Insights into the Tumor Microenvironment-Components, Functions and Therapeutics.

Similarly to our healthy organs, the tumor tissue also constitutes an ecosystem. This implies that stromal cells acquire an altered phenotype in tandem with tumor cells, thereby promoting tumor survival. Cancer cells are fueled by abnormal blood vessels, allowing them to develop and proliferate. Tumor-associated fibroblasts adapt their cytokine and chemokine production to the needs of tumor cells and alter the peritumoral stroma by generating more collagen, thereby stiffening the matrix; these processes promote epithelial-mesenchymal transition and tumor cell invasion. Chronic inflammation and the mobilization of pro-tumorigenic inflammatory cells further facilitate tumor expansion. All of these events can impede the effective administration of tumor treatment; so, the successful inhibition of tumorous matrix remodeling could further enhance the success of antitumor therapy. Over the last decade, significant progress has been made with the introduction of novel immunotherapy that targets the inhibitory mechanisms of T cell activation. However, extensive research is also being conducted on the stromal components and other cell types of the tumor microenvironment (TME) that may serve as potential therapeutic targets.

Dynamic Interplay in Tumor Ecosystems: Communication between Hepatoma Cells and Fibroblasts.

Tumors are intricate ecosystems where cancer cells and non-malignant stromal cells, including cancer-associated fibroblasts (CAFs), engage in complex communication. In this study, we investigated the interaction between poorly (HLE) and well-differentiated (HuH7) hepatoma cells and LX2 fibroblasts. We explored various communication channels, including soluble factors, metabolites, extracellular vesicles (EVs), and miRNAs. Co-culture with HLE cells induced LX2 to produce higher levels of laminin ß1, type IV collagen, and CD44, with pronounced syndecan-1 shedding. Conversely, in HuH7/LX2 co-culture, fibronectin, thrombospondin-1, type IV collagen, and cell surface syndecan-1 were dominant matrix components. Integrins α6ß4 and α6ß1 were upregulated in HLE, while α5ß1 and αVß1 were increased in HuH7. HLE-stimulated LX2 produced excess MMP-2 and 9, whereas HuH7-stimulated LX2 produced excess MMP-1. LX2 activated MAPK and Wnt signaling in hepatoma cells, and conversely, hepatoma-derived EVs upregulated MAPK and Wnt in LX2 cells. LX2-derived EVs induced over tenfold upregulation of SPOCK1/testican-1 in hepatoma EV cargo. We also identified liver cancer-specific miRNAs in hepatoma EVs, with potential implications for early diagnosis. In summary, our study reveals tumor type-dependent communication between hepatoma cells and fibroblasts, shedding light on potential implications for tumor progression. However, the clinical relevance of liver cancer-specific miRNAs requires further investigation.

Corrigendum: SPOCK1 promotes the development of hepatocellular carcinoma.

[This corrects the article DOI: 10.3389/fonc.2022.819883.].

SPOCK1 Overexpression Suggests Poor Prognosis of Ovarian Cancer.

PURPOSE: Sparc/osteonectin, cwcv, and kazal-like domains proteoglycan 1 (SPOCK1) has been found in a variety of malignant tumors and is associated with a poor prognosis. We aimed to explore the role of SPOCK1 in ovarian cancer. METHODS: Ovarian cancer cell lines SKOV3 and SW626 were transfected with SPOCK1 overexpressing or empty vector using electroporation. Cells were studied by immunostaining and an automated Western blotting system. BrdU uptake and wound healing assays assessed cell proliferation and migration. SPOCK1 expression in human ovarian cancer tissues and in blood samples were studied by immunostaining and ELISA. Survival of patients with tumors exhibiting low and high SPOCK1 expression was analyzed using online tools. RESULTS: Both transfected cell lines synthesized different SPOCK1 variants; SKOV3 cells also secreted the proteoglycan. SPOCK1 overexpression stimulated DNA synthesis and cell migration involving p21CIP1. Ovarian cancer patients had increased SPOCK1 serum levels compared to healthy controls. Tumor cells of tissues also displayed abundant SPOCK1. Moreover, SPOCK1 levels were higher in untreated ovarian cancer serum and tissue samples and lower in recipients of chemotherapy. According to in silico analyses, high SPOCK1 expression was correlated with shorter survival. CONCLUSION: Our findings suggest SPOCK1 may be a viable anti-tumor therapeutic target and could be used for monitoring ovarian cancer.

Syndecan-1 in liver pathophysiology.

Syndecan-1 (SDC-1) is a heparan sulfate (HS)/chondroitin sulfate proteoglycan (PG) of the cell surface and the extracellular matrix (ECM), which regulates a broad spectrum of physiological and pathological processes such as cell proliferation, migration, inflammation, matrix remodeling, wound healing, and tumorigenesis. Syndecan-1 represents the major PG of the liver, expressed by hepatocytes and cholangiocytes, and its elevated expression is a characteristic feature of liver diseases. The highest syndecan-1 expression is found in liver cirrhosis and in hepatocellular carcinoma (HCC) developed in cirrhotic livers. In addition, as being a hepatitis C receptor, hepatitis C virus (HCV)-infected livers produce extremely large amounts of syndecan-1. The serum levels of the cleaved (shedded) extracellular domain have clinical significance, as their increased concentration reflects on poor prognosis in cirrhosis as well as in cancer. In vivo experiments confirmed that syndecan-1 protects against early stages of fibrogenesis mainly by enhanced clearance of transforming growth factor ß1 (TGFß1) and thrombospondin-1 (THBS1) via circulation, and against hepatocarcinogenesis by interfering with several signaling pathways and enhancing cell cycle blockade. In addition, syndecan-1 is capable to hinder lipid metabolism and ribosomal biogenesis in induced cancer models. These observations together with its participation in the uptake of viruses (e.g., HCV and SARS-CoV-2) indicate that syndecan-1 is a central player in liver pathologies.

SPOCK1 with unexpected function. The start of a new career.

SPOCK1, 2, and 3 are considered matricellular proteoglycans without a structural role. Their functions are only partly elucidated. SPOCK1 was detected in the brain as a member of the neural synapses, then in the neuromuscular junctions. It plays a role in the regulation of the blood-brain barrier. Its best-characterized activity was its oncogenic potential discovered in 2012. Its deleterious effect on tumor progression was detected on 36 different types of tumors by the end of 2020. However, its mode of action is still not completely understood. Furthermore, even less was discovered about its physiological function. The fact that it was found to localize in the mitochondria and interfered with the lipid metabolism indicated that the full discovery of SPOCK1 is still waiting for us.

SPOCK1 Promotes the Development of Hepatocellular Carcinoma.

The extracellular matrix proteoglycan SPOCK1 is increasingly recognized as a contributor to the development and progression of cancers. Here, we study how SPOCK1, which is present in non-tumorous hepatocytes at low concentrations, promotes the development and progression of malignant hepatocellular tumors. Although SPOCK1 is an extracellular matrix proteoglycan, its concentration increases in the cytoplasm of hepatocytes starting with very low expression in the normal cells and then appearing in much higher quantities in cells of cirrhotic human liver and hepatocellular carcinoma. This observation is similar to that observed after diethylnitrosamine induction of mouse hepatocarcinogenesis. Furthermore, syndecan-1, the major proteoglycan of the liver, and SPOCK1 are in inverse correlation in the course of these events. In hepatoma cell lines, the cytoplasmic SPOCK1 colocalized with mitochondrial markers, such as MitoTracker and TOMM20, a characteristic protein of the outer membrane of the mitochondrion and could be detected in the cell nucleus. SPOCK1 downregulation of hepatoma cell lines by siRNA inhibited cell proliferation, upregulated p21 and p27, and interfered with pAkt and CDK4 expression. A tyrosine kinase array revealed that inhibition of SPOCK1 in the liver cancer cells altered MAPK signaling and downregulated several members of the Sarc family, all related to the aggressivity of the hepatoma cell lines. These studies support the idea that SPOCK1 enhancement in the liver is an active contributor to human and rodent hepatocarcinogenesis and cancer progression. However, its mitochondrial localization raises the possibility that it has a currently unidentified physiological function in normal hepatocytes.

Efficacy of carboplatin chemotherapy in a metastatic, castration-resistant BRCA2 mutation positive prostate cancer patient / A karboplatin-kemoterápia hatékonysága egy áttétes, kasztrációrezisztens, BRCA2-mutáció-pozitív prosztatarákos betegben.

Összefoglaló. A sérült BRCA1/2 gént hordozó prosztatadaganatok klinikai szempontból elkülönülo, agresszív altípust képviselnek. Ugyanakkor a BRCA1/2 gén sérülése a DNS-támadáspontú kemoterápiákkal szemben érzékennyé teszi a daganatot, ami terápiás szempontból kihasználható. A platinaalapú kemoterápia hatékonysága prosztatarákban klinikai vizsgálatokkal nincs alátámasztva, ezért annak alkalmazására igen ritkán kerül sor. Közleményünkben egy elorehaladott stádiumú, agresszív prosztata adenocarcinomával diagnosztizált beteg esetét mutatjuk be, akinél a BRCA2-gén patogén mutációját találtuk, és akinél az elozoleg alkalmazott androgénmegvonásos, valamint docetaxelkezelések sikertelensége miatt karboplatinkezelést alkalmaztunk - ez a beteg állapotának, valamint radiológiai és biokémiai paramétereinek látványos javulásához vezetett. Ez az eset rámutat a DNS-hiba-javító mechanizmusban szerepet játszó gének terápiás szempontból történo felhasználásának potenciális elonyeire prosztatarákban. Orv Hetil. 2021; 162(25): 1004-1008. Summary. BRCA1/2 deficient prostate cancers represent a clinically distinct aggressive subtype. However, the presence of BRCA1/2 alterations enhance the sensitivity to platinum-based chemotherapies. The efficacy of platinum-based chemotherapies in prostate cancer has not been proven in prospective clinical studies and therefore these treatments are rarely used in prostate adenocarcinomas. Here we present a case of BRCA2 mutant prostate cancer, which was diagnosed at a metastatic stage and showed no or only little response to androgen deprivation and docetaxel therapies. Therefore, we started carboplatin chemotherapy which resulted in an exceptional response regarding biochemical, radiographic parameters accompanied by significant improvement of patients' physical condition. This case underlines the potential therapeutic benefits of testing for genes involved in the DNA repair mechanism. Orv Hetil. 2021; 162(25): 1004-1008.

Overexpression of Human Syndecan-1 Protects against the Diethylnitrosamine-Induced Hepatocarcinogenesis in Mice.

Although syndecan-1 (SDC1) is known to be dysregulated in various cancer types, its implication in tumorigenesis is poorly understood. Its effect may be detrimental or protective depending on the type of cancer. Our previous data suggest that SDC1 is protective against hepatocarcinogenesis. To further verify this notion, human SDC1 transgenic (hSDC1+/+) mice were generated that expressed hSDC1 specifically in the liver under the control of the albumin promoter. Hepatocarcinogenesis was induced by a single dose of diethylnitrosamine (DEN) at an age of 15 days after birth, which resulted in tumors without cirrhosis in wild-type and hSDC1+/+ mice. At the experimental endpoint, livers were examined macroscopically and histologically, as well as by immunohistochemistry, Western blot, receptor tyrosine kinase array, phosphoprotein array, and proteomic analysis. Liver-specific overexpression of hSDC1 resulted in an approximately six month delay in tumor formation via the promotion of SDC1 shedding, downregulation of lipid metabolism, inhibition of the mTOR and the ß-catenin pathways, and activation of the Foxo1 and p53 transcription factors that lead to the upregulation of the cell cycle inhibitors p21 and p27. Furthermore, both of them are implicated in the regulation of intermediary metabolism. Proteomic analysis showed enhanced lipid metabolism, activation of motor proteins, and loss of mitochondrial electron transport proteins as promoters of cancer in wild-type tumors, inhibited in the hSDC1+/+ livers. These complex mechanisms mimic the characteristics of nonalcoholic steatohepatitis (NASH) induced human liver cancer successfully delayed by syndecan-1.

The Protective Role of Decorin in Hepatic Metastasis of Colorectal Carcinoma.

Decorin, the prototype member of the small leucine-rich proteoglycan gene family of extracellular matrix (ECM) proteins, acts as a powerful tumor suppressor by inducing the p21Waf1/Cip1 cyclin-dependent kinase inhibitor, as well as through its ability to directly bind and block the action of several tyrosine kinase receptors. Our previous studies suggested that the lack of decorin promotes hepatic carcinogenesis in mice. Based on this, we set out to investigate whether excess decorin may protect against the liver metastases of colon carcinoma. We also analyzed the effect of decorin in tissue microarrays of human colon carcinoma liver metastasis and examined whether the tumor cells can directly influence the decorin production of myofibroblasts. In humans, low levels of decorin in the liver facilitated the development of colon carcinoma metastases in proportion with more aggressive phenotypes, indicating a possible antitumor action of the proteoglycan. In vitro, colon carcinoma cells inhibited decorin expression in LX2 hepatic stellate cells. Moreover, liver-targeted decorin delivery in mice effectively attenuated metastasis formation of colon cancer. Overexpressed decorin reduced the activity of multiple receptor tyrosine kinases (RTKs) including the epidermal growth factor receptor (EGFR), an important player in colorectal cancer (CRC) pathogenesis. Downstream of that, we observed weakened signaling of ERK1/2, PLCγ, Akt/mTOR, STAT and c-Jun pathways, while p38 MAPK/MSK/CREB and AMPK were upregulated culminating in enhanced p53 function. In conclusion, decorin may effectively inhibit metastatic tumor formation in the liver.

Decorin in the Tumor Microenvironment.

The tumor microenvironment plays a determining role in cancer development through a plethora of interactions between the extracellular matrix and tumor cells. Decorin is a prototype member of the SLRP family found in a variety of tissues and is expressed in the stroma of various forms of cancer. Decorin has gained recognition for its essential roles in inflammation, fibrotic disorders, and cancer, and due to its antitumor properties, it has been proposed to act as a "guardian from the matrix." Initially identified as a natural inhibitor of transforming growth factor-ß, soluble decorin is emerging as a pan-RTK inhibitor targeting a multitude of RTKs, including EGFR, Met, IGF-IR, VEGFR2, and PDGFR. Besides initiating signaling, decorin/RTK interaction can induce caveosomal internalization and receptor degradation. Decorin also triggers cell cycle arrest and apoptosis and evokes antimetastatic and antiangiogenic processes. In addition, as a novel regulatory mechanism, decorin was shown to induce conserved catabolic processes, such as endothelial cell autophagy and tumor cell mitophagy. Therefore, decorin is a promising candidate for combatting cancer, especially the cancer types heavily dependent on RTK signaling.

Protective Role of Decorin in Primary Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) represents one of the most frequent type of primary liver cancers. Decorin, a small leucine-rich proteoglycan of the extracellular matrix, represents a powerful tumor cell growth and migration inhibitor by hindering receptor tyrosine kinases and inducing p21WAF1/CIP1. In this study, first we tested decorin expression in HCCs utilizing in silico data, as well as formalin fixed paraffin embedded tissue samples of HCC in a tissue microarray (TMA). In silico data revealed that DCN/SMA mRNA ratio is decreased in HCC compared to normal tissues and follows the staging of the disease. Among TMA samples, 52% of HCCs were decorin negative, 33% exhibited low, and 15% high decorin levels corroborating in silico results. In addition, applying conditioned media of hepatoma cells inhibited decorin expression in LX2 stellate cells in vitro. These results raise the possibility that decorin acts as a tumor suppressor in liver cancer and that is why its expression decreased in HCCs. To further test the protective role of decorin, the proteoglycan was overexpressed in a mouse model of hepatocarcinogenesis evoked by thioacetamide (TA). After transfection, the excessive proteoglycan amount was mainly detected in hepatocytes around the central veins. Upon TA-induced hepatocarcinogenesis, the highest tumor count was observed in mice with no decorin production. Decorin gene delivery reduced tumor formation, in parallel with decreased pEGFR, increased pIGF1R levels, and with concomitant induction of pAkt (T308) and phopho-p53, suggesting a novel mechanism of action. Our results suggest the idea that decorin can be utilized as an anti-cancer agent.

Inhibitory Effect of (2R)-1-(1-Benzofuran-2-yl)-N-propylpentan-2-amine on Lung Adenocarcinoma.

BPAP is a potent enhancer substance with catecholaminergic and serotoninergic activity in the brain. It was discovered that it is also effective against certain types of experimental cancers, showing the most promising results in case of lung cancer. That is why we tested its efficacy in two different doses in a newly developed EGFR wild type mouse lung adenocarcinoma xenograft model. Experiments were conducted on FVB/N and SCID mouse strains treated with low and high dose of BPAP. Body weight, survival, and tumor volumes were recorded. Furthermore, the activity of major signaling pathways of NSCLC such as MAPK and Akt/mTOR as well as cell cycle regulation were determined. Significant inhibition of tumor growth was exerted by both doses, but the mechanism of action was different. High dose directly inhibited, whereas low dose activated the main signaling pathways. Exposure to low dose BPAP resulted in elevated activity of the mTOR pathway together with p16INK-induced cell cycle arrest, a typical feature of geroconversion, a senescent state characterized by loss of cell proliferation. Finally the events culminated in cell cycle inhibition point in case of both doses mirrored by the decrease of cyclin D1, CDK4 and PCNA. In addition, BPAP treatment had a beneficial effect on bodyweight suggesting that the compound at least in part is able to compensate the cancer-related wasting. In view of the low toxicity and confirmed antitumor effect of BPAP against experimental lung adenocarcinoma, this novel compound deserves further attention.

Synthetic enhancer compounds, besides acting on biogenic amine system, influence the glutamate transmission and stress response.

Pharmaceutically available enhancer selegiline/(-)-deprenyl (DEP) in the clinically used dose shows antidepressant effect, but nothing is known about this effect in enhancer dose, and its effect on co-morbid anxiety. Moreover, data about the antidepressant/antianxiety effects of the serotonin-influencing enhancer, (2R)-1-(1-benzofuran-2-yl)-N-propylpentane-2-amine (BPAP) are also missing. The aim of the present paper is to establish the role of enhancer regulation in anxiety and follow the changes in the phosphorylation of glutamate subunits in prefrontal cortex as well as stress-related organ and hormonal changes as possible background mechanism. The effect of 3-week-treatment of rats with specific (0.001 mg/kg for DEP, 0.0001 mg/kg for BPAP) and non-specific (0.1 mg/kg for DEP, 0.05 mg/kg for BPAP) enhancer doses were evaluated on anxiety-like behavior in the elevated plus maze (EPM) and open-field (OF) tests. Phosphorylated glutamatergic GluR1 and GluN2B subunits were analyzed by Western blot. Changes in the stress-regulatory system were evaluated by measuring the organ weights and blood corticosterone concentrations. Non-specific enhancer doses had a tendency for anxiolysis on EPM, while only 0.1 mg/kg DEP elevated motility in OF. Specific enhancer doses significantly increased the expression of both glutamatergic receptor subunits; non-specific doses elevated only pGluR1. Treatments had no effects on stress-like organ weights; however, the specific enhancer doses significantly reduced the dark phase resting corticosterone levels. The study proved the enhancer-sensitivity of the glutamatergic transmitter system and suggested enhancer-induced stabilization of stress-hormone levels without major impact on non-stimulated anxiety-like behavior.

Chronic Hyperglycaemia Induced Alterations of Hepatic Stellate Cells Differ from the Effect of TGFB1, and Point toward Metabolic Stress.

The deleterious effect of hyperglycemia on the biology of the liver is supported by clinical evidence. It can promote the development of fatty liver, liver fibrosis, even liver cancer as complication of diabetes mellitus. As liver fibrosis is the consequence of hepatic stellate cell (HSC) activation, the questions were addressed whether alterations induced by high glucose concentration are directly related to TGFB1 effect, or other mechanisms are activated. In order to obtain information on the response of HSC for high glucose, LX-2 cells (an immortalized human HSC cell lineage) were cultured in 15.3 mM glucose containing medium for 21 days. The effect of glucose was compared to that of TGFB1. Our data revealed that chronic exposure of high glucose concentration initiated profound alteration of LX-2 cells and the effect is different from those observed upon interaction with TGFB1. Whereas TGFB1 induced the production of extracellular matrix proteins, high glucose exposure resulted in decreased MMP2 activity, retardation of type I collagen in the endoplasmic reticulum, with decreased pS6 expression, pointing to development of endoplasmic stress and sequestration of p21CIP1/WAF1 in the cytoplasm which can promote the proliferation of LX2 cells.

Syndecan-1 in Liver Diseases.

Liver diseases such as liver cirrhosis, primary and metastatic liver cancers are still a major medical challenge. Syndecan-1 is one of the most important proteoglycans in the liver. Syndecan-1 is normally expressed on the surfaces of hepatocytes and cholangiocytes. Due to liver diseases the amount of syndecan-1 increases in the liver. Despite the emerging data of the biological function of syndecan-1, the clinical usefulness of this proteoglycan is still unknown. In our study we correlated syndecan-1 expression to clinico-pathological data. We found that syndecan-1 proved to be a good marker for hepatitis C virus based hepatocellular carcinoma and increased with liver dysfunction.

Germline BRCA1 Mutation Detected in a Multiple Endocrine Neoplasia Type 2 Case With RET Codon 634 Mutation.

Coincidences of more than one pathogenic mutation in high and/or moderate risk-associated cancer genes have been rarely reported, and the implication for disease progression has been debated. We present a case harboring two autosomal dominant inherited mutations potentially aggravating the phenotype. Case report: A 16-year-old female was referred to the Endocrine Unit due to two palpable thyroid nodules and hair loss. Two hypoechoic, inhomogeneous masses with microcalcification in the thyroid gland were confirmed as medullary thyroid carcinoma. Genetic testing revealed a pathogenic heterozygous RET mutation associated with multiple endocrine neoplasia type 2 (MEN2). Furthermore, genetic screening identified the same mutation in the proband's clinically negative brother as well as in his two sons. The proband's mother and maternal aunt died of breast cancer. No samples were available from the deceased. The proband underwent further genetic counseling and BRCA1/2 testing. A novel, frameshift heterozygous BRCA1 mutation (BRCA1 p.Ile90Serfs, NC_000017.10:g.41256905_41256917) was identified in the proband, but it was absent in the brother and father, indicative of maternal inheritance. Breast or ovarian cancer was neither detected in our case at initial presentation nor during the 6-year follow-up. Conclusion: Coincidence of two monogenic autosomal dominant tumor syndromes is extremely rare, but it represents a significant therapeutic and cancer surveillance challenge. Due to the wider use of next generation sequencing in clinical practice, similar situations may occur more frequently.

Tumor-specific inhibitory action of decorin on different hepatoma cell lines.

BACKGROUND: In spite of therapeutic approaches, liver cancer is still one of the deadliest type of tumor in which tumor microenvironment may play an active role in the outcome of the disease. Decorin, a small leucine-rich proteoglycan is not only responsible for assembly and maintenance of the integrity of the extracellular matrix, but a natural inhibitor of cell surface receptors, thus it exerts antitumorigenic effects. Here we addressed the question whether this effect of decorin is independent of the tumor phenotypes including differentiation, proliferation and invasion. METHOD: Four hepatoma cell lines HepG2, Hep3B, HuH7 and HLE, possessing different molecular backgrounds, were selected to investigate. After proliferation tests, pRTK arrays, WB analyses, and immunofluorescent examinations were performed on decorin treated and control cells for comparison. RESULTS: Significant growth inhibitory potential of decorin on three out of four hepatoma cell lines was proven, however the mode of its action was different. Induction of p21WAF1/CIP1, increased inactivation of c-myc and ß-catenin, and decrease of EGFR, GSK3ß and ERK1/2 phosphorylation levels were observed in HepG2 cells, pathways already well-described in literature. However, in the p53 deficient Hep3B and HuH7, InsR and IGF-1R were the main receptors transmitting signals. In harmony with its receptor status, Hep3B cells displayed high level of activated AKT. As the cell line is retinoblastoma mutant, ATR/Chk1/Wee1 system might hinder the cell cycle in G2/M phase via phosphorylation of CDK1. In Huh7 cells, all RTKs were inhibited by decorin followed by downregulation of AKT. Furthermore, HuH7 cell line responded with concentration-dependent ERK activation and increased phospho-c-myc level. Decorin had only a non-significant effect on the proliferation rate of HLE cell line. However, it responded with a significant decrease of pAKT, c-myc and ß-catenin activity. In this special cell line, the inhibition of TGFß may be the first step of the protective effect of decorin. CONCLUSIONS: Based on our results decorin may be a candidate therapeutic agent in the battle against liver cancer, but several questions need to be answered. It is certain that decorin is capable to exert its suppressor effect in hepatoma cells without respect to their phenotype and molecular background.

Exploring Differential Connexin Expression across Melanocytic Tumor Progression Involving the Tumor Microenvironment.

The incidence of malignant melanoma, one of the deadliest cancers, continues to increase. Here we tested connexin (Cx) expression in primary melanocytes, melanoma cell lines and in a common nevus, dysplastic nevus, and thin, thick, and metastatic melanoma tumor progression series involving the tumor microenvironment by utilizing in silico analysis, qRT-PCR, immunocyto-/histochemistry and dye transfer tests. Primary melanocytes expressed GJA1/Cx43, GJA3/Cx46 and low levels of GJB2/Cx26 and GJC3/Cx30.2 transcripts. In silico data revealed downregulation of GJA1/Cx43 and GJB2/Cx26 mRNA, in addition to upregulated GJB1/Cx32, during melanoma progression. In three melanoma cell lines, we also showed the loss of GJA1/Cx43 and the differential expression of GJB1/Cx32, GJB2/Cx26, GJA3/Cx46 and GJC3/Cx30.2. The dominantly paranuclear localization of connexin proteins explained the ~10⁻90 times less melanoma cell coupling compared to melanocytes. In melanocytic tumor tissues, we confirmed the loss of Cx43 protein, fall of cell membrane and elevated paranuclear Cx32 with moderately increased cytoplasmic Cx26 and paranuclear Cx30.2 positivity during tumor progression. Furthermore, we found Cx43, Cx26 and Cx30 proteins upregulated in the melanoma adjacent epidermis, and Cx43 in the tumor flanking vessels. Therefore, differential connexin expression is involved in melanocytic tumor progression where varying connexin isotypes and levels reflect tumor heterogeneity-related bidirectional adaptive interactions with the microenvironment.

Chemodiversity of Cirsium fruits: Antiproliferative lignans, neolignans and sesquineolignans as chemotaxonomic markers.

While analyzing the fruit composition of nine European Cirsium species representing three sections (i.e., Cephalonoplos, Chamaeleon and Eriolepis), four lignans, three neolignans and three sesquineolignans were determined and used as chemotaxonomic markers. Among them, desmethyl balanophonin and desmethyl picrasmalignan were determined for the first time in the plant kingdom, as the main metabolites of the Chamaeleon section. Prebalanophonin and prepicrasmalignan, identified so far exclusively in C. eriophorum, were also confirmed in C. boujartii and C. vulgare, highlighting the chemotaxonomic significance of these compounds in the Eriolepis section. The antiproliferative assay of the compounds isolated from their optimum sources, confirmed a dose-dependent inhibitory effect of the structures bearing the 4',7-epoxy moiety (balanophonin, picrasmalignan, desmethyl balanophonin, desmethyl picrasmalignan) against SW480 colon cancer cells, while those bearing the 4',7-dihydroxy motif (prebalanophonin, prepicrasmalignan) were inactive.