Med19 promotes gastric cancer progression and cellular growth

LCMR1 Promotes Large-Cell Lung Cancer Proliferation and Metastasis by Downregulating HLA-Encoding Genes

Lung cancer is notorious for its high global morbidity and mortality. Here, we examined whether the LCMR1 gene, which we previously cloned from a human large-cell lung carcinoma cell line, contributes to the proliferation and metastasis of large-cell lung carcinoma. To this end, we performed pan-cancer and non-small cell lung cancer (NSCLC) cell line-based LCMR1 expression profiling. Results revealed that LCMR1 was expressed at high levels in most solid tumors, including NSCLC. LCMR1 expression was the highest in the 95D large cell lung cancer cell line. Functional studies using lentivirus-based knockdown revealed that LCMR1 was critical for the proliferation, migration, and invasion of cultured large cell lung cancer cells. Moreover, blocking this gene significantly reduced tumor growth in a 95D cell xenograft mouse model. A multiple sequence-based assay revealed a mechanism by which LCMR1 diminished the RNA Pol II occupancy at the promoter of human leukocyte antigen (HLA)-encoding genes to prevent their transcription. The HLA genes play vital roles in cancer-specific antigen presentation and anticancer immunity. A correlation assay using TCGA database identified a negative relationship between the expression levels of LCMR1 and HLA coding genes. Taken together, our findings demonstrate that LCMR1 is required for large cell lung cancer cell growth and invasion and suggest its potential as a valid target in clinical treatment.

MED19 encodes two unique protein isoforms that confer prostate cancer growth under low androgen through distinct gene expression programs

MED19, a component of the mediator complex and a co-regulator of the androgen receptor (AR), is pivotal in prostate cancer cell proliferation. MED19 has two isoforms: a full-length "canonical" and a shorter "alternative" variant. Specific antibodies were developed to investigate these isoforms. Both exhibit similar expression in normal prostate development and adult prostate tissue, but the canonical isoform is elevated in prostate adenocarcinomas. Overexpression of canonical MED19 in LNCaP cells promotes growth under conditions of androgen deprivation in vitro and in vivo, mirroring earlier findings with alternative MED19-overexpressing LNCaP cells. Interestingly, alternative MED19 cells displayed strong colony formation in clonogenic assays under conditions of androgen deprivation, while canonical MED19 cells did not, suggesting distinct functional roles. These isoforms also modulated gene expression differently. Canonical MED19 triggered genes related to extracellular matrix remodeling while suppressing those involved in androgen-inactivating glucuronidation. In contrast, alternative MED19 elevated genes tied to cell movement and reduced those associated with cell adhesion and differentiation. The ratio of MED19 isoform expression in prostate cancers shifts with the disease stage. Early-stage cancers exhibit higher canonical MED19 expression than alternative MED19, consistent with canonical MED19's ability to promote cell proliferation under androgen deprivation. Conversely, alternative MED19 levels were higher in later-stage metastatic prostate cancer than in canonical MED19, reflecting alternative MED19's capability to enhance cell migration and autonomous cell growth. Our findings suggest that MED19 isoforms play unique roles in prostate cancer progression and highlights MED19 as a potential therapeutic target for both early and late-stage prostate cancer.

Mediator Complex Subunit 19 Promotes the Development of Hepatocellular Carcinoma by Regulating the AKT/mTOR Signaling Pathway

Background

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors, the pathogenesis of which remains unclear. Mediator complex subunit 19 (MED19), a subunit of the Mediator complex, is a multi-protein co-activator necessary for DNA transcription factors to induce RNA polymerase II transcription. In the current study, we aimed to study the role of MED19 in HCC and elucidate its mechanism.

Methods

MED19 expression in HCC tissues was determined. The relationship between MED19 and the clinical prognosis was explored. The influence of MED19 on HCC cell viability, migration, invasion, and apoptosis was studied. The expression of AKT/mTOR pathway genes and proteins was detected by qRT-PCR and western blot. The correlation between MED19 and immune infiltration was investigated.

Results

MED19 was upregulated in HCC tissues compared with tumor-adjacent tissues, and was associated with a poor prognosis. Furthermore, high MED19 expression was correlated with race, gender, etc. Knockdown of MED19 inhibited cell proliferation, migration, invasion, and promoted apoptosis. Knockdown of MED19 decreased p-AKT and p-mTOR protein expression. Additionally, the downstream effectors of the AKT/mTOR pathway, p70S6K1 and 4EBP1, were affected by MED19. Notably, MED19 expression was positively correlated with the infiltration levels of B cells, CD4⁺ T cells, CD8⁺ T cells, macrophages, etc.

Conclusion

MED19 is significantly upregulated in HCC tissues and cells. MED19 may promote the progression of HCC in vitro and may be related to immune infiltration. Together, our data show that MED19 could be considered as a new possible biomarker as well as a novel therapeutic target for HCC.

Identification of potential biomarkers in ovarian carcinoma and an evaluation of their prognostic value

Background

Ovarian cancer is one of the most common malignant tumors in female genital organs, and its incidence rate is high. However, the pathogenesis and prognostic markers of ovarian cancer are unclear. This study sought to screen potential markers of ovarian cancer and to explore their prognostic value.

Methods

The Cancer Genome Atlas, Gene Expression Omnibus, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes databases were used in this study. The least absolute shrinkage and selection operator (LASSO), multivariate Cox regression and stepwise regression analysis were chosen to screen genes and construct risk model. Gene Set Enrichment Analysis (GSEA) and an immune-infiltration analysis were performed.

Results

One hundred thirty two co-expressed genes were found. They involved in metabolism, protein phosphorylation, mitochondria, and immune signaling pathways. Twelve genes significantly related to the survival of ovarian cancer were identified. Eight risk genes (i.e., CACNB1, FAM120B, HOXB2, MED19, PTPN2, SMU1, WAC.AS1, and BCL2L11) were further screened and used to construct the risk model. The risk status might be an independent prognostic factor of ovarian cancer, and most of the biological functions of genes expressed in high-risk ovarian cancer were related to synapse, adhesion, and immune-related functions. The clusters of CD4+ T cells and M2 macrophages were high in high-risk status samples.

Conclusions

In ovarian cancer, the abnormal expression of 8 genes, including CACNB1, FAM120B, HOXB2, MED19, PTPN2, SMU1, WAC.AS1, and BCL2L11, is closely related to ovarian cancer progression, and these genes can serve as independent prognosis markers of ovarian cancer.

The role of mediator complex subunit 19 in human diseases

Mediator is an evolutionarily conserved multi-protein complex that mediates the interaction between different proteins as a basic linker in the transcription mechanism of eukaryotes. It interacts with RNA polymerase II and participates in the process of gene expression. Mediator complex subunit 19 or regulation by oxygen 3, or lung cancer metastasis-related protein 1 is located at the head of the mediator complex; it is a multi-protein co-activator that induces the transcription of RNA polymerase II by DNA transcription factors. It is a tumor-related gene that plays an important role in transcriptional regulation, cell proliferation, and apoptosis and is closely related to the occurrence and development of the cancers of the lung, bladder, skin, etc. Here, we used the structure of mediator complex subunit 19 to review its role in tumor progression, fat metabolism, drug therapy, as well as the novel coronavirus, which has attracted much attention at present, suggesting that mediator complex subunit 19 has broad application in the occurrence and development of clinical diseases. As a tumor-related gene, the role and mechanism of mediator complex subunit 19 in the regulation of tumor growth could be of great significance for the diagnosis, prognosis, and treatment of mediator complex subunit 19 -related tumors.

A functional genetic screen identifies the Mediator complex as essential for SSX2-induced senescence

The senescence response to oncogenes is believed to be a barrier to oncogenic transformation in premalignant lesions, and describing the mechanisms by which tumor cells evade this response is important for early diagnosis and treatment. The male germ cell-associated protein SSX2 is ectopically expressed in many types of cancer and is functionally involved in regulating chromatin structure and supporting cell proliferation. Similar to many well-characterized oncogenes, SSX2 has the ability to induce senescence in cells. In this study, we performed a functional genetic screen to identify proteins implicated in SSX2-induced senescence and identified several subunits of the Mediator complex, which is central in regulating RNA polymerase-mediated transcription. Further experiments showed that reduced levels of MED1, MED4, and MED14 perturbed the development of senescence in SSX2-expressing cells. In contrast, knockdown of MED1 did not prevent development of B-Raf- and Epirubicin-induced senescence, suggesting that Mediator may be specifically linked to the cellular functions of SSX2 that may lead to development of senescence or be central in a SSX2-specific senescence response. Indeed, immunostaining of melanoma tumors, which often express SSX proteins, exhibited altered levels of MED1 compared to benign nevi. Similarly, RNA-seq analysis suggested that MED1, MED4, and MED14 were downregulated in some tumors, while upregulated in others. In conclusion, our study reveals the Mediator complex as essential for SSX2-induced senescence and suggests that changes in Mediator activity could be instrumental for tumorigenesis.

Med19 is involved in chemoresistance by mediating autophagy through HMGB1 in breast cancer

Adriamycin (ADM)-based regimens are the most effective chemotherapeutic treatments for breast cancer. However, intrinsic and acquired chemoresistance is a major therapeutic problem. Our goal was to clarify the role of mediator complex subunit 19 (Med19) in chemotherapy resistance and to elucidate the related molecular mechanisms. In this study, ADM-resistant human cells (MCF-7/ADM) and tissues exhibited increased Med19 expression and autophagy levels relative to the corresponding control groups. Additionally, MCF-7/ADM cells showed changes in two selective markers of autophagy. There was a dose-dependent increase in the light chain 3 (LC3)-II/LC3-I ratio and a decrease in sequestosome 1 (P62/SQSTMl) expression. Furthermore, lentivirus-mediated Med19 inhibition significantly attenuated the LC3-II/LC3-I ratio, autophagy-related gene 3 (Atg3) and autophagy-related gene 5 (Atg5) expression, P62 degradation, and red fluorescent protein-LC3 dot formation after treatment with ADM or rapamycin, an autophagy activator. Furthermore, the antiproliferative effects of ADM, cisplatin (DDP), and taxol (TAX) were significantly enhanced after suppressing Med19 expression. Notably, the effects of Med19 on autophagy were mediated through the high-mobility group box-1 (HMGB1) pathway. Our findings suggest that Med19 suppression increased ADM chemosensitivity by downregulating autophagy through the inhibition of HMGB1 signaling in human breast cancer cells. Thus, the regulatory mechanisms of Med19 in autophagy should be investigated to reduce tumor resistance to chemotherapy.

LCMR1 interacts with DEK to suppress apoptosis in lung cancer cells

To win the war against lung cancer, the molecular mechanisms underlying its oncogenesis and metastasis must be identified in order to develop novel diagnosis and treatment strategies. We previously identified a novel gene, namely lung cancer metastasis related protein 1 (LCMR1; GenBank accession no. AY148462), which was demonstrated to be overexpressed in non‑small‑cell lung cancer. LCMR1 expression was significantly associated with clinical stage. To further understand the mechanism of LCMR1 in lung cancer, the present study screened a cDNA library from the lung cancer cell line 95D for proteins interacting with LCMR1 by yeast two‑hybrid assay, and the protein DEK was identified. Co‑immunoprecipitation and glutathione S‑transferase pull‑down assays were performed to confirm the interaction between LCMR1 and DEK in vivo and in vitro. The results demonstrated that the interaction was mediated primarily by the N‑terminal region of DEK, suggesting that LCMR1 may be involved in the regulation of cell apoptosis. Using RNA interference, DEK and LCMR1 were demonstrated to cooperate in the inhibition of apoptosis in lung cancer cells, and this effect was associated with the induced myeloid leukemia protein cell differentiation protein 1 pathway. The present findings suggest that LCMR1 might serve as a potential molecular target for lung cancer therapy.

Knockdown of Mediator Complex Subunit 19 Suppresses the Growth and Invasion of Prostate Cancer Cells

Prostate cancer (PCa) is one of the most common cancers in elderly men. Mediator Complex Subunit 19 (Med19) is overexpressed and plays promotional roles in many cancers. However, the roles of Med19 in PCa are still obscure. In this study, by using immunohistochemical staining, we found higher expression level of Med19 in PCa tissues than in adjacent benign prostate tissues. We then knocked down the Med19 expression in PCa cell lines LNCaP and PC3 by using lentivirus siRNA. Cell proliferation, anchor-independent growth, migration, and invasion were suppressed in Med19 knockdown PCa cells. In nude mice xenograft model, we found that Med19 knockdown PCa cells formed smaller tumors with lower proliferation index than did control cells. In the mechanism study, we found that Med19 could regulate genes involved in cell proliferation, cell cycle, and epithelial-mesenchymal transition, including P27, pAKT, pPI3K, IGF1R, E-Cadherin, N-Cadherin, Vimentin, ZEB2, Snail-1 and Snail-2. Targeting Med19 in PCa cells could inhibit the PCa growth and metastasis, and might be a therapeutic option for PCa in the future.

A large-scale RNAi screen identifies LCMR1 as a critical regulator of Tspan8-mediated melanoma invasion

Melanoma is the deadliest form of skin cancer owing to its proclivity to metastasise, and recently developed therapies have not yielded the expected results, because almost all patients relapse. Therefore, understanding the molecular mechanisms that underlie early invasion by melanoma cells is crucial to improving patient survival. We have previously shown that, whereas the Tetraspanin 8 protein (Tspan8) is undetectable in normal skin and benign lesions, its expression arises with the progression of melanoma and is sufficient to increase cell invasiveness. Therefore, to identify Tspan8 transcriptional regulators that could explain the onset of Tspan8 expression, thereby conferring an invasive phenotype, we performed an innovative RNA interference-based screen, which, for the first time, identified several Tspan8 repressors and activators, such as GSK3β, PTEN, IQGAP1, TPT1 and LCMR1. LCMR1 is a recently identified protein that is overexpressed in numerous carcinomas; its expression and role, however, had not previously been studied in melanoma. The present study identified Tspan8 as the first LCMR1 target that could explain its function in carcinogenesis. LCMR1 modulation was sufficient to positively regulate endogenous Tspan8 expression, with concomitant in vitro phenotypic changes such as loss of melanoma cell-matrix adherence and increase in invasion, and Tspan8 expression promoted tumourigenicity in vivo. Moreover, LCMR1 and Tspan8 overexpression were shown to correlate in melanoma lesions, and both proteins could be downregulated in vitro by vemurafenib. In conclusion, this study highlights the importance of Tspan8 and its regulators in the control of early melanoma invasion and suggests that they may be promising new therapeutic targets downstream of the RAF-MEK-ERK signalling pathway.

Med19 promotes breast cancer cell proliferation by regulating CBFA2T3/HEB expression

BACKGROUND

Mediator complex 19 (Med19) is a pivotal subunit of the Mediator complex, and its aberrant expression is involved in tumourigenesis. We aimed to explore the mechanism by which Med19 promotes the proliferation of breast cancer.

METHODS

Lentivirus-mediated inhibition of Med19, ectopic expression of Med19 and ectopic expression of core-binding factor subunit alpha 2 to translocation 3 (CBFA2T3) were applied in human breast cancer cell lines. Human breast cancer cell proliferation was determined using CCK8 and colony formation assays after lentivirus infection. The expression of Med19, CBFA2T3 and HEB was measured by real-time reverse transcription polymerase chain reaction and Western blotting. The correlation between Med19 and CBFA2T3 expression in tissue from 25 cases of human breast cancer was analysed.

RESULTS

In this study, we demonstrate that cell proliferation and colony formation capacity were significantly inhibited after Med19 inhibition in vitro. The expression of CBFA2T3 was distinctly up-regulated in MDA-MB-231 and MCF-7 human breast cancer cells when Med19 was knocked down; however, the expression of HEB, which is targeted by CBFA2T3, was down-regulated. Meanwhile, ectopic expression of Med19 in BT-549 and Hs578T human breast cancer cells inhibited CBFA2T3 expression but enhanced HEB expression. The proliferation capacity of human breast cancer cells was increased when Med19 was overexpressed, but the effect of Med19 up-regulation could be reversed by CBFA2T3 overexpression. Furthermore, a negative correlation between Med19 and CBFA2T3 expression was demonstrated by Western blotting in human breast cancer tissue.

CONCLUSIONS

These results suggest that Med19 promotes breast cancer cell proliferation and that this effect is associated with CBFA2T3 and HEB. These results provide new insights into the potential role of Med19 in the regulation of breast carcinogenesis, and Med19 may be a useful therapeutic target in breast cancer therapy.

Lentivirus-mediated knockdown of CTDP1 inhibits lung cancer cell growth in vitro

BACKGROUND

CTDP1 catalyzes serine phosphorylation and dephosphorylation of the mobile carboxy-terminal domain of the RNA polymerase II. It is conserved among eukarya and is essential for cell growth for its ability in regulation of transcription machinery. However, its function in the process of tumorigenesis is unclear. In the present study, we aim to explore the roles of CTDP1 in the progression of human lung cancer. To our knowledge, this is the first study that reports the functions of CTDP1 in human lung cancer.

METHODS

We first detected the expression level of CTDP1 in four human lung cancer cell lines: H-125, H1299, LTEP-A-2 and NCI-H446 by semiquantitative RT-PCR. We compared the expression level of CTDP1 in lung cancer tissues and paired adjacent normal tissues on 29 pathologically confirmed patients by real-time quantitative PCR. To further explore the effect of CTDP1 on cell proliferation, a lentiviral vector expressing CTDP1 short hairpin RNA (shRNA) was constructed and infected into human lung cell lines H1299. Interference efficiency was determined by western blot analysis and real-time quantitative PCR. The effects of knockdown of CTDP1 on cell growth, cell cycle and apoptosis and cell colony formation were explored by Cellomics, fluorescence-activated cells sorting and fluorescence microscopy, respectively.

RESULTS

CTDP1 was expressed in all four human lung cancer cell lines. The expression of CTDP1 in tumor tissues was significantly higher than paired adjacent normal tissues in 29 patients with lung cancer. The expression of CTDP1 was markedly reduced in cells infected with lentivirus delivering shRNA against CTDP1. Inhibition of CTDP1 expression significantly suppressed cell growth, induced G0/G1 phase arrest and repressed cell colony formation.

CONCLUSIONS

Our results demonstrated that CTDP1 was upregulated in human lung cancer tissues. In addition, it implied that CTDP1 played an important role in cell proliferation and may be a useful therapeutic target in human lung cancer.

The Brakeless co-regulator can directly activate and repress transcription in early Drosophila embryos

The Brakeless protein performs many important functions during Drosophila development, but how it controls gene expression is poorly understood. We previously showed that Brakeless can function as a transcriptional co-repressor. In this work, we perform transcriptional profiling of brakeless mutant embryos. Unexpectedly, the majority of affected genes are down-regulated in brakeless mutants. We demonstrate that genomic regions in close proximity to some of these genes are occupied by Brakeless, that over-expression of Brakeless causes a reciprocal effect on expression of these genes, and that Brakeless remains an activator of the genes upon fusion to an activation domain. Together, our results show that Brakeless can both repress and activate gene expression. A yeast two-hybrid screen identified the Mediator complex subunit Med19 as interacting with an evolutionarily conserved part of Brakeless. Both down- and up-regulated Brakeless target genes are also affected in Med19-depleted embryos, but only down-regulated targets are influenced in embryos depleted of both Brakeless and Med19. Our data provide support for a Brakeless activator function that regulates transcription by interacting with Med19. We conclude that the transcriptional co-regulator Brakeless can either activate or repress transcription depending on context.

MED30 Regulates the Proliferation and Motility of Gastric Cancer Cells

MED30 is an essential member of the mediator complex that forms a hub between transcriptional activators and RNA polymerase II. However, the expressions and roles of MED30 have been poorly characterized in cancer. In this study, we examined the functional roles of MED30 during gastric cancer progression. It was found that MED30 was overexpressed in gastric cancer tissues and cell lines. Moreover, MED30 overexpression increased the proliferation, migration, and invasion of gastric cancer cells, whereas MED30 knockdown inhibited these effects. Furthermore the knockdown significantly inhibited tumorigenicity in SCID mice. MED30 also promoted the expressions of genes related to epithelial-mesenchymal transition and induced a fibroblast-like morphology. This study shows MED30 has pathophysiological roles in the proliferation, migration, and invasion of gastric cancer cells and suggests that MED30 should be viewed as a potent therapeutic target for malignant gastric carcinoma.

Drosophila melanogaster Hox transcription factors access the RNA polymerase II machinery through direct homeodomain binding to a conserved motif of mediator subunit Med19

Hox genes in species across the metazoa encode transcription factors (TFs) containing highly-conserved homeodomains that bind target DNA sequences to regulate batteries of developmental target genes. DNA-bound Hox proteins, together with other TF partners, induce an appropriate transcriptional response by RNA Polymerase II (PolII) and its associated general transcription factors. How the evolutionarily conserved Hox TFs interface with this general machinery to generate finely regulated transcriptional responses remains obscure. One major component of the PolII machinery, the Mediator (MED) transcription complex, is composed of roughly 30 protein subunits organized in modules that bridge the PolII enzyme to DNA-bound TFs. Here, we investigate the physical and functional interplay between Drosophila melanogaster Hox developmental TFs and MED complex proteins. We find that the Med19 subunit directly binds Hox homeodomains, in vitro and in vivo. Loss-of-function Med19 mutations act as dose-sensitive genetic modifiers that synergistically modulate Hox-directed developmental outcomes. Using clonal analysis, we identify a role for Med19 in Hox-dependent target gene activation. We identify a conserved, animal-specific motif that is required for Med19 homeodomain binding, and for activation of a specific Ultrabithorax target. These results provide the first direct molecular link between Hox homeodomain proteins and the general PolII machinery. They support a role for Med19 as a PolII holoenzyme-embedded “co-factor” that acts together with Hox proteins through their homeodomains in regulated developmental transcription.

Mutations of Hox developmental genes in the fruit fly Drosophila melanogaster may provoke spectacular changes in form: transformations of one body part into another, or loss of organs. This attribute identifies them as important developmental genes. Insect and vertebrate Hox proteins contain highly related homeodomain motifs used to bind to regulatory DNA and influence expression of developmental target genes. This occurs at the level of transcription of target gene DNA to messenger RNA by RNA polymerase II and its associated protein machinery (>50 proteins). How Hox homeodomain proteins induce fine-tuned transcription remains an open question. We provide an initial response, finding that Hox proteins also use their homeodomains to bind one machinery protein, Mediator complex subunit 19 (Med19) through a Med19 sequence that is highly conserved in animal phyla. Med19 mutants isolated in this work (the first animal mutants) show that Med19 assists Hox protein functions. Further, they indicate that homeodomain binding to the Med19 motif is required for normal expression of a Hox target gene. Our work provides new clues for understanding how the specific transcriptional inputs of the highly conserved Hox class of transcription factors are integrated at the level of the whole transcription machinery.

Mediator of RNA polymerase II transcription subunit 19 promotes osteosarcoma growth and metastasis and associates with prognosis

Osteosarcoma (OS) is the most common primary malignant tumour of bone. Nearly 30-40% of OS patients have a poor prognosis despite multimodal treatments. Because the carcinogenesis of OS remains unclear, the identification of new oncogenes that control the tumourigenesis and progression of OS is crucial for developing new therapies. Here, we found that the expression of Mediator of RNA polymerase II transcription subunit 19 (Med19) was increased in OS samples from patients compared to normal bone tissues. Cyclin D1 and cyclin B1 are upregulated in Med19 positive OS tissues. Importantly, among 97 OS patients of Enneking stage IIB or IIIB, Med19 expression was correlated with metastasis (P<0.05) and poor prognosis (P<0.01). Med19 knockdown significantly induced growth inhibition, reduced colony-forming ability and suppressed migration in the OS cell lines Saos-2 and U2OS, along with the downregulated expression of cyclin D1 and cyclin B1. Med19 knockdown also induced apoptosis in Saos-2 cells via induction of caspase-3 and poly ADP-ribose polymerase (PARP). In addition, Med19 knockdown significantly suppressed tumour growth in an OS xenograft nude mouse model via suppression of cyclin D1 and cyclin B1. Simultaneously, Med19 downregulation decreased the expression of Ki67 and proliferating cell nuclear antigen (PCNA) in tumour samples from OS xenograft nude mice. Med19 depletion remarkably reduced tumour metastasis in a model of OS metastatic spreading. Taken together, our data suggest that Med19 acts as an oncogene in OS via a possible cyclin D1/cyclin B1 modulation pathway.

Involvement of Mediator complex in malignancy

Mediator complex (MED) is an evolutionarily conserved multiprotein, fundamental for growth and survival of all cells. In eukaryotes, the mRNA transcription is dependent on RNA polymerase II that is associated to various molecules like general transcription factors, MED subunits and chromatin regulators. To date, transcriptional machinery dysfunction has been shown to elicit broad effects on cell proliferation, development, differentiation, and pathologic disease induction, including cancer. Indeed, in malignant cells, the improper activation of specific genes is usually ascribed to aberrant transcription machinery. Here, we focus our attention on the correlation of MED subunits with carcinogenesis. To date, many subunits are mutated or display altered expression in human cancers. Particularly, the role of MED1, MED28, MED12, CDK8 and Cyclin C in cancer is well documented, although several studies have recently reported a possible association of other subunits with malignancy. Definitely, a major comprehension of the involvement of the whole complex in cancer may lead to the identification of MED subunits as novel diagnostic/prognostic tumour markers to be used in combination with imaging technique in clinical oncology, and to develop novel anti-cancer targets for molecular-targeted therapy.

Disruption of mediator complex subunit 19 (Med19) inhibits cell growth and migration in tongue cancer

Background

Mediator complex subunit 19 (Med19) is a critical subunit of the mediator complex that forms a bridge between the transcription factors and RNA polymerase II. Although it has been reported that Med19 plays an important role in stabilizing the whole mediator complex, its biological importance in tongue cancer cell proliferation and migration has not been addressed.

Methods

By using MTT, BrdU incorporation, colony formation, flow cytometric, tumorigenesis and transwell assays, We tested the Med19 role on tongue cancer cell growth and migration.

Results

We demonstrated that lentivirus-mediated Med19 knockdown could arrest tongue cancer cells at G1 phase, inhibit tongue cancer cell proliferation and migration in vitro. The tumorigenicity of Med19 short hairpin RNA (shRNA)-expressing lentivirus infected tongue cancer cells were decreased after inoculating into nude mice.

Conclusions

These results indicate that Med19 plays an important role in tongue cancer proliferation and migration, and suggest possible applications for tongue cancer therapy.