Sp1-mediated ectopic expression of T-cell lymphoma invasion and metastasis 2 in hepatocellular carcinoma

TIAM2S Operates Multifaced Talents to Alleviate Radiosensitivity, Restrict Apoptosis, Provoke Cell Propagation, and Escalate Cell Migration for Aggravating Radioresistance-Intensified Cervical Cancer Progression

Radioresistance remains a major obstacle in cervical cancer treatment, frequently engendering tumor relapse and metastasis. However, the details of its mechanism of action remain largely enigmatic. This study delineates the prospective impacts of short-form human T-cell lymphoma invasion and metastasis 2 (TIAM2S) involving the radiation resistance of cervical cancer. In this study, we established three pairs of radioresistant (RR) cervical cancer cells (HeLa, C33A and CaSki) and their parental wild-type (WT) cells. We revealed a consistent augmentation of TIAM2S, but not long-form human T-cell lymphoma invasion and metastasis 2 (TIAM2L) were displayed in RR cells that underwent a 6 Gy radiation administration. Remarkably, RR cells exhibited decreased radiosensitivity and abridged apoptosis, as estimated through a clonogenic survival curve assay and Annexin V/Propidium Iodide apoptosis assay, respectively. TIAM2S suppression increased radiosensitivity and enhanced cell apoptosis in RR cells, whereas its forced introduction modestly abolished radiosensitivity and diminished WT cell apoptosis. Furthermore, TIAM2S overexpression notably aggravated RR cell migration, whereas its blockage reduced WT cell mobilities, as confirmed by an in vitro time-lapse recording assay. Notably, augmented lung localization was revealed after a tail-vein injection of CaSki-RR cells using the in vivo short-term lung locomotion BALB/c nude mouse model. TIAM2S impediment notably reduced radioresistance-increased lung locomotion. This study provides evidence that TIAM2S may operate as an innovative signature in cervical cancer that is resistant to radiotherapy. It displays multi-faceted roles including radioprotection, restricting apoptosis, promoting cell proliferation, and escalating cell migration/metastasis. Targeting TIAM2S, together with conventional radiotherapy, may be an innovative strategy for intensifying radiosensitivity and protecting against subsequent uncontrolled tumor growth and metastasis in cervical cancer treatment.

TIAM2S-positive microglia enhance inflammation and neurotoxicity through soluble ICAM-1-mediated immune priming

TIAM Rac1-associated GEF 2 short form (TIAM2S) as an oncoprotein alters the immunity of peripheral immune cells to construct an inflammatory tumor microenvironment. However, its role in the activation of microglia, the primary innate immune cells of the brain, and neuroinflammation remains unknown. This study investigated the mechanism underlying TIAM2S shapes immune properties of microglia to facilitate neuron damage. Human microglial clone 3 cell line (HMC3) and human brain samples were applied to determine the presence of TIAM2S in microglia by western blots and double immunostaining. Furthermore, TIAM2S transgenic mice combined with multiple reconstituted primary neuron-glial culture systems and a cytokine array were performed to explore how TIAM2S shaped immune priming of microglia and participated in lipopolysaccharide (LPS)-induced neuron damage. TIAM2S protein was detectable in HMC3 cells and presented in a small portion (~11.1%) of microglia in human brains referred to as TIAM2S-positive microglia. With the property of secreted soluble factor-mediated immune priming, TIAM2S-positive microglia enhanced LPS-induced neuroinflammation and neural damage in vivo and in vitro. The gain- and loss-of-function experiments showed soluble intercellular adhesion molecule-1 (sICAM-1) participated in neurotoxic immune priming of TIAM2S+ microglia. Together, this study demonstrated a novel TIAM2S-positive microglia subpopulation enhances inflammation and neurotoxicity through sICAM-1-mediated immune priming.

Elevated TIAM2 expression promotes tumor progression and is associated with unfavorable prognosis in pancreatic cancer

BACKGROUND AND AIM

As a Rac1 guanine nucleotide exchange factor, T-cell lymphoma invasion and metastasis 2 (TIAM2) has been reported to be correlated with malignant phenotypes in several cancers, but its prognostic significance and function in pancreatic ductal adenocarcinoma (PDAC) was not investigated.

METHODS

The expression patterns of TIAM2 and patient survival were analyzed in a large cohort of 303 patients with radical surgical resection of PDAC, using immunohistochemical staining in tissue microarrays. Data mining was applied to evaluate TIAM2 expression and patient survival at the mRNA level. The function of TIAM2 in proliferation, motility and invasion of pancreactic cancer (PC) cells was also investigated.

RESULTS

TIAM2 expression was significantly increased in PDAC compared with para-tumor tissues (p < .0001). The expression of TIAM2 was associated with histopathological grade (p = .008), tumor location (p = .013), and pathological T stage (p = .029). For survival, patients with high TIAM2 expression had significantly poor prognosis in some subgroups. In addition, multivariate analyses showed that the combination of TIAM2 and the pathological N stage largely enhanced the prognostic efficiency, and was found to be as an independent prognostic indicator in patients with PDAC. Data mining elucidated that TIAM2 mRNA expression level was increased in tumor tissues and correlated with patient survival. Furthermore, high TIAM2 expression was common in PC cells. Downregulation of TIAM2 suppressed cell proliferation, migration and invasion in PC.

CONCLUSIONS

High expression of TIAM2 might be a meaningful prognostic factor for PDAC patients, and TIAM2 participates in tumor progression in PDAC.

FGF9 is a downstream target of SRY and sufficient to determine male sex fate in ex vivo XX gonad culture

Fibroblast growth factor 9 (FGF9) is an autocrine/paracrine growth factor that plays critical roles in embryonic and organ developments and is involved in diverse physiological events. Loss of function of FGF9 exhibits male-to-female sex reversal in the transgenic mouse model and gain of FGF9 copy number was found in human 46, XX sex reversal patient with disorders of sex development. These results suggested that FGF9 plays a vital role in male sex development. Nevertheless, how FGF9/Fgf9 expression is regulated during testis determination remains unclear. In this study, we demonstrated that human and mouse SRY bind to -833 to -821 of human FGF9 and -1010 to -998 of mouse Fgf9, respectively, and control FGF9/Fgf9 mRNA expression. Interestingly, we showed that mouse SRY cooperates with SF1 to regulate Fgf9 expression, whereas human SRY-mediated FGF9 expression is SF1 independent. Furthermore, using an ex vivo gonadal culture system, we showed that FGF9 expression is sufficient to switch cell fate from female to male sex development in 12-16 tail somite XX mouse gonads. Taken together, our findings provide evidence to support the SRY-dependent, fate-determining role of FGF9 in male sex development.

NF90 modulates processing of a subset of human pri-miRNAs

MicroRNAs (miRNAs) are predicted to regulate the expression of >60% of mammalian genes and play fundamental roles in most biological processes. Deregulation of miRNA expression is a hallmark of most cancers and further investigation of mechanisms controlling miRNA biogenesis is needed. The double stranded RNA-binding protein, NF90 has been shown to act as a competitor of Microprocessor for a limited number of primary miRNAs (pri-miRNAs). Here, we show that NF90 has a more widespread effect on pri-miRNA biogenesis than previously thought. Genome-wide approaches revealed that NF90 is associated with the stem region of 38 pri-miRNAs, in a manner that is largely exclusive of Microprocessor. Following loss of NF90, 22 NF90-bound pri-miRNAs showed increased abundance of mature miRNA products. NF90-targeted pri-miRNAs are highly stable, having a lower free energy and fewer mismatches compared to all pri-miRNAs. Mutations leading to less stable structures reduced NF90 binding while increasing pri-miRNA stability led to acquisition of NF90 association, as determined by RNA electrophoretic mobility shift assay (EMSA). NF90-bound and downregulated pri-miRNAs are embedded in introns of host genes and expression of several host genes is concomitantly reduced. These data suggest that NF90 controls the processing of a subset of highly stable, intronic miRNAs.

TIAM2S Mediates Serotonin Homeostasis and Provokes a Pro-Inflammatory Immune Microenvironment Permissive for Colorectal Tumorigenesis

The short isoform of human TIAM2 has been shown to promote proliferation and invasion in various cancer cells. However, the roles of TIAM2S in immune cells in relation to tumor development have not been investigated. To characterize the effects of TIAM2S, we generated TIAM2S-overexpressing mouse lines and found that aged TIAM2S-transgenic (TIAM2S-TG) developed significantly higher occurrence of lymphocytic infiltration and tumorigenesis in various organs, including colon. In addition, TIAM2S-TG is more sensitized to AOM-induced colon tumor development, suggesting a priming effect toward tumorigenesis. In the light of our recent findings that TIAM2S functions as a novel regulator of cellular serotonin level, we found that serotonin, in addition to Cox2, is a unique inflammation marker presented in the colonic lesion sites in the aged TG animals. Furthermore, our results demonstrated that ectopic TIAM2S altered immunity via the expansion of T lymphocytes; this was especially pronounced in CD8⁺ T cells in combination with CXCL13/BCA-1 pro-inflammatory chemokine in the serum of TIAM2S-TG mice. Consequently, T lymphocytes and B cells were recruited to the lesion sites and stimulated IL-23/IL17A expression to form the tertiary lymphoid organs. Collectively, our research suggests that TIAM2S provokes a pro-inflammatory immune microenvironment permissive to colorectal tumorigenesis through the serotonin-induced immunomodulatory effects.

MiRNA-130a-3p inhibits cell proliferation, migration, and TMZ resistance in glioblastoma by targeting Sp1

Specificity protein 1 (Sp1) is aberrantly expressed and involved in the development and metastasis of glioblastoma. In this study, we observed that the expression of Sp1 was upregulated while that of microRNA (miR)-130a-3p was downregulated in glioblastoma cell lines. Sp1 was validated as a target of miR-130a-3p; increased levels of miR-130a-3p inhibited the proliferation, migration, and temozolomide (TMZ) resistance of the glioblastoma cells. However, Sp1 overexpression compromised the inhibitory effects of miR-130a-3p. Our study elucidates the functional interaction between miR-130a-3p and Sp1 in the development and progression of glioblastoma, suggesting a potential therapeutic target for the disease.

Expression of Rho Guanine Nucleotide Exchange Factor 39 (ARHGEF39) and Its Prognostic Significance in Hepatocellular Carcinoma

BACKGROUND Previous studies have reported that ARHGEF39 might be frequently upregulated in different cancer types and relevant to cancer progression. However, the expression pattern and clinicopathological features of ARHGEF39 in patients with hepatocellular carcinoma (HCC) needs further exploration. MATERIAL AND METHODS ARHGEF39 expression level of HCC in The Cancer Genome Atlas (TCGA) dataset was analyzed. Quantitative real-time polymerase chain reaction and immunohistochemistry were employed to determine ARHGEF39 mRNA and protein levels in our own study collected HCC tissues and matched non-cancerous tissues. Moreover, the association of ARHGEF39 expression with the clinicopathological factors and prognosis of HCC were investigated. RESULTS The level of ARHGEF39 in HCC tissues was significantly higher than that in adjacent normal tissues (P<0.05) from TCGA database. High level of ARHGEF39 was a significant prognostic factor of poor overall survival (OS) (TCGA, P=0.006). Consistently, the expression levels of ARHGEF39 mRNA and protein in HCC specimens were significantly higher than those in adjacent liver specimens (P<0.05) from our cohort. Further analysis revealed that high ARHGEF39 level was significantly associated with poor OS (P<0.001) and short disease-free survival (DFS) (P<0.001). Cox multivariate analysis indicated that ARHGEF39 was an independent, unfavorable prognostic factor (P=0.000) of OS and DFS. CONCLUSIONS ARHGEF39 might act as an oncogene in the progression of HCC and might serve as a promising potential prognostic indicator and therapeutic target for HCC.

MicroRNA-548b inhibits proliferation and invasion of hepatocellular carcinoma cells by directly targeting specificity protein 1

Emerging studies have revealed that microRNAs (miRNAs) are aberrantly expressed in hepatocellular carcinoma (HCC), and the dysregulation of miRNAs exerts crucial roles in the carcinogenesis and development of HCC. Therefore, elucidating the relationship between miRNAs and HCC progression is of great importance to develop novel therapeutic techniques and to improve the prognosis of patients with this malignancy. Recently, miR-548b-3p (miR-548b) has been demonstrated to be a cancer-associated miRNA in tongue squamous cell carcinoma and glioma. However, the expression and function of miR-548b in HCC remain poorly understood. In the present study, it was found that miR-548b is expressed at low levels in HCC tissues and cell lines. Decreased miR-548b expression was found to be positively associated with the clinical features of HCC, including the TNM stage and lymph node metastasis. Functional experiments revealed that upregulation of miR-548b expression decreased proliferation and invasion of HCC cells. Specificity protein 1 (SP1) was verified to be a direct target of miR-548b in HCC cells; as Spearman's correlation analysis identified miR-548b expression to be negatively correlated with that of SP1 expression in HCC tissue specimens. In addition, SP1 inhibition exhibited similar effects as miR-548b overexpression in HCC cells. SP1 reintroduction significantly reversed the suppressive effects of miR-548b upregulation on the proliferation and invasion of HCC cells. In conclusion, the results presented in the present study demonstrated that miR-548b may serve as a tumor suppressive miRNA that inhibits the proliferation and invasion of HCC cells by directly targeting SP1. Consequently, miR-548b can be exploited as a novel therapeutic target for treating patients with HCC in the future, but this needs to be investigated further.

Impact of Nuclear Interleukin-1 Alpha and EGFR Expression on Recurrence and Survival Outcomes in Oral Squamous Cell Carcinomas

Interleukin-1 alpha (IL-1α) is a pleiotropic cytokine involved in inflammation and immune response and is upregulated in many solid tumors including head and neck squamous cell carcinomas. Although IL-1α expression is generally associated with poor prognosis, the implications of the subcellular localization of IL-1α expression in patient outcomes are poorly understood. This study is aimed at investigating the prognostic value of nuclear and cytoplasmic immunohistochemical IL-1α expression in oral squamous cell carcinomas (OSCCs). Tissue microarrays containing 146 OSCCs were analyzed for IL-1α and epidermal growth factor receptor (EGFR) expression by immunohistochemistry. IL-1α and EGFR expression scores were correlated with clinicopathological parameters and survival outcomes. IL-1α expression was observed in the nuclear and/or cytoplasmic compartments in 98% of evaluable tumors and 78% of tumors expressed IL-1α in both compartments. There were no differences observed in overall survival or progression-free survival between high, moderate, or negative IL-1α nuclear/cytoplasmic expression scores. When IL-1α nuclear/cytoplasmic expression scores were stratified by positive or negative EGFR expression, tumors with a combined EGFR-positive and high nuclear IL-1α expression profile were significantly more likely to possess perineural invasion and were significantly associated with a high risk of tumor recurrence and worse progression-free survival compared to all other EGFR and combined IL-1α/EGFR expression profiles. Altogether, nuclear IL-1α expression may enhance the prognostic value of EGFR in OSCC and warrants further study as a prognostic biomarker for recurrence.

FAM84B promotes prostate tumorigenesis through a network alteration

Background:

The aim of this study was to investigate the contributions of FAM84B in prostate tumorigenesis and progression.

Methods:

A FAM84B mutant with deletion of its HRASLS domain (ΔHRASLS) was constructed. DU145 prostate cancer (PC) cells stably expressing an empty vector (EV), FAM84B, or FAM84B (ΔHRASLS) were produced. These lines were examined for proliferation, invasion, and growth in soft agar in vitro. DU145 EV and FAM84B cells were investigated for tumor growth and lung metastasis in NOD/SCID mice. The transcriptome of DU145 EV xenografts (n = 2) and DU145 FAM84B tumors (n = 2) was determined using RNA sequencing, and analyzed for pathway alterations. The FAM84B-affected network was evaluated for an association with PC recurrence.

Results:

FAM84B but not FAM84B (ΔHRASLS) increased DU145 cell invasion and growth in soft agar. Co-immunoprecipitation and co-localization analyses revealed an interaction between FAM84B and FAM84B (ΔHRASLS), suggesting an intramolecular association among FAM84B molecules. FAM84B significantly enhanced DU145 cell-derived xenografts and lung metastasis. In comparison with DU145 EV cell-produced tumors, those generated by DU145 FAM84B cells showed a large number of differentially expressed genes (DEGs; n = 4976). A total of 51 pathways were enriched in these DEGs, which function in the Golgi-to-endoplasmic reticulum processes, cell cycle checkpoints, mitochondrial events, and protein translation. A novel 27-gene signature (SigFAM) was derived from these DEGs; SigFAM robustly stratifies PC recurrence in two large PC populations (n = 490, p = 0; n = 140, p = 4e⁻¹¹), and remains an independent risk factor of PC recurrence after adjusting for age at diagnosis, Gleason scores, surgical margin, and tumor stages.

Conclusions:

FAM84B promotes prostate tumorigenesis through a complex network that predicts PC recurrence.

The Fibroblast TIAM2 Promotes Lung Cancer Cell Invasion and Metastasis

Purpose: TIAM2 (T-cell lymphoma invasion and metastasis 2), a RAC1 guanine nucleotide exchange factor, plays crucial roles in human cancer cells. Its homolog, TIAM1, has been reported to promote the migration and invasion of cancer cells through regulating the functions of cancer associated fibroblasts (CAFs). However, the functions of TIAM2 in CAFs have not been investigated. In this study, we explored how fibroblast TIAM2 influences the migration and invasion of lung cancer cells.

Methods: We cultured primary lung CAFs and adjacent normal lung fibroblasts (NFs) from 12 non-small cell lung cancer (NSCLC) patients. RT-PCR and western blot were used to compare TIAM2 levels between CAFs and NFs. Two co-culture systems were designed, in which cancer cells were directly co-cultured with fibroblasts and indirectly co-cultured with conditional medium (CM) from fibroblasts. Subsequently, the wound healing and transwell tests were conducted to assess the migration and invasion ability of fibroblasts and co-cultured cancer cells. Finally, cytokine antibody arrays were used to screen differentially secreted cytokines in the CM.

Results: The expression levels of TIAM2 were significantly higher in CAFs than NFs, and TIAM2-silenced fibroblasts showed decreased migration and invasion ability. In the direct co-culture system, the migration and invasion of cancer cells were retarded when co-culturing with TIAM2-silenced fibroblasts, and the expression levels of EMT-related genes also changed in cancer cells. Decreased migration and invasion of cancer cells were also observed when culturing with the CM from TIAM2-silenced fibroblasts. In addition, the cytokine antibody arrays revealed that Osteoprotegerin (OPG) was significantly decreased in the CM of TIAM2-silenced fibroblasts. This result suggested that OPG might be one of the main cytokines contributing to the migration and invasion of cancer cells in co-culture systems.

Conclusion: Our results suggest that fibroblast TIAM2 promotes the invasion and migration of lung cancer cell, and OPG might be one of the main cytokines contributing to this pro-cancer process.

MiR-326/Sp1/KLF3: A novel regulatory axis in lung cancer progression

OBJECTIVES

To investigate the function and regulatory mechanism of Krüppel-like factor 3 (KLF3) in lung cancer.

MATERIALS AND METHODS

KLF3 expression was analysed by qRT-PCR and Western blot assays. The proliferation, migration, invasion, cycle and apoptosis were measured by CCK-8 and EdU, wound-healing and Transwell, and flow cytometry assays. The tumour growth was detected by nude mouse tumorigenesis assay. In addition, the interaction between KLF3 and Sp1 was accessed by luciferase reporter, EMSA and ChIP assay. JAK2, STAT3, PI3K and p-AKT levels were evaluated by Western blot and IHC assays.

RESULTS

The results indicated that KLF3 expression was elevated in lung cancer tissues. Knockdown of KLF3 inhibited lung cancer cell proliferation, migration and invasion, and induced cell cycle arrest and apoptosis. In addition, the downregulation of KLF3 suppressed tumour growth in vivo. KLF3 was transcriptionally activated by Sp1. miR-326 could bind to 3'UTR of Sp1 but not KLF3 and decreased the accumulation of Sp1, which further indirectly reduced KLF3 expression and inactivated JAK2/STAT3 and PI3K/AKT signaling pathways in vitro and in vivo.

CONCLUSIONS

Our data demonstrate that miR-326/Sp1/KLF3 regulatory axis is involved in the development of lung cancer, which hints the potential target for the further therapeutic strategy against lung cancer.

Sp1 Suppresses miR-3178 to Promote the Metastasis Invasion Cascade via Upregulation of TRIOBP

Specificity protein (Sp1) plays an important role in invasion-metastasis cascade. Sp1 regulation on protein coding genes has been extensively investigated; however, little is known about its regulation on protein non-coding genes. In this study, miR-3178 is reported as a novel target of Sp1 in multiple cancer cell models. Sp1 functions as its transcriptional suppressor as evidenced by luciferase reporter and chromatin immunoprecipitation (ChIP) assays. In line with the pro-metastatic role of Sp1, miR-3178 exerts anti-metastasis function. Overexpression of miR-3178 inhibits both migration and invasion of highly metastatic prostate, lung, and breast cancer cells whereas antagonizing miR-3178 promotes those events in their lowly metastatic counterparts. The in vivo study demonstrates that miR-3178 suppresses the tail vein inoculated prostate cancer cells to form colonies in lung, lymph node, and liver of BALB/c nude mice. miR-3178 directly targets the 3′ UTR of TRIOBP-1 and TRIOBP-5, two isoforms of TRIOBP expressed in prostate, lung, and breast cancer cells. Overexpression of TRIOBP-1 could rescue miR-3178 inhibition on cell migration and invasion. Collectively, our findings reveal the regulatory axis of Sp1/miR-3178/TRIOBP in metastasis cascade. Our results suggest miR-3178 as a promising application to suppress metastasis in Sp1-overexpressed cancers.

MicroRNA-22 suppresses the growth, migration and invasion of colorectal cancer cells through a Sp1 negative feedback loop

MicroRNAs have recently emerged as regulators of many biological processes including cell proliferation, development and differentiation. This study identified that miR-22 was statistically decreased in colorectal cancer clinical specimens and highly metastatic cell lines. Moreover, low miR-22 expression was associated with tumor metastasis, advanced clinical stage and relapse. Consistent with clinical observations, miR-22 significantly suppressed the ability of colorectal cancer cells to growth and metastasize in vitro and in vivo. Sp1 was validated as a target of miR-22, and ectopic expression of Sp1 compromised the inhibitory effects of miR-22. In addition, Sp1 repressed miR-22 transcription by binding to the miR-22 promoter, hence forming a negative feedback loop. Further study has shown that miR-22 suppresses the activity of PTEN/AKT pathway by Sp1. Our present results implicate the newly indentified miR-22/Sp1/PTEN/AKT axis might represent a potential therapeutic target for colorectal cancer.

MicroRNA‑376a inhibits cell proliferation and invasion in glioblastoma multiforme by directly targeting specificity protein 1

Glioblastoma multiforme (GBM), a World Health Organization grade IV glioma, is the most common and aggressive primary brain tumor in humans. microRNAs (miRNAs) are aberrantly expressed in numerous cancer types, including GBM. Abnormally expressed miRNAs are commonly associated with malignant characteristics of GBM, including malignant growth, proliferation, apoptosis, invasion, metastasis and resistance to chemotherapy. miRNA (miR)‑376a is abnormally expressed in multiple human cancers; however, the expression pattern and role of miR‑376a in GBM, and the underlying molecular mechanisms by which miR‑376a exerts its functions remain to be elucidated. Therefore, the aim of this study was to measure miR‑376a expression and determine its biological roles in GBM as well as its associated molecular mechanism. In the present study, miR‑376a expression was markedly downregulated in GBM tissues and cell lines. Overexpression of miR‑376a markedly decreased the proliferation and invasion of GBM cells in vitro. In the present study, specificity protein 1 (SP1) was demonstrated to be a direct target of miR‑376a. In addition, a negative association between SP1 mRNA and miR‑376a expression was observed in GBM tissues. SP1 upregulation reduced the effects of miR‑376a overexpression on GBM cell proliferation and invasion. miR‑376a may be a therapeutic target for the treatment of patients with GBM.

A regulatory loop involving miR-29c and Sp1 elevates the TGF-β1 mediated epithelial-to-mesenchymal transition in lung cancer

Specificity protein1 (Sp1) is required for TGF-β-induced epithelial-to-mesenchymal transition (EMT) which has been demonstrated to aggravate the progression of cancer including lung cancer. microRNA-29c (miR-29c) is identified to inhibit EMT, but the correlation between miR-29c and Sp1 in human lung cancer remain incompletely clarified. Here, we confirmed decreased expression of miR-29c and enhanced expression of Sp1 in lung cancer tissues (n = 20) and found that Sp1 could be targeted and inhibited by miR-29c. Besides, the expression of miR-29c was down-regulated in high-metastatic lung cancer cell lines and TGF-β1-treated cells. The inhibition of miR-29c or overexpression of Sp1 in 95C and A549 cells dramatically enhanced the cell migration and invasion, and also induced the decrease in the expression of epithelial markers, e.g. thyroid transcription factor 1 (TTF-1) and E-cadherin, together with an increase in mesenchymal markers including vimentin, α-smooth muscle actin (α-SMA), which could be restored by overexpression of miR-29c mimics during the TGF-β-induced EMT. Moreover, dual-luciferase reporter assay was performed and the results indicated that miR-29c/Sp1 could form an auto-regulatory loop with TGF-β1, which impaired TGFB1 transcription. Furthermore, miR-29c overexpression could abrogate the tumor progression and inhibit the Sp1/TGF-β expressions in vivo, indicating that miR-29c could be a tumor suppressor and repress the Sp1/TGF-β axis-induced EMT in lung cancer.

MicroRNA-137 suppresses tongue squamous carcinoma cell proliferation, migration and invasion

OBJECTIVES

Tongue squamous cell carcinoma (TSCC) is the most frequent type of oral malignancy. Increasing evidence has shown that miRNAs play key roles in many biological processes such as cell development, invasion, proliferation, differentiation, metabolism, apoptosis and migration.

MATERIALS AND METHODS

qRT-PCR analysis was performed to measure miR-137 expression. CCK-8 analysis, cell colony formation, wound-healing analysis and invasion were performed to detect resultant cell functions. The direct target of miR-137 was labelled and measured by luciferase assay and Western blotting.

RESULTS

We demonstrated that expression of miR-137 was downregulated in TSCC tissues compared to matched normal ones. miR-137 expression was downregulated in TSCC lines (SCC4, SCC1, UM1 and Cal27) compared to the immortalized NOK16B cell line and normal oral keratinocytes in culture (NHOK). In addition, we have shown that miR-137 expression was epigenetically regulated in TSCCs. Overexpression of miR-137 suppressed TSCC proliferation and colony formation. Ectopic expression of miR-137 promoted expression of the epithelial biomarker, E-cadherin, and inhibited the mesenchymal biomarker, N-cadherin, as well as vimentin and Snail expression, indicating that miR-137 suppressed TSCC epithelial-mesenchymal transition (EMT). We also showed that ectopic expression of miR-137 inhibited TSCC invasion and migration. In addition, we identified SP1 as a direct target gene of miR-137 in SCC1 cells. SP1 overexpression rescued inhibitory effects exerted by miR-137 on cell proliferation and EMT.

CONCLUSIONS

These results indicate that miR-137 acted as a tumour suppressor in TSCC by targeting SP1.

Sp1-mediated ectopic expression of T-cell lymphoma invasion and metastasis 2 in hepatocellular carcinoma

T-cell lymphoma invasion and metastasis 2 (TIAM2) is a neuron-specific protein that has been found ectopically expressed in hepatocellular carcinoma (HCC). Results from clinical specimens and cellular and animal models have shown that the short form of TIAM2 (TIAM2S) functions as an oncogene in the tumorigenesis of liver cancer. However, the regulation of TIAM2S ectopic expression in HCC cells remains largely unknown. This study aimed to identify the mechanism underlying the ectopic expression of TIAM2S in liver cancer cells. In this report, we provide evidence illustrating that Sp1 binds directly to the GC box located in the TIAM2S core promoter. We further demonstrated that overexpression of Sp1 in HepaRG cells promotes endogenous TIAM2S mRNA and protein expressions, and knockdown of Sp1 in 2 HCC cell lines, HepG2 and PLC/PRF/5, led to a substantial reduction in TIAM2S mRNA and protein in these cells. Of 60 paired HCC samples, 70% showed a significant increase (from 1.1- to 3.6-fold) in Sp1 protein expression in the tumor cells. The elevated Sp1 expression was highly correlated with both TIAM2S mRNA and protein expressions in these samples. Together, these results illustrate that Sp1 positively controls TIAM2S transcription and that Sp1-mediated transcriptional activation is essential for TIAM2S ectopic expression in liver cancer cells.