Increased expression and serum levels of the stromal cell‐secreted protein periostin in breast cancer bone metastases

Periostin, a matricellular protein, is overexpressed in the stroma of several cancers. The aim of our study was to investigate more specifically whether periostin expression is associated with bone metastases from breast cancer and to determine its source in the affected bone. Nude mice were inoculated with human MDA‐B02 breast cancer cells. Bone metastases‐bearing mice were treated with zoledronic acid—an antiresorptive drug—or vehicle. Bone metastases were examined for tumor‐ and stroma‐derived periostin expression by quantitative polymerase chain reaction with human‐ and mouse‐specific primers and immunohistochemistry. Serum periostin and conventional bone turnover markers were also measured. MDA‐B02 cells did not express periostin both in vitro and in vivo. However, mouse‐derived periostin was markedly overexpressed (eightfold) in metastatic legs compared to noninoculated mice. Serum periostin levels were also markedly increased in metastatic mice and correlated with in situ expression levels. Immunostaining showed that periostin derived from the environing stromal cells of bone metastasis. Bone turnover blockade by zoledronic acid markedly decreased osteolytic lesions but only slightly modulated serum periostin levels. Bone metastases from breast cancer induce overexpression of periostin by surrounding stromal cells. Periostin could be a biochemical marker of the early stromal response associated to breast cancer bone metastasis formation.     

Hyperthermia‐treated mesenchymal stem cells exert antitumor effects on human carcinoma cell line

BACKGROUND:

Mesenchymal stem cells (MSCs) possess the potential for differentiation into multilineages. MSCs have been reported to play a role as precursors for tumor stroma in providing a favorable environment for tumor progression. Hyperthermia destroys cancer cells by raising the temperature of tumor‐loaded tissue to 40°C to 43°C and causes indirect sensitizing effects when combined with chemo‐ and/or radiotherapy. However, how hyperthermia affects the tumor‐supportive stroma is unknown. Here, the authors investigated the effects of hyperthermia‐treated MSCs, from different sources, on the human ovarian cancer cell line SK‐OV‐3.

METHODS:

MSCs from adipose tissue and amniotic fluid were untreated or heat‐treated (HS‐MSCs). The culture supernatant of each treatment group was collected and transferred to the SK‐OV‐3 cells.

RESULTS:

The morphological analysis and cell proliferation assay showed a reduced viability of the tumor cells in the conditioned medium with the HS‐MSCs. Further investigations revealed that the conditioned medium of the HS‐MSCs induced a higher nuclear condensation and a greater number of sub‐G1 cells among the tumor cells. Analysis of the mRNA expression demonstrated that the conditioned medium of the HS‐MSCs induced up‐regulation or down‐regulation of several tumor‐associated molecules. Finally, the cytokine array of each conditioned medium showed that angiogenin, insulin‐like growth factor binding protein 4, neurotrophin 3, and chemokine (C‐C motif) ligand 18 are involved as main factors.

CONCLUSIONS:

This study showed that the conditioned medium of the HS‐MSCs exerted a suppressive effect on tumor progression and malignancy, suggesting that hyperthermia enables tumor stromal cells to provide a sensitizing environment for tumor cells to undergo cell death. Cancer 2009. © 2009 American Cancer Society.     

Loss of HSulf‐1 expression enhances tumorigenicity by inhibiting Bim expression in ovarian cancer

The expression of human Sulfatase1 (HSulf‐1) is downregulated in the majority of primary ovarian cancer tumors, but the functional consequence of this downregulation remains unclear. Using two different shRNAs (Sh1 and Sh2), HSulf‐1 expression was stably downregulated in ovarian cancer OV202 cells. We found that HSulf‐1‐deficient OV202 Sh1 and Sh2 cells formed colonies in soft agar. In contrast, nontargeting control (NTC) shRNA‐transduced OV202 cells did not form any colonies. Moreover, subcutaneous injection of OV202 HSulf‐1‐deficient cells resulted in tumor formation in nude mice, whereas OV202 NTC cells did not. Also, ectopic expression of HSulf‐1 in ovarian cancer SKOV3 cells significantly suppressed tumor growth in nude mice. Here, we show that HSulf‐1‐deficient OV202 cells have markedly decreased expression of proapoptotic Bim protein, which can be rescued by restoring HSulf‐1 expression in OV202 Sh1 cells. Enhanced expression of HSulf‐1 in HSulf‐1‐deficient SKOV3 cells resulted in increased Bim expression. Decreased Bim levels after loss of HSulf‐1 were due to increased p‐ERK, because inhibition of ERK activity with PD98059 resulted in increased Bim expression. However, treatment with a PI3 kinase/AKT inhibitor, LY294002, failed to show any change in Bim protein level. Importantly, rescuing Bim expression in HSulf‐1 knockdown cells significantly retarded tumor growth in nude mice. Collectively, these results suggest that loss of HSulf‐1 expression promotes tumorigenicity in ovarian cancer through regulating Bim expression.     

Induction of Invasive Growth in a Gallbladder Cancer Cell Line by Hepatocyte Growth Factor in vitro

To study the mechanism of invasion and metastasis of gallbladder cancer cells, we established a cancer cell line, GB-d1, from a metastatic lymphnode of poorly differentiated adenocarcinoma of the gallbladder. GB-d1 cells proliferate well in a dish culture and form small cystic cell clusters in a collagen gel containing 10% fetal bovine serum. A conditioned medium of human embryonic lung fibroblasts (HEL) stimulated the proliferation of GB-d1 cells and induced cell scattering in the dish culture. In the gel culture, the conditioned medium induced a transformation of the spherical clusters to arborizating colonies with tubular projections that mimicked an invasion of cancer cells into the surrounding tissue. Similar results were obtained when 10 ng/ml of human recombinant hepatocyte growth factor (h-rHGF) was added to the culture medium. The proliferative and morphological changes induced by the conditioned medium were inhibited by antiserum against h-rHGF. HEL and human gallbladder stromal fibroblast-like cells produced substantial levels of HGF in the culture media, while GB-d1 did not produce any detectable level of HGF. These results suggest that HGF promotes the invasive growth of gallbladder cancer cells in vitro , and it was also suggested that stromal fibroblasts may play an important role in the invasive progression of gallbladder cancer in a paracrine fashion.     

Cross‐talk between ovarian cancer cells and macrophages through periostin promotes macrophage recruitment

Tumor‐associated macrophages (TAMs) contribute to tumor progression, but it is not clear how they are recruited to tumor sites. Here we showed that periostin (POSTN) was present at high levels in ovarian cancer ascetic fluids and was correlated with CD163⁺ TAMs. The high POSTN level and macrophage infiltration were inversely associated with relapse‐free survival for ovarian cancer patients. In vitro studies showed that coculture with macrophages significantly increased POSTN production in ovarian cancer cells. Further investigation found that POSTN production in ovarian cancer cells was promoted by transforming growth factor‐β generated by macrophages. Moreover, siRNA of POSTN and POSTN neutralizing antibody treatment showed that ovarian cancer cell‐derived POSTN promoted the recruitment of macrophages and modulated their cytokine secretion profile. Collectively, these data indicated that POSTN was an important factor for macrophage recruitment in the tumor microenvironment and is involved in the interactions between macrophages and ovarian cancer cells.     

Inhibition of Nox4‐dependent ROS signaling attenuates prostate fibroblast activation and abrogates stromal‐mediated protumorigenic interactions

Carcinoma‐associated fibroblasts (CAFs) play a key onco‐supportive role during prostate cancer (PCa) development and progression. We previously reported that the reactive oxygen species (ROS)‐producing enzyme NADPH oxidase 4 (Nox4) is essential for TGFβ1‐mediated activation of primary prostate human fibroblasts to a CAF‐like phenotype. This study aimed to further investigate the functional relevance of prostatic Nox4 and determine whether pharmacological inhibition of stromal Nox4 abrogates paracrine‐mediated PCa‐relevant processes. RNA in situ hybridization revealed significantly elevated Nox4 mRNA levels predominantly in the peri‐tumoral stroma of clinical PCa with intense stromal Nox4 staining adjacent to tumor foci expressing abundant TGFβ protein levels. At pharmacologically relevant concentrations, the Nox1/Nox4 inhibitor GKT137831 attenuated ROS production, CAF‐associated marker expression and migration of TGFβ1‐activated but not nonactivated primary human prostate fibroblasts. Similar effects were obtained upon shRNA‐mediated silencing of Nox4 but not Nox1 indicating that GKT137831 primarily abrogates TGFβ1‐driven fibroblast activation via Nox4 inhibition. Moreover, inhibiting stromal Nox4 abrogated the enhanced proliferation and migration of PCa cell lines induced by TGFβ1‐activated prostate fibroblast conditioned media. These effects were not restricted to recombinant TGFβ1 as conditioned media from PCa cell lines endogenously secreting high TGFβ1 levels induced fibroblast activation in a stromal Nox4‐ and TGFβ receptor‐dependent manner. Importantly, GKT137831 also attenuated PCa cell‐driven fibroblast activation. Collectively, these findings suggest the TGFβ‐Nox4 signaling axis is a key interface to dysregulated reciprocal stromal–epithelial interactions in PCa pathophysiology and provide a strong rationale for further investigating the applicability of Nox4 inhibition as a stromal‐targeted approach to complement current PCa treatment modalities.     

Expression and functions of galectin-7 in ovarian cancer

There is a critical need to develop effective new strategies for diagnosis and treatment of ovarian cancer. In the present work, we investigated the expression of galectin-7 (gal-7) in epithelial ovarian cancer (EOC) cells and studied its functional relevance. Immunohistochemical analysis of gal-7 expression in tissue microarrays showed that while gal-7 was not detected in normal ovarian tissues, positive cytoplasmic staining of gal-7 was detected in epithelial cells in all EOC histological subtypes but was more frequent in high grade tumors and metastatic samples. Gal-7 expression correlated with a significant difference in the overall survival of patients with ovarian serous cystadenocarcinoma. Furthermore, using human EOC cell lines, we found that gal-7 expression was induced by mutant p53. Mechanistically, Matrigel invasion assays and live cell imaging showed that gal-7 increased the invasive behavior of ovarian cancer cells by inducing MMP-9 and increasing cell motility. EOC cells can also secrete gal-7. Recombinant human gal-7 kills Jurkat T cells and human peripheral T cells, suggesting that gal-7 also has immunosuppressive properties. Taken together, our study validates the clinical significance of gal-7 overexpression in ovarian cancer and provides a rationale for targeting gal-7 to improve the outcome of patients with this disease.     

Sphingosine kinase 1 as a potential therapeutic target in epithelial ovarian cancer

Sphingosine kinase 1 (SK1) is over‐expressed in multiple types of human cancer. SK1 has growth‐promoting effects and has been proposed as a potential therapeutic target. We investigated the therapeutic effects of SK1 inhibition in epithelial ovarian carcinoma (EOC). SK1 siRNA or inhibitors were tested in EOC cell lines, including A2780, SKOV3ip1, A2780‐CP20, SKOV3‐TR, ES2 and RMG2. Cells were treated with SK inhibitor or FTY720, and cell proliferation, apoptosis, angiogenesis and invasion were examined by MTT, FACS, ELISA and wound‐healing assays, respectively. In vivo experiments were performed to test the effects of FTY720 on tumor growth in orthotopic mouse xenografts of EOC cell lines A2780 or SKOV3ip1 and a patient‐derived xenograft (PDX) model of clear cell ovarian carcinoma (CCC). Blocking SK1 with siRNA or inhibitors significantly reduced proliferation, angiogenesis and invasion, and increased apoptosis in chemosensitive (A2780 and SKOV3ip1) and chemoresistant (A2780‐CP20, SKOV3‐TR, ES2 and RMG2) EOC cells. SK1 inhibitors also decreased the intracellular enzymatic activity of SK1. Furthermore, FTY720 treatment significantly decreased the in vivo tumor weight in xenograft models of established cell lines (A2780 and SKOV3ip1) and a PDX model for CCC compared to control (p < 0.05). These results support therapeutic targeting of SK1 as a potential new strategy for EOC.     

Hospicells (ascites‐derived stromal cells) promote tumorigenicity and angiogenesis

The microenvironment is known to play a dominant role in cancer progression. Cells closely associated with tumoral cells, named hospicells, have been recently isolated from the ascites of ovarian cancer patients. Whilst these cells present no specific markers from known cell lineages, they do share some homology with bone marrow‐derived or adipose tissue‐derived human mesenchymal stem cells (CD9, CD10, CD29, CD146, CD166, HLA‐1). We studied the role of hospicells in ovarian carcinoma progression. In vitro, these cells had no effect on the growth of human ovarian carcinoma cell lines OVCAR‐3, SKOV‐1 and IGROV‐1. In vivo, their co‐injection with adenocarcinoma cells enhanced tumor growth whatever the tumor model used (subcutaneous and intraperitoneally established xenografts in athymic mice). In addition, their injection increased the development of ascites in tumor‐bearing mice. Fluorescent macroscopy revealed an association between hospicells and ovarian adenocarcinoma cells within the tumor mass. Tumors obtained by coinjection of hospicells and human ovarian adenocarcinoma cells presented an increased microvascularization indicating that the hospicells could promote tumorigenicity of ovarian tumor cells in vivovia their action on angiogenesis. This effect on angiogenesis could be attributed to the increased HIF1α and VEGF expression associated with the presence of the hospicells. Collectively, these data indicate a role for these ascite‐derived stromal cells in promoting tumor growth by increasing angiogenesis.     

NPPB is a novel candidate biomarker expressed by cancer‐associated fibroblasts in epithelial ovarian cancer

Most solid tumors contain cancer‐associated fibroblasts (CAFs) that support tumorigenesis and malignant progression. However, the cellular origins of CAFs in epithelial ovarian cancers (EOCs) remain poorly understood, and their utility as a source of clinical biomarkers for cancer diagnosis has not been explored in great depth. Here, we report establishing in vitro and in vivo models of CAFs in ovarian cancer development. Normal ovarian fibroblasts and mesenchymal stem cells cultured in the presence of EOC cells acquired a CAF‐like phenotype, and promoted EOC cell migration in vitro. CAFs also promoted ovarian cancer growth in vivo in both subcutaneous and intraperitoneal murine xenograft assays. Molecular profiling of CAFs identified gene expression signatures that were highly enriched for extracellular and secreted proteins. We identified novel candidate CAF‐specific biomarkers for ovarian cancer including NPPB, which was expressed in the stroma of 60% primary ovarian cancer tissues (n = 145) but not in the stroma of normal ovaries (n = 4). NPPB is a secreted protein that was also elevated in the blood of 50% of women with ovarian cancer (n = 8). Taken together, these data suggest that the tumor stroma is a novel source of biomarkers, including NPPB, that may be of clinical utility for detection of EOC.     

The expression of asparaginyl endopeptidase promotes growth potential in epithelial ovarian cancer

Epithelial ovarian cancer (EOC) is the most common and lethal cancer-related death among females in the world. Asparaginyl endopeptidase (AEP) is a member of C13 family peptidases and expressed in the extracellular matrix and tumor cells. The aim of this article is to explore the function of asparaginyl endopeptidase in epithelial ovarian cancer. The expression of AEP was examined in 20 EOC samples, 3 EOC metastasis samples, 6 fallopian tube metastasis samples, 4 peritoneum metastasis samples and 20 benign ovarian tumor samples by immunohistochemistry. The expression of AEP was also evaluated in serum and ascites of EOC patients by elisa. And we used a lentiviral vector to overexpress AEP in human epithelial ovarian cancer cell lines SKOV3ip and detected the function of AEP-SKOV3ip cells both in vitro and in vivo. The growth of AEP-SKOV3ip cells was observed by MTT, migration and tube formation assays in vitro. Additionally, the subcutaneous mice model was used to identify the tumor growth and metastasis in vivo. Mice tumors were stained for CD31 to determine the microvessel density (MVD). We demonstrated that AEP was highly expressed in the EOC patient tissues and ascites. The AEP transfected SKOV3ip cells could both promote tumor growth in vitro and in vivo. The MVD in AEP-SKOV3ip group was higher than that in NC-SKOV3ip group. Therefore, our results demonstrated that AEP could induce EOC growth and progressionboth in vitro and in vivo.     

Interaction of monocytes/macrophages with ovarian cancer cells promotes angiogenesis in vitro

It has been established that macrophages and endothelial cells infiltrate peritoneum in the vicinity of tumor implants of epithelial ovarian cancer (EOC). This study investigates whether the interaction of ovarian cancer cells and tumor‐associated macrophages could promote the involvement of endothelial cells in angiogenesis. Macrophage phenotypes were detected by fluorescence‐activated cell sorting, and cytokine/chemokine secretion was measured by enzyme linked immunosorbent assay. The effect of co‐culture of ovarian cancer cells and tumor‐associated macrophage (TAM) cells on endothelial cell migration and tube formation was investigated. Signaling pathway mediators were also evaluated for their potential roles in endothelial cell activation by ovarian cancer cells co‐cultured with TAM cells. Our results showed that higher expression of interleukin‐8 (IL‐8) expression associated with 54.26 ± 34.46% of TAM infiltration of peritoneum was significantly higher than 16.58 ± 17.74% of CD3⁺ T‐cell by immunofluorescence co‐staining and confocal microscopy. THP‐1 cells exhibited M2‐polarized phenotype markers with high proportion of CD68⁺, CD206⁺ and CD204⁺ markers after phorbol 12‐myristate 13‐acetate (PMA) treatment, After co‐culturing with TAM cells in a transwell chamber system, EOC cells (SKOV3) increased their IL‐8 expression at the level of mRNA and protein. After exposure to the conditioned medium obtained by co‐culturing TAM and SKOV3 cells, the migration and tube formation of endothelial cells were enhanced significantly. Furthermore, the upregulation of IL‐8 expression in ovarian cancer cells induced by macrophages could be inhibited by pyrollidine dithiocarbamate, an inhibitor of nuclear factor (NF)‐ κB signal pathway. We suggest that the interaction of ovarian cancer cells and tumor‐associated macrophages enhances the ability of endothelial cells to promote the progression of ovarian cancer.     

Instructions for Authors

Tissue remodeling is a key element in the local invasion and metastasis of malignant breast tumors. The degradation of extracellular matrix that is associated with this process is thought to be mediated by a number of Zn²⁺-dependent matrix metalloproteinases (MMPs). In most cases these enzymes are not produced by the malignant epithelium itself but by adjacent breast stroma, suggesting an important role for cell-cell interactions. We have analyzed Gelatinase A (MMP-2) and Gelatinase B (MMP-9) gene expression in a panel of six breast cancer cell lines and six primary cultures of stromal cells deriving from breast cancer biopsies. With one exception we did not detect MMP-2 or MMP-9 gene expression in any of the established tumor cell lines. Conversely, tumor stroma-derived fibroblasts expressed MMP-2 mRNA, although no MMP-9 mRNA was seen in RNase protection assays. When fibroblasts were cultured in the presence of media conditioned by MCF-7 tumor cells, MMP-2 enzyme production increased but MMP-9 activity remained undetectable. However, when fibroblasts and MCF-7 tumor cells were co-cultured together, MMP-9 was induced. These observations were confirmed by immunocytochemical analysis of co-cultures of MCF-7 and tumor-derived fibroblasts in which MMP-2 and MMP-9 protein expression was confined to stromal cells adjacent to MCF-7 tumor cells. No MMP-2 or MMP-9 staining was detected in monocultures of the two respective cell types. We conclude that MMP-2 expression is present in the stroma of malignant tumors and is increased by paracrine stimulation mediated by soluble factors. In contrast, MMP-9 expression tumor-derived fibroblasts requires direct contact with malignant tumor epithelium.     

Stromal expression of cancer-associated fibroblast-related molecules,versican and lumican,is strongly associated with worse relapse-free and overall survival times in patients with esophageal squamous cell carcinoma

Cancer-associated fibroblasts (CAFs) in the tumor microenvironment play an essential role in the tumor progression of esophageal squamous cell carcinoma (ESCC). The present study aimed to investigate the expression of CAF-related molecules, versican, periostin and lumican, in cancer stroma, to provide prognostic stratification for patients with ESCC after surgery. A total of 106 patients with ESCC who underwent curative esophagectomy without preoperative chemotherapy or radiotherapy were enrolled. The expression of CAF-related stromal proteins, including versican, periostin and lumican, was examined using immunohistochemistry, and the prognostic value was assessed by Kaplan-Meier survival analysis, and univariate and multivariate Cox regression models. The expression of versican, periostin and lumican was found specifically in the stromal component of ESCC. Kaplan-Meier analysis demonstrated that, compared with a low expression level, a high expression level of versican, periostin or lumican in the cancer stroma was significantly associated with worse relapse-free survival (RFS) and overall survival times in patients with ESCC. The prognostic values of stromal versican and lumican remained significant in a stratified analysis of stage I patients. Moreover, univariate and multivariate analysis revealed that high stromal versican or lumican expression was an independent prognostic factor for RFS in the patients. The present study demonstrated that CAF-related molecules, including versican, periostin and lumican, were expressed in the stroma of ESCC, and that stromal expression of versican and lumican in particular may have clinical utility as a prognostic biomarker for poor RFS in postoperative patients with ESCC.     

Fibroblasts in omentum activated by tumor cells promote ovarian cancer growth, adhesion and invasiveness

Omentum metastasis is a common occurrence in epithelial ovarian cancer (EOC), which is often accompanied by ascites that facilitates the spread of EOC cells. A subpopulation of fibroblasts-the cancer-associated fibroblasts (CAFs) are important promoters of tumor progression. We have shown previously that CAFs exist not only in omentum with EOC metastasis but also in omentum without metastasis. In the present study, using primary human fibroblasts isolated from normal omentum (NFs) and omentum with ovarian cancer metastasis (CAFs), we established in vitro coculture models and a 3D culture model mimicking human omentum structure for investigation of interactions between fibroblasts and cancer cells. We demonstrate that EOC cells activate NFs and promote their proliferation via transforming growth factor-β1 (TGF-β1) signaling, and the activated fibroblasts contribute to the invasion and adhesion of EOC cells. Moreover, EOC cells and NFs coculture led to overexpression of hepatocyte growth factor (HGF) and matrix metalloproteinase-2 (MMP-2) and adhesion and invasion of EOC cells could be partially suppressed by blocking the function of HGF or MMP-2. Additionally, mouse peritoneal dissemination models of EOC confirmed the activation of fibroblasts by cancer cells and the tumor growth- and metastasis-promoting effects of activated fibroblasts in vivo. Our findings indicate that activated fibroblasts in omentum form a congenial environment to promote EOC cells implantation. It is an intriguing concept that targeting the activation of omentum fibroblast through the inhibition of TGF-β1 signaling can be used as a new therapeutic strategy against ovarian cancer omentum metastases, which needs further study.     

Lung cancer secreted microvesicles: Underappreciated modulators of microenvironment in expanding tumors

Microvesicles (MVs) are shed from cell membranes of several cell types and have an important function in cell‐to‐cell communication. Exponentially growing lung cancer cells secrete large quantities of MVs and we were interested in their role in tumor progression. We observed that both human and murine lung cancer cell lines secrete more MVs in response to non‐apoptotic doses of hypoxia and irradiation. These tumor‐derived (t)MVs activate and chemoattract stroma fibroblasts and endothelial cells. Furthermore, they induce expression of several pro‐angiopoietic factors in stromal cells such as IL‐8, VEGF, LIF, OSM, IL‐11 and MMP‐9. We also noticed that conditioned media harvested from stroma cells stimulated by tMVs enhanced the metastatic potential of both human and murine lung cancer cells in vivo. Thus, we postulated that tMVs are underappreciated constituents of the tumor microenvironment and play a pivotal role in tumor progression, metastasis and angiogenesis. © 2009 UICC     

Role of cancer-associated stromal fibroblasts in metastatic colon cancer to the liver and their expression profiles

The cancer microenvironment and interaction between cancer and stromal cells play critical roles in tumor development and progression. The molecular features of cancer stroma are less well understood than those of cancer cells. Cancer-associated stromal fibroblasts are the predominant component of stroma associated with colon cancer and its functions remain unclear. Fibroblast cell cultures were established from metastatic colon cancer in liver, liver away from the metastatic lesions, and skin from three patients with metastatic colorectal cancer. We generated expression profiles of cancer-associated fibroblasts using oligochip arrays and compared them to those of uninvolved fibroblasts. The conditioned media from the cancer-associated fibroblast cultures enhanced proliferation of colon cancer cell line HCT116 to a greater extent than cultures from uninvolved fibroblasts. In microarray expression analysis, cancer-associated fibroblasts clustered tightly into one group and skin fibroblasts into another. Approximately 170 of 22,000 genes were up-regulated in cancer-associated fibroblasts (fold change > 2, P < 0.05) as compared to skin fibroblasts, including many genes encoding cell adhesion molecules, growth factors, and COX2. By immunohistochemistry in-vivo, we confirmed COX2 and TGFB2 expression in cancer-associated fibroblasts in metastatic colon cancer. The distinct molecular expression profiles of cancer-associated fibroblasts in colon cancer metastasis support the notion that these fibroblasts form a favorable microenvironment for cancer cells.     

Cancer‐associated fibroblasts contribute to cisplatin resistance by modulating ANXA3 in lung cancer cells

Cancer tissues consist of cancer cells, surrounding stromal cells and the extracellular matrix. Cancer‐associated fibroblasts (CAF) are one of the key components of stromal cells. CAF have a great impact on the behavior of cancer cells, including proliferation, invasion, metastasis and chemoresistance in many ways. However, the underlying mechanism had not been fully elucidated. In this study, we investigated the role of CAF in cisplatin resistance of lung cancer cells. By using conditioned medium from CAF (CAF‐CM), we found that CAF decreased the sensitivity of lung cancer cells to cisplatin. RNA sequencing results showed that CAF expressed a higher level of Annexin A3 (ANXA3) than normal fibroblasts (NF), and CAF‐CM incubation increased the ANXA3 level in lung cancer cells. Overexpression of ANXA3 in lung cancer cells increased cisplatin resistance and activated c‐jun N‐terminal kinase (JNK), whereas knockdown of ANXA3 increased cisplatin sensitivity. Further study showed that CAF‐CM enhanced cisplatin resistance by inhibiting cisplatin‐induced apoptosis, determined by repression of caspase‐3 and caspase‐8, through activation of the ANXA3/JNK pathway. Conversely, suppression of JNK activation by specific inhibitor retarded the effect of CAF‐CM and ANXA3 on cisplatin sensitivity. Taken together, our study demonstrated that CAF potentiated chemoresistance of lung cancer cells through a novel ANXA3/JNK pathway both in vitro and in vivo, suggesting ANXA3 could be a potential therapeutic target for the treatment of chemoresistant cancer.