Potentiation of cell invasion and matrix metalloproteinase production by alpha3beta1 integrin-mediated adhesion of gastric carcinoma cells to laminin-5

Characterization of the Tumor Microenvironment and the Biological Processes with a Role in Prostatic Tumorigenesis

Prostate intratumoral heterogeneity, driven by epithelial−mesenchymal plasticity, contributes to the limited treatment response, and it is therefore necessary to use the biomarkers to improve patient prognostic survival. We aimed to characterize the tumor microenvironment (T lymphocyte infiltration, intratumoral CD34, and KI-67 expressions) by immunohistochemistry methods and to study the biological mechanisms (cell cycle, cell proliferation by adhesion glycoproteins, cell apoptosis) involved in the evolution of the prostate tumor process by flow-cytometry techniques. Our results showed that proliferative activity (S-phase) revealed statistically significant lower values of prostate adenocarcinoma (PCa) and benign prostatic hyperplasia (BPH) reported at non-malignant adjacent cell samples (PCa 4.32 ± 4.91; BPH 2.35 ± 1.37 vs. C 10.23 ± 0.43, p < 0.01). Furthermore, 68% of BPH cases and 88% of patients with PCa had aneuploidy. Statistically increased values of cell proliferation (CD34+ CD61+) were observed in prostate adenocarcinoma and hyperplasia cases reported to non-malignant adjacent cell samples (PCa 28.79 ± 10.14; BPH 40.65 ± 11.88 vs. C 16.15 ± 2.58, p < 0.05). The CD42b+ cell population with a role in cell adhesion, and metastasis had a significantly increased value in PCa cases (38.39 ± 11.23) reported to controls (C 26.24 ± 0.62, p < 0.01). The intratumoral expression of CD34 showed a significantly increased pattern of PCa tissue samples reported to controls (PCa 26.12 ± 6.84 vs. C 1.50 ± 0.70, p < 0.01). Flow cytometric analysis of the cell cycle, apoptosis, and adhesion glycoproteins with a critical role in tumoral cell proliferation, T cell infiltrations, Ki-67, and CD 34 expressions by IHC methods are recommended as techniques for the efficient means of measurement for adenocarcinoma and hyperplasia prostate tissue samples and should be explored in the future.

Roles of Integrins in Gastrointestinal Cancer Metastasis

Integrins are a large family of heterodimeric transmembrane receptors which mediate cell adhesion and transmit signals to the cell interior. The mechanistic roles of integrins have long been an enigma in cancer, given its complexity in regulating different cellular behaviors. Recently, however, increasing research is providing new insights into its function and the underlying mechanisms, which collectively include the influences of altered integrin expression on the aberrant signaling pathways and cancer progression. Many studies have also demonstrated the potentiality of integrins as therapeutic targets in cancer treatment. In this review, we have summarized these recent reports and put a particular emphasis on the dysregulated expression of integrins and how they regulate related signaling pathways to facilitate the metastatic progression of gastrointestinal cancer, including gastric cancer (GC) and colorectal cancer (CRC), which will address the crucial roles of integrins in gastrointestinal cancer.

Smilax glabra Roxb. Inhibits Collagen Induced Adhesion and Migration of PC3 and LNCaP Prostate Cancer Cells through the Inhibition of Beta 1 Integrin Expression

Smilax glabra Roxb. (SGR) has been used as a traditional medicine for brucellosis and syphilis. In this study, we investigated whether nontoxicological levels of water extract of SGR (WESGR) are effective for suppressing steps in the progression of prostate cancer, such as collagen-mediated migration and adhesion and identified the target molecule responsible for such effects. We found that nontoxicological levels of WESGR did not attenuate PC3 and LNCaP cell adhesion to serum but did significantly do so with collagen. In addition, using the Boyden chamber assay, we found that nontoxicological levels of WESGR did not inhibit the migration of PC3 and LNCaP cells to a serum-coated area but did significantly attenuate migration to a collagen-coated area. Interestingly, the expression of α2β1 integrin, a known receptor of collagen, was not affected by ectopic administration of WESGR. However, WESGR significantly attenuated the expression of β1 integrin, but not α2 integrin when PC3 and LNCaP cells were placed on a collagen-coated plate, resulting in attenuation of focal adherent kinase phosphorylation. Finally, 5-O-caffeoylquinic acid was determined as a functional single component which is responsible for antiprostate cancer effects of WESGR. Taken together, our results suggest a novel molecular mechanism for WESGR-mediated antiprostate cancer effects at particular steps such as with migration and adhesion to collagen, and it could provide the possibility of therapeutic use of WESGR against prostate cancer progression.

Pressurized intraperitoneal aerosol chemotherapy and its effect on gastric-cancer-derived peritoneal metastases: an overview

This manuscript aspires to portray a review of the current literature focusing on manifest peritoneal metastasis (PM) derived from gastric cancer and its treatment options. Despite the development of chemotherapy and multimodal treatment options during the last decades, mortality remains high worldwide. After refreshing important epidemiological considerations, the molecular mechanisms currently accepted through which PM occurs are revised. Palliative chemotherapy is the only recommended treatment option for patients with PM of gastric cancer according to the National Comprehensive Cancer Network guidelines, although cytoreductive surgery in combination with hyperthermic intraperitoneal chemotherapy demonstrated promising results in selected patients with regional PM and localized intraabdominal tumor spread. A novel treatment named pressurized intraperitoneal aerosol chemotherapy may have a promising future in improving overall survival with an acceptable postoperative complication rate and stabilizing quality of life during treatment. Additionally, the procedure has been proved to be safe for the patient and medical personnel and a feasible, repeatable method to deter metastatic proliferation. This overview comprehensively addresses this novel and promising treatment in the context of a scientifically and clinically challenging disease.

Stimulation of Peritoneal Mesothelial Cells to Secrete Matrix Metalloproteinase-9 (MMP-9) by TNF-α: A Role in the Invasion of Gastric Carcinoma Cells

It has recently been recognized that inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), upregulate the secretion of matrix metalloproteinase-9 (MMP-9) from cancer cells and thereby promote peritoneal dissemination. In this study, we found that TNF-α also stimulated peritoneal mesothelial cells to secrete MMP-9 as assessed by zymography. MMP-9 gene expression in mesothelial cells induced by TNF-α was confirmed by quantitative RT-PCR analysis. We then utilized the reconstituted artificial mesothelium, which was composed of a monolayer of mesothelial cells cultured on a Matrigel layer in a Boyden chamber system, to examine the effects of TNF-α on carcinoma cell invasion. The transmigration of MKN1 human gastric carcinoma cells through the reconstituted mesothelium was promoted by TNF-α in a dose-dependent manner. The increased MKN1 cell migration was partially inhibited by the anti-α3 integrin antibody, indicating that the invasion process involves an integrin-dependent mechanism. Finally, we observed that the invasion of MMP-9-knockdown MKN1 cells into Matrigel membranes was potentiated by the exogenous addition of purified proMMP-9. These results suggest that TNF-α-induced MMP-9 secretion from mesothelial cells plays an important role in the metastatic dissemination of gastric cancer.

Establishing a xenograft mouse model of peritoneal dissemination of gastric cancer with organ invasion and fibrosis

Background

The clinical prognosis of gastric cancer with peritoneal dissemination is poor because of its chemoresistance and rich fibrosis. While several gastric cancer cell lines have been used to establish models of peritoneal dissemination by intraperitoneal injection, most peritoneal tumors that form adopt a medullary pattern in microscopic appearance. This histological finding for the model differs from that in the clinical situation. This study was performed to demonstrate the contribution of human peritoneal mesothelial cells (HPMCs) to fibrotic tumor formation and to establish a new xenograft model with high potential for peritoneal dissemination with organ invasion and extensive fibrosis.

Methods

We established four types of xenograft model: i) intraperitoneal injection of MKN45-P cells alone (control group), ii) injection of MKN45-P cells co-cultured with HPMCs (co-cultured group), iii) scratching the parietal peritoneum (parietal group), and iv) scratching the visceral peritoneum (visceral group) with a cotton swab before injection of co-cultured cells. Fibrosis, α-smooth muscle actin expression, and organ invasion by tumor cells were all assessed by immunohistochemical examination.

Results

All mice developed abdominal swelling with peritoneal tumors and bloody ascites. Tumors of the control and co-cultured groups were not invasive or fibrotic. Contrastingly, tumors of the scratch groups exhibited rich stromal fibrosis and possessed increased α-smooth muscle actin (α-SMA) expression. In particular, the visceral group showed edematous and spreading tumors invading the intestinal wall.

Conclusion

We established a model of peritoneal dissemination with organ invasion and stromal fibrosis. Formation of peritoneal dissemination required a favorable environment for cell adhesion, invasion, and growth. This model may be useful for analyzing the pathogenesis and treatment of peritoneal dissemination of gastric cancer.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-016-2991-9) contains supplementary material, which is available to authorized users.

CXCL12/CXCR4 activation by cancer-associated fibroblasts promotes integrin β1 clustering and invasiveness in gastric cancer

Cancer-associated fibroblasts (CAFs) are reportedly involved in invasion and metastasis in several types of cancer, including gastric cancer (GC), through the stimulation of CXCL12/CXCR4 signaling. However, the mechanisms underlying these tumor-promoting effects are not well understood, which limits the potential to develop therapeutic targets against CAF-mediated CXCL12/CXCR4 signaling. CXCL12 expression was analyzed in resected GC tissues from 110 patients by immunohistochemistry (IHC). We established primary cultures of normal fibroblasts (NFs) and CAFs from the GC tissues and examined the functional differences between these primary fibroblasts using co-culture assays with GC cell lines. We evaluated the efficacy of a CXCR4 antagonist (AMD3100) and a FAK inhibitor (PF-573,228) on the invasive ability of GC cells. High CXCL12 expression levels were significantly associated with larger tumor size, increased tumor depth, lymphatic invasion and poor prognosis in GC. CXCL12/CXCR4 activation by CAFs mediated integrin β1 clustering at the cell surface and promoted the invasive ability of GC cells. Notably, AMD3100 was more efficient than PF-573,228 at inhibiting GC cell invasion through the suppression of integrin β1/FAK signaling. These results suggest that CXCL12 derived from CAFs promotes GC cell invasion by enhancing the clustering of integrin β1 in GC cells, resulting in GC progression. Taken together, the inhibition of CXCL12/CXCR4 signaling in GC cells may be a promising therapeutic strategy against GC cell invasion.

Epithelial mesenchymal transition related molecular markers and invasion and metastasis of cholangiocarcinoma

Tumor metastasis is a major cause of death in patients with solid tumors. Epithelial mesenchymal transition (EMT) is a process in which the epithelial cells are transformed into the stroma cells. This process is accompanied by changes in gene expression and cell phenotype, which are often activated during tumor invasion and metastasis. Cholangiocarcinoma is a kind of malignancy originating from the bile duct epithelium, and its main biological characteristics are early invasion, metastasis and recurrence. The research of cholangiocarcinoma metastasis could provide a theoretical basis for the development of new treatment strategies to manage this malignancy. This paper reviews the roles of EMT related molecular markers metastasis in the invasion and metastasis of cholangiocarcinoma.

Connective tissue growth factor inhibits gastric cancer peritoneal metastasis by blocking integrin α3β1-dependent adhesion

BACKGROUND

Connective tissue growth factor (CTGF) plays important roles in normal and pathological conditions. The aim of this study was to investigate the role of CTGF in peritoneal metastasis as well as the underlying mechanism in gastric cancer progression.

METHODS

CTGF expression levels for wild-type and stable overexpression clones were determined by Western blotting and quantitative polymerase chain reaction (Q-PCR). Univariate and multivariate analyses, immunohistochemistry, and survival probability analyses were performed on gastric cancer patients. The extracellular matrix components involved in CTGF-regulated adhesion were determined. Recombinant CTGF was added to cells or coinoculated with gastric cancer cells into mice to evaluate its therapeutic potential.

RESULTS

CTGF overexpression and treatment with the recombinant protein significantly inhibited cell adhesion. In vivo peritoneal metastasis demonstrated that CTGF-stable transfectants markedly decreased the number and size of tumor nodules in the mesentery. Statistical analysis of gastric cancer patient data showed that patients expressing higher CTGF levels had earlier TNM staging and a higher survival probability after the surgery. Integrin α3β1 was the cell adhesion molecule mediating gastric cancer cell adhesion to laminin, and blocking of integrin α3β1 prevented gastric cancer cell adhesion to recombinant CTGF. Coimmunoprecipitation results indicated that CTGF binds to integrin α3. Coinoculation of recombinant CTGF and gastric cancer cell lines in mice showed effective inhibition of peritoneal dissemination.

CONCLUSIONS

Our results suggested that gastric cancer peritoneal metastasis is mediated through integrin α3β1 binding to laminin, and CTGF effectively blocks the interaction by binding to integrin α3β1, thus demonstrating the therapeutic potential of recombinant CTGF in gastric cancer patients.

Tumor-environment biomimetics delay peritoneal metastasis formation by deceiving and redirecting disseminated cancer cells

Peritoneal metastasis is life threatening and is the result of an extensive communication between disseminated cancer cells, mesothelial cells and cancer-associated fibroblasts (CAF). CAFs secrete extracellular matrix (ECM) proteins creating a receptive environment for peritoneal implantation. Considering cancer as an ecosystem may provide opportunities to exploit CAFs to create biomimetic traps to deceive and redirect cancer cells. We have designed microparticles (MP) containing a CAF-derived ECM-surface that is intended to compete with natural niches. CAFs were encapsulated in alginate/gelatine beads (500-750 μm in diameter) functionalised with a polyelectrolyte coating (MP[CAF]). The encapsulated CAFs remain viable and metabolically active (≥35 days), when permanently encapsulated. CAF-derived ECM proteins are retained by the non-biodegradable coating. Adhesion experiments mimicking the environment of the peritoneal cavity show the selective capture of floating cancer cells from different tumor origins by MP[CAF] compared to control MP. MP[CAF] are distributed throughout the abdominal cavity without attachment to intestinal organs and without signs of inflammatory reaction. Intraperitoneal delivery of MP[CAF] and sequential removal redirects cancer cell adhesion from the surgical wound to the MP[CAF], delays peritoneal metastasis formation and prolongs animal survival. Our experiments suggest the use of a biomimetic trap based on tumor-environment interactions to delay peritoneal metastasis.

Association between polymorphisms of microRNA-binding sites in integrin genes and gastric cancer in Chinese Han population

Highly elevated expression of integrin has been observed in a variety of malignant tumors. Single nucleotide polymorphisms (SNPs) in the microRNA-binding sites in the 3' UTR region of target genes may result in the level change of target gene expression and subsequently susceptible to diseases, including cancer. In this study, we aimed to investigate the association between polymorphisms of microRNA-binding sites of integrin genes and gastric cancer (GC) in Chinese Han population. Five SNPs of the microRNA-binding sites in the 3' UTR region of integrin genes (rs1062484 C/T in ITGA3, rs17664 A/G in ITGA6, rs3809865 A/T in ITGB3, rs743554 C/T in ITGB4, and rs2675 A/C in ITGB5) were studied using high resolution melting (HRM) analysis in 1000 GC patients and 1000 unrelated controls. The polymorphism of SNP rs2675 was associated with susceptibility of GC [odds ratio (OR) = 0.52, 95% confidence interval (CI) = 0.28-0.97, P = 0.028]. In addition, genotype AA of rs2675 and genotype GG of rs17664 were associated with a lower chance of GC at stage 1b [OR = 0.39 (0.18-0.85), P = 0.009; and OR = 0.37 (0.17-0.78), P = 0.004, respectively]; also, the frequency of allele G of rs17664 was associated with a lower chance of stage 1b tumor [OR = 0.50 (0.26-0.95), P = 0.021]. Furthermore, the frequency of genotype AA and allele A of rs3809865 were associated with a higher risk of stage 4 GC [OR = 1.85 (1.11-3.09), P = 0.012; and OR = 1.52 (0.99-2.33), P = 0.043, respectively]. For rs17664, GG genotype and allele G appeared to be associated with a higher risk with GC with lymphatic metastasis 3b [OR = 1.76 (1.00-3.11), P = 0.036; and OR = 1.64 (0.98-2.75), P = 0.048, respectively]. Our data suggest that polymorphisms of the microRNA-binding sites in the 3' UTR region of integrin are associated with GC susceptibility (rs2675), tumor stage (rs2675, rs17664, and rs3809865), and lymphatic metastasis (rs17664) in Chinese Han population.

MGr1-Ag/37LRP induces cell adhesion-mediated drug resistance through FAK/PI3K and MAPK pathway in gastric cancer

It is well known that tumor microenvironment plays a vital role in drug resistance and cell adhesion-mediated drug resistance (CAM-DR), a form of de novo drug resistance. In our previous study, we reported that MGr1-Ag/37LRP ligation-induced adhesion participated in protecting gastric cancer cells from a number of apoptotic stimuli caused by chemotherapeutic drugs. Further study suggested that MGr1-Ag could prompt CAM-DR through interaction with laminin. However, the MGr1-Ag-initiated intracellular signal transduction pathway is still unknown. In this study, our experimental results showed that gastric cancer MDR cell lines mediated CAM-DR through upregulation of Bcl-2 by MGr1-Ag interaction with laminin. Further study found that, as a receptor of ECM components, MGr1-Ag/37LRP may activate the downstream signal pathway PI3K/AKT and MAPK/ERK through interaction with phosphorylated FAK. Moreover, the sensitivity to chemotherapeutic drugs could be significantly enhanced by inhibiting MGr1-Ag/37LRP expression through mAbs, siRNA, and antisense oligonucleotide. According to these results, we concluded that the FAK/PI3K and MAPK signal pathway plays an important role in MGr1-Ag-mediated CAM-DR in gastric cancer. MGr1-Ag/37LRP might be a potential effective reversal target to MDR in gastric cancer.

DNA methylation status of a distinctively different subset of genes is associated with each histologic Lauren classification subtype in early gastric carcinogenesis

DNA methylation change is known to play a crucial role in early gastric carcinogenesis. The present study aimed to identify and validate the correlation between differentially methylated regions (DMRs) and the subtypes of early gastric cancers (EGCs). Illumina Infinium methylation assay (IIMA; 450K BeadChip kit) was performed on fresh tumor and non‑tumor tissues of 12 EGCs to screen the methylation status of 450,000 CpG sites. To evaluate the significance of DNA methylation in each histologic subtype, pyrosequencing assay (PA) was performed on 38 EGCs (18 intestinal-, 12 mixed- and 8 diffuse-type) using 12 genes selected from the screening. Between tumors of the intestinal-type (n=6), and diffuse- (n=4) plus mixed-types (n=2), 169 regions showed significant differences (intensity>3,000, Δβ>0.2) in IIMA. Hierarchical clustering using the 169 DMRs revealed distinct separation between the two groups. In PA using 12 selected genes from the IIMA results, the aberrant methylation statuses of DVL2 (p=0.0186) and ETS1 (p=0.0222) were significantly related to diffuse- and mixed-types rather than the intestinal-type, while C19orf35 (p=0.019) and CNRIP1 (p=0.0473) were related to the diffuse‑type rather than intestinal‑type, and GAL3ST2 (p=0.0158) and ITGA3 (p=0.0273) were related to the mixed-type rather than the other two types. The methylation of other genes, CLIP4, XKR6, CCDC57, MAML3 and SDC2, was related with age, tumor location, or Helicobacter infection rather than the histologic subtype. Aberrant DNA methylation of certain genes may be independently involved in each histologic subtype of EGC. Furthermore, mixed-type EGCs may be a distinctive histologic subtype based on the different subset of DMRs compared to those of other subtypes.

Expression of integrins α3β1 and α5β1 and GlcNAc β1,6 glycan branching influences metastatic melanoma cell migration on fibronectin

Acquisition of metastatic potential is accompanied by changes in cell surface N-glycosylation. One of the best-studied changes is increased expression of N-acetylglucosaminyltransferase V enzyme (GnT-V) and its products, β1,6-branched N-linked oligosaccharides, observed in the tumorigenesis of many cancers. In this study we demonstrate that during the transition from the vertical growth phase (VGP) (WM793 cell line) to the metastatic stage (WM1205Lu line), β1,6 glycosylation of melanoma cell surface proteins increases as a consequence of elevated expression of the GnT-V-encoding Mgat-5 gene. Treatment with swainsonine led to reduced cell motility on fibronectin in both cell lines; the effect was stronger in metastatic cells, probably due to the higher content of GlcNAc β1,6-branched glycans on the main fibronectin receptors - integrins α5β1 and α3β1. Our results show that GlcNAc β1,6 N-glycosylation of cell surface receptors, which increases with the aggressiveness of melanoma cells, is an important factor influencing melanoma cell migration.

Aberrant expression of laminin γ2 correlates with poor prognosis and promotes invasion in extrahepatic cholangiocarcinoma

BACKGROUND

To investigate the potential role of laminin γ2 and its correlation with prognosis in patients with extrahepatic cholangiocarcinoma (CCA).

MATERIALS AND METHODS

Laminin γ2 expression was evaluated by immunohistochemistry in 72 extrahepatic CCA patients after surgical resection. Knockdown of laminin γ2 was achieved via small interfering RNA transfection in the extrahepatic CCA cell line QBC939.

RESULTS

Thirty-six of 72 extrahepatic CCAs (50%) stained positive for laminin γ2 in two types of patterns: stromal staining (28/72, 39%) and cytoplasmic staining (24/72, 33%). All 16 paracancerous tissue samples showed negative staining. Both stromal and cytoplasmic laminin γ2 expressions correlated with lymph node metastasis. Kaplan-Meier analysis showed that aberrant expression of laminin γ2 correlated with poor overall survival and early recurrence. Cox regression analysis further demonstrated that laminin γ2 expression was a significant independent predictor of poor overall survival and early recurrence. Immunofluorescence staining revealed cytoplasmic expression of laminin γ2 in QBC939 cells. Knockdown of laminin γ2 significantly reduced QBC939 cell invasion and migration.

CONCLUSIONS

Aberrant expression of laminin γ2 correlates with poor prognosis and promotes invasion in extrahepatic CCA.

Overexpression of CD151 predicts prognosis in patients with resected gastric cancer

PURPOSE

The tetraspanin CD151 acts as a promoter of metastasis and invasion in several tumors. However, the role of CD151 in human gastric cancer (HGC) remains unclear.

METHODS

Twenty HGC specimens and matched nontumor samples, human gastric epithelial cells (HGEC), and four gastric cancer cell lines were used to analyze CD151 expression. Short hairpin RNA-mediated downregulation of CD151 expression in HGC cells was performed to examine the role of CD151 in the proliferation and metastasis/invasion of HGC cells in vivo and in vitro. The relationship of CD151 with integrin α3 in HGC cells was investigated by silencing integrin α3 followed by co-immunoprecipitation and immunofluorescence staining. Finally, the prognostic value of CD151 and integrin α3 was evaluated by immunohistochemistry in tissue microarrays of 76 HGC patients.

RESULTS

CD151 was expressed at higher levels in HGC tissues and HGC cells than in nontumor tissues and HGEC cells. Down-regulation of CD151 by vshRNA-CD151 impaired metastasis and invasion of HGC-27 cells, but did not affect cell proliferation. CD151 formed a complex with integrin α3 in HGC cells. CD151-cDNA transfection rescued the metastatic potential and invasiveness of HGC-27-vshCD151 cells, but not those of HGC-27-vshintegrin α3 cells in vitro. Clinically, CD151 overexpression was significantly correlated with high TNM stage, depth of invasion and positive lymph node involvement (p<0.05), and high levels of integrin α3 were associated with large tumor size, high TNM stage, depth of invasion and lymph node involvement (p<0.05). Importantly, the postoperative 5-year overall survival of patients with CD151(low) and/or integrin α3(low) was higher than that of patients with CD151(high) and/or integrin α3(high).

CONCLUSION

CD151 is positively associated with the invasiveness of HGC, and CD151 or the combination of CD151 and integrin α3 is a novel marker for predicting the prognosis of HGC patients and may be potential therapeutic targets.

High adhesion of tumor cells to mesothelial monolayers derived from peritoneal wash of disseminated gastrointestinal cancers

The role of the mesothelial layer in the peritoneal spreading of cancer cells is only partially clarified. Here we attempted to better define the mesothelial contribution to the tumor cell adhesion using a direct adhesion test applied to human primary cultures of mesothelial cells (HPMCs) derived from the peritoneal washes of patients with gastric and colorectal cancers. Gastric and colon carcinoma cells were seeded on different mesothelial monolayers and quantitative fluorescence analysis was performed to analyze their growth and adhesive properties. The adhesion of the cancer cells was not affected by the origin of the HPMCs when derived from patients with different cancers or with benign disease. In contrast, the high levels of ICAM1 expression and ROS production, which characterize these senescent mesothelial cells, enhanced the tumor cell adhesion. These results suggest that the mesothelial adhesive properties are dependent on the cell senescence, while are not affected by the tumor environment. The use of peritoneal washes as a source to isolate HPMCs provides a practical and reliable tool for the in vitro analysis of the mesothelial conditions affecting the peritoneal carcinomatosis.

The diagnostic and biological implications of laminin expression in serous tubal intraepithelial carcinoma

There is compelling evidence to suggest that serous tubal intraepithelial carcinoma (STIC) is the likely primary site for the development of many pelvic high-grade serous carcinomas (HGSCs). Identifying molecules that are upregulated in STIC is important not only to provide biomarkers to assist in the diagnosis of STIC but also to elucidate our understanding of the pathogenesis of HGSC. In this study, we performed RNA sequencing to compare transcriptomes between HGSC and normal fallopian tube epithelium (FTE), and we identified LAMC1 encoding laminin γ1 as one of the preferentially upregulated genes associated with HGSC. Reverse transcription polymerase chain reaction further validated LAMC1 upregulation in HGSC as compared with normal FTE. Immunohistochemical analysis was performed on 32 cases of concurrent HGSC and STIC. The latter was diagnosed on the basis of morphology, TP53 mutations, and p53 and Ki-67 immunohistochemical patterns. Laminin γ1 immunostaining intensity was found to be significantly higher in STIC and HGSC compared with adjacent FTE in all cases (P<0.001). In normal FTE, laminin γ1 immunoreactivity was predominantly localized in the basement membrane or on the apical surface of ciliated cells, whereas in STIC and HGSC cells, laminin γ1 staining was diffuse and intense throughout the cytoplasm. More importantly, strong laminin γ1 staining was detected in all 13 STICs, which lacked p53 immunoreactivity because of null mutations. These findings suggest that the overexpression of laminin γ1 immunoreactivity and alteration of its staining pattern in STICs can serve as a useful tissue biomarker, especially for those STICs that are negative for p53 and have a low Ki-67 labeling index.

Differential roles of uPAR in peritoneal ovarian carcinomatosis

Epithelial ovarian cancer is the fourth leading cause of death from gynecologic malignancies in the United States. Most cases are diagnosed at late stages, with the solid tumor masses growing as peritoneal implants, or floating within the ascitic fluid (peritoneal ovarian carcinomatosis). Despite aggressive surgical "debulking," recurrence of recalcitrant disease is frequent with poor patient survival. Efforts to improve survival rates are hindered by lack of biomarkers that can detect and effectively treat ovarian cancer in its early stages. Urokinase plasminogen activator receptor (uPAR) is a multifunctional receptor involved in a myriad of tumor cell processes. However, the role of host uPAR in ovarian cancer is still elusive. To define the potential proinflammatory role of uPAR in ovarian cancer, first, using a syngeneic murine model in uPAR(-/-) mice, we found that ablation of uPAR restrained tumor take and peritoneal implants and prolonged the survival of uPAR(-/-) mice compared with their uPAR(+/+) counterparts. Ascitic fluid accumulation was significantly decreased in uPAR(-/-) mice with decreased macrophage infiltration. Second, in vitro mechanistic studies revealed that host uPAR is involved in the multiple steps of peritoneal metastatic cascade. Third, we evaluated the prognostic utility of tumor and stromal uPAR in human ovarian cancer tissue microarray. In summary, our studies indicated that uPAR plays a significant role in ovarian cancer cell-stromal crosstalk and contributes to increased vascular permeability and inflammatory ovarian cancer microenvironment. This provides a rationale for targeting the uPAR with either specific neutralizing antibodies or targeting its downstream inflammatory effectors in patients with ovarian cancer.

Mitochondrial dysfunction promotes cell migration via reactive oxygen species-enhanced β5-integrin expression in human gastric cancer SC-M1 cells

BACKGROUND

Mitochondrial dysfunction has been shown to promote cancer cell migration. However, molecular mechanism by which mitochondrial dysfunction enhances gastric cancer (GC) cell migration remains unclear.

METHODS

Mitochondria specific inhibitors, oligomycin and antimycin A, were used to induce mitochondrial dysfunction and to enhance cell migration of human gastric cancer SC-M1 cells. Antioxidant N-acetylcysteine (NAC) was used for evaluating the effect of reactive oxygen species (ROS). Protein expressions of epithelial-to-mesenchymal transition (EMT) markers and the cell-extracellular matrix (ECM) adhesion molecules, the integrin family, were analyzed. A migratory subpopulation of SC-M1 cells (SC-M1-3rd) was selected using a transwell assay for examining the association of mitochondrial bioenergetic function, intracellular ROS content and β5-integrin expression. Clinicopathologic characteristics of β5-integrin expression were analyzed in GC specimens by immunohistochemical staining.

RESULTS

Treatments with mitochondrial inhibitors elevated mitochondria-generated ROS and cell migration of SC-M1 cells. The protein expression of β5-integrin and cell surface expression of αvβ5-integrin were upregulated, and which were suppressed by NAC. Pretreatments with NAC and anti-αvβ5-integrin neutralizing antibody respectively prevented the mitochondrial dysfunction-induced cell migration. The selected migratory SC-M1-3rd cells showed impaired mitochondrial function, higher mitochondria-generated ROS, and increased β5-integrin expression. The migration ability was also repressed by anti-αvβ5-integrin neutralizing antibody. In clinical specimens, GCs with higher β5-integrin protein expression had more aggressive behavior. In conclusion, mitochondrial dysfunction may lead to GC progression by enhancing migration through mitochondria-generated ROS mediated β5-integrin expression.

GENERAL SIGNIFICANCE

These results support the role of mitochondrial dysfunction in GC progression.

HAX1 Augments Cell Proliferation, Migration, Adhesion, and Invasion Induced by Urokinase-Type Plasminogen Activator Receptor

The urokinase-type plasminogen activator receptor (uPAR) is a cell surface receptor which has a multifunctional task in the process of tumorigenesis including cell proliferation, adhesion, migration, and invasion. Many of the biological functions of uPAR necessitate interactions with other proteins. We have shown previously that uPAR interacts with HAX1 protein (HS-1-associated protein X-1). In the current study, to gain insight into the possible role of HAX1 overexpression in regulation of uPAR signal transduction pathway, several function assays were used. We found that, upon stimulation of uPAR, HAX1 colocalizes with uPAR suggesting a physiological role for HAX1 in the regulation of uPAR signal transduction. HAX1 overexpression augments cell proliferation and migration in uPAR-stimulated cells. Moreover, HAX1 over-expression augmented uPAR-induced cell adhesion to vitronectin as well as cellular invasion. Our results suggest that HAX1 over-expression may underlay a novel mechanism to regulate uPAR-induced functions in cancer cells.

Increased neointimal formation in cystathionine gamma-lyase deficient mice: role of hydrogen sulfide in α5β1-integrin and matrix metalloproteinase-2 expression in smooth muscle cells

The physiological and pathological roles of hydrogen sulfide (H(2)S) in the regulation of cardiovacular functions have been recognized. Vascular smooth muscle cells (SMCs) express cystathionine gamma-lyase (CSE) and produce significant amount of H(2)S. Although growing evidence demonstated the anti-atherosclerotic effect of H(2)S, less is known about the contribution of the endogenous CSE/H(2)S pathway to the development of vascular remodeling. This study investigated the roles of the CSE/H(2)S pathway on SMC migration and neoimtimal formation by using CSE knockout (KO) mice. SMCs and aortic explants isolated from CSE KO mice exhibited more migration and outgrowth compared with that from wild-type (WT) mice, and exogenously applied NaHS (a H(2)S donor) at 100 μM significantly inhibited SMC migration and outgrowth. SMCs became more elongated and spread in the absence of CSE, and fibronectin significantly stimulated adhesion and migration of SMCs from CSE KO mice (KO-SMCs) in comparison with SMCs from WT mice (WT-SMCs). The expressions of α5- and β1-integrins were significantly higher in KO-SMCs, and functional blocking of α5β1-integrin effectively abrogated KO-SMC migration. CSE deficiency also enhanced matrix metalloproteinase-2 (MMP-2) expression, and the selective blocking of MMP-2 decreased KO-SMC migration. NaHS treatment decreased both the expressions of α5- and β1-integrins and MMP-2. We further found that the expressions of α5- and β1-integrins as well as MMP-2, were stimulated by fibronectin, and that the blockage of α5β1-integrin reduced but overexpression of α5β1-integrin induced MMP-2 expression in both WT-SMCs and KO-SMCs. We also noticed that CSE deficiency in mice led to increased neointima formation in carotid arteries 4 weeks after ligation, which were attenuated by NaHS administration. In conclusion, inhibition of SMC migration by H(2)S may be a novel target for the treatment of vascular occlusive disorder.

Role of integrins in invasion and metastasis of gastric cancer: potential therapeutic implications

Integrins are a large family of cell adhesion molecules that are involved in many important cellular and pathological functions including cell survival, growth, differentiation, migration, inflammatory responses, platelet aggregation, tissue repair and tumor invasion. Over the past two decades, several integrin-targeted drugs have made their way into clinical practice, many others are increasing each year in clinical trials and still more are showing promising potential for therapeutic development based on preclinical studies. Additionally, the role of integrins in pathological conditions combined with their druggability by means of cell surface accessibility makes them attractive pharmacological targets in cancer research. As such, the identification of key roles of integrins in gastric cancer has revealed their substantial potential as therapeutic targets. This review summarizes recent progress in the study of correlation between integrins and invasion and metastasis of gastric cancer and evaluates their values in developing molecularly targeted therapies for this disease.