Tumors are not merely masses of neoplastic cells but complex tissues composed of cellular and noncellular elements. This review provides recent data on the main components of a dynamic system, such as carcinoma associated fibroblasts that change the extracellular matrix (ECM) topology, induce stemness and promote metastasis-initiating cells. Altered production and characteristics of collagen, hyaluronan and other ECM proteins induce increased matrix stiffness. Stiffness along with tumor growth-induced solid stress and increased interstitial fluid pressure contribute to tumor progression and therapy resistance. Second, the role of immune cells, cytokines and chemokines is outlined. We discuss other noncellular characteristics of the tumor microenvironment such as hypoxia and extracellular pH in relation to neoangiogenesis. Overall, full understanding of the events driving the interactions between tumor cells and their environment is of crucial importance in overcoming treatment resistance and improving patient outcome.

Although the induction of senescence in cancer cells is a potent mechanism of tumor suppression, senescent cells remain metabolically active and may secrete a broad spectrum of factors that promote tumorigenicity in neighboring malignant cells. Here we show that androgen deprivation therapy (ADT), a widely used treatment for advanced prostate cancer, induces a senescence-associated secretory phenotype in prostate cancer epithelial cells, indicated by increases in senescence-associated β-galactosidase activity, heterochromatin protein 1β foci, and expression of cathepsin B and insulin-like growth factor binding protein 3. Interestingly, ADT also induced high levels of vimentin expression in prostate cancer cell lines in vitro and in human prostate tumors in vivo. The induction of the senescence-associated secretory phenotype by androgen depletion was mediated, at least in part, by down-regulation of S-phase kinase-associated protein 2, whereas the neuroendocrine differentiation of prostate cancer cells was under separate control. These data demonstrate a previously unrecognized link between inhibition of androgen receptor signaling, down-regulation of S-phase kinase-associated protein 2, and the appearance of secretory, tumor-promoting senescent cells in prostate tumors. We propose that ADT may contribute to the development of androgen-independent prostate cancer through modulation of the tissue microenvironment by senescent cells.

Background: Androgen receptor targeted therapies have emerged as an effective tool to manage advanced prostate cancer (PCa). Nevertheless, frequent occurrence of therapy resistance represents a major challenge in the clinical management of patients, also because the molecular mechanisms behind therapy resistance are not yet fully understood. In the present study, we therefore aimed to identify novel targets to intervene with therapy resistance using gene expression analysis of PCa co-culture spheroids where PCa cells are grown in the presence of cancer-associated fibroblasts (CAFs) and which have been previously shown to be a reliable model for antiandrogen resistance. Methods: Gene expression changes of co-culture spheroids (LNCaP and DuCaP seeded together with CAFs) were identified by Illumina microarray profiling. Real-time PCR, Western blotting, immunohistochemistry and cell viability assays in 2D and 3D culture were performed to validate the expression of selected targets in vitro and in vivo. Cytokine profiling was conducted to analyze CAF-conditioned medium. Results: Gene expression analysis of co-culture spheroids revealed that CAFs induced a significant upregulation of cholesterol and steroid biosynthesis pathways in PCa cells. Cytokine profiling revealed high amounts of proinflammatory, pro-migratory and pro-angiogenic factors in the CAF supernatant. In particular, two genes, 3-hydroxy-3-methylglutaryl-Coenzyme A synthase 2 (HMGCS2) and aldo-keto reductase family 1 member C3 (AKR1C3), were significantly upregulated in PCa cells upon co-culture with CAFs. Both enzymes were also significantly increased in human PCa compared to benign tissue with AKR1C3 expression even being associated with Gleason score and metastatic status. Inhibiting HMGCS2 and AKR1C3 resulted in significant growth retardation of co-culture spheroids as well as of various castration and enzalutamide resistant cell lines in 2D and 3D culture, underscoring their putative role in PCa. Importantly, dual targeting of cholesterol and steroid biosynthesis with simvastatin, a commonly prescribed cholesterol synthesis inhibitor, and an inhibitor against AKR1C3 had the strongest growth inhibitory effect.

CTHRC1 and periostin play important roles in breast cancer progression. These preliminary results show that combined evaluation of CTHRC1 and periostin could serve as a potential marker for breast cancer bone metastasis; the other observations contribute to the description of the tumour microenvironment, with implications for lymph node and bone metastasis.

The identification of fibroblasts and cancer-associated fibroblasts from human cancer tissue using surface markers is difficult, especially because the markers used currently are usually not expressed solely by fibroblasts, and the identification of fibroblast-specific surface molecules is still under investigation. It was aimed to compare three commercially available antibodies in the detection of different surface epitopes of fibroblasts (anti-fibroblast, fibroblast activation protein α, and fibroblast surface protein). The specificity of their expression, employing fibroblast cell lines and tumor-derived fibroblasts from breast and prostate tissues was investigated. Both the established fibroblast cell line HFF-1 and ex vivo primary fibroblasts isolated from breast and prostate cancer tissues expressed the tested surface markers to different degrees. Surprisingly, those markers were expressed also by permanent cell lines of epithelial origin, both benign and cancer-derived (breast-cell lines MCF 10A, HMLE and prostate-cell lines BPH-1, DU 145, and PC-3). The expression of fibroblast activation protein α increased on the surface of previously described models of epithelial cells undergoing epithelial-to-mesenchymal transition in response to treatment with TGF-β1. To prove the co-expression of the fibroblast markers on cells of epithelial origin, we used freshly dissociated human prostate and breast cancer tissues. The results confirmed the co-expression of anti-fibroblast and fibroblast surface protein on CD31/CD45-negative/EpCAM-positive epithelial cells. In summary, our data support the findings that the tested fibroblast markers are not fibroblast specific and may be expressed also by cells of epithelial origin (e.g., cells undergoing EMT). Therefore, the expression of these markers should be interpreted with caution, and the combination of several epitopes for both positive (anti-fibroblast or fibroblast activation protein α) and negative (EpCAM) identification of fibroblasts from breast and prostate tumor tissues is advised. © 2017 International Society for Advancement of Cytometry.

Sphingosine 1-phosphate (S1P) is a bioactive lipid metabolite associated with cancer cell proliferation, survival, migration and regulation of tumor angiogenesis in various cellular and animal models. Sphingosine kinase-1 (SphK1) and S1P lyase are the main enzymes that respectively control the synthesis and degradation of S1P. The present study analyzed the prognostic and predictive value of SphK1 and S1P lyase expression in patients with non-small cell lung cancer (NSCLC), treated with either surgery alone or in combination with adjuvant carboplatin and navelbine. Formalin-fixed, paraffin-embedded tissue samples from 176 patients with NSCLC were stained immunohistochemically using antibodies against SphK1 and S1P lyase, and their expression was correlated with all available clinicopathological factors. Increased expression of SphK1 was significantly associated with shorter overall and disease free survival in patients treated with adjuvant platinum-based chemotherapy. No prognostic relevance for S1P lyase expression was observed. Collectively, the results suggest that the immunohistochemical detection of SphK1 may be a promising predictive marker in NSCLC patients treated with adjuvant platinum-based chemotherapy.

Asporin has been reported as a tumor suppressor in breast cancer, while asporin-activated invasion has been described in gastric cancer. According to our in silico search, high asporin expresion associates with significantly better relapse free survival (RFS) in patients with low-grade tumors but RFS is significantly worse in patients with grade 3 tumors. In line with other studies, we have confirmed asporin expression by RNA scope in situ hybridization in cancer associated fibroblasts. We have also found asporin expression in the Hs578T breast cancer cell line which we confirmed by quantitative RT-PCR and western blotting. From multiple testing, we found that asporin can be downregulated by bone morphogenetic protein 4 while upregulation may be facilited by serum-free cultivation or by three dimensional growth in stiff Alvetex scaffold. Downregulation by shRNA inhibited invasion of Hs578T as well as of CAFs and T47D cells. Invasion of asporin-negative MDA-MB-231 and BT549 breast cancer cells through collagen type I was enhanced by recombinant asporin. Besides other investigations, large scale analysis of aspartic acid repeat polymorphism will be needed for clarification of the asporin dual role in progression of breast cancer.

BCL2 protein expression is a positive prognostic factor in BC. Better survival of patients with BCL2 positivity (BCL2+) has been explained by the correlation with estrogen receptor positive (ER+) status. BCL2+ is however not simply a surrogate marker for ER+. Moreover, BCL2 protein expression is also a positive prognostic marker in the TNBC subgroup. We and others show, that low BCL2 expression was associated with good outcome of TNBC patients treated with both adjuvant and neoadjuvant anthracycline-based chemotherapy. On the other hand, recent studies have shown that a subset of TNBC patients may benefit from the classical adjuvant CMF (cyclophosphamide, methotrexate, 5-fluorouracil) regimen. Given the heterogeneity of TNBC there is an urgent need to find and validate the sensitivity predictors to these regimens making them usable in clinical practice. BCL2 enrichment has been described in the mesenchymal stem-like (MSL) TNBC subgroup.