two paralogous kinases have been reported, many converge to similar pathways and outcomes. Interestingly, the regulatory networks controlling the mRNA expression pattern of LATS1 and LATS2 differ strongly, and may contribute to the differences in protein binding partners of each kinase and in the subcellular locations in which each kinase exerts its functions.

Molecular Alterations and Expression Dynamics of LATS1 and LATS2 Genes in Non-Small-Cell Lung Carcinoma

Large tumor suppressor (LATS) is an important member of the Hippo pathway which can regulate organ size and cell proliferation. However, very little is known about the expression and clinical significance of LATS in lung cancer especially from this part of the world. We elucidated the frequency of LATS1 &LATS2 promoter hypermethylation (by methylation-specific PCR) and expression (by real-time PCR) in sixty nine (n = 69) Non-Small Cell Lung Cancer (NSCLC) patients and their corresponding normal lung tissue samples. We found promoter hypermethylation frequencies of LATS1 & LATS1to be 66.66% (46/69) and 71% (49/69) in NSCLC tissues. Decreased LATS1 & LATS2 mRNA expression was found in 55% and 66.66% of NSCLC patients. The LATS1 mRNA expression was significantly higher in normal lung tissues. Also, the mRNA levels of LATS1 and LATS2 NSCLC tissues with hypermethylation were significantly lower. Multivariable analysis confirmed that LATS1 under expression increased the hazard of death after adjusting for other clinicopathological factors. Importantly, the loss of LATS1 mRNA expression was associated with overall short survival. LATS1 is an independent prognostic factor and may play an important role in NSCLC progression and may serve as a novel therapeutic target of NSCLC.

Contribution of LATS1 and LATS2 promoter methylation in OSCC development

The aberrant DNA methylation of the tumor suppressor genes involved in DNA Damage Response (DDR) signaling and cell cycle regulation may lead to the tumorigenesis. Our purpose here is to analyze the promoter methylation and mRNA expression levels of LATS1 and LATS2 (LATS1/2) genes in OSCC. Promoter methylation status of LATS1/2 genes was evaluated in 70 OSCC paraffin-embedded tissues and 70 normal oral samples, using Methylation Specific PCR (MSP). LATS1/2 mRNA expression profiles were also investigated in 14 OSCC patients and 14 normal samples, using real-time PCR. In both candidate genes, promoter methylation assessment revealed significant relationship between cases and controls (OR = 2.24, 95 % CI = 1.40-3.54, P = 0.001; LATS1 and OR = 15.5, 95%CI = 3.64-64.76, P < 0.001; LATS2). As well as, the evaluation of mRNA expression levels showed decreased expression in OSCC tissues in compare to control tissues. (Mean ± SD 1.74 ± 0.14 in OSCC versus 2.10 ± 0.24 in controls, P < 0.001; LATS1 and Mean ± SD 1.36 ± 0.077 in OSCC versus 1.96 ± 0.096 in controls, P < 0.001; LATS2). To the best our knowledge, this is the first report regarding the down-regulation of LATS1/2 through promoter methylation in OSCC. It is suggested to explore the down-stream transcription factors of both genes for finding the molecular mechanism of this deregulation in OSCC.

Long Noncoding RNA PVT1 Promotes Non-Small Cell Lung Cancer Cell Proliferation through Epigenetically Regulating LATS2 Expression

Long noncoding RNAs (lncRNA) are a novel class of transcripts with no protein coding capacity, but with diverse functions in cancer cell proliferation, apoptosis, and metastasis. The lncRNA PVT1 is 1,716 nt in length and located in the chr8q24.21 region, which also contains the myelocytomatosis (MYC) oncogene. Previous studies demonstrated that MYC promotes PVT1 expression in primary human cancers. However, the expression pattern and potential biologic function of PVT1 in non-small cell lung cancer (NSCLC) is still unclear. Here, we found that PVT1 was upregulated in 105 human NSCLC tissues compared with normal samples. High expression of PVT1 was associated with a higher tumor-node-metastasis stage and tumor size, as well as poorer overall survival. Functional analysis revealed that knockdown of PVT1 inhibited NSCLC cell proliferation and induced apoptosis both in vitro and in vivo RNA immunoprecipitation and chromatin immunoprecipitation assays demonstrated that PVT1 recruits EZH2 to the large tumor suppressor kinase 2 (LATS2) promoter and represses LATS2 transcription. Furthermore, ectopic expression of LATS2 increased apoptosis and repressed lung adenocarcinoma cell proliferation by regulating the Mdm2-p53 pathway. Taken together, our findings indicated that PVT1/EZH2/LATS2 interactions might serve as new target for lung adenocarcinoma diagnosis and therapy. Mol Cancer Ther; 15(5); 1082-94. ©2016 AACR.

Evaluation of LATS1 and LATS2 Promoter Methylation with the Risk of Pterygium Formation

Purpose. Pterygium is a serious eye problem in countries with high exposure to UV. However, despite numerous studies, the molecular etiology of pterygium is unclear. Recent studies have indicated that LATS1 and LATS2 genes are involved in DDR signaling pathways against continuous UV exposure. Our aim was to evaluate the LATS1 and LATS2 promoter methylation with the risk of pterygium formation. Methods. We evaluated the promoter methylation status of LATS1 and LATS2 using methylation-specific PCR technique. Also, mRNA expression of LATS1 and LATS2 was assessed in 14 cases of pterygium and 14 normal specimens by real-time PCR. Results. Promoter methylation of LATS1 and LATS2 was detected significantly between pterygium tissues and normal tissues [LATS1; OR = 4.9; 95% CI: 1.54 to 15.48, P = 0.003; LATS2; OR = 7.1; 95% CI: 1.53 to 33.19, P = 0.004]. The gene expression analysis showed a statistically significant difference between pterygium tissues and healthy controls for both LATS1 and LATS2 (P < 0.05). Conclusions. The data of this study is the first report regarding the effect of promoter methylation of the LATS1 and LATS2 in the pterygium. To confirm these data, doing further studies in various genetic populations with large sample sizes using advanced molecular techniques is proposed.

17-AAG suppresses growth and invasion of lung adenocarcinoma cells via regulation of the LATS1/YAP pathway

The large tumour suppressor 1 (LATS1) signalling network has been proved to be an essential regulator within the cell, participating in multiple cellular phenotypes. However, it is unclear concerning the clinical significance of LATS1 and the regulatory mechanisms of 17-Allylamino-17- demethoxygeldanamycin (17-AAG) in lung adenocarcinoma (LAC). The aim of the present study was to investigate the correlation of LATS1 and yes-associated protein (YAP) expression with clinicopathological characteristics in LAC patients, and the effects of 17-AAG on biological behaviours of LAC cells. Subcutaneous LAC tumour models were further established to observe the tumour growth in nude mice. The results showed that the positive expression of LATS1 was significantly lowered (26.7% versus 68.0%, P < 0.001), while that of YAP was elevated (76.0% versus 56.0%, P + 0.03) in LAC tissues compared to the adjacent non-cancerous tissues; LAST1 expression was negatively correlated with YAP expression (r + 0.432, P < 0.001) and lymphatic invasion of the tumour (P + 0.015). In addition, 17-AAG inhibited proliferation and invasion, and induced cell apoptosis and cycle arrest in LAC cells together with increased expression of E-cadherin and p-LATS1, and decreased expression of YAP and connective tissue growth factor. Tumour volumes and weight were much smaller in 17-AAG-treated groups than those in untreated group (P < 0.01). Taken together, our findings indicate that decreased expression of LATS1 is associated with lymphatic invasion of LAC, and 17-AAG suppresses growth and invasion of LAC cells via regulation of the LATS1/YAP pathway in vitro and in vivo, suggesting that we may provide a promising therapeutic strategy for the treatment of human LAC.

Aberrant large tumor suppressor 2 (LATS2) gene expression correlates with EGFR mutation and survival in lung adenocarcinomas

BACKGROUND

Large tumor suppressor 2 (LATS2) gene is a putative tumor suppressor gene with potential roles in regulation of cell proliferation and apoptosis in lung cancer. The aim of this study is to explore the association of aberrant LATS2 expression with EGFR mutation and survival in lung adenocarcinoma (AD), and the effects of LATS2 silencing in both lung AD cell lines.

METHODS

LATS2 mRNA and protein expression in resected lung AD were correlated with demographic characteristics, EGFR mutation and survival. LATS2-specific siRNA was transfected into four EGFR wild-type (WT) and three EGFR mutant AD cell lines and the changes in LATS2 expression and relevant signaling molecules before and after LATS2 knockdown were assayed.

RESULTS

Fifty resected lung AD were included (M:F=23:27, smokers:non-smokers=19:31, EGFR mutant:wild-type=21:29) with LATS2 mRNA levels showed no significant difference between gender, age, smoking and pathological stages while LATS2 immunohistochemical staining on an independent set of 79 lung AD showed similar trend. LATS2 mRNA level was found to be a significant independent predictor for survival status (disease-free survival RR=0.217; p=0.003; Overall survival RR=0.238; p=0.036). siRNA-mediated suppression of LATS2 expression resulted in augmentation of ERK phosphorylation in EGFR wild-type AD cell lines with high basal LATS2 expression, discriminatory modulation of Akt signaling between EGFR wild-type and mutant cells, and induction of p53 accumulation in AD cell lines with low baseline p53 levels.

CONCLUSIONS

LATS2 expression level is predictive of survival in patients with resected lung AD. LATS2 may modulate and contribute to tumor growth via different signaling pathways in EGFR mutant and wild-type tumors.

Expression of LATS1 contributes to good prognosis and can negatively regulate YAP oncoprotein in non-small-cell lung cancer

Large tumor suppressor (LATS) is a Ser/Thr kinase originally isolated from Drosophila. Recent studies demonstrate that LATS is an important member of the Hippo pathway which can regulate organ size and cell proliferation. However, little is known about the expression and clinical significance of LATS in lung cancer. In this study, we aimed to assess the clinical significance and biological functions of LATS1 in non-small-cell lung cancer (NSCLC). We investigated the expression of LATS1 in 136 cases of NSCLC tissue and 30 cases of normal lung tissue by immunohistochemical staining. The results confirmed that LATS1 expression was higher in normal lung tissues, but significantly lower in NSCLC tissues. Moreover, the expression of LATS1 in NSCLC was significantly correlated with p-TNM stage (p = 0.038) and lymph node metastasis (p = 0.014). Importantly, the loss of LATS1 expression was associated with short overall survival. Further study in NSCLC cell lines in which LATS1 was either overexpressed or depleted confirmed that LATS1 markedly inhibited cell proliferation and invasion and could regulate the nuclear location of yes-associated protein (YAP). These results indicate that LATS1 may play an important role in NSCLC, and may serve as a novel therapeutic target of NSCLC.