Downregulation of tropomyosin-1 in squamous cell carcinoma of esophagus, the role of Ras signaling and methylation

miRNA‑183‑5p.1 promotes the migration and invasion of gastric cancer AGS cells by targeting TPM1

MicroRNA-183 (miR-183) is a small, non-coding RNA that is involved in post-transcriptional processes, is upregulated in gastric cancer and acts as an oncogene in cancer migration. Although fragmentary reports have demonstrated the importance of miR-183 in gastric cancer, its biofunctions and regulatory effects are still unknown. In the present study, the gene and protein expression levels were determined by reverse transcription-quantitative PCR and western blot analysis. The connection between miR-183-5p.1 and tropomyosin 1 (TPM1) was tested through luciferase reporter experiments. Cell viability, apoptosis and related proteins were detected by MTT assay, flow cytometry, immunofluorescence and western blotting, respectively. The migration and invasion of AGS cells modulated by miR-183-5p.1 were analyzed by Transwell assay. TPM1 expression was found to be decreased in gastric cancer tissues and cell lines when compared with normal and adjacent tissues and gastric epithelial cells, and was regulated by miR-183-5p.1 targeting TPM1. miR-183-5p.1 overexpression facilitated the growth and suppressed the death of AGS cells through Bcl-2 and P53 proteins. In addition, miR-183-5p.1 restricted TPM1, TPM2 and TPM3 protein expression in AGS cells. The excessive levels of miR-183-5p.1 promoted the migration and invasion of AGS cells, and inhibited the apoptosis of AGS cells. However, the knockdown of miR-183-5p.1 induced the opposite in AGS cells. In conclusion, miR-183-5p.1 promotes cell proliferation, migration and invasion by downregulating TPM1 and deactivating the Bcl-2/P53 signaling pathways in gastric cancer, indicating that miR-183-5p.1 and TPM1 may be potential targets for the diagnosis or therapy of gastric cancer in the future.

Research on the establishment of a TPM3 monoclonal stable transfected PANC-1 cell line and the experiment of the EMT occurrence in human pancreatic cancer

Background: Pancreatic cancer is one of the most aggressive human malignancies that is associated with early metastasis and chemoresistance. Tropomyosin (TPM) is an indispensable regulatory protein for muscle contraction, Abnormal expressions of TPM gene are closely related to the carcinogenesis and metastasis of malignant tumors.

Purpose: In this experiment, a monoclonal stable transfected cell line was established by the knock-down of TMP3 expression in PANC-1 cells with the lentivirus method, and the impacts of the downregulated TPM3 gene expression on the EMT-related molecules and biological behaviors of PANC-1 cells were explored.

Methods: Based on the TPM3 gene sequence, we designed the RNA interference sequence, constructed and screened out the recombinant plasmid segment TPM3-shRNA with the optimal silencing effect, and carried out lentivirus titer determination and packaging. The recombinant lentiviral interference vector LV-TPM3-shRNA was transfected into PANC-1 cells; the transfection efficiency was then evaluated to screen out the monoclonal stable transfected PANC-1 cell line with downregulated TPM3 expression. The qRT-PCR and Western blot were used to detect the changes in the gene- and protein-levels expressions of EMT-related transcription factors in the target cell line and to respectively test the variations of the invasion and proliferation capacities.

Results: It is shown that the monoclonal stable transfected PANC-1 cell line with downregulated TPM3 expression was successfully established with the recombinant lentiviral vector. After knocking down the expression of TPM3 gene in PANC-1 cells, EMT occurred in the cells; the cell phenotype showed malignant transformation, and the in vitro biological behaviors of the cells (such as proliferation and invasion) were enhanced to different degrees.

Conclusion: It is indicated that the TPM3 gene can be a potential target spot for the treatment of pancreatic cancer.

Tropomyosins: Potential Biomarkers for Urothelial Bladder Cancer

Despite the incidence and prevalence of urothelial bladder cancer (UBC), few advances in treatment and diagnosis have been made in recent years. In this review, we discuss potential biomarker candidates: the tropomyosin family of genes, encoded by four loci in the human genome. The expression of these genes is tissue-specific. Tropomyosins are responsible for diverse cellular roles, most notably based upon their interplay with actin to maintain cellular processes, integrity and structure. Tropomyosins exhibit a large variety of splice forms, and altered isoform expression levels have been associated with cancer, including UBC. Notably, tropomyosin isoforms are detectable in urine, offering the potential for non-invasive diagnosis and risk-stratification. This review collates the basic knowledge on tropomyosin and its isoforms, and discusses their relationships with cancer-related phenomena, most specifically in UBC.

Considering the downregulation of Tpm1.6 and Tpm1.7 in squamous cell carcinoma of esophagus as a potent biomarker

AIM

Squamous cell carcinoma of esophagus (SCCE) is an aggressive disease with a poor prognosis. Tropomyosins attach to actin microfilaments, providing its stability. Nonmuscle cells express Tpm isoforms such as Tpm1.6 and Tpm1.7 which are involved in cytoskeleton functional properties regulation.

MATERIALS & METHODS

The expression of Tpm1.6 and Tpm1.7 was analyzed in SCCE tissues and its association with clinicopathological parameters and survival of patients was assessed.

RESULTS

Tpm1.6 and Tpm1.7, besides TPM1 mRNA decreased considerably in SCCE tissues relative to normal esophageal tissues (p < 0.001). TPM1 downregulation level was significantly associated with the degree of tumor differentiation (p = 0.017).

CONCLUSION

Tpm1.6 and Tpm1.7 suppression play a crucial role in esophagus tumorigenesis and could be associated with SCCE poor prognosis.

Natural antisense transcript TPM1-AS regulates the alternative splicing of tropomyosin I through an interaction with RNA-binding motif protein 4

LncRNAs play a vital role in alternative splicing of target genes. However, the mechanisms underlying lncRNAs involvement in splicing are poorly understood. In the present study, we identified a previously uncharacterized lncRNA, which is denoted as TPM1-AS, is reverse-transcribed from the fourth intronic region of the tropomyosin I (TPM1). In situ hybridization and RNA immunoprecipitation assays demonstrated that TPM1-AS was located in the nucleus and interacted with RNA-binding motif protein 4 (RBM4) in human esophageal cancer cells. TPM1-AS overexpression or RBM4 knockdown decreased endogenous exon 2a expression of TPM1, resulting in specifically down-regulation of TPM1variant V2 and V7 in human esophageal cancer cells. Mechanismly, the interaction of TPM1-AS with RBM4 hindered binding of RBM4 to TPM1 pre-mRNA and inhibited RBM4 to promote endogenous exon 2a inclusion of TPM1. Importantly, overexpression of TPM1-AS inhibited migration and filopodium formation, whereas TPM1variant V2 and V7 promoted these behaviors of human esophageal cancer cells. Taken together, the results suggest that a natural antisense TPM1-AS regulates the alternative splicing of TPM1 through an interaction with RBM4 and involves in TPM1-mediated filopodium formation and migration of cancer cells.

A new long noncoding RNA (lncRNA) is induced in cutaneous squamous cell carcinoma and down-regulates several anticancer and cell differentiation genes in mouse

Keratinocyte-derived cutaneous squamous cell carcinoma (cSCC) is the most common metastatic skin cancer. Although some of the early events involved in this pathology have been identified, the subsequent steps leading to tumor development are poorly defined. We demonstrate here that the development of mouse tumors induced by the concomitant application of a carcinogen and a tumor promoter (7,12-dimethylbenz[a]anthracene (DMBA) and 12-O-tetradecanoylphorbol-13-acetate (TPA), respectively) is associated with the up-regulation of a previously uncharacterized long noncoding RNA (lncRNA), termed AK144841. We found that AK144841 expression was absent from normal skin and was specifically stimulated in tumors and highly tumorigenic cells. We also found that AK144841 exists in two variants, one consisting of a large 2-kb transcript composed of four exons and one consisting of a 1.8-kb transcript lacking the second exon. Gain- and loss-of-function studies indicated that AK144841 mainly inhibited gene expression, specifically down-regulating the expression of genes of the late cornified envelope-1 (Lce1) family involved in epidermal terminal differentiation and of anticancer genes such as Cgref1, Brsk1, Basp1, Dusp5, Btg2, Anpep, Dhrs9, Stfa2, Tpm1, SerpinB2, Cpa4, Crct1, Cryab, Il24, Csf2, and Rgs16 Interestingly, the lack of the second exon significantly decreased AK144841's inhibitory effect on gene expression. We also noted that high AK144841 expression correlated with a low expression of the aforementioned genes and with the tumorigenic potential of cell lines. These findings suggest that AK144841 could contribute to the dedifferentiation program of tumor-forming keratinocytes and to molecular cascades leading to tumor development.

Novel Epigenetic Controlling of Hypoxia Pathway Related to Overexpression and Promoter Hypomethylation of TET1 and TET2 in RPE Cells

CpG methylation of DNA takes part in a specific epigenetic memory that plays crucial roles in the differentiation and abnormality of the cells. The methylation pattern aberration of genomes is affected in three ways, namely DNA methyltransferase (DNMT), ten-eleven translocation (TET), and methyl-binding domain (MBD) proteins. Of these, TET enzymes have recently been demonstrated to be master modifier enzymes in the DNA methylation process. Additionally, recent studies emphasize that not only epigenetic phenomena play a role in controlling hypoxia pathway, but the hypoxia condition also triggers hypomethylation of genomes that may help with the expression of hypoxia pathway genes. In this study, we suggested that TET1 and TET2 could play a role in the demethylation of genomes under chemical hypoxia conditions. Herein, the evaluating methylation status and mRNA expression of mentioned genes were utilized through real-time PCR and methylation-specific PCR (MSP), respectively. Our results showed that TET1 and TET2 genes were overexpressed (P < 0.05) under chemical hypoxia conditions in Retinal Pigment Epithelial (RPE) cells, whereas the promoter methylation status of them were hypomethylated in the same condition. Therefore, chemical hypoxia not only causes overexpression of TET1 and TET2 but also could gradually do promoter demethylation of same genes. This is the first study to show the relationship between epigenetics and the expression of mentioned genes related to hypoxia pathways. Furthermore, it seems that these associations in RPE cells are subjected to chemical hypoxia as a mechanism that could play a crucial role in methylation pattern changes of hypoxia-related diseases such as cancer and ischemia. J. Cell. Biochem. 118: 3193-3204, 2017. © 2017 Wiley Periodicals, Inc.

Tropomyosin-1 acts as a potential tumor suppressor in human oral squamous cell carcinoma

It is widely accepted that oral squamous cell carcinoma (OSCC) is a major contributor to the incidence and mortality of neck and head cancer. Tropomyosin-1 (TPM1), which is expressed at a low level, has been considered a prominent tumor-suppressing gene in a variety of solid tumors, although the precise mechanism of the TPM1 gene in OSCC progression remains unknown. We found that TPM1 expression levels decreased in OSCC patients and OSCC cell lines. The overall and cancer-specific survival of patients who exhibited low TPM1 levels were inferior to those of patients who had high TPM1 levels. It was also found that OSCC patients who suffered from disease stageⅠ-Ⅱ were more likely to have an up-regulated TPM1 expression level, and OSCC patients with lymph node metastasis had a higher probability of exhibiting reduced TPM1 expression. We show that overexpression of TPM1 can promote cell apoptosis and inhibit migration. Our results suggest that TPM1 can suppress tumors in OSCC, and the TPM1 expression level is related to OSCC patient prognosis.

Inflammatory Adipokines Decrease Expression of Two High Molecular Weight Isoforms of Tropomyosin Similar to the Change in Type 2 Diabetic Patients

Cardiovascular disease and cancer are increased in Type 2 diabetes. TPM1 and TPM4 genes encode proteins associated with cardiovascular and neoplastic disease. High (HMW) and low (LMW) molecular weight isoforms from TPM1 and TPM4 are altered in several cancer cells and the 3'UTR of TPM1 mRNA is tumour suppressive. Leukocytes influence cardiovascular and neoplastic disease by immunosurveillance for cancer and by chronic inflammation in Type 2 diabetes and cardiovascular disease. The aim was to determine changes in expression of isoforms from TPM1 and TPM4 genes in leukocytes from Type 2 diabetic patients and to use the leukocyte cell line THP1 to identify possible mediators of changes in the patients. Gene expression was determined by RT-qPCR. In diabetes, expression of HMW isoforms from TPM1 were markedly decreased (0.55 v 1.00; p = 0.019) but HMW isoforms from TPM4 were not significantly different (0.76 v 1.00; p = 0.205). Within individual variance in expression of HMW isoforms was very high. The change in expression in HMW isoforms from TPM1 and TPM4 was replicated in THP1 cells treated with 1 ng/ml TNFα (0.10 and 0.12 v 1.00 respectively) or 10 ng/ml IL-1α (0.17 and 0.14 v 1.00 respectively). Increased insulin or glucose concentrations had no substantial effects on TPM1 or TPM4 expression. Decreased TPM1 mRNA resulted in decreases in HMW protein levels. Expression of HMW isoforms from TPM1 is decreased in Type 2 diabetes. This is probably due to increased levels of inflammatory cytokines TNFα and IL-1α in Type 2 diabetes. Lower levels of TPM1 mRNA reduce tumour suppression and could contribute to increased cancer risk in Type 2 diabetes. Decreased HMW tropomyosin isoforms are associated with cancer. Decreased HMW isoforms give rise to cells that are more plastic, motile, invasive and prone to dedifferentiation resulting in leukocytes that are more invasive but less functionally effective.

The Role of Heat Shock Protein 90B1 in Patients with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a heterogenetic disorder in women that is characterized by arrested follicular growth and anovulatory infertility. The altered protein expression levels in the ovarian tissues reflect the molecular defects in folliculogenesis. To identify aberrant protein expression in PCOS, we analyzed protein expression profiles in the ovarian tissues of patients with PCOS. We identified a total of 18 protein spots that were differentially expressed in PCOS compared with healthy ovarian samples. A total of 13 proteins were upregulated and 5 proteins were downregulated. The expression levels of heat shock protein 90B1 (HSP90B1) and calcium signaling activator calmodulin 1 (CALM1) were increased by at least two-fold. The expression levels of HSP90B1 and CALM1 were positively associated with ovarian cell survival and negatively associated with caspase-3 activation and apoptosis. Knock-down of HSP90B1 with siRNA attenuated ovarian cell survival and increased apoptosis. In contrast, ovarian cell survival was improved and cell apoptosis was decreased in cells over-expressing HSP90B1. These results demonstrated the pivotal role of HSP90B1 in the proliferation and survival of ovarian cells, suggesting a critical role for HSP90B1 in the pathogenesis of PCOS. We also observed a downregulation of anti-inflammatory activity-related annexin A6 (ANXA6) and tropomyosin 2 (TPM2) compared with the normal controls, which could affect cell division and folliculogenesis in PCOS. This is the first study to identify novel altered gene expression in the ovarian tissues of patients with PCOS. These findings may have significant implications for future diagnostic and treatment strategies for PCOS using molecular interventions.

Clinical and tumor significance of tropomyosin-1 expression levels in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common type of kidney cancer in adults and has been described as one of the deadliest of cancers affecting the genitourinary tract. Tropomyosin is a two-stranded α-helical coiled coil protein found in cell cytoskeletons. One of its isoforms, tropomyosin-1 (TPM1) has been reported as a novel tumor-suppressor gene and is downregulated in many solid tumors. However the expression level and function of TPM1 in RCC have not yet been determined. In the present study, we evaluated the TPM1-4 mRNA and TPM1 protein levels in RCC tissue samples. TPM1-overexpressing OSRC-2 and 786-O cell lines were also used to investigate the impact of TPM1 on RCC cells. We found that TPM1 was significantly and specifically downregulated in the RCC tissues. TPM1 expression was associated with tumor size, smoking status, Fuhrman grade and the prognosis of RCC patients. After TPM1 transfection, the migratory and invasive abilities of the OSRC-2 and 786-O cell lines were both reduced when compared to the control groups. Meanwhile, apoptosis was also enhanced in these two RCC cell lines following TPM1 transfection. Taken together, TPM1 exhibits characteristics of a tumor-suppressor gene while being overexpressed in RCC cell lines.

Proteomics of a new esophageal cancer cell line established from Persian patient

Although the highest incidence of esophageal squamous cell carcinoma (ESCC) has repeatedly been reported from Persia (Iran), nevertheless the so far proteomic published reports were limited to one study on tissue specimens. Here we report the proteome of a newly established cell line from Persian ESCC patients and compare it with the normal primary cell proteome. Among polypeptides, whose expression was different in cell line sixteen polypeptides were identified by MALDI/TOF/TOF spectrometry. S100-A8 protein, annexin A1, annexin A2, regulatory subunit of calpain, subunit alpha type-3 of proteasome and glutamate dehydrogenase 1 were proteins down-regulated in cell line while peroxiredoxin-5, non-muscle myosin light polypeptide 6, keratin 1, annexin A4, keratin 8, tropomyosin 3, stress-induced-phosphoprotein 1 and albumin were found to be subject of up-regulation in cell line compared to the primary normal cells. The proteomic results were further verified by western blotting and RT-PCR on annexin A1 and keratin 8. In addition, among the aforementioned proteins, glutamate dehydrogenase 1, regulatory subunit of calpain, subunit alpha of type-3 proteasome and annexin A4 are proteins whose deregulation in ESCC is reported for the first time by this study.