Activin B promotes endometrial cancer cell migration by down-regulating E-cadherin via SMAD-independent MEK-ERK1/2-SNAIL signaling

Inhibin subunit beta B (INHBB): an emerging role in tumor progression

The gene inhibin subunit beta B (INHBB) encodes the inhibin βB subunit, which is involved in forming protein members of the transforming growth factor-β (TGF-β) superfamily. The TGF-β superfamily is extensively involved in cell proliferation, differentiation, adhesion, movement, metabolism, communication, and death. Activins and inhibins, which belong to the TGF-β superfamily, were first discovered in ovarian follicular fluid. They were initially described as regulators of pituitary follicle-stimulating hormone (FSH) secretion both in vivo and in vitro. Later studies found that INHBB is expressed not only in reproductive organs such as the ovary, uterus, and testis but also in numerous other organs, including the brain, spinal cord, liver, kidneys, and adrenal glands. This wide distribution implies its involvement in the normal physiological functions of various organs; however, the mechanisms underlying these functions have not yet been fully elucidated. Recent studies suggest that INHBB plays a significant, yet complex role in tumorigenesis. It appears to have dual effects, promoting tumor progression in some contexts while inhibiting it in others, although these roles are not yet fully understood. In this paper, we review the different expression patterns, functions, and mechanisms of INHBB in normal and tumor tissues to illustrate the research prospects of INHBB in tumor progression.

RNA methylation-related genes INHBB and SOWAHA are associated with MSI status in colorectal cancer patients and may serve as prognostic markers for predicting immunotherapy efficacy

The role of RNA methylation is vital in the advancement and spread of tumors. However, its exact role in microsatellite instability in colorectal cancer (CRC) is still not fully understood. To address this gap in knowledge, this study investigated the impact of genes associated with RNA methylation on the prognosis and response to immunotherapy in individuals diagnosed with low microsatellite instability (MSI-L) or microsatellite stable (MSS) CRC. The differentially expressed genes (DEGs) in two groups of patients: those with high microsatellite instability (MSI-H) and those with MSI-L/MSS was thoroughly investigated and compared with aims of exploring the association between them and the 60 RNA methylation regulators. We employed these genes and developed an MSI-RMscore to establish a risk signature capable of forecasting patient outcomes. Furthermore, an investigation of the immunophenotypic traits was conducted encompassing patients categorized as high-risk and low-risk. By combining the MSI-RMscore and clinicopathological features, a predictive nomogram was developed, which was subsequently validated using the GEO database. Furthermore, immunohistochemistry was employed to establish the correlation between INHBB and SOWAHA and the MSI status, as well as patient prognosis. Our findings indicated that the high-risk subgroup exhibited unfavorable overall survival rates, reduced responsiveness to immune checkpoint blockers, elevated estimate scores, and increased infiltration of macrophages and fibroblasts. We also confirmed that INHBB and SOWAHA were associated with CRC patient prognosis and MSI status, as well as immunotherapy response. These findings suggest that targeting INHBB and SOWAHA could be a promising strategy to enhance patient responsiveness to immunotherapy.

Snail mediates GDF-8-stimulated human extravillous trophoblast cell invasion by upregulating MMP2 expression

BACKGROUND

Extravillous trophoblast (EVT) cell invasion is a tightly regulated process that requires for a normal pregnancy. The epithelial-mesenchymal transition (EMT) has been implicated in EVT cell invasion. Growth differentiation factor-8 (GDF-8), a member of the transforming growth factor-beta (TGF-β) superfamily, is expressed in the human placenta and promotes EVT cell invasion by upregulating the expression of matrix metalloproteinase 2 (MMP2). However, the underlying molecular mechanism of GDF-8-induced MMP2 expression remains undetermined. Therefore, the present study aims to examine the role of Snail and Slug, the EMT-related transcriptional regulators, in GDF-8-stimulated MMP2 expression and cell invasion in HTR-8/SVneo human EVT cell line and primary cultures of human EVT cells.

METHODS

HTR-8/SVneo and primary cultures of human EVT cells were used to examine the effect of GDF-8 on MMP2 expression and explore the underlying mechanism. For gene silencing and overexpression, the HTR-8/SVneo cell line was used to make the experiments more technically feasible. The cell invasiveness was measured by Matrigel-coated transwell invasion assay.

RESULTS

GDF-8 stimulated MMP2 expression in both HTR-8/SVneo and primary EVT cells. The stimulatory effect of GDF-8 on MMP2 expression was blocked by the inhibitor of TGF-β type-I receptors, SB431542. Treatment with GDF-8 upregulated Snail and Slug expression in both HTR-8/SVneo and primary EVT cells. The stimulatory effects of GDF-8 on Snail and Slug expression were blocked by pretreatment of SB431542 and siRNA-mediated knockdown of SMAD4. Interestingly, using the siRNA knockdown approach, our results showed that Snail but not Slug was required for the GDF-8-induced MMP2 expression and cell invasion in HTR-8/SVneo cells. The reduction of MMP2 expression in the placentas with preeclampsia (PE) was also observed.

CONCLUSIONS

These findings discover the physiological function of GDF-8 in the human placenta and provide important insights into the regulation of MMP2 expression in human EVT cells. Video Abstract.

Activin and inhibin signaling: From regulation of physiology to involvement in the pathology of the female reproductive system

Activins and inhibins - comprising activin A, B, AB, C and E, and inhibin A and B isoforms - belong to the transforming growth factor beta (TGFβ) superfamily. They regulate several biological processes, including cellular proliferation, differentiation and invasiveness, to enhance the formation and functioning of many human tissues and organs. In this review, we have discussed the role of activin and inhibin signaling in the physiological and female-specific pathological events that occur in the female reproductive system. The up-to-date evidence indicates that these cytokines regulate germ cell development, follicular development, ovulation, uterine receptivity, decidualization and placentation through the activation of several signaling pathways; and that their dysregulated expression is involved in the pathogenesis and pathophysiology of the numerous diseases, including pregnancy complications, that disturb reproduction. Hence, some of the isoforms have been suggested as potential biomarkers and therapeutic targets for the management of some of these diseases. Tackling the research directions highlighted in this review will enhance a detailed comprehension and the clinical utility of these cytokines.

Differential Urinary Proteomic Analysis of Endometrial Cancer

Endometrial cancer is one of the most frequent gynecological malignancies present in more than 95 % of all uterine cancers. In spite of that, screening of such disease is not commonly performed in clinical practice due to enormous costs and relatively low sensitivity. Therefore, developing an effective screening test to diagnose endometrial cancer at early stages is of great importance for the clinical area of investigation. In this work, we applied urinary proteomics (i.e., bottom-up proteomic approach followed by nano HPLC-ESI-MS/MS) in patients with endometrial cancer, with respect to find proteins aimed for the early diagnostics and screening. According to the results, the significant semi-quantitative changes were observed in urinary proteome of treated patients. The proteins that may be pivotal in pathogenesis of endometrial cancer, like cadherin-1 (CDH1), vitronectin (VTN) and basement membrane specific-heparan sulphate proteoglycan core protein (HSPG2) were down-regulated, when compared to the control group. Ultimately, it can be stated that urinary proteomics has a potential for the searching of cancer protein biomarkers based on their altered concentration.

eIF4E‑related miR‑320a and miR‑340‑5p inhibit endometrial carcinoma cell metastatic capability by preventing TGF‑β1‑induced epithelial‑mesenchymal transition

Endometrial cancer (EC) is a common form of cancer in women. Metastasis is the main cause of EC treatment failure. Eukaryotic translation initiation factor 4E (eIF4E) is an oncogene that is overexpressed in a variety of malignancies and their distant metastases. The present study analyzed microarray data from the Oncomine database and revealed that high eIF4E expression was associated with poor prognosis and high pathological grade of EC. The expression of eIF4E was higher in EC tissues compared with in adjacent normal tissues. In addition, microRNA (miR)-320a and miR-340-5p expression levels were downregulated in EC tissues compared with those in adjacent normal tissues, which suggested that these microRNAs may serve as EC tumor suppressor genes. miR-320a and miR-340-5p could bind to the 3′-UTR of eIF4E mRNA, thus downregulating the expression of eIF4E and phosphorylated (p)-eIF4E in EC cells. Overexpression of miR-320a or miR-340-5p effectively suppressed HEC-1A cell migration and invasion. The downregulation of eIF4E and p-eIF4E following miR-320a or miR-340-5p transfection reduced the invasiveness and metastatic capability of EC cells in a manner associated with decreased expression of matrix metallopeptidase (MMP)-3 and MMP-9. In addition, one of the effects of transforming growth factor β1 (TGF-β1), which is to induce the phosphorylation of eIF4E, was suppressed by miR-320a and miR-340-5p overexpression. These two microRNAs also attenuated the features of TGF-β1-induced epithelial-mesenchymal transition (EMT). In conclusion, the results of the present study demonstrated that eIF4E was upregulated in EC, whereas miR-320a and miR-340-5p were downregulated in EC compared with adjacent normal tissues. In vitro, miR-320a and miR-340-5p inhibited the migratory capability of EC cells by downregulating MMP-3 and MMP-9 and prevented TGF-β1-induced EMT through p-eIF4E.

Gain-of-function pathogenic variants in SMAD4 are associated with neoplasia in Myhre syndrome

Myhre syndrome is an increasingly diagnosed rare syndrome that is caused by one of two specific heterozygous gain-of-function pathogenic variants in SMAD4. The phenotype includes short stature, characteristic facial appearance, hearing loss, laryngotracheal stenosis, arthritis, skeletal abnormalities, learning and social challenges, distinctive cardiovascular defects, and a striking fibroproliferative response in the ear canals, airways, and serosal cavities (peritoneum, pleura, pericardium). Confirmation of the clinical diagnosis is usually prompted by the characteristic appearance with developmental delay and autistic-like behavior using targeted gene sequencing or by whole exome sequencing. We describe six patients (two not previously reported) with molecularly confirmed Myhre syndrome and neoplasia. Loss-of-function pathogenic variants in SMAD4 cause juvenile polyposis syndrome and we hypothesize that the gain-of-function pathogenic variants observed in Myhre syndrome may contribute to neoplasia in the patients reported herein. The frequency of neoplasia (9.8%, 6/61) in this series (two new, four reported patients) and endometrial cancer (8.8%, 3/34, mean age 40 years) in patients with Myhre syndrome, raises the possibility of cancer susceptibility in these patients. We alert clinicians to the possibility of detecting this syndrome when cancer screening panels are used. We propose that patients with Myhre syndrome are more susceptible to neoplasia, encourage increased awareness, and suggest enhanced clinical monitoring.

RAC1B: A Guardian of the Epithelial Phenotype and Protector Against Epithelial-Mesenchymal Transition

The small GTPase Ras-related C3 botulinum toxin substrate 1B (RAC1B) has been shown to potently inhibit transforming growth factor (TGF)-β1-induced cell migration and epithelial-mesenchymal transition (EMT) in pancreatic and breast epithelial cells, but the underlying mechanism has remained obscure. Using a panel of pancreatic ductal adenocarcinoma (PDAC)-derived cell lines of different differentiation stages, we show that RAC1B is more abundantly expressed in well differentiated as opposed to poorly differentiated cells. Interestingly, RNA interference-mediated knockdown of RAC1B decreased expression of the epithelial marker protein E-cadherin, encoded by CDH1, and enhanced its TGF-β1-induced downregulation, whereas ectopic overexpression of RAC1B upregulated CDH1 expression and largely prevented its TGF-β1-induced silencing of CDH1. Conversely, knockdown of RAC1B, or deletion of the RAC1B-specific exon 3b by CRISPR/Cas-mediated genomic editing, enhanced basal and TGF-β1-induced upregulation of mesenchymal markers like Vimentin, and EMT-associated transcription factors such as SNAIL and SLUG. Moreover, we demonstrate that knockout of RAC1B enhanced the cells’ migratory activity and derepressed TGF-β1-induced activation of the mitogen-activated protein kinase ERK2. Pharmacological inhibition of ERK1/2 activation in RAC1B-depleted cells rescued cells from the RAC1B knockdown-induced enhancement of cell migration, TGF-β1-induced downregulation of CDH1, and upregulation of SNAI1. We conclude that RAC1B promotes epithelial gene expression and suppresses mesenchymal gene expression by interfering with TGF-β1-induced MEK-ERK signaling, thereby protecting cells from undergoing EMT and EMT-associated responses like acquisition of cell motility.

The systemic activin response to pancreatic cancer: implications for effective cancer cachexia therapy

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a particularly lethal malignancy partly due to frequent, severe cachexia. Serum activin correlates with cachexia and mortality, while exogenous activin causes cachexia in mice.

METHODS

Isoform-specific activin expression and activities were queried in human and murine tumours and PDAC models. Activin inhibition was by administration of soluble activin type IIB receptor (ACVR2B/Fc) and by use of skeletal muscle specific dominant negative ACVR2B expressing transgenic mice. Feed-forward activin expression and muscle wasting activity were tested in vivo and in vitro on myotubes.

RESULTS

Murine PDAC tumour-derived cell lines expressed activin-βA but not activin-βB. Cachexia severity increased with activin expression. Orthotopic PDAC tumours expressed activins, induced activin expression by distant organs, and produced elevated serum activins. Soluble factors from PDAC elicited activin because conditioned medium from PDAC cells induced activin expression, activation of p38 MAP kinase, and atrophy of myotubes. The activin trap ACVR2B/Fc reduced tumour growth, prevented weight loss and muscle wasting, and prolonged survival in mice with orthotopic tumours made from activin-low cell lines. ACVR2B/Fc also reduced cachexia in mice with activin-high tumours. Activin inhibition did not affect activin expression in organs. Hypermuscular mice expressing dominant negative ACVR2B in muscle were protected for weight loss but not mortality when implanted with orthotopic tumours. Human tumours displayed staining for activin, and expression of the gene encoding activin-βA (INHBA) correlated with mortality in patients with PDAC, while INHBB and other related factors did not.

CONCLUSIONS

Pancreatic adenocarcinoma tumours are a source of activin and elicit a systemic activin response in hosts. Human tumours express activins and related factors, while mortality correlates with tumour activin A expression. PDAC tumours also choreograph a systemic activin response that induces organ-specific and gene-specific expression of activin isoforms and muscle wasting. Systemic blockade of activin signalling could preserve muscle and prolong survival, while skeletal muscle-specific activin blockade was only protective for weight loss. Our findings suggest the potential and need for gene-specific and organ-specific interventions. Finally, development of more effective cancer cachexia therapy might require identifying agents that effectively and/or selectively inhibit autocrine vs. paracrine activin signalling.

X chromosome-linked long noncoding RNA lnc-XLEC1 regulates c-Myc-dependent cell growth by collaborating with MBP-1 in endometrial cancer

LncRNAs (long noncoding RNAs) are noncoding transcripts that are more than 200 nt long and have been described as the largest subclass in the noncoding transcriptome in humans. Although studies of lncRNAs in cancer have been continuing for a long time, no much has been known about X chromosome-linked lncRNAs. Here, by using RNA-seq we report the identification of a new X chromosome-linked lncRNA (lnc-XLEC1) that is aberrantly downregulated during the development of endometrial carcinoma (EC). The overexpression of lnc-XLEC1 reduces the migration and proliferation of EC cells. Flow cytometry analysis indicated that lnc-XLEC1 overexpression resulted in a substantial accumulation of EC cells in the G1 phase. In addition, lnc-XLEC1 had inhibitive effects that may result from its collaboration with MBP-1 during the suppression of the c-Myc expression and the negative regulating of the Cdk/Rb/E2F pathway. The anti-tumor effects of lnc-XLEC1 on EC progression suggest that lnc-XLEC1 has some potential value in anti-carcinoma therapies and deserves further investigation. Our study reported for the first time that the lnc-XLEC1 might be related to the incidence and prognosis of EC. Moreover, we discovered that this process might be related to somatic X dosage compensation and skewed X chromosome inactivation (SXCI).

Signaling Pathways Induced by Leptin during Epithelial⁻Mesenchymal Transition in Breast Cancer

Leptin is an adipokine that is overexpressed in obese and overweight people. Interestingly, women with breast cancer present high levels of leptin and of its receptor ObR. Leptin plays an important role in breast cancer progression due to the biological processes it participates in, such as epithelial⁻mesenchymal transition (EMT). EMT consists of a series of orchestrated events in which cell⁻cell and cell⁻extracellular matrix interactions are altered and lead to the release of epithelial cells from the surrounding tissue. The cytoskeleton is also re-arranged, allowing the three-dimensional movement of epithelial cells into the extracellular matrix. This transition provides cells with the ability to migrate and invade adjacent or distal tissues, which is a classic feature of invasive or metastatic carcinoma cells. In recent years, the number of cases of breast cancer has increased, making this disease a public health problem worldwide and the leading cause of death due to cancer in women. In this review, we focus on recent advances that establish: (1) leptin as a risk factor for the development of breast cancer, and (2) leptin as an inducer of EMT, an event that promotes tumor progression.

Bone morphogenetic protein 2 increases lysyl oxidase activity via up-regulation of snail in human granulosa-lutein cells

Lysyl oxidase (LOX) is a copper-dependent enzyme that maintains and stabilizes the extracellular matrix (ECM) by catalyzing the cross-linking of elastin and collagen. ECM within the ovarian follicle plays a crucial role in regulating follicular development and oocyte maturation. Bone morphogenetic protein 2 (BMP2) belongs to the BMP subfamily that has been shown to be involved in the process of ovarian folliculogenesis and luteal formation. To date, whether BMP2 regulates the activity of LOX during human follicular development remains to be elucidated. The aim of this study was to investigate the effect of BMP2 on the regulation of LOX expression and activity in human granulosa-lutein cells (hGL) and the underlying mechanisms. Using both primary and immortalized (SVOG cells) hGL cells, we demonstrated that BMP2 up-regulated the expression and activity of LOX and hence decreased the soluble collagens in cultured medium in hGL cells. Additionally, the mRNA and protein levels of two transcriptional factors, SNAIL and SLUG, were increased following cell exposure to BMP2. Knockdown of SNAIL, but not SLUG partially reversed BMP2-induced increases in LOX expression and activity. The BMP2-induced up-regulation of SNAIL expression was abolished by the pre-treatment with two BMP type I receptor inhibitors, dorsomorphin and DMH-1, but not SB431542. Moreover, knockdown of SMAD4 completely abolished BMP2-induced up-regulation of SNAIL expression and the subsequent increases in LOX expression and activity. Our results suggest that BMP2 increases LOX expression and activity via the up-regulation of SNAIL in hGL cells. These findings may provide insights into the functional role of BMP2 in the regulation of ECM formation during folliculogenesis.

AGO1 may influence the prognosis of hepatocellular carcinoma through TGF-β pathway

AGO1 is a major component of RNA-induced silencing complexes and plays a crucial role in solid tumors. The aim of our study was to investigate AGO1 functions in hepatocellular carcinoma (HCC). Using small interfering RNA, AGO1 functions were investigated in HCCLM3 cell lines. Cell proliferation, immigration, and invasion significantly decreased after AGO1 depletion using MTT, wound-healing, and transwell assay. The associated proteins in the epithelial–mesenchymal transition (EMT) and the activation of its signal pathways were measured using western blot. After AGO1 depleted, increased E-cadherin and decreased N-cadherin, Vimentin, Snail, and Zeb1 were founded. In its upstream pathway, the phosphorylation of ERK1/2(Thr202/Tyr204), Smad2(S425/250/255), and Smad4 were significantly inhibited. Meanwhile, inhibitor of ERK1/2(LY3214996) significantly inhibited the growth and migration of the AGO1 cells. The nuclear importing of Smad4 was blocked and furthermore, the transcription of Snail was also influenced for the decrease of combination between Smad4 and the promotor region of Snail. After Snail was overexpressed, the invasion of HCCLM3 cells was significantly rescued. Immunohistochemistry in tissue microarrays consisting of 200 HCC patients was used to analyze the associations between AGO1 expression and prognosis. Intratumoral AGO1 expression was an independent risk factor for overall survival (P = 0.008) and recurrence-free survival (P < 0.001). In conclusion, AGO1 may promote HCC metastasis through TGF-β pathway, and AGO1 may be a reliable prognostic factor in HCC.

A guide for endometrial cancer cell lines functional assays using the measurements of electronic impedance

Endometrial cancer cell lines are critical tools to investigate the molecular mechanism of tumorigenesis using the end point cell-based assay such as proliferation, cytotoxicity, apoptosis, anoikis or migration and invasion. The proper assay optimization and performance is essential for physiologically relevant results interpretation. In this study we use label-free real-time cell analysis platform (xCELLigence) to optimize growing conditions for proliferation and migration experiments of two types of endometrial cancer cell lines HEC-1-B, HEC-1-A, KLE, and Ishikawa. Profiling of cell lines by cell index measurement in proliferation and migration experiments was performed. Our experimental approach allowed us to monitor particular stage of the cell growth, to see the relation between seeding density and dynamic cell growth as well as to choose the optimal serum concentration as chemoattractant in migration experiment. The highest rate of proliferation was shown for Ishikawa cells. The rapid pace of cellular migration was observed in case of KLE and HEC-1-B cells as compared to weak migratory activity of Ishikawa cells. The cell index that reflects the cell status characterized real-time cytological profile of each analyzed cell line. These cell profiles were crucial for better planning the classical end-point assays used in further research.

FAK regulates E-cadherin expression via p-SrcY416/p-ERK1/2/p-Stat3Y705 and PPARγ/miR-125b/Stat3 signaling pathway in B16F10 melanoma cells

Focal adhesion kinase (FAK) is involved in tumor cell migration and metastasis. However, the underlying mechanism remains unclear. Here, we present a signaling pathway involved in the regulation of melanoma cell migration by FAK. We found that the interference of FAK expression suppressed B16F10 cell migration/metastasis, and altered the expressions of genes involved in melanoma migration/metastasis. The down-regulation of FAK inhibited the expression of p-Src^Y416, p-ERK_1/2, Stat3 and p-Stat3^Y705, while promoted the expression of PPARγ, miR-125b and E-cadherin. Then we found that FAK inhibited E-cadherin expression via p-Src^Y416/p-ERK_1/2/ p-Stat3^Y705 and PPARγ/miR-125b/Stat3 signaling pathway in B16F10 cell. Moreover, miR-125b inhibited B16F10 cell migration. Furthermore, we repeated the key data with human melanoma cell line A375. The results obtained from A375 cells fell in line with those from B16F10 cells. Using Oncomine database, we found that the mRNA levels of FAK, Src, ERK_1/2 and Stat3 increased, while the mRNA levels of PPARγ, C21orf34 (miR-125b host gene) and E-cadherin decreased in human metastatic melanoma. The data from human breast cancer confirmed those from metastatic melanoma.

Taken together, our study suggests that down-regulation of FAK promotes E-cadherin expression via p-Src^Y416/p-ERK_1/2/p-Stat3^Y705 and PPARγ/miR-125b/Stat3 signaling pathway. Our findings provide a novel explanation regarding how FAK promotes melanoma cell migration, suggesting that FAK might be a potential target for melanoma therapy.

Inhibition of PI3K-AKT-mTOR pathway sensitizes endometrial cancer cell lines to PARP inhibitors

BACKGROUND

Phosphatase and Tensin homolog (PTEN) is a tumor suppressor gene. Loss of its function is the most frequent genetic alteration in endometrioid endometrial cancers (70-80%) and high grade tumors (90%). We assessed the sensitivity of endometrial cancer cell lines to PARP inhibitors (olaparib and BMN-673) and a PI3K inhibitor (BKM-120), alone or in combination, in the context of their PTEN mutation status. We also highlighted a direct pathway linking PTEN to DNA repair.

METHODS

Using endometrial cancer cellular models with known PTEN status, we evaluated their homologous recombination (HR) functionality by RAD51 foci formation assay. The 50% Inhibitory concentration (IC50) of PI3K and PARP inhibitors in these cells was assessed, and western blotting was performed to determine the expression of proteins involved in the PI3K/mTOR pathway. Moreover, we explored the interaction between RAD51 and PI3K/mTOR by immunofluorescence. Next, the combination effect of PI3K and PARP inhibitors on cell proliferation was evaluated by a clonogenic assay.

RESULTS

Cells with mutated PTEN showed over-activation of the PI3K/mTOR pathway. These cells were more sensitive to PARP inhibition compared to PTEN wild-type cells. In addition, PI3K inhibitor treatment reduced RAD51 foci formation in PTEN mutated cells, and sensitized these cells to PARP inhibitor.

CONCLUSION

Targeting both PARP and PI3K might lead to improved personalized therapeutic approaches in endometrial cancer patients with PTEN mutations. Understanding the complex interaction of PTEN mutations with DNA repair in endometrial cancer will help to better select patients that are likely to respond to some of the new and costly targeted therapies.

Activin B Regulates Adhesion, Invasiveness, and Migratory Activities in Oral Cancer: a Potential Biomarker for Metastasis

Activin B, a homodimer of inhibin beta b (INHBB), is a multifunctional cytokine belonging to the transforming growth factor-β (TGF-β) family. However, the molecular functions and clinical relevance of activin B have not been determined in oral cancer. We investigated the critical roles of activin B in oral squamous cell carcinoma (OSCC). We performed quantitative reverse transcriptase-polymerase chain reaction, Western blotting, and immunohistochemistry to study INHBB expression in OSCC-derived cell lines and OSCC clinical samples. The INHBB expression levels were significantly (P < 0.05) overexpressed in OSCCs compared to normal counterparts in vitro and in vivo. Activin B-positivity in OSCC cases was significantly (P < 0.05) correlated with regional lymph node metastasis. The INHBB knockdown (shINHBB) cells promoted cellular adhesion and suppression of cellular invasiveness and migration. After treatment of shINHBB cells with activin B, those activities were restored similar to the shMock cells. In the processes of invasiveness and metastasis, the cells cause epithelial-mesenchymal transition (EMT). TGF-β and its family members are promoters of the EMT process. To investigate whether activin B is related to EMT, we examined the expressions of EMT-related genes and found that INHBB was related closely to EMT. Our results suggested for the first time that activin B indicates tumoral metastasis in OSCCs and might be a useful biomarker for OSCC metastasis.