Phenotypic characterization and prognostic impact of circulating γδ and αβ T‐cells in metastatic malignant melanoma

Human T cells carrying γδ T‐cell receptors (TCRs) represent a minor population relative to those with αβ TCRs. There has been much interest recently in the possibility of using these γδ T‐cells in cancer therapy because they can kill tumor cells in vitro in an MHC‐unrestricted manner, and possess potential regulatory capability and antigen‐presenting capacity. The presence of γδ T‐cells in late‐stage melanoma patients and their relationship with survival has not been extensively explored, although relatively lower percentages of total γδ T‐cells and Vδ2+ cells have been reported. Here, we present a detailed analysis of associations of γδ T‐cell subsets and differentiation stages with survival in Stage IV patients, compared with CD4+ and CD8+ αβ T‐cells. We found an increased Vδ1:Vδ2‐ratio and a decreased CD4:CD8‐ratio in patients compared to healthy controls, on the basis both of relative frequencies and absolute cell counts per μL blood. Nonetheless, Kaplan–Meier analyses showed that a higher than median frequency of Vδ1+ cells was negatively associated with survival, whereas there were no positive or negative associations with frequencies of Vδ2+ cells. Correlations of cell differentiation status with survival revealed a negative association of early‐differentiated Vδ1+ T cells with survival, both on the basis of relative frequencies and absolute counts. There was also a positive correlation between the frequencies of early‐differentiated CD8+ αβ T‐cells and survival. Our findings suggest peripheral blood frequencies of Vδ1+ T‐cells as a potential prognostic marker in melanoma. The mechanisms by which higher abundance of Vδ1+ cells are associated with poorer survival require determination.     

Regulation of peroxisome proliferator‐activated receptor‐β/δ by the APC/β‐CATENIN pathway and nonsteroidal antiinflammatory drugs

Studies indicate that peroxisome proliferator‐activated receptor‐β/δ (PPARβ/δ) can either attenuate or potentiate colon cancer. One hypothesis suggests that PPARβ/δ is upregulated by the adenomatous polyposis coli (APC)/β‐CATENIN pathway and a related hypothesis suggests that PPARβ/δ is downregulated by nonsteroidal antiinflammatory drugs (NSAIDs). The present study examined these possibilities using in vivo and in vitro models. While APC/β‐CATENIN‐dependent expression of CYCLIN D1 was observed in vivo and in vitro, expression of PPARβ/δ was not different in colon or intestinal polyps from wild‐type or Apc^min heterozygous mice or in human colon cancer cell lines with mutations in APC and/or β‐CATENIN. No difference in the level of PPARβ/δ was found in colon from wild‐type or Apc^min heterozygous mice following treatment with NO‐donating aspirin (NO‐ASA). NSAIDs inhibited cell growth in RKO (wild‐type APC) and DLD1 (mutant APC) human colon cancer cell lines but expression of PPARβ/δ was not downregulated in these cell lines in response to a broad concentration range of celecoxib, indomethacin, NS‐398, or nimesulide. However, indomethacin caused an increase in PPARβ/δ mRNA and protein that was accompanied with increased expression of a known PPARβ/δ target gene. Interestingly, expression of PPARα was also increased in the human colon cancer cell lines by several NSAIDs at the highest concentration examined. Results from these studies provide additional evidence indicating that PPARβ/δ is not upregulated by the APC/β‐CATENIN pathway. Further, these studies suggest that increased PPARβ/δ and/or PPARα by NSAIDs in human colon cancer cell lines could contribute to the mechanisms underlying the chemopreventive effects of NSAIDs. Mol. Carcinog. © 2009 Wiley‐Liss, Inc.     

Estrogen receptor β and breast cancer

A second estrogen receptor, estrogen receptor-beta, was identified in 1996 and has led to an intensive re-evaluation of the role of estrogens in normal physiological and disease processes. While much has been learnt about this new receptor, there remain many outstanding questions, particularly regarding its prognostic significance and therapeutic implications.     

TNF‐α enhances TGF‐β‐induced endothelial‐to‐mesenchymal transition via TGF‐β signal augmentation

The tumor microenvironment (TME) consists of various components including cancer cells, tumor vessels, cancer‐associated fibroblasts (CAFs), and inflammatory cells. These components interact with each other via various cytokines, which often induce tumor progression. Thus, a greater understanding of TME networks is crucial for the development of novel cancer therapies. Many cancer types express high levels of TGF‐β, which induces endothelial‐to‐mesenchymal transition (EndMT), leading to formation of CAFs. Although we previously reported that CAFs derived from EndMT promoted tumor formation, the molecular mechanisms underlying these interactions remain to be elucidated. Furthermore, tumor‐infiltrating inflammatory cells secrete various cytokines, including TNF‐α. However, the role of TNF‐α in TGF‐β‐induced EndMT has not been fully elucidated. Therefore, this study examined the effect of TNF‐α on TGF‐β‐induced EndMT in human endothelial cells (ECs). Various types of human ECs underwent EndMT in response to TGF‐β and TNF‐α, which was accompanied by increased and decreased expression of mesenchymal cell and EC markers, respectively. In addition, treatment of ECs with TGF‐β and TNF‐α exhibited sustained activation of Smad2/3 signals, which was presumably induced by elevated expression of TGF‐β type I receptor, TGF‐β2, activin A, and integrin αv, suggesting that TNF‐α enhanced TGF‐β‐induced EndMT by augmenting TGF‐β family signals. Furthermore, oral squamous cell carcinoma‐derived cells underwent epithelial‐to‐mesenchymal transition (EMT) in response to humoral factors produced by TGF‐β and TNF‐α‐cultured ECs. This EndMT‐driven EMT was blocked by inhibiting the action of TGF‐βs. Collectively, our findings suggest that TNF‐α enhances TGF‐β‐dependent EndMT, which contributes to tumor progression.     

Endoplasmic reticulum stress‐mediated autophagy protects against β,β‐dimethylacrylshikonin‐induced apoptosis in lung adenocarcinoma cells

β,β‐Dimethylacrylshikonin (DMAS) is an anti‐cancer compound extracted from the roots of Lithospermum erythrorhizon. The present study aims to investigate the effects of DMAS on human lung adenocarcinoma cells in vitro and explore the mechanisms of its anti‐cancer action. We showed that DMAS markedly inhibited cell viability in a dose‐ and time‐dependent way, and induced apoptosis as well as autophagy in human lung adenocarcinoma cells. Furthermore, we found that DMAS stimulated endoplasmic reticulum stress and mediated autophagy through the PERK‐eIF2α‐ATF4‐CHOP and IRE1‐TRAF2‐JNK axes of the unfolded protein response in human lung adenocarcinoma cells. We also showed that the autophagy induced by DMAS played a prosurvival role in human lung adenocarcinoma cells and attenuated the apoptotic cascade. Collectively, combined treatment of DMAS and pharmacological autophagy inhibitors could offer an effective therapeutic strategy for lung adenocarcinoma treatment.     

Modulation of TGF‐β activity by latent TGF‐β‐binding protein 1 in human malignant glioma cells

High biological activity of the transforming growth factor (TGF)‐β‐Smad pathway characterizes the malignant phenotype of malignant gliomas and confers poor prognosis to glioma patients. Accordingly, TGF‐β has become a novel target for the experimental treatment of these tumors. TGF‐β is processed by furin‐like proteases (FLP) and secreted from cells in a latent complex with its processed propeptide, the latency‐associated peptide (LAP). Latent TGF‐β‐binding protein 1 (LTBP‐1) covalently binds to this small latent TGF‐β complex (SLC) and regulates its function, presumably via interaction with the extracellular matrix (ECM). We report here that the levels of LTBP‐1 protein in vivo increase with the grade of malignancy in gliomas. LTBP‐1 is associated with the ECM as well as secreted into the medium in cultured malignant glioma cells. The release of LTBP‐1 into the medium is decreased by the inhibition of FLP activity. Gene‐transfer mediated overexpression of LTBP‐1 in glioma cell lines results in an increase inTGF‐β activity. Accordingly, Smad2 phosphorylation as an intracellular marker of TGF‐β activity is enhanced. Conversely, LTBP‐1 gene silencing reduces TGF‐β activity and Smad2 phosphorylation without affecting TGF‐β protein levels. Collectively, we identify LTBP‐1 as an important modulator of TGF‐β activation in glioma cells, which may contribute to the malignant phenotype of these tumors. © 2009 UICC     

CDH6‐activated αIIbβ3 crosstalks with α2β1 to trigger cellular adhesion and invasion in metastatic ovarian and renal cancers

Cadherin 6 (CDH6) is significantly overexpressed in advanced ovarian and renal cancers. However, the role of CDH6 in cancer metastasis is largely unclear. Here, we investigated the impact of CDH6 expression on integrin‐mediated metastatic progression. CDH6 preferentially bound to αIIbβ3 integrin, a platelet receptor scarcely expressed in cancer cells, and this interaction was mediated through the cadherin Arginine–glycine–aspartic acid (RGD) motif. Furthermore, CDH6 and CDH17 were found to interact with α2β1 in αIIbβ3^low cells. Transient silencing of CDH6, ITGA2B, or ITGB3 genes caused a significant loss of proliferation, adhesion, invasion, and lung colonization through the downregulation of SRC, FAK, AKT, and ERK signaling. In ovarian and renal cancer cells, integrin αIIbβ3 activation appears to be a prerequisite for proper α2β1 activation. Interaction of αIIbβ3 with CDH6, and subsequent αIIbβ3 activation, promoted activation of α2β1 and cell adhesion in ovarian and renal cancer cells. Additionally, monoclonal antibodies specific to the cadherin RGD motif and clinically approved αIIbβ3 inhibitors could block pro‐metastatic activity in ovarian and renal tumors. In summary, the interaction between CDH6 and αIIbβ3 regulates α2β1‐mediated adhesion and invasion of ovarian and renal cancer metastatic cells and constitutes a therapeutic target of broad potential for treating metastatic progression.     

Clinicopathological analysis of 17 primary cutaneous T‐cell lymphoma of the γδ phenotype from Japan

Primary cutaneous γδ T‐cell lymphoma (PCGD‐TCL) is an aggressive lymphoma consisting of clonal proliferation of mature activated γδ T‐cells of a cytotoxic phenotype. Because primary cutaneous γδ T‐cell lymphoma is a rare disease, there are few clinicopathological studies. In addition, T‐cell receptor (TCR) γδ cells are typically immunostained in frozen sections or determined by TCRβ negativity. We retrospectively analyzed 17 primary cutaneous T‐cell lymphomas of the γδ phenotype (CTCL‐γδ) in a clinicopathological and molecular study using paraffin‐embedded sections. Among 17 patients, 11 had CTCL‐γδ without subcutaneous panniculitis‐like T‐cell lymphoma (SPTCL) features and six had CTCL‐γδ with SPTCL features. Immunophenotypically, some significant differences were found in CD8 and CD56 positivity between our patient series of CTCL‐γδ patients with SPTCL features and SPTCL‐γδ patients described in the previous literature. A univariate analysis of 17 CTCL‐γδ patients showed that being more than 60 years old, presence of visceral organ involvement, and small‐to‐medium cell size were poor prognostic factors. In addition, the 5‐year overall survival rate was 42.4% for the CTCL‐γδ patients without SPTCL features and 80.0% for those with SPTCL features. Consequently, there was a strikingly significant difference in overall survival among SPTCL, CTCL‐γδ with SPTCL features and CTCL‐γδ without SPTCL features (P = 0.0005). Our data suggests that an indolent subgroup may exist in CTCL‐γδ. Studies on more cases, including those from other countries, are warranted to delineate the clinicopathological features and the significance in these rare lymphomas.     

Dkk3, downregulated in cervical cancer,functions as a negative regulator of β‐catenin

The Wnt/β‐catenin signaling pathway is activated during the malignant transformation of keratinocytes that originate from the human uterine cervix. Dkk1, 2 and 4 have been shown to modulate the Wnt‐induced stabilization of the β‐catenin signaling pathway. However, the function of Dkk3 in this pathway is unknown. Comparison of the Dkk3 gene expression profiles in cervical cancer and normal cervical tissue by cDNA microarray and subsequent real‐time PCR revealed that the Dkk3 gene is frequently downregulated in the cancer. Methylation studies showed that the promoter of Dkk3 was methylated in cervical cancer cell lines and 22 (31.4%) of 70 cervical cancer tissue specimens. This promoter methylation was associated with reduced expression of Dkk3 mRNA in the paired normal and tumor tissue samples. Further, the reintroduction of Dkk3 into HeLa cervical cancer cells resulted in reduced colony formation and retarded cell growth. The forced expression of Dkk3 markedly attenuated β‐catenin‐responsive luciferase activity in a dose‐dependent manner and decreased the β‐catenin levels. By utilizing a yeast two‐hybrid screen, βTrCP, a negative regulator of β‐catenin was identified as a novel Dkk3‐interacting partner. Coexpression with βTrCP synergistically enhanced the inhibitory function of Dkk3 on β‐catenin. The stable expression of Dkk3 blocks the nuclear translocation of β‐catenin, resulting in downregulation of its downstream targets (VEGF and cylcin D), whereas knockdown of Dkk3 abrogates this blocking. We conclude from our finding that Dkk3 is a negative regulator of β‐catenin and its downregulation contribute to an activation of the β‐catenin signaling pathway. © 2008 Wiley‐Liss, Inc.     

Retinoid X receptor α enhances human cholangiocarcinoma growth through simultaneous activation of Wnt/β‐catenin and nuclear factor‐κB pathways

Retinoid X receptor α (RXRα) plays important roles in the malignancy of several cancers such as human prostate tumor, breast cancer, and thyroid tumor. However, its exact functions and molecular mechanisms in cholangiocarcinoma (CCA), a chemoresistant carcinoma with poor prognosis, remain unclear. In this study we found that RXRα was frequently overexpressed in human CCA tissues and CCA cell lines. Downregulation of RXRα led to decreased expression of mitosis‐promoting factors including cyclin D1and cyclin E, and the proliferating cell nuclear antigen, as well as increased expression of cell cycle inhibitor p21, resulting in inhibition of CCA cell proliferation. Furthermore, RXRα knockdown attenuated the expression of cyclin D1 through suppression of Wnt/β‐catenin signaling. Retinoid X receptor α upregulated proliferating cell nuclear antigen expression through nuclear factor‐κB (NF‐κB) pathways, paralleled with downregulation of p21. Thus, the Wnt/β‐catenin and NF‐κB pathways account for the inhibition of CCA cell growth induced by RXRα downregulation. Retinoid X receptor α plays an important role in proliferation of CCA through simultaneous activation of Wnt/β‐catenin and NF‐κB pathways, indicating that RXRα might serve as a potential molecular target for CCA treatment.     

Evaluation of the safety,pharmacokinetics and treatment effects of an ανβ3 integrin inhibitor on bone turnover and disease activity in men with hormone‐refractory prostate cancer and bone metastases

Aim: This study aimed to evaluate the safety, pharmacokinetics and treatment effects of an α_νβ₃ integrin inhibitor on bone turnover and disease activity in men with hormone‐refractory prostate cancer (HRPC) and bone metastases. Methods: A total of 21 patients with bone metastases and HRPC were randomized to receive MK‐0429 200 mg b.i.d. or 1600 mg b.i.d. for 4 weeks. Toxicity, pharmacokinetics and markers of bone turnover and tumor activity were examined. Results: Nausea was the most common adverse event: one (200‐mg group) and 11 (1600‐mg group) patients. At 4 weeks, mean AUC_{0–12 h} was 210 mmol*h (200‐mg group) and 673 mmol*h (1600‐mg group); mean C_max values were 42 mmol/L (200‐mg group) and 154 mmol/L (1600‐mg group). Urinary cross‐linked N‐telopeptides of type I collagen to creatinine ratio (uNTx), a bone turnover biomarker, showed a change from baseline of ?43.4 percent (200‐mg group) and ?34.1 percent (1600‐mg group). There was an increase in serum prostate specific antigen (PSA), a marker for disease activity, of 54.1 percent (200‐mg group) and 44.5 percent (1600‐mg group). Conclusion: MK‐0429 was generally well tolerated, with the most common side‐effect being nausea. There was some evidence of an early reduction of bone turnover, indicating a potential for clinical use in the treatment of MBD although serum PSA was unexpectedly increased during the study.     

Regulatory mechanisms mediated by peroxisome proliferator‐activated receptor‐β/δ in skin cancer

Considerable progress has been made during the past 20 years towards elucidating the role of peroxisome proliferator‐activated receptor‐β/δ (PPARβ/δ) in skin cancer. In 1999, the original notion that PPARβ/δ was involved with epithelial cell function was postulated based on a correlation between PPARβ/δ expression and the induction of messenger RNAs encoding proteins that mediate terminal differentiation in keratinocytes. Subsequent studies definitively revealed that PPARβ/δ could induce terminal differentiation and inhibit proliferation of keratinocytes. Molecular mechanisms have since been discovered to explain how this nuclear receptor can be targeted for preventing and treating skin cancer. This includes the regulation of terminal differentiation, mitotic signaling, endoplasmic reticulum stress, and cellular senescence. Interestingly, the effects of activating PPARβ/δ can preferentially target keratinocytes with genetic mutations associated with skin cancer. This review provides the history and current understanding of how PPARβ/δ can be targeted for both nonmelanoma skin cancer and melanoma and postulates how future approaches that modulate PPARβ/δ signaling may be developed for the prevention and treatment of these diseases.     

Extracellular 5′‐nucleotidase (CD73) promotes human breast cancer cells growth through AKT/GSK‐3β/β‐catenin/cyclinD1 signaling pathway

To identify the role and to explore the mechanism of extracellular 5′‐nucleotidase (CD73) in human breast cancer growth, CD73 expression was measured firstly in breast cancer tissues and cell lines, and then interfered with or over‐expressed by recombinant lentivirus in cell lines. Impacts of CD73 on breast cancer cell proliferation and cell cycle were investigated with colony formation assay, CCK‐8 and flow cytometry. The relationship between CD73 and AKT/GSK‐3β/β‐catenin pathway was assessed with adenosine, adenosine 2A receptor antagonist (SCH‐58261), adenosine 2A receptor agonist (NECA), CD73 enzyme inhibitor (APCP) and Akt inhibitor (MK‐2206). Moreover, the effect of CD73 on breast cancer growth in vivo was examined with human breast cancer transplanting model of nude mice. The results showed that the expression of CD73 was high in breast cancer tissues and increased with advanced tumor grades and lympho‐node status. CD73 expression was higher in more malignant cells, and CD73 overexpression promoted breast cancer cell proliferation in both in vivo and in vitro. It activated AKT/GSK‐3β/β‐catenin/cyclinD1 signaling pathway through CD73 enzyme activity and other mechanism.     

Bone sialoprotein‐αvβ3 integrin axis promotes breast cancer metastasis to the bone

The underlying mechanisms of breast cancer cells metastasizing to distant sites are complex and multifactorial. Bone sialoprotein (BSP) and αvβ3 integrin were reported to promote the metastatic progress of breast cancer cells, particularly metastasis to bone. Most theories presume that BSP promotes breast cancer metastasis by binding to αvβ3 integrin. Interestingly, we found the αvβ3 integrin decreased in BSP silenced cells (BSPi), which have weak ability to form bone metastases. However, the relevance of their expression in primary tumor and the way they participate in metastasis are not clear. In this study, we evaluated the relationship between BSP, αvβ3 integrin levels, and the bone metastatic ability of breast cancer cells in patient tissues, and the data indicated that the αvβ3 integrin level is closely correlated to BSP level and metastatic potential. Overexpression of αvβ3 integrin in cancer cells could reverse the effect of BSPi in vitro and promote bone metastasis in a mouse model, whereas knockdown of αvβ3 integrin have effects just like BSPi. Moreover, The Cancer Genome Atlas data and RT‐PCR analysis have also shown that SPP1, KCNK2, and PTK2B might be involved in this process. Thus, we propose that αvβ3 integrin is one of the downstream factors regulated by BSP in the breast cancer‐bone metastatic cascade.