Promotion of hepatocellular carcinoma metastasis through matrix metalloproteinase activation by epithelial‐mesenchymal transition regulator Twist1

E‐cadherin loss is a key biological mechanism in tumour invasion. As a main regulator of epithelial‐mesenchymal transition (EMT) mechanism‐mediated invasion and metastasis, Twist1 plays an important role through its regulation of E‐cadherin expression. However, whether or not Twist2 has the same function in tumour metastasis remains unclear. The purpose of this study is to investigate the expressions and different roles of Twist1 and Twist2 in human hepatocellular carcinoma (HCC). The expressions of Twist1 and Twist2 in HCC tissue were evaluated by immunohistochemical staining. The role of Twist1 and Twist2 in invasiveness was also evaluated in vitro by using HCC cell lines. Twist1 nuclear overexpression is found to be correlated with HCC metastasis, and its expression is negatively correlated with E‐cadherin expression in human tissue. Twist2, a Twist1 homology protein, only expresses in the cytoplasm and shows no significant correlation with HCC metastasis. By ectopic transfection of Twist1 and Twist2 into the HCC cells, HepG2 and PLC, Twist1 is able to down‐regulate E‐cadherin expression and promote matrix metalloproteinase (MMP) activation, specifically in MMP2 and MMP9. In functional assays, Twist1 is found to promote invasion in HepG2 and PLC cells, but the invasion ability of the groups is not affected Twist2. Our findings indicate that Twist1 induces HCC invasion via increased activity in MMPs, leading to poor clinical prognoses. The results of this study also demonstrate a novel cogitation in Twist2, which has no effect on HCC invasion and metastasis. Twist1 may contribute to HCC invasion and metastasis and may be used as a novel therapeutic target for the inhibition of HCC metastasis.     

AEG‐1 induces gastric cancer metastasis by upregulation of eIF4E expression

Gastric cancer is the third leading cause of cancer‐related deaths worldwide, and patients with lymph node, peritoneal and distant metastasis have a poor prognosis. Overexpression of Astrocyte‐elevated gene‐1 (AEG‐1) has been reported to be correlated with the progression and metastasis of gastric cancer. However, its mechanisms are quite unclear. In this study, we found that elevated expression of AEG‐1 was correlated with metastasis in human gastric cancer tissues. Moreover, gain‐ or loss‐of‐function of AEG‐1, respectively, promoted or suppressed epithelial–mesenchymal transition (EMT), migration and invasion of gastric cancer cells. AEG‐1 positively regulated eIF4E, MMP‐9 and Twist expression. Manipulating eIF4E expression by transfection of overexpression constructs or siRNAs partially eliminated AEG‐1‐regulated EMT, cell migration and invasion. In addition, overexpression or knockdown of eIF4E promoted or suppressed EMT, cell migration and invasion in parallel with upregulation of MMP‐9 and Twist expression, while manipulating eIF4E expression partially abrogated AEG‐1‐induced MMP‐9 and Twist. Finally, silencing of AEG‐1 expression not only inhibited tumour growth in parallel with downregulation of eIF4E, MMP‐9 and Twist expression in a xenograft nude mouse model, but also suppressed lymph node and peritoneal metastasis of gastric cancer in an orthotopic nude mouse model. These findings suggest that AEG‐1 promotes gastric cancer metastasis through upregulation of eIF4E‐mediated MMP‐9 and Twist, which provides new diagnostic markers and therapeutic targets for cancer metastasis.     

Osteopontin increases migration and MMP‐9 up‐regulation via αvβ3 integrin,FAK, ERK,and NF‐κB‐dependent pathway in human chondrosarcoma cells

Tumor malignancy is associated with several features such as proliferation ability and frequency of metastasis. Osteopontin (OPN), which abundantly expressed in bone matrix, is involved in cell adhesion, migration, invasion and proliferation via interaction with its receptor, that is, αvβ3 integrin. However, the effect of OPN on migration activity in human chondrosarcoma cells is mostly unknown. Here we found that OPN increased the migration and expression of matrix metalloproteinase (MMP)‐9 in human chondrosarcoma cells (JJ012 cells). RGD peptide, αvβ3 monoclonal antibody and MAPK kinase (MEK) inhibitors (PD98059 and U0126) but not RAD peptide inhibited the OPN‐induced increase of the migration and MMP‐9 up‐regulation of chondrosarcoma cells. OPN stimulation increased the phosphorylation of focal adhesion kinase (FAK), MEK and extracellular signal‐regulated kinase (ERK). In addition, treatment of JJ012 cells with NF‐κB inhibitor (PDTC) or IκB protease inhibitor (TPCK) inhibited OPN‐induced cell migration and MMP‐9 up‐regulation. Stimulation of JJ012 cells with OPN also induced IκB kinase α/β (IKK α/β) phosphorylation, IκBα phosphorylation, p65 Ser⁵³⁶ phosphorylation, and κB‐luciferase activity. The OPN‐mediated increases in MMP‐9 and κB‐luciferase activities were inhibited by RGD peptide, PD98059 or FAK and ERK2 mutant. Taken together, our results indicated that OPN enhances the migration of chondrosarcoma cells by increasing MMP‐9 expression through the αvβ3 integrin, FAK, MEK, ERK and NF‐κB signal transduction pathway. J. Cell. Physiol. 221: 98–108, 2009. © 2009 Wiley‐Liss, Inc     

Tanshinone I attenuates proliferation and chemoresistance of cervical cancer in a KRAS‐dependent manner

Chemoresistance is a common occurrence during advanced or recurrent cervical cancer therapy when treated by conventional treatment, platinum‐based chemotherapy. This study aimed to investigate the effect and underlying mechanism of tanshinone I on attenuating proliferation and chemoresistance of cervical cancer cells. In cervical cancer cells, cell proliferation was examined by 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT), cell count, and soft‐agar colony‐formation assay. rVista analysis and luciferase reporter assay were used to explore the upstream regulator of KRAS, and the expression levels of key genes were also detected. Western blot analysis showed that tanshinone I significantly suppressed KRAS expression and inhibited AKT phosphorylation. rVista analysis and luciferase reporter assay demonstrated that ELK1 can binds directly to KRAS promoter and positively regulates KRAS expression. MTT assay showed that KRAS or ELK1 overexpression significantly attenuated the suppressive effects of tanshinone I on HeLa cells proliferation. In addition, tanshinone I recovered the cisplatin sensitivity of HeLa CR cells, whereas KRAS or ELK1 overexpression significantly inhibited this phenomenon. Our results suggested that tanshinone I had anticancer effects on cervical cancer cells via inhibiting ELK1 and downregulating KRAS‐AKT axis, which subsequently suppressed the proliferation and cisplatin resistance of cervical cancer cells.     

E‐cadherin determines Caveolin‐1 tumor suppression or metastasis enhancing function in melanoma cells

The role of caveolin‐1 (CAV1) in cancer is highly controversial. CAV1 suppresses genes that favor tumor development, yet also promotes focal adhesion turnover and migration of metastatic cells. How these contrasting observations relate to CAV1 function in vivo is unclear. Our previous studies implicate E‐cadherin in CAV1‐dependent tumor suppression. Here, we use murine melanoma B16F10 cells, with low levels of endogenous CAV1 and E‐cadherin, to unravel how CAV1 affects tumor growth and metastasis and to assess how co‐expression of E‐cadherin modulates CAV1 function in vivo in C57BL/6 mice. We find that overexpression of CAV1 in B16F10 (cav‐1) cells reduces subcutaneous tumor formation, but enhances metastasis relative to control cells. Furthermore, E‐cadherin expression in B16F10 (E‐cad) cells reduces subcutaneous tumor formation and lung metastasis when intravenously injected. Importantly, co‐expression of CAV1 and E‐cadherin in B16F10 (cav‐1/E‐cad) cells abolishes tumor formation, lung metastasis, increased Rac‐1 activity, and cell migration observed with B16F10 (cav‐1) cells. Finally, consistent with the notion that CAV1 participates in switching human melanomas to a more malignant phenotype, elevated levels of CAV1 expression correlated with enhanced migration and Rac‐1 activation in these cells.     

A novel synthetic small molecule YH‐306 suppresses colorectal tumour growth and metastasis via FAK pathway

Cell migration and invasion are key processes in the metastasis of cancer, and suppression of these steps is a promising strategy for cancer therapeutics. The aim of this study was to explore small molecules for treating colorectal cancer (CRC) and to investigate their anti‐metastatic mechanisms. In this study, six CRC cell lines were used. We showed that YH‐306 significantly inhibited the migration and invasion of CRC cells in a dose‐dependent manner. In addition, YH‐306 inhibited cell adhesion and protrusion formation of HCT116 and HT‐29 CRC cells. Moreover, YH‐306 potently suppressed uninhibited proliferation in all six CRC cell lines tested and induced cell apoptosis in four cell lines. Furthermore, YH‐306 inhibited CRC colonization in vitro and suppressed CRC growth in a xenograft mouse model, as well as hepatic/pulmonary metastasis in vivo. YH‐306 suppressed the activation of focal adhesion kinase (FAK), c‐Src, paxillin, and phosphatidylinositol 3‐kinases (PI3K), Rac1 and the expression of matrix metalloproteases (MMP) 2 and MMP9. Meanwhile, YH‐306 also inhibited actin‐related protein (Arp2/3) complex‐mediated actin polymerization. Taken together, YH‐306 is a candidate drug in preventing growth and metastasis of CRC by modulating FAK signalling pathway.     

Post-Operative Plasma Osteopontin Predicts Distant Metastasis in Human Colorectal Cancer

BackgroundThe overall prognosis of colorectal cancer (CRC) patients is unsatisfactory due to cancer metastasis after operation. This study aims to investigate the clinical significance of plasma osteopontin (OPN) levels as minimally invasive, predictive, and surrogate biomarkers for prognosis of CRC patients.MethodsThis randomized study design consists of pre-operative and post-operative plasma samples from a total of 79 patients. We determined plasma levels of OPN by ELISA and examined their correlation with the clinicopathological parameters of CRC patients. The effects of endogenous and exogenous OPN on CRC metastasis were investigated by examination of the effect on regulators of epithelial to messenchymal transition and migration assay.ResultsOur findings demonstrated for the first time the clinical correlation of plasma OPN with metastasis of CRC patients. High post-operative plasma OPN level (>153.02 ng/ml) associated with development of metastasis after curative resection (p<0.001). Moreover, post-operative plasma OPN level correlated with disease-free survival of CRC patients (p=0.009) and was an independent factor for predicting development of metastasis in CRC patients after curative resection (p=0.036). Our in vitro model showed that OPN ectopic expression induced DLD1 cell migration through Snail and Twist1 overexpression and E-cadherin repression, and secretory OPN level enhanced cell migration.ConclusionsThe results of the current study suggest that post-operative plasma OPN correlated with post-operative metastasis, suggesting that it is a potential non-invasive biomarker for the development of future metastasis in CRC patients. In addition, OPN was shown to be involved in the metastatic process and thus inhibition of OPN is a potential therapeutic approach to treat CRC patients.     

The epithelial polarity regulator LGALS9/galectin-9 induces fatal frustrated autophagy in KRAS mutant colon carcinoma that depends on elevated basal autophagic flux

Oncogenic mutation of KRAS (Kirsten rat sarcoma viral oncogene homolog) in colorectal cancer (CRC) confers resistance to both chemotherapy and EGFR (epidermal growth factor receptor)-targeted therapy. We uncovered that KRAS mutant (KRAS^mut) CRC is uniquely sensitive to treatment with recombinant LGALS9/Galectin-9 (rLGALS9), a recently established regulator of epithelial polarity. Upon treatment of CRC cells, rLGALS9 rapidly internalizes via early- and late-endosomes and accumulates in the lysosomal compartment. Treatment with rLGALS9 is accompanied by induction of frustrated autophagy in KRAS^mut CRC, but not in CRC with BRAF (B-Raf proto-oncogene, serine/threonine kinase) mutations (BRAF^mut). In KRAS^mut CRC, rLGALS9 acts as a lysosomal inhibitor that inhibits autophagosome-lysosome fusion, leading to autophagosome accumulation, excessive lysosomal swelling and cell death. This antitumor activity of rLGALS9 directly correlates with elevated basal autophagic flux in KRAS^mut cancer cells. Thus, rLGALS9 has potent antitumor activity toward refractory KRAS^mut CRC cells that may be exploitable for therapeutic use.     

The 3p14.2 tumour suppressor ADAMTS9 is inactivated by promoter CpG methylation and inhibits tumour cell growth in breast cancer

Chromosome region 3p12‐14 is an important tumour suppressor gene (TSG) locus for multiple cancers. ADAMTS9, a member of the metalloprotease large family, has been identified as a candidate 3p14.2 TSG inactivated by aberrant promoter CpG methylation in several carcinomas, but little known about its expression and function in breast cancer. In this report, ADAMTS9 expression and methylation was analysed in breast cancer cell lines and tissue samples. ADAMTS9 RNA was significantly down‐regulated in breast cancer cell lines (6/8). After treating the cells with demethylation agent Aza and TSA, ADAMTS9 expression was dramatically increased. Bisulphite genomic sequencing and methylation‐specific PCR detected promoter methylation, which was associated with decreased ADAMTS9 expression. Hypermethylation was also detected in 130/219 (59.4%) of primary tumours but only in 4.5% (2/44) of paired surgical margin tissues. Ectopic expression of ADAMTS9 in tumor cells induced significant growth suppression, cell cycle arrest at the G0/G1 phase, enhanced apoptosis and reduced cell migration and invasion. Conditioned culture medium from ADAMTS9‐transfected BT549 cells markedly disrupted tube formation ability of human umbilical vein endothelial cell (HUVEC) in Matrigel. Furthermore, ADAMTS9 inhibited AKT signaling and its downstream targets (MDM2, p53, p21, p27, E‐cadherin, VIM, SNAIL, VEGFA, NFκB‐p65 and MMP2). In addition, we demonstrated, for the first time, that ADAMTS9 inhibits AKT signaling, through suppressing its upstream activators EGFR and TGFβ1/TβR(I/II) in breast cancer cells. Our results suggest that ADAMTS9 is a TSG epigenetically inactivated in breast cancer, which functions through blocking EGFR‐ and TGFβ1/TβR(I/II)‐activated AKT signaling.     

The lncRNA TP73‐AS1 promotes ovarian cancer cell proliferation and metastasis via modulation of MMP2 and MMP9

Ovarian cancer is one of the most common gynecologic malignancy with poor prognosis. Recently, long noncoding RNAs (lncRNAs) have been identified as key regulators in cancer development. The current study investigated the role of lncRNA P73 antisense RNA 1T (TP73‐AS1) in ovarian cancer. Quantitative real‐time polymerase chain reaction determined the expression levels of TP‐73AS1, matrix metallopeptidases (MMPs) messenger RNA. Cell proliferative ability, cell invasion, and migration were CCK‐8 and colony formation, and transwell invasion and migration assays, respectively. The protein levels of matrix metallopeptidase 2 (MMP2) and MMP9 were measured by Western blot. TP73‐AS1 was upregulated in the ovarian cancer tissues and ovarian cancer cells, and upregulation of TP73‐AS1 was associated with poor prognosis. Knockdown of TP73‐AS1 significantly suppressed cell proliferation, invasion, and migration of SKOV3 cells, and overexpression of TP73‐AS1 promoted cell proliferation, invasion, and migration of OVCA429 cells. In addition, knockdown of TP73‐AS1 suppressed the in vivo tumor growth. Tumor metastasis RT² profiler polymerase chain reaction array showed that MMP2 and MMP9 was significantly upregulated by TP73‐AS1 overexpression in ovarian cancer cells. TP73‐AS1 overexpression enhanced the expression of MMP2 and MMP9 in ovarian cancer cells. Knockdown of MMP2 and MMP9 attenuated the effects of TP73‐AS1 overexpression on cell invasion and migration. The clinical data showed that MMP2 and MMP9 were upregulated and positively correlated with TP73‐AS1 expression in ovarian cancer tissues. Collectively, our results demonstrated the oncogenic role of TP73‐AS1 in ovarian cancer, and targeting TP73‐AS1 may represent a novel approach in battling against ovarian cancer.     

Flt-1 in colorectal cancer cells is required for the tumor invasive effect of placental growth factor through a p38-MMP9 pathway

Background

Placenta growth factor (PlGF), a dimeric glycoprotein with 53% homology to VEGF, binds to VEGF receptor-1 (Flt-1), but not to VEGF receptor-2 (Flk-1), and may function by modulating VEGF activity. We previously have showed that PlGF displays prognostic value in colorectal cancer (CRC) but the mechanism remains elucidated.

Results

Overexpression of PlGF increased the invasive/migration ability and decreased apoptosis in CRC cells showing Flt-1 expression. Increased migration was associated with increasing MMP9 via p38 MAPK activation. Tumors grew faster, larger; with higher vascularity from PlGF over-expression cells in xenograft assay. In two independent human CRC tissue cohorts, PlGF, MMP9, and Flt-1 expressions were higher in the advanced than the localized disease group. PlGF expression correlated with MMP9, and Flt-1 expression. CRC patients with high PlGF and high Flt-1 expression in tissue had poor prognosis.

Conclusion

PlGF/Flt-1 signaling plays an important role in CRC progression, blocking PlGF/Flt-1 signaling maybe an alternative therapy for CRC.     

Osteoactivin regulates head and neck squamous cell carcinoma invasion by modulating matrix metalloproteases

Nearly 60% of patients with head and neck squamous cell carcinoma (HNSCC) die of metastases or locoregional recurrence. Metastasis is mediated by cancer cell migration and invasion, which are in part dependent on extracellular matrix degradation by matrix metalloproteinases. Osteoactivin (OA) overexpression plays a role in metastases in several malignancies, and has been shown to upregulate matrix metalloproteinase (MMP) expression and activity. To determine how OA modulates MMP expression and activity in HNSCC, and to investigate OA effects on cell invasion, we assessed effects of OA treatment on MMP mRNA and protein expression, as well as gelatinase and caseinolytic activity in HNSCC cell lines. We assessed the effects of OA gene silencing on MMP expression, gelatinase and caseinolytic activity, and cell invasion. OA treatment had differential effects on MMP mRNA expression. OA treatment upregulated MMP‐10 expression in UMSCC14a (p = 0.0431) and SCC15 (p < 0.0001) cells, but decreased MMP‐9 expression in UMSCC14a cells (p = 0.0002). OA gene silencing decreased MMP‐10 expression in UMSCC12 cells (p = 0.0001), and MMP‐3 (p = 0.0005) and ‐9 (p = 0.0036) expression in SCC25 cells. In SCC15 and SCC25 cells, OA treatment increased MMP‐2 (p = 0.0408) and MMP‐9 gelatinase activity (p < 0.0001), respectively. OA depletion decreased MMP‐2 (p = 0.0023) and ‐9 (p < 0.0001) activity in SCC25 cells. OA treatment increased 70 kDa caseinolytic activity in UMSCC12 cells consistent with tissue type plasminogen activator (p = 0.0078). OA depletion decreased invasive capacity of UMSCC12 cells (p < 0.0001). OA's effects on MMP expression in HNSCC are variable, and may promote cancer cell invasion.     

p120RasGAP Is a Mediator of Rho Pathway Activation and Tumorigenicity in the DLD1 Colorectal Cancer Cell Line

KRAS is mutated in ∼40% of colorectal cancer (CRC), and there are limited effective treatments for advanced KRAS mutant CRC. Therefore, it is crucial that downstream mediators of oncogenic KRAS continue to be studied. We identified p190RhoGAP as being phosphorylated in the DLD1 CRC cell line, which expresses a heterozygous KRAS G13D allele, and not in DKO4 in which the mutant allele has been deleted by somatic recombination. We found that a ubiquitous binding partner of p190RhoGAP, p120RasGAP (RasGAP), is expressed in much lower levels in DKO4 cells compared to DLD1, and this expression is regulated by KRAS. Rescue of RasGAP expression in DKO4 rescued Rho pathway activation and partially rescued tumorigenicity in DKO4 cells, indicating that the combination of mutant KRAS and RasGAP expression is crucial to these phenotypes. We conclude that RasGAP is an important effector of mutant KRAS in CRC.     

Many new down‐ and up‐regulatory signaling pathways,from known cancer progression suppressors to matrix metalloproteinases,differ widely in cells of various cancers

Previously we detected new signaling pathways, some downregulatory and others upregulatory, from seven known suppressors of cancer progression to the expression of eight cancer‐promoting matrix metalloproteinases (MMPs) in breast cancer cells. The goals of the present study were to test whether the preceding observations occur only in breast cancer cells and, if not, whether the same downregulatory and upregulatory signaling pathways are active in cells of other human cancers, focusing on activator protein‐2α, E‐cadherin, fibulin1D, interleukin 4, p16^INK4α, p53, PTEN, and RKIP, and on MMP1, MMP2, MMP7, MMP13, MMP14, MMP16, MMP19, and MMP25. To this end, in the present study we tested the effects of raising the cellular levels of wild‐type copies of these known suppressors of cancer progression on the expression of these MMPs. This study yielded several unexpected results. We have detected 53 new signaling pathways in cells of prostate, brain, lung, ovarian and breast human cancers, with an abundance of signaling pathways as high as ～40% of the cancer progression regulator/MMP pairs tested in cells of prostate and breast cancers. Cells of various cancers differed widely and sequence‐specifically in the identity of their signaling pathways, so that almost 90% of the pathways were different in cells from one cancer to another. In each of 18 out of 51 signaling pathways, a known suppressor of cancer progression stimulated, rather than inhibited, the expression of a cancer‐promoting MMP. Ten signaling pathways were upregulatory in cells of some cancers and downregulatory in cells of other cancers. J. Cell. Physiol. 224: 549–558, 2010. © 2010 Wiley‐Liss, Inc.     

Dickkopf‐1‐promoted vasculogenic mimicry in non‐small cell lung cancer is associated with EMT and development of a cancer stem‐like cell phenotype

To characterize the contributions of Dickkopf‐1 (DKK1) towards the induction of vasculogenic mimicry (VM) in non‐small cell lung cancer (NSCLC), we evaluated cohorts of primary tumours, performed in vitro functional studies and generated xenograft mouse models. Vasculogenic mimicry was observed in 28 of 205 NSCLC tumours, while DKK1 was detected in 133 cases. Notably, DKK1 was positively associated with VM. Statistical analysis showed that VM and DKK1 were both related to aggressive clinical course and thus were indicators of a poor prognosis. Moreover, expression of epithelial‐mesenchymal transition (EMT)‐related proteins (vimentin, Slug, and Twist), cancer stem‐like cell (CSC)‐related proteins (nestin and CD44), VM‐related proteins (MMP2, MMP9, and vascular endothelial‐cadherin), and β‐catenin‐nu were all elevated in VM‐positive and DKK1‐positive tumours, whereas the epithelial marker (E‐cadherin) was reduced in the VM‐positive and DKK1‐positive groups. Non‐small cell lung cancer cell lines with overexpressed or silenced DKK1 highlighted its role in the restoration of mesenchymal phenotypes and development of CSC characteristics. Moreover, DKK1 significantly promotes NSCLC tumour cells to migrate, invade and proliferate. In vivo animal studies demonstrated that DKK1 enhances the growth of transplanted human tumours cells, as well as increased VM formation, mesenthymal phenotypes and CSC properties. Our results suggest that DKK1 can promote VM formation via induction of the expression of EMT and CSC‐related proteins. As such, we feel that DKK1 may represent a novel target of NSCLC therapy.     

Knockdown of mediator subunit Med19 suppresses bladder cancer cell proliferation and migration by downregulating Wnt/β‐catenin signalling pathway

Mediator complex subunit 19 (Med19), a RNA polymerase II‐embedded coactivator, is reported to be involved in bladder cancer (BCa) progression, but its functional contribution to this process is poorly understood. Here, we investigate the effects of Med19 on malignant behaviours of BCa, as well as to elucidate the possible mechanisms. Med19 expression in 15 BCa tissues was significantly higher than adjacent paired normal tissues using real‐time PCR and Western blot analysis. Immunohistochemical staining of 167 paraffin‐embedded BCa tissues was performed, and the results showed that high Med19 protein level was positively correlated with clinical stages and histopathological grade. Med19 was knocked down in BCa cells using short‐hairpin RNA. Functional assays showed that knocking‐down of Med19 can suppress cell proliferation and migration in T24, UM‐UC3 cells and 5637 in vitro, and inhibited BCa tumour growth in vivo. TOP/FOPflash reporter assay revealed that Med19 knockdown decreased the activity of Wnt/β‐catenin pathway, and the target genes of Wnt/β‐catenin pathway were down‐regulated, including Wnt2, β‐catenin, Cyclin‐D1 and MMP‐9. However, protein levels of Gsk3β and E‐cadherin were elevated. Our data suggest that Med19 expression correlates with aggressive characteristics of BCa and Med19 knockdown suppresses the proliferation and migration of BCa cells through down‐regulating the Wnt/β‐catenin pathway, thereby highlighting Med19 as a potential therapeutic target for BCa treatment.     

Porphyromonas gingivalis promotes invasion of oral squamous cell carcinoma through induction of proMMP9 and its activation

Recent epidemiological studies have revealed a significant association between periodontitis and oral squamous cell carcinoma (OSCC). Furthermore, matrix metalloproteinase 9 (MMP9) is implicated in the invasion and metastasis of tumour cells. We examined the involvement of Porphyromonas gingivalis, a periodontal pathogen, in OSCC invasion through induced expression of proMMP and its activation. proMMP9 was continuously secreted from carcinoma SAS cells, while P. gingivalis infection increased proenzyme expression and subsequently processed it to active MMP9 in culture supernatant, which enhanced cellular invasion. In contrast, Fusobacterium nucleatum, another periodontal organism, failed to demonstrate such activities. The effects of P. gingivalis were observed with highly invasive cells, but not with the low invasivetype. P. gingivalis also stimulated proteinase‐activated receptor 2 (PAR2) and enhanced proMMP9 expression, which promoted cellular invasion. P. gingivalis mutants deficient in gingipain proteases failed to activate MMP9. Infected SAS cells exhibited activation of ERK1/2, p38, and NF‐kB, and their inhibitors diminished both proMMP9‐overexpression and cellular invasion. Together, our results show that P. gingivalis activates the ERK1/2‐Ets1, p38/HSP27, and PAR2/NF‐kB pathways to induce proMMP9 expression, after which the proenzyme is activated by gingipains to promote cellular invasion of OSCC cell lines. These findings suggest a novel mechanism of progression and metastasis of OSCC associated with periodontitis.