Recruitment of podoplanin positive cancer-associated fibroblasts in metastatic lymph nodes predicts poor prognosis in pathological N2 stage III lung adenocarcinoma

Identification of Cancer-Associated Fibroblasts in Metastatic Lymph Nodes of Colorectal Carcinoma

Cancer-associated fibroblasts (CAF) are a heterogeneous group of tumor microenvironment cells that are barely studied in metastatic lymph nodes. The presence of CAF in regional metastases of colorectal cancer was assessed by using SMA, PDGFRb, and POD markers; the obtained subpopulations were compared with the primary tumor. A total of 26 cases of colon adenocarcinoma with metastases to regional lymph nodes were studied. Duplex immunohistochemical detection (POD+SMA and PDGFRb+SMA) was carried out by the immunohistochemical method. In most cases, POD was absent in metastases (65.4%) and PDGFRb was present (88.5%). The POD and PDGFRb staining in the invasive edge of the tumor did not correlate with metastasis. Attention was drawn to the absence of POD and PDGFRb reactions in a blood vessel embolus, as well as to negative PDGFRb in metastasis in the presence of pronounced PDGFRb in the primary tumor in patients after neoadjuvant therapy.

Research Progress on Therapeutic Targeting of Cancer-Associated Fibroblasts to Tackle Treatment-Resistant NSCLC

Non-small cell lung cancer (NSCLC) accounts for most lung cancer cases and is the leading cause of cancer-related deaths worldwide. Treatment options for lung cancer are no longer limited to surgery, radiotherapy, and chemotherapy, as targeted therapy and immunotherapy offer a new hope for patients. However, drug resistance in chemotherapy and targeted therapy, and the low response rates to immunotherapy remain important challenges. Similar to tumor development, drug resistance occurs because of significant effects exerted by the tumor microenvironment (TME) along with cancer cell mutations. Cancer-associated fibroblasts (CAFs) are a key component of the TME and possess multiple functions, including cross-talking with cancer cells, remodeling of the extracellular matrix (ECM), secretion of various cytokines, and promotion of epithelial-mesenchymal transition, which in turn provide support for the growth, invasion, metastasis, and drug resistance of cancer cells. Therefore, CAFs represent valuable therapeutic targets for lung cancer. Herein, we review the latest progress in the use of CAFs as potential targets and mediators of drug resistance for NSCLC treatment. We explored the role of CAFs on the regulation of the TME and surrounding ECM, with particular emphasis on treatment strategies involving combined CAF targeting within the current framework of cancer treatment.

Cancer-associated fibroblasts in nonsmall cell lung cancer: From molecular mechanisms to clinical implications

Lung cancer is the common and leading cause of cancer death worldwide. The tumor microenvironment has been recognized to be instrumental in tumorigenesis. To have a deep understanding of the molecular mechanism of nonsmall cell lung carcinoma (NSCLC), cancer-associated fibroblasts (CAFs) have gained increasing research interests. CAFs belong to the crucial and dominant cell population in the tumor microenvironment to support the cancer cells. The interplay and partnership between cancer cells and CAFs contribute to each stage of tumorigenesis. CAFs exhibit prominent heterogeneity and secrete different kinds of cytokines and chemokines, growth factors and extracellular matrix proteins involved in cancer cell proliferation, invasion, metastasis and chemoresistance. Many studies focused on the protumorigenic functions of CAFs, yet many challenges about the heterogeneity of CAFS remain unresolved. This review comprehensively summarized the tumor-promoting role and molecular mechanisms of CAFs in NSCLC, including their origin, phenotypic changes and heterogeneity and their functional roles in carcinogenesis. Meanwhile, we also highlighted the updated molecular classifications based on the molecular features and functional roles of CAFs. With the development of cutting-edge platforms and further investigations of CAFs, novel therapeutic strategies for accurately targeting CAFs in NSCLC may be developed based on the increased understanding of the relevant molecular mechanisms.

Roles of Podoplanin in Malignant Progression of Tumor

Podoplanin (PDPN) is a cell-surface mucin-like glycoprotein that plays a critical role in tumor development and normal development of the lung, kidney, and lymphatic vascular systems. PDPN is overexpressed in several tumors and is involved in their malignancy. PDPN induces platelet aggregation through binding to platelet receptor C-type lectin-like receptor 2. Furthermore, PDPN modulates signal transductions that regulate cell proliferation, differentiation, migration, invasion, epithelial-to-mesenchymal transition, and stemness, all of which are crucial for the malignant progression of tumor. In the tumor microenvironment (TME), PDPN expression is upregulated in the tumor stroma, including cancer-associated fibroblasts (CAFs) and immune cells. CAFs play significant roles in the extracellular matrix remodeling and the development of immunosuppressive TME. Additionally, PDPN functions as a co-inhibitory molecule on T cells, indicating its involvement with immune evasion. In this review, we describe the mechanistic basis and diverse roles of PDPN in the malignant progression of tumors and discuss the possibility of the clinical application of PDPN-targeted cancer therapy, including cancer-specific monoclonal antibodies, and chimeric antigen receptor T technologies.

Screening and Identification of Key Genes for Activation of Islet Stellate Cell

Background

It has been demonstrated that activated islet stellate cells (ISCs) play a critical role in islet fibrogenesis and significantly contribute to the progression of type 2 diabetes mellitus. However, the key molecules responsible for ISCs activation have not yet been determined. This study aimed to identify the potential key genes involved in diabetes-induced activation of ISCs.

Method

Stellate cells were isolated from three 10-week-old healthy male Wistar rats and three Goto-Kakizaki (GK) rats. Cells from each rat were primary cultured under the same condition. A Genome-wide transcriptional sequence of stellate cells was generated using the Hiseq3000 platform. The identified differentially expressed genes were validated using quantitative real-time PCR and western blotting in GK rats, high fat diet (HFD) rats, and their controls.

Results

A total of 204 differentially expressed genes (DEGs) between GK. ISCs and Wistar ISCs (W.ISCs) were identified, accounting for 0.58% of all the 35,362 genes detected. After the Gene Ontology (GO) and Kyoto encyclopedia of genes and genomes (KEGG) enrichment analyses, the mRNA levels of these genes were further confirmed by real-time PCR in cultured ISCs. We then selected Fos, Pdpn, Bad as the potential key genes for diabetes-induced activation of ISCs. Finally, we confirmed the protein expression levels of FOS, podoplanin, and Bad by western blotting and immunofluorescence in GK rats, HFD rats, and their controls. The results showed that the expression level of FOS was significantly decreased, while podoplanin and Bad were significantly increased in GK.ISCs and HFD rats compared with controls, which were consistent with the expression of α-smooth muscle actin.

Conclusions

A total of 204 DEGs were found between the GK.ISCs and W.ISCs. After validating the expression of potential key genes from GK rats and HFD rats, Fos, Pdpn, and Bad might be potential key genes involved in diabetes-induced activation of ISCs.

Relationship between podoplanin-expressing cancer-associated fibroblasts and the immune microenvironment of early lung squamous cell carcinoma

AIM

Cancer-associated fibroblasts (CAFs) expressing podoplanin (PDPN) harbor a fibrous tumor microenvironment that promotes cancer progression in lung adenocarcinoma. In this study, we investigated whether tumor-promoting PDPN⁺ CAFs contribute to the immunosuppressive microenvironment in lung squamous cell carcinoma (SqCC). M&M: The gene expression profiles of immunosuppressive cytokines were compared using The Cancer Genome Atlas (TCGA) microarray lung SqCC data (n = 484) between a PDPN-high group and a PDPN-low group. Further, using patient-derived CAFs from surgically resected lung SqCC, the PDPN⁺ fraction was sorted and gene and protein expressions were analyzed. Finally, immunohistochemical staining was conducted on 131 surgically resected lung SqCC; CD8⁺ and FOXP3⁺ tumor infiltrating lymphocytes (TILs), and CD204⁺ tumor-associated macrophages (TAMs) were evaluated in cases with PDPN⁺ and PDPN^- CAFs.

RESULTS

Analysis of TCGA database revealed that the PDPN-high group exhibited significantly higher expression of interleukin (IL)-1A, IL-1B, IL-6, IL-10, monocyte chemoattractant protein-1 (CCL2), colony stimulating factor 1 (CSF1), fibroblast growth factor 2 (FGF2), galectin 1 (LGALS1), platelet derived growth factor subunit A (PDGFA), PDGFB, and transforming growth factor-β1 (TGFB1) than those in the PDPN-low group. Among them, it was found that TGFB1 expression was higher in patient-derived PDPN⁺ CAFs. Immunohistochemical analyses revealed that more CD204⁺ TAMs infiltrated the tumor tissues in cases with PDPN⁺ CAFs than in cases with PDPN^- CAFs (P <  0.03), while CD8⁺ and FOXP3⁺ TILs did not. Furthermore, in the same tumor, CD204⁺ TAMs infiltrated more in PDPN⁺ CAF-rich areas (P =  0.005).

CONCLUSION

PDPN⁺ CAFs showed higher expression of TGFB1 and were associated with CD204⁺ TAM infiltration in stage-I lung SqCC, suggesting that PDPN⁺ CAFs were associated with the immunosuppressive tumor microenvironment.

Cancer-Associated Fibroblasts: Accomplices in the Tumor Immune Evasion

Simple Summary

A growing number of studies suggest that cancer-associated fibroblasts (CAFs) modulate both myeloid and lymphoid cells through secretion of molecules (i.e., chemical function) and production of the extracellular matrix (ECM), i.e., physical function. Even though targeting functions CAFs is a relevant strategy, published clinical trials solely aimed at targeting the stroma showed disappointing results, despite being based on solid preclinical evidence. Our review dissects the interactions between CAFs and immune cells and explains how a deeper understanding of CAF subpopulations is the cornerstone to propose relevant therapies that will ultimately improve survival of patients with cancer.

Abstract

Cancer-associated fibroblasts (CAFs) are prominent cells within the tumor microenvironment, by communicating with other cells within the tumor and by secreting the extracellular matrix components. The discovery of the immunogenic role of CAFs has made their study particularly attractive due to the potential applications in the field of cancer immunotherapy. Indeed, CAFs are highly involved in tumor immune evasion by physically impeding the immune system and interacting with both myeloid and lymphoid cells. However, CAFs do not represent a single cell entity but are divided into several subtypes with different functions that may be antagonistic. Considering that CAFs are orchestrators of the tumor microenvironment and modulate immune cells, targeting their functions may be a promising strategy. In this review, we provide an overview of (i) the mechanisms involved in immune regulation by CAFs and (ii) the therapeutic applications of CAFs modulation to improve the antitumor immune response and the efficacy of immunotherapy.

Immunohistochemical analysis of cancer-associated fibroblasts and podoplanin in head and neck cancer

Background

To immunohistochemically evaluate the association between the presence of cancer-associated fibroblasts (CAFs) and the tumour expression of podoplanin (PDPN) in head and neck squamous cell carcinoma (HNSCC) and their association with clinicopathological variables.

Material and Methods

A tissue microarray (TMA) with biopsy sections from patients diagnosed with HNSCC was stained with antibodies against the CAFs marker, α-smooth muscle actin (α-SMA), and PDPN. We subsequently evaluated their expression to determine the association between them and with clinicopathological variables including age, primary tumour site, TNM stage, and tumour differentiation grade.

Results

Positive reaction to α-SMA was observed in the tumour stroma, revealing spindle-shaped cells compatible with CAFs, which showed a high expression in 62% of cases and a significant association with laryngeal carcinomas, advanced clinical stages, and lower tumour differentiation (P ≤ 0.05). PDPN staining on tumour cells showed low expression in 72% of cases, and it was not associated with any clinicopathological variable or with the presence of CAFs.

Conclusions

The presence of CAFs in the tumour stroma is related to an aggressive phenotype and could increase as the disease progresses, although based on our findings, it would have no relationship, at least directly, with the expression of PDPN.

Key words:Cancer-associated fibroblasts, myofibroblasts, head and neck neoplasms, podoplanin, immunohistochemistry.

[Cancer-associated fibroblasts and their significance in tumor progression]

Carcinogenesis and tumor progression are not caused not only by malignant epithelial cells, but also by the tumor stroma around cancer stem cells which performs regulatory, nutritional and 'framework' functions. It is represented by mesenchymal cells of various types predominantly by cancer-associated fibroblasts (CAF). αSMA, FAP-1, desmin, podoplanin, neuron-glial antigen 2 (NG2), PDGFR-α and -β are used for CAF identification but there is no universal markers due to the plasticity of the cell population that underlies the subpopulation division CAF. CAF subpopulations are not described for many tumor types. Recently, evidence has accumulated that CAFs mediate many adverse processes in the tumor, including can support stromal inflammation and cause fibrosis. By forming a niche in cancer stem cells, CAFs mediate chemoresistance and the appearance of dormant metastases. The study of the role of CAF will allow not only to form a fundamentally new understanding of the mechanisms of carcinogenesis, but also to create new diagnostic and therapeutic targets for treating tumors.

Desmoplasia in Lymph Node Metastasis of Pancreatic Adenocarcinoma Reveals Activation of Cancer-Associated Fibroblasts Pattern and T-helper 2 Immune Cell Infiltration

OBJECTIVES

Pancreatic ductal adenocarcinoma (PDAC) is characterized by a peritumoral proliferation of fibroblasts and extracellular matrix production known as desmoplasia. We aimed to study desmoplasia in PDAC lymph node (LN) metastases.

METHODS

We evaluated LNs from 66 patients with PDAC and LN metastases. We used immunohistochemistry and real-time polymerase chain reaction to phenotype the desmoplastic response.

RESULTS

Desmoplasia was identified in 57% of patients with LN metastases (Des+). Cancer-associated fibroblasts (CAFs) in Des+ expressed α-smooth muscle actin and collagen 11A1. The latter expression was present only in CAFs but not in LN stroma or in LN metastases without desmoplasia (Des-). Desmoplasia was associated with upregulation of transforming growth factor β messenger RNA. Whereas numbers of CD8+ in tumor vicinity were not different between Des+ and Des- patients (78 [standard deviation {SD}, 57] vs 92 [SD, 52], P = 0.48, respectively), the numbers of GATA-3+ cells, a marker of T-helper 2 immune response was significantly increased (3.7 [SD, 6.3] for Des+ vs 1.3 [SD, 2.7] for Des-, P < 0.05).

CONCLUSIONS

Lymph node desmoplasia is associated with CAF pattern activation and Th2 infiltration. Therapeutic modulation of desmoplasia may be relevant in the metastatic phase and influence antitumor immune response.

Prognostic impact of microscopic vessel invasion and visceral pleural invasion and their correlations with epithelial-mesenchymal transition, cancer stemness, and treatment failure in lung adenocarcinoma

OBJECTIVES

Microscopic vessel invasion (MVI) and visceral pleural invasion (VPI) have been recently reported as poor prognostic factors of non-small cell lung cancer. Epithelial-mesenchymal transition (EMT) and cancer stemness (CS) are known malignant phenotypes that induce resistance to cancer therapy. We aimed to assess the prognostic significance of MVI and the correlations among VPI/MVI, EMT, CS, and treatment failure for recurrent tumor.

MATERIALS AND METHODS

From 2002 to 2013, 1034 consecutive patients with pathological T1-4N0-2M0 lung adenocarcinoma underwent complete resection. Moreover, we established 206 tissue microarray (TMA) samples from 2002 to 2007. We then evaluated the prognostic impact of MVI, including conventional clinicopathological factors, and analyzed the VPI/MVI, EMT, CS, and treatment failure by TMA immunohistochemical staining.

RESULTS

Among the 1034 cases, the proportion of patients with a 5-year overall survival (OS) period was 63.9% and 88.2% (MVI: +/-; p < .001). Multivariate analysis revealed that both MVI and VPI were independent predictors of OS (HR 1.57 and 1.47, respectively). Significant separation of the OS rate curves was observed among the 3 groups [VPI/MVI: both positive (2), either positive (1), and both negative (0)]. Among the 206 TMA cases, these 3 groups of VPI/MVI were significantly correlated with EMT and CS. The median time to progression after recurrence were 3.8, 8.9, and 15.9 months, respectively (VPI/MVI: 2/1/0; p =  0.016).

CONCLUSION

MVI and VPI are significant prognostic factors of lung cancer, and they are correlated with EMT, CS, and treatment failure for recurrent tumor.

Podoplanin-positive cancer-associated fibroblasts predict poor prognosis in lung cancer patients

Background

Cancer-associated fibroblasts (CAFs) are a heterogeneous population, and different subpopulations play differential roles in tumor microenvironment. However, the prognostic role of podoplanin-positive CAFs in human lung cancer still remains controversial.

Methods

Herein, we performed a meta-analysis including 12 published studies with 1,802 patients identified from PubMed and EBSCO to assess the prognostic impact of podoplanin-positive CAFs in lung cancer patients.

Results

We found that podoplanin⁺ fibroblast infiltration significantly decreased overall survival (OS), disease-free survival (DFS), and progression-free survival in patients. In stratified analyses, podoplanin⁺ fibroblast infiltration was significantly associated with worse OS and DFS in both squamous cell carcinoma and adenocarcinoma of lung. In addition, high density of podoplanin-positive CAFs significantly correlated with unfavorable clinicopathological features such as lymph node metastasis, and lymphatic, vascular, and pleural invasion of patients.

Conclusion

Podoplanin⁺ fibroblast infiltration leads to worse clinical outcome in lung cancer patients, implicating that it is a valuable prognostic biomarker and targeting it may have a potential for effective treatment.

Generation of sphingosine-1-phosphate is enhanced in biliary tract cancer patients and is associated with lymphatic metastasis

Lymphatic metastasis is known to contribute to worse prognosis of biliary tract cancer (BTC). Recently, sphingosine-1-phosphate (S1P), a bioactive lipid mediator generated by sphingosine kinase 1 (SPHK1), has been shown to play an important role in lymphangiogenesis and lymph node metastasis in several types of cancer. However, the role of the lipid mediator in BTC has never been examined. Here we found that S1P is elevated in BTC with the activation of ceramide-synthetic pathways, suggesting that BTC utilizes SPHK1 to promote lymphatic metastasis. We found that S1P, sphingosine and ceramide precursors such as monohexosyl-ceramide and sphingomyelin, but not ceramide, were significantly increased in BTC compared to normal biliary tract tissue using LC-ESI-MS/MS. Utilizing The Cancer Genome Atlas cohort, we demonstrated that S1P in BTC is generated via de novo pathway and exported via ABCC1. Further, we found that SPHK1 expression positively correlated with factors related to lymphatic metastasis in BTC. Finally, immunohistochemical examination revealed that gallbladder cancer with lymph node metastasis had significantly higher expression of phospho-SPHK1 than that without. Taken together, our data suggest that S1P generated in BTC contributes to lymphatic metastasis.

Fibrosis in metastatic lymph nodes is clinically correlated to poor prognosis in colorectal cancer

Background

Tumor microenvironment including fibrosis has a pivotal role in cancer growth and distant metastasis. Fibrosis is a known risk factor for carcinogenesis, but its biological role in disease invasion and metastasis in colorectal cancer (CRC) remains unclear. In particular, there is no report on how fibrosis of metastatic lymph nodes (MLNs) in CRC contributes to prognosis.

Methods

We reviewed 94 colorectal adenocarcinoma patients with MLNs who underwent colectomy. Both the primary tumors and MLNs were analyzed for alpha-smooth muscle actin (α-SMA) expression and collagen deposition.

Results

Higher α-SMA expression and collagen deposition in MLNs were associated with significantly shorter relapse-free survival and overall survival in CRC patients. α-SMA expression in MLNs (HR, 1.53; p = 0.034) was independent predictive factor of overall survival in multivariate Cox proportional hazards regression analysis of clinicopathological factors. In the Stage III patient subgroup, α-SMA expression in MLNs was a strong prognostic marker (HR, 3.01; p = 0.006). On the other hand, higher α-SMA expression and collagen deposition in primary tumors were associated with short overall survival, but they were not significant factors in multivariate Cox regression analyses. In MLNs, the podoplanin signals co-localized with α-SMA expression and were confirmed by the dual immunofluorescence staining, implying that the MLN stromal cells were fibroblastic reticular cells.

Conclusion

Both high collagen deposition and high α-SMA expression in MLNs predicted poor prognosis in CRC.

Tissue analyses reveal a potential immune-adjuvant function of FAP-1 positive fibroblasts in non-small cell lung cancer

Objectives

Selective targeting of cancer-associated fibroblasts (CAFs) has been proposed to synergize with immune-checkpoint inhibitors. While the roles of CAFs in cancer development are well described, their immune-regulatory properties remain incompletely understood. This study investigates correlations between CAF and immune-markers in tumor stroma from non-small cell lung cancer (NSCLC) patients, and examines whether a combination of CAF and immune cell scores impact patient prognosis.

Methods

Tumor specimens from 536 primary operable stage I-III NSCLC patients were organized in tissue microarrays. Expression of protein-markers was evaluated by immunohistochemistry.

Results

Fibroblast and stromal markers PDGFRα, PDGFRβ, FAP-1 and vimentin showed weak correlations while αSMA, and Masson’s trichrome did not correlate with any of the investigated markers. Hierarchical clustering indicated the existence of different CAF-subsets. No relevant correlations were found between any CAF-marker and the immune-markers CD3, CD4, CD8, CD20, CD68, CD1a, CD56, FoxP3 and CD45RO. High density of fibroblast-activation protein positive mesenchymal cells (CAF^FAP) was associated with better prognosis in tumors with high infiltration of CD8 and CD3 T-lymphocytes.

Conclusions

The presented data suggest that CAFs, irrespective of identity, have low influence on the degree of tumor infiltration by inflammatory- and/or immune-cells. However, CAF^FAP may exert immuno-adjuvant roles in NSCLC, and targeting CAFs should be cautiously considered.

Thy-1+ Cancer-associated Fibroblasts Adversely Impact Lung Cancer Prognosis

Cancer-associated fibroblasts (CAFs) regulate diverse intratumoral biological programs and can promote or inhibit tumorigenesis, but those CAF populations that negatively impact the clinical outcome of lung cancer patients have not been fully elucidated. Because Thy-1 (CD90) marks CAFs that promote tumor cell invasion in a murine model of Kras^G12D-driven lung adenocarcinoma (Kras^LA1), here we postulated that human lung adenocarcinomas containing Thy-1⁺ CAFs have a worse prognosis. We first examined the location of Thy-1⁺ CAFs within human lung adenocarcinomas. Cells that co-express Thy-1 and α-smooth muscle actin (αSMA), a CAF marker, were located on the tumor periphery surrounding collectively invading tumor cells and in perivascular regions. To interrogate a human lung cancer database for the presence of Thy-1⁺ CAFs, we isolated Thy-1⁺ CAFs and normal lung fibroblasts (LFs) from the lungs of Kras^LA1 mice and wild-type littermates, respectively, and performed global proteomic analysis on the murine CAFs and LFs, which identified 425 proteins that were differentially expressed. Used as a probe to identify Thy-1⁺ CAF-enriched tumors in a compendium of 1,586 lung adenocarcinomas, the presence of the 425-gene signature predicted a significantly shorter survival. Thus, Thy-1 marks a CAF population that adversely impacts clinical outcome in human lung cancer.

CCR7 promote lymph node metastasis via regulating VEGF-C/D-R3 pathway in lung adenocarcinoma

Lymph node metastasis is still an important issue in metastatic process of lung adenocarcinoma. C-C chemokine receptor 7 (CCR7) has been proved to be closely associated with the metastasis of lung adenocarcinoma, and the mechanism is poorly understood. In order to investigate the relationship between CCR7 and lymph node metastasis in lung adenocarcinoma, and to explore the role of CCR7 in treating lung adenocarcinoma, 40 clinical specimens were collected to define the relationship between CCR7 and lymph node metastasis in lung adenocarcinoma by immunohistochemistry. The siRNA was used to suppress CCR7 expression in A549 cells. The scratch test, transwell test, qRT-PCR, western blot, flow cytometry and immunofluorescence were used to investigate the lymph node metastasis-related function of CCR7 in vitro. The athymic mice subcutaneous injection was used to research lung adenocarcinoma formation in vivo. Clinical case studies show that higher expression of CCR7 in lung adenocarcinoma tissues was associated with a higher lymph node metastasis. Inhibition of expression of CCR7 can reduce the migration and invasion and suppress the expression of VEGF-C, VEGF-D and VEGF-R3 in vitro and in vivo. Moreover, CCR7 silence also suppressed WNT and p-ERK pathways in vitro. All the results indicate that CCR7 can promote lymph node metastasis in lung adenocarcinoma by regulating VEGF-C/D-R3 pathway. Thus CCR7 is proposed to be a potential prediction for poor prognosis of lung adenocarcinoma, and a therapeutic target for lymph node metastasis.

Podoplanin expression is correlated with the prognosis of lung squamous cell carcinoma

Podoplanin is a 38 kDa transmembrane protein that is involved in cell migration and cancer cell invasion. Some studies have reported that podoplanin expression was correlated with poor prognosis in lung squamous cell carcinoma (SqCC). However, there have been no clinicopathological studies of podoplanin membrane expression and localization in lung SqCC. In this study, we focused on the intensity and localization of podoplanin membrane expression, and its clinicopathological significance for lung SqCC. Strong membrane expression of podoplanin was significantly associated with lymph node metastasis, lymphatic invasion, and histological differentiation. Cases with strong podoplanin expression at cell membrane showed better prognosis of lung SqCC (HR, 3.301). Peripheral localization of podoplanin was associated with tumor size, lymphatic invasion, and histological differentiation. Cases with peripheral podoplanin expression showed favorable prognosis of lung SqCC (HR, 2.830). Both strong membrane expression and peripheral expression of podoplanin were independent predictors of mortality of lung SqCC (HR, 2.869; HR, 2.443, respectively). The cases with strong or peripheral podoplanin expression showed better overall survival (P = 0.001, both). Podoplanin intensity is significantly associated with podoplanin localization (P < 0.001), and its correlation coefficient was 0.678. We concluded that podoplanin membrane expression, not only its localization, is a useful prognostic indicator of lung SqCC patients.

Cancer Associated Fibroblasts in Stage I-IIIA NSCLC: Prognostic Impact and Their Correlations with Tumor Molecular Markers

Background

Cancer Associated Fibroblasts (CAFs) are thought to regulate tumor growth and metastasis. Fibroblast Activating Protein 1 (FAP-1) is a marker for fibroblast activation and by many recognized as the main marker of CAFs. Alpha Smooth Muscle Actin (α-SMA) is a general myofibroblast marker, and can be used to identify CAFs. This study investigates the prognostic impact of FAP-1 and α-SMA in non-small cell lung cancer (NSCLC) patients and correlates their expression to 105 proteins investigated in the same cohort.

Methods

Tumor specimens from 536 NSCLC patients were obtained and tissue micro-arrays were constructed. Immunohistochemistry was used to evaluate the expression of FAP-1 and α-SMA and explore their impact on survival and association with other tumor molecular markers in NSCLC patients.

Results

High expression of FAP-1, but not α-SMA, in squamous cell carcinoma (SCC, P = 0.043, HR = 0.63 95% CI 0.40–0.99) was significantly associated with increased disease-specific survival. FAP-1 and α-SMA were not significantly correlated to each other. Analyses of FAP-1 and α-SMA associated with other tumor-related proteins revealed histotype-specific correlation patterns.

Conclusion

The presence of FAP-1 expressing CAFs is an indicator of positive outcome for NSCLC-SCC patients. In addition, correlation analyses suggest FAP-1 and α-SMA to label different subsets of fibroblasts and their associations with other tumor-related proteins diverge according to histological subtype.

PKA and CDK5 can phosphorylate specific serines on the intracellular domain of podoplanin (PDPN) to inhibit cell motility

Podoplanin (PDPN) is a transmembrane glycoprotein that promotes tumor cell migration, invasion, and cancer metastasis. In fact, PDPN expression is induced in many types of cancer. Thus, PDPN has emerged as a functionally relevant cancer biomarker and chemotherapeutic target. PDPN contains 2 intracellular serine residues that are conserved between species ranging from mouse to humans. Recent studies indicate that protein kinase A (PKA) can phosphorylate PDPN in order to inhibit cell migration. However, the number and identification of specific residues phosphorylated by PKA have not been defined. In addition, roles of other kinases that may phosphorylate PDPN to control cell migration have not been investigated. We report here that cyclin dependent kinase 5 (CDK5) can phosphorylate PDPN in addition to PKA. Moreover, results from this study indicate that PKA and CDK5 cooperate to phosphorylate PDPN on both intracellular serine residues to decrease cell motility. These results provide new insight into PDPN phosphorylation dynamics and the role of PDPN in cell motility. Understanding novel mechanisms of PDPN intracellular signaling could assist with designing novel targeted chemotherapeutic agents and procedures.

Podoplanin-expressing cancer-associated fibroblasts lead and enhance the local invasion of cancer cells in lung adenocarcinoma

Cancer-associated fibroblasts (CAFs) communicate with cancer cells and play important roles in cancer invasion. We previously reported that local invasion of cancer cells was frequently observed in lung adenocarcinoma patients with podoplanin (PDPN)-expressing CAFs. However, the underlying mechanisms of this phenomenon have remained unclear. In this study, we established a novel collagen invasion assay model in which cancer cells and CAFs were cocultured; we analyzed the mechanisms governing how cancer cell invasion was promoted by PDPN(+)CAFs. By observing the dynamic movement of both CAFs and cancer cells in the collagen matrix, we found that PDPN(+)CAFs invaded the matrix to a greater extent, with more cancer cells invading within the "tracks" created by the CAFs, compared with control CAFs. The knockdown of PDPN in CAFs decreased the invasion of both the CAFs and the cancer cells. PDPN(+)CAFs displayed a higher RhoA activity and treatment with a ROCK inhibitor cancelled the increased invasion ability of PDPN(+)CAFs and subsequently decreased the number of invaded cancer cells. After intravenous injection in the mouse tail vein, PDPN(+)CAFs invaded and promoted cancer cell invasion into the lung parenchyma, compared with control CAFs. Among the patients with lung adenocarcinoma, we observed some cases with PDPN(+)CAFs at the invasive front of the tumor. These cases predominantly exhibited pleural invasion of cancer cells, known as pathological invasiveness. Our results indicated that PDPN(+)CAFs were tumor-promoting CAFs that lead and enhance the local invasion of cancer cells, suggesting that the invasion activity of CAFs themselves could be rate-determining for cancer cell invasion.

Comparison of the expression levels of molecular markers among the peripheral area and central area of primary tumor and metastatic lymph node tumor in patients with squamous cell carcinoma of the lung

PURPOSE

Immunohistochemical analysis for the identification of clinically relevant biomarkers is important. However, there have been no detailed reports about the heterogeneous expressions of the various markers in squamous cell carcinoma of the lung.

METHODS

A total of 113 patients with squamous cell carcinoma of the lung with lymph node metastasis were included. The expression levels of 9 molecules (E-cadherin, S100A4, CD44, ALDH1, SOX2, EGFR, HER2, FGFR1 and VEGFR2) in the peripheral area and central area of primary tumor and metastatic lymph nodes were evaluated by immunohistochemistry. The differences in the staining scores of these molecules among the three areas were assessed. We also analyzed the relationships between the expression levels of these molecules and the recurrence-free survival.

RESULTS

The E-cadherin expression was higher in the central area than in the peripheral area and metastatic lymph nodes (median staining score: 60 vs. 50, 30); the CD44 expression was higher in the central area than in the metastatic lymph nodes (117 vs. 90); and the EGFR expression was higher in the central area than in the peripheral area and metastatic lymph nodes (163 vs. 130, 110). Low CD44 expression in the central area, low EGFR expression in the peripheral area and high SOX2 expression in the metastatic lymph nodes were associated with a shorter recurrence-free survival (p < 0.01, p = 0.02, p = 0.03, respectively).

CONCLUSIONS

Our findings confirmed that some molecular markers exhibited different expression levels in anatomically different areas and suggested that area-by-area immunohistochemical analysis for biomarkers may provide useful information for more precise prediction of the recurrence.

Podoplanin-positive cancer-associated fibroblasts in the tumor microenvironment induce primary resistance to EGFR-TKIs in lung adenocarcinoma with EGFR mutation

PURPOSE

The biologic characteristics of microenvironmental constituents, especially cancer-associated fibroblasts (CAF), can be key regulators of the cellular sensitivity to molecular-targeted therapy. Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKI) have marked therapeutic effects against non-small cell lung cancer (NSCLC) with EGFR mutations, but some patients have exhibited primary resistance to EGFR-TKIs. We recently reported that podoplanin-positive fibroblasts are associated with a tumor-promoting phenotype of CAFs in lung adenocarcinoma. The aim of this study was to evaluate whether the susceptibility of NSCLC to EGFR-TKIs could be affected by podoplanin-expressing CAFs.

EXPERIMENTAL DESIGN

We evaluated the EGFR-TKI sensitivity of EGFR-mutant lung adenocarcinoma cell lines cocultured with podoplanin-expressing CAFs. We also examined the association between the expression of podoplanin in CAFs in surgical specimens and EGFR-TKI response of postoperative recurrent patients with EGFR mutations (N = 106).

RESULTS

Lung adenocarcinoma cell lines became more resistant to EGFR-TKI when cocultured with podoplanin-expressing CAFs, compared with control CAFs in vitro. The knockdown of podoplanin expression on CAFs cancelled the resistance to EGFR-TKIs in cancer cells. Compared with control CAFs, the cancer cells that were cocultured with podoplanin-positive CAFs continued to exhibit significantly higher p-ERK levels after treatment with gefitinib. Furthermore, postoperative recurrent patients with podoplanin-positive CAFs had a significantly lower overall response rate to EGFR-TKIs compared with those with podoplanin-negative CAFs (53% vs. 83%; P < 0.01).

CONCLUSIONS

Podoplanin-positive CAFs play an important role in primary resistance to EGFR-TKIs and may be an ideal therapeutic target for use in combination therapy with EGFR-TKIs.

Podoplanin expressing cancer-associated fibroblasts in oral cancer

Podoplanin is a mucin-type glycoprotein widely used as a lymphatic endothelial marker. It is well known that podoplanin is expressed in various neoplasms including oral squamous cell carcinoma (OSCC). Apart from podoplanin expression in cancer cells, recent studies have suggested that podoplanin expression in stromal cancer-associated fibroblasts (CAFs) may be an indicator of poor prognosis in various cancers. In the present study, we performed immunohistochemical analyses of podoplanin and alpha-smooth muscle actin (α-SMA) in OSCC in order to clarify the significance of podoplanin-positive CAFs. Paraffin-embedded tissue specimens of 69 primary and 29 corresponding metastatic lesions in lymph nodes were examined immunohistochemically using antibodies against podoplanin and α-SMA. Podoplanin-positive stromal fibroblasts were detected in 51 (73.9%) of the 69 primary OSCCs and 24 (82.8%) of the 29 lymph nodes metastases. α-SMA immunoreactivity was observed in 39 (56.5%) of the primaries and 24 (82.8%) of the metastases. Further examination showed that 38 (74.5%) of the primary lesions and 23 (95.8%) of the metastases with podoplanin positivity were also positive for α-SMA. In addition, the intensity of α-SMA immunoreactivity increased as that of podoplanin became stronger. Podoplanin-positive CAFs are considered to be myofibroblasts that may contribute to progression of oral cancer.

Prognostic significance of epithelial-mesenchymal transition-related markers in extrahepatic cholangiocarcinoma: comprehensive immunohistochemical study using a tissue microarray

Background:

Epithelial–mesenchymal transition (EMT) is characterised by the loss of cell-to-cell adhesion and gaining of mesenchymal phenotypes. Epithelial–mesenchymal transition is proposed to occur in various developmental processes and cancer progression. ‘Cadherin switch', a process in which cells shift to express different isoforms of the cadherin transmembrane protein and usually refers to a switch from the expression of E-cadherin to N-cadherin, is one aspect of EMT and can have a profound effect on tumour invasion/metastasis. The aim of this study was to investigate the clinicopathological significance of EMT-related proteins and cadherin switch in extrahepatic cholangiocarcinoma (EHCC).

Methods:

We investigated the association between altered expression of 12 EMT-related proteins and clinical outcomes in patients with EHCC (n=117) using immunohistochemistry on tissue microarrays.

Results:

Univariate and multivariate analyses revealed that, in addition to N classification (P=0.0420), the expression of E-cadherin (P=0.0208), N-cadherin (P=0.0038) and S100A4 (P=0.0157) was each an independent and a significant prognostic factor. We also demonstrated that cadherin switch was independently associated with poor prognosis (P=0.0143) in patients with EHCC.

Conclusions:

These results may provide novel information for selection of patients with EHCC who require adjuvant therapy and strict surveillance.

Immunophenotypic features of metastatic lymph node tumors to predict recurrence in N2 lung squamous cell carcinoma

Patients with mediastinal lymph node metastasis (N2) in squamous cell carcinoma (SqCC) of the lung have poor prognosis after surgical resection of the primary tumor. The aim of this study was to clarify predictive factors of the recurrence of pathological lung SqCC with N2 focusing on the biological characteristics of both cancer cells and cancer-associated fibroblasts (CAFs) in primary and metastatic lymph node tumors. We selected 64 patients with pathological primary lung N2 SqCC who underwent surgical complete resection and investigated the expressions of four epithelial–mesenchymal transition-related markers (caveolin, clusterin, E-cadherin, ZEB2), three cancer stem cell-related markers (ALDH-1, CD44 variant6, podoplanin) of cancer cells, and four markers of CAFs (caveolin, CD90, clusterin, podoplanin) in both primary and matched metastatic lymph node tumors in the N2 area. In the primary tumors, the expressions of all the examined molecules were not related to recurrence. However, in the metastatic lymph node tumors, high clusterin and ZEB2 expressions in the cancer cells and high podoplanin expression in the CAFs were significantly correlated with recurrence (P = 0.03, 0.04, and 0.007, respectively). In a multivariate analysis, only podoplanin expression in the CAFs in metastatic lymph node tumors was identified as a significantly independent predictive factor of recurrence (P = 0.03). Our study indicated that the immunophenotypes of both cancer cells and CAFs in metastatic lymph node tumors, but not primary tumors, provide useful information for predicting the recurrence of pathological N2 lung SqCC.

Significance of podoplanin expression in cancer-associated fibroblasts: a comprehensive review

Cancer-associated fibroblasts (CAFs) are well-known to be part of the tumor microenvironment. This heterogeneous population of cells of the tumor microenvironment via secretion of various growth factors and cytokines was shown to contribute to increased cancer cell proliferation rate, migration, invasiveness and other key processes such as angiogenesis and lymphangiogenesis. Recent studies identified podoplanin as a marker of CAFs in various malignancies and its expression in these cells was shown to influence cancer progression. In some studies it yielded a prognostic impact on patient survival which was strongly dependent on the entity of the tumor. This review summarizes recent findings concerning the biology of podoplanin in cancer progression with particular emphasis on its expression in CAFs.

Podoplanin expressing cancer associated fibroblasts are associated with unfavourable prognosis in adenocarcinoma of the esophagus

Overexpression of the mucin-type sialoglycoprotein podoplanin in cancer associated fibroblasts (CAFs) was recently shown to be associated with tumor progression, metastasis and poor prognosis in lung and breast cancer. Here we investigate the role of podoplanin expressing CAFs in esophagal adenocarcinoma (AC), its precursor lesions and metastases. Podoplanin expression was investigated immunohistochemically in 200 formalin-fixed, paraffin embedded specimens of invasive esophagal ACs, their corresponding metastases and 35 precursor lesions. Podoplanin expressing CAFs (CAF+) were observed in 22 % of patients with invasive AC, but not in precursor lesions. CAF+ correlated with tumor stage (p = 0.004), lymphovascular tumor invasion (p = 0.018) and lymph node metastasis (p = 0.0016). Patients with CAF+ had a significant shorter disease free and overall survival (p < 0.05, Cox regression). Podoplanin expressing CAFs were only rarely observed in lymph node and distant metastases, as well as in local recurrences of ACs. Podoplanin expression in AC tumor cells was seen in only four cases. In around 20 % of patients with esophagal AC, podoplanin expressing CAFs are evident, defining a high risk subgroup. In these patients, podoplanin expressing CAFs might represent new therapeutical targets.