Ezrin-expressing lung adenocarcinoma cells and podoplanin-positive fibroblasts form a malignant microenvironment

New insights into cancer pathology learned from the dynamics of cancer-associated fibroblasts

Paget's "Seed and Soil" theory, proposed in 1889, emphasizes the importance of the microenvironment where cancer cells grow in metastatic sites. Over a century later, this concept remains a cornerstone in comprehending cancer biology and devising treatment strategies. The "Seed and Soil" theory, which initially explained how cancer spreads to distant organs, now also applies to the tumor microenvironment (TME) within primary tumors. This theory emphasizes the critical interaction between cancer cells ("seeds") and their surrounding environment ("soil") and how this interaction affects both tumor progression within the primary site and at metastatic sites. An important point to note is that the characteristics of the TME are not static but dynamic, undergoing substantial changes during tumor progression and after treatment with therapeutic drugs. Cancer-associated fibroblasts (CAFs), recognized as the principal noncancerous cellular component within the TME, play multifaceted roles in tumor progression including promoting angiogenesis, remodeling the extracellular matrix, and regulating immune responses. In this comprehensive review, we focus on the findings regarding how the dynamics of CAFs contribute to cancer progression and drug sensitivity. Understanding the dynamics of CAFs could provide new insights into cancer pathology and lead to important advancements in cancer research and treatment.

Prognostic Impact of Stromal Profiles Educated by Gastric Cancer

BACKGROUND

Cancer-associated fibroblasts exhibit diversity and have several subtypes. The underlying relationship between the diversity of cancer-associated fibroblasts and their effect on gastric cancer progression remains unclear. In this study, mesenchymal stem cells were differentiated into cancer-associated fibroblasts with gastric cancer cell lines; clinical specimens were used to further investigate the impact of cancer-associated fibroblast diversity on cancer progression.

METHODS

Nine gastric cancer cell lines (NUGC3, NUGC4, MKN7, MKN45, MKN74, FU97, OCUM1, NCI-N87, and KATOIII) were used to induce mesenchymal stem cell differentiation into cancer-associated fibroblasts. The cancer-associated fibroblasts were classified based on ACTA2 and PDPN expression. Cell function analysis was used to examine the impact of cancer-associated fibroblast subtypes on cancer cell phenotype. Tissue samples from 97gastric patients who underwent gastrectomy were used to examine the clinical significance of each subtype classified according to cancer-associated fibroblast expression.

RESULTS

Co-culture of mesenchymal stem cells with nine gastric cancer cell lines revealed different subtypes of ACTA2 and PDPN expression in differentiated cancer-associated fibroblasts. Cancer-associated fibroblast subtypes with high ACTA2 plus PDPN expression levels significantly increased gastric cancer cell migration, invasion, and proliferation. The cancer-associated fibroblast subtype with ACTA2 plus PDPN expression was an independent prognostic factor along with lymph node metastasis for patients who had gastric cancer and were undergoing surgery.

CONCLUSIONS

Cancer-associated fibroblasts are educated by gastric cancer cells during the development of cancer-associated fibroblast diversity. Differentiated cancer-associated fibroblasts with distinct expression patterns could affect gastric cancer progression and enable prognostic stratification for gastric cancer.

Podoplanin promotes the carcinogenicity of gastric cancer by activating ezrin and mediating the crosstalk between tumour cells and cancer-associated fibroblasts

NEW FINDINGS

What is the central question of this study? To reveal the role and biological mechanism of PDPN in the progression of gastric cancer. What is the main finding and its importance? This study focused on a prognostic predictor, PDPN, which acted as a promoter in the progression of gastric cancer through the activation of Ezrin expression and CAFs. This finding may expand a new route for the gene-targeted therapy in gastric cancer.

ABSTRACT

Gastric cancer (GC) is a frequent malignant disease and the main cause of cancer-related death in the world. Podoplanin (PDPN) has been proved to be involved in the progression of various cancers. However, the role and biological mechanism of PDPN in GC are still vague. In our study, we detected the expression of PDPN in GC tissues and cell lines using RT-qPCR, western blot and datasets. The overall survival of GC patients was analysed with a Kaplan-Meier plot. The effects of PDPN overexpression and silencing on GC cell progression were assessed by Cell Counting Kit-8, flow cytometry and a wound healing assay. Besides, the modulation of PDPN on ezrin activation was investigated. We further explored the role of PDPN in the crosstalk between GC cells and cancer associated fibroblasts (CAFs). Results showed that PDPN was upregulated in GC tissues and cell lines. High expression of PDPN was correlated with poor prognosis of GC patients. PDPN positively regulated the viability, migration and invasion, but inhibited apoptosis, of GC cells by mediating the activation of ezrin. Meanwhile, the change in PDPN in GC cells activated CAFs and promoted the production of cytokines secreted by CAFs, which induced the progression of GC cells. These findings may provide a novel target for GC therapy.

Ezrin regulates the progression of NSCLC by YAP and PD-L1

PURPOSE

To determine whether ezrin regulates Yes-associated protein (YAP) and programed cell death ligand-1 (PD-L1), which are involved in the invasion and metastasis of non-small cell lung cancer (NSCLC).

METHODS

Immunohistochemistry of 164 NSCLC and 16 para-cancer tissues was performed to detect ezrin, YAP, and PD-L1 expression. Further, H1299 and A549 cells were transfected with lentivirus, and then colony formation, CCK8, transwell, and wound-healing assays were used to assess cell proliferation, migration, and invasion. RT-qPCR and western blotting were used for quantitative analysis of ezrin, PD-L1, and YAP expression. Moreover, the role of ezrin in tumor growth was assessed in vivo, and immunohistochemistry and western blotting were performed to evaluate changes in ezrin expression in mouse samples.

RESULTS

The positive protein expression rates of these molecules in NSCLC were as follows: ezrin, 43.9% (72/164); YAP, 54.3% (89/164); and PD-L1, 47.6% (78/164); these were higher than those in normal lung tissues. Moreover, YAP and ezrin expression positively correlated with PD-L1 expression. Ezrin promoted proliferation, migration, invasion, and expression of YAP and PD-L1in NSCLC. Inhibition of ezrin expression reduced the effects of ezrin on cell proliferation, migration, invasion, inhibited the expression of YAP and PD-L1, and obviously reduced experimental tumor volume in vivo.

CONCLUSIONS

Ezrin is overexpressed in NSCLC patients and correlates with PD-L1 and YAP expression. Ezrin regulates YAP and PD-L1 expression. Inhibition of ezrin delayed NSCLC progression.

Ezrin gone rogue in cancer progression and metastasis: An enticing therapeutic target

Cancer metastasis is the primary cause of morbidity and mortality in cancer as it remains the most complicated, devastating, and enigmatic aspect of cancer. Several decades of extensive research have identified several key players closely associated with metastasis. Among these players, cytoskeletal linker Ezrin (the founding member of the ERM (Ezrin-Radixin-Moesin) family) was identified as a critical promoter of metastasis in pediatric cancers in the early 21st century. Ezrin was discovered 40 years ago as a aminor component of intestinal epithelial microvillus core protein, which is enriched in actin-containing cell surface structures. It controls gastric acid secretion and plays diverse physiological roles including maintaining cell polarity, regulating cell adhesion, cell motility and morphogenesis. Extensive research for more than two decades evinces that Ezrin is frequently dysregulated in several human cancers. Overexpression, altered subcellular localization and/or aberrant activation of Ezrin are closely associated with higher metastatic incidence and patient mortality, thereby justifying Ezrin as a valuable prognostic biomarker in cancer. Ezrin plays multifaceted role in multiple aspects of cancer, with its significant contribution in the complex metastatic cascade, through reorganizing the cytoskeleton and deregulating various cellular signaling pathways. Current preclinical studies using genetic and/or pharmacological approaches reveal that inactivation of Ezrin results in significant inhibition of Ezrin-mediated tumor growth and metastasis as well as increase in the sensitivity of cancer cells to various chemotherapeutic drugs. In this review, we discuss the recent advances illuminating the molecular mechanisms responsible for Ezrin dysregulation in cancer and its pleiotropic role in cancer progression and metastasis. We also highlight its potential as a prognostic biomarker and therapeutic target in various cancers. More importantly, we put forward some potential questions, which we strongly believe, will stimulate both basic and translational research to better understand Ezrin-mediated malignancy, ultimately leading to the development of Ezrin-targeted cancer therapy for the betterment of human life.

Exosomal microRNAs derived from colon cancer cells promote tumor progression by suppressing fibroblast TP53 expression

The tumor microenvironment offers favorable conditions for tumor progression, and activated fibroblasts, known as cancer-associated fibroblasts, play a pivotal role. TP53-deficient cancer cells are known to induce strong fibroblast activation. We aimed to elucidate the oncogenic role of exosomes derived from TP53-deficient colon cancer cells in fibroblast proliferation and tumor growth. Cancer cell-derived exosomes (CDEs) were isolated from the conditioned media of cancer cells using a sequential ultracentrifugation method. The effects of exosomes on tumor growth were evaluated using human cell lines (TP53-WT colon cancer, HCT116; TP53-mutant colon cancer, HT29; and fibroblasts, CCD-18Co and WI-38) and an immune-deficient nude mouse xenograft model. HCT116 (HCT116^{sh p53} ) cells deficient in TP53 accelerated cocultured fibroblast proliferation compared to TP53-WT HCT116 (HCT116^{sh control} ) cells in vitro. Exosomes from HCT116^{sh p53} cells suppressed TP53 expression of fibroblasts and promoted their proliferation. Xenografts of HCT116^{sh p53} cells grew significantly faster than those of HCT116^{sh control} cells in the presence of co-injected fibroblasts, but this difference was diminished by CDE inhibition. Microarray analysis identified upregulation of several microRNAs (miR-1249-5p, miR-6737-5p, and miR-6819-5p) in TP53-deficient CDEs, which were functionally proven to suppress TP53 expression in fibroblasts. Exosomes derived from TP53-mutant HT29 cells also suppressed TP53 expression in fibroblasts and accelerated their growth. The proliferative effect of HT29 on cocultured fibroblasts was diminished by inhibition of these miRNAs in fibroblasts. Our results suggest that CDEs play a pivotal role in tumor progression by fibroblast modification. Cancer cell-derived exosomes might, therefore, represent a novel therapeutic target in colon cancer.

Abundant tumor promoting stromal cells in lung adenocarcinoma with hypoxic regions

OBJECTIVES

Carbonic anhydrase IX (CAIX) is a marker of hypoxia and its expression by cancer associated fibroblasts (CAFs) was reportedly associated with the poor prognosis of lung adenocarcinoma. This study aimed to characterize the hypoxic microenvironment containing CAIX (+) CAFs.

MATERIALS AND METHODS

First, we evaluated the clinicopathological significance of CAIX expression by CAFs in 3cm and above lung adenocarcinoma (n=188). We then compared the expressions of E-cadherin, ezrin, ALDH-1, CD44, EGFR, HSF-1, Glut-1, and PD-L1 in cancer cells, as well as those of CD204 and podoplanin in stromal cells between CAIX (+) CAFs and CAIX (-) CAFs cases (n=25, each).

RESULTS

In total, 48 patients had CAIX (+) CAFs (26%). Multivariate analysis revealed that CAIX expression by CAFs could serve as an independent unfavorable prognostic factor for recurrence-free survival (p<0.05). The staining score of hypoxia marker Glut-1 in cancer cells was significantly higher in cases with CAIX (+) CAFs than in those with CAIX (-) CAFs (median: 20 vs. 0, p<0.01). In addition, the numbers of CD204 (+) tumor-associated macrophages (TAMs) and podoplanin (+) CAFs were significantly higher in the CAIX (+) CAFs group than in the CAIX (-) CAFs group (TAMs: 31.5 vs. 17.0: p<0.01, CAFs: 20 vs. 0: p<0.05). The staining score of the other markers did not differ between the groups.

CONCLUSION

Our results indicate that the presence of abundant tumor promoting stromal cells, CD204 (+) TAMs, and podoplanin (+) CAFs is characteristic of the tumor microenvironment containing CAIX (+) CAFs, which contributes to an increase in aggressive behavior in lung adenocarcinoma with hypoxic regions.

Ezrin as a possible diagnostic and/or prognostic biomarker in mice lymphatic metastatic hepatocellular carcinoma in vivo

Hepatocellular carcinoma (HCC) ranks in the top of cancers leading to death. Early diagnosis is the big challenge in the case of HCC. Our in vitro study showed that Ezrin expression in lymphatic metastasis hepatocellular carcinoma (LNM-HCC) was associated with the metastatic rate. Here we aim to evaluate Ezrin expression as diagnostic and/or prognostic biomarker of LNM-HCC in mice. Chinese inbred 615 mice, Hca-F and Hca-P cell lines were used in the study. Histological changes were determined by Hematoxylin and Eosin, while Ezrin expression was assessed by qRT-PCR, western blot, immunohistochemistry, and enzyme-linked immunosorbent assay. Ezrin expression in this study gives credit to our in vitro study which Ezrin expression was positively correlated with LNM-HCC and negatively with Annexin7 (A7) expression. The highest histological changes were observed in high metastatic primary/secondary tumors combined with high Ezrin expression. Ezrin and A7 are higher in total primary tumors than in total secondary tumors (P = 0.0001, P = 0.021), respectively. Ezrin expression was enhanced in Hca-P A7 down-regulated primary/secondary tumors (P = 0.004), whereas, Ezrin expression was suppressed in Hca-F A7 upregulated primary/secondary tumors. Serum ELISA indicated differential expression of Ezrin among the study groups (P ≤ 0.0001). Ezrin expression was higher in NC-Hca-F than NC-Hca-P (P ≤ 0.0001), suppressed in Hca-F A7 upregulation (P ≤ 0.0001) and in enhanced in Hca-P A7 down-regulation (P = 0.0001). In conclusion, Ezrin level may serve as a differential diagnostic and/or prognostic biomarker for high and low LNM-HCC and may be beneficial in the diagnosis of HCC disease. © 2017 BioFactors, 43(5):662-672, 2017.

Microenvironmental changes in the progression from adenocarcinoma in situ to minimally invasive adenocarcinoma and invasive lepidic predominant adenocarcinoma of the lung

OBJECTIVES

Invasive lepidic predominant adenocarcinoma (LPA) of the lung is thought to progress in a stepwise fashion from adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA). The aim of this study was to investigate the microenvironmental changes during the development from AIS to LPA.

MATERIALS AND METHODS

Clinicopathological characteristics of AIS (n=51), MIA (n=59), LPA smaller than 3cm (LPA-S, n=113), and LPA larger than 3cm (LPA-L, n=47) were analyzed. We then evaluated the expression levels of epithelial-mesenchymal transition (EMT)-related molecules (E-cadherin, S100A4), invasion-related molecules (laminin-5, ezrin), stem-cell-related molecules (ALDH-1), and growth factor receptors (c-Met, EGFR) in cancer cells of each group (n=20). The number of tumor-promoting stromal cells, including podoplanin-positive cancer-associated fibroblasts (PDPN+ CAFs), CD204-positive tumor-associated macrophages (CD204+ TAMs), and CD34+ microvessel cells, were also analyzed.

RESULTS

No significant difference in these characteristics was found between LPA-S and LPA-L. Laminin-5 expression in the non-invasive carcinoma component of MIA was significantly higher than that of AIS (p<0.001). During the progression from MIA to LPA-S, the expression level of laminin-5 in the invasive carcinoma component was significantly elevated (p<0.01). Moreover, tumor-promoting stromal cells were more frequently recruited in the invasive area of LPA-S (PDPN+ CAFs; p<0.05, CD204+ TAMs; p<0.001, CD34+ microvessel; p<0.05). Ezrin expression in the invasive carcinoma component of LPA-L was significantly increased (p<0.05) compared to LPA-S; however, the number of tumor-promoting stromal cells were not different between these two groups.

CONCLUSION

Our current results indicated that microenvironmental molecular changes occur during the progression from MIA to LPA-S and suggested that this process may play an important role in disease progression from AIS to LPA.

The difference in Ezrin-pAkt signaling axis between lepidic and papillary predominant invasive adenocarcinomas of the lung

PURPOSE

Histologic classification of invasive lung adenocarcinomas by predominant subtype has prognostic value. Papillary predominant adenocarcinoma (PPA) reportedly shows poorer prognosis than lepidic predominant adenocarcinoma (LPA); however, biological differences between PPA and LPA are unclear. The purpose of this study was to clarify biological differences between PPA and LPA.

METHODS

Clinicopathological characteristics of invasive 62 PPAs and 117 LPAs smaller than 30 mm were investigated. Furthermore, we compared immunochemical staining scores of 9 molecular markers (E-cadherin, S100A4, fibronectin, integrinβ1, ezrin, GLUT1, ALDH1, SOX2 and Nanog) between PPA and LPA. We performed Western blot analysis using ezrin shRNA-knockdown lung adenocarcinoma cell lines to examine whether molecules that are highly expressed in PPA, such as ezrin, affect pAkt. Finally, we performed immunochemical staining to compare pAkt expression level in PPA and LPA.

RESULTS

Lymphovascular and pleural invasion and lymph node metastasis were significantly more often detected in PPA than in LPA (lymphatic permeation: 31 vs 3 %, vascular invasion: 35 vs 3 %, pleural invasion: 29 vs 5 %, lymph node metastasis: 18 vs 1 %; all P < 0.01). Immunohistochemical (IHC) study revealed that expression score of ezrin was significantly higher in PPA than in LPA (38.3 vs 15.0; P < 0.01). The level of pAkt decreased in shEzrin-induced PC-9 and A549 cancer cells. Moreover, the IHC staining score of pAkt was significantly higher in PPA than in LPA (13.3 vs 0.0; P < 0.01).

CONCLUSIONS

Our results show that the activation of the ezrin-pAkt signaling axis is associated with the more aggressive clinicopathological features of PPA compared with LPA.

Co-culture with podoplanin+ cells protects leukemic blast cells with leukemia-associated antigens in the tumor microenvironment

Podoplanin+ cells are indispensable in the tumor microenvironment. Increasing evidence suggests that podoplanin may support the growth and metastasis of solid tumors; however, to the best of our knowledge no studies have determined whether or not podoplanin serves a supportive role in acute myeloid leukemia (AML). The effects of co‑culture with podoplanin+ cells on the cellular activities of the leukemic cells, such as apoptosis and cell proliferation, in addition to the expression of podoplanin in leukemic cells, were investigated. Due to the fact that genetic abnormalities are the primary cause of leukemogenesis, the overexpression of the fibromyalgia‑like tyrosine kinase‑3 gene in colony forming units was also examined following cell sorting. Podoplanin+ cells were found to play a protective role against apoptosis in leukemic cells and to promote cell proliferation. Tumor‑associated antigens, including Wilms' tumor gene 1 and survivin, were increased when leukemic cells were co‑cultured with podoplanin+ cells. In combination, the present results also suggest that podoplanin+ cells can function as stromal cells for blast cell retention in the AML tumor microenvironment.

Podoplanin-expressing cancer-associated fibroblasts inhibit small cell lung cancer growth

Cancer-associated fibroblasts (CAFs) expressing podoplanin (PDPN) are a favorable prognosticator in surgically resected small cell lung cancer (SCLC). Here we explore whether CAFs expressing PDPN influence proliferation of SCLC cells. Compared with control group (SCLC cells co-cultured with CAFs-Ctrl), numbers of SCLC cells co-cultured with CAFs overexpressing PDPN were decreased. Suppression of PDPN expression by shRNA in CAFs resulted in increased numbers of SCLC cells. In surgically resected human SCLC specimens, the frequency of Geminin-positive cancer cells was significantly higher in the cases with PDPN-positive CAFs than in the cases with PDPN-negative CAFs. Thus CAFs expressing PDPN inhibit growth of SCLC cells, suggesting that CAFs expressing PDPN represent a tumor inhibitory stromal cell component in SCLC.