Increased Fas expression reduces the metastatic potential of human osteosarcoma cells.

PURPOSE: The process of metastasis requires the single tumor cell that seeds the metastatic clone to complete a complex series of steps. Identifying factors responsible for these steps is essential in developing and improving targeted therapy for metastasis. Resistance to receptor-mediated cell death, such as the Fas/Fas ligand pathway, is one mechanism commonly exploited by metastatic cell populations. EXPERIMENTAL DESIGN AND RESULTS: LM7, a subline of the SAOS human osteosarcoma cell line with low Fas expression, was selected for its high metastatic potential in an experimental nude mouse model. When transfected with the full-length Fas gene (LM7-Fas), these cells expressed higher levels of Fas than the parental LM7 cells or LM7-neo control-transfected cells. These cells were also more sensitive to Fas-induced cell death than controls. When injected intravenously into nude mice, the LM7-Fas cell line produced a significantly lower incidence of tumor nodules than control cell lines. Lung weight and tumor nodule size were also decreased in those mice injected with LM7-Fas. Levels of Fas were quantified in osteosarcoma lung nodules from 17 patients. Eight samples were Fas negative, whereas the remaining 9 were only weakly positive compared with normal human liver (positive control). CONCLUSIONS: Our results demonstrate that altering Fas expression can impact the metastatic potential of osteosarcoma cells. We conclude that the increase of Fas on the surface of the LM7 osteosarcoma cells increased their sensitivity to Fas-induced cell death in the microenvironment of the lung, where Fas ligand is constitutively expressed. Thus, loss of Fas expression is one mechanism by which osteosarcoma cells may evade host resistance mechanisms in the lung, increasing metastatic potential. Fas may therefore be a new therapeutic target for osteosarcoma.     

miR-20a encoded by the miR-17-92 cluster increases the metastatic potential of osteosarcoma cells by regulating Fas expression

The ability of osteosarcoma cells to form lung metastases has been inversely correlated to cell surface Fas expression. Downregulation of Fas allows osteosarcoma cells to circumvent FasL-mediated apoptosis upon entrance into the FasL(+) lung microenvironment. However, the mechanism of Fas regulation remains unclear. Here, we show that miRNA plays a role in the downregulation of Fas expression in osteosarcoma. Expression levels of several members of the miR-17-92 cluster including miR-20a and miR-19a were found to be higher in metastatic low-Fas-expressing LM7 cells than in the parental nonmetastatic high-Fas-expressing SAOS-2 cells. We also found an inverse correlation between Fas and miR-20a expression in all 8 cell lines derived from patient samples. Overexpression of miR-20a consistently resulted in the downregulation of Fas expression in SAOS-2 cells and thus in decreased sensitivity to FasL. Conversely, inhibiting miR-20a in LM7 cells increased Fas expression and their sensitivity to FasL. Mice injected with LM7 stably transfected with anti-miR-20a had fewer metastases than those with control plasmids. Taken together, our findings suggest that miR-20a, encoded by miR-17-92, downregulates Fas expression in osteosarcoma, thus contributing to the metastatic potential of osteosarcoma cells by altering the phenotype and allowing survival in the FasL(+) lung microenvironment.     

Interleukin (IL)-12 and IL-12 gene transfer up-regulate Fas expression in human osteosarcoma and breast cancer cells

Expression of Fas (CD95, APO-1), a cell surface receptor capable of inducing ligand-mediated apoptosis, is involved in tissue homeostasis and elimination of targeted cells by natural killer and T cells. Corruption of this pathway, such as reduced Fas expression, can allow tumor cells to escape elimination and promote metastatic potential. In this study, the status of Fas expression has been examined in the parental SAOS human osteosarcoma cells that do not metastasize and in selected variants that cause lung metastases in 16 weeks (LM2) or 8 weeks (LM6) after i.v. injection into nude mice. Fas expression correlated with the metastatic potentials of the three cell lines. Northern and fluorescence-activated cell-sorting analyses indicated that LM6 cells expressed Fas at a lower level than seen in the parental cells. Infection of the LM6 cells with an adenoviral vector containing the murine interleukin (IL)-12 gene (AD:mIL-12) or treatment with recombinant murine IL-12 resulted in a dose-dependent up-regulation of FAS: The up-regulation of Fas by IL-12 was also demonstrated in human etoposide-resistant MDA-MB-231 breast cancer cells. [(3)H]Thymidine growth inhibition studies indicated that the cell surface Fas induced after IL-12 exposure was functional and able to mediate cell death on cross-linking with anti-FAS: We also demonstrate that this effect is independent of IFN-gamma. Whereas these cell lines are sensitive to IFN-gamma, incubation with IFN-gamma does not increase susceptibility to Fas-mediated cell death, nor do these cells produce IFN-gamma with or without IL-12 treatment. We hypothesize that expression of Fas may play a role in the elimination of metastatic tumor cells in the lung, an organ in which Fas ligand is expressed. The antitumor activity of IL-12 may be secondary in part to its ability to up-regulate Fas expression on tumor cells, which subsequently increases immune-mediated destruction of osteosarcoma cells.     

Effect of the histone deacetylase inhibitor SNDX-275 on Fas signaling in osteosarcoma cells and the feasibility of its topical application for the treatment of osteosarcoma lung metastases

BACKGROUND:

Patients with lung metastases from osteosarcoma (OS) have poor response to salvage therapy. Understanding the mechanisms involved in the metastatic process of OS may lead to new effective therapeutic approaches. The authors reported previously that up‐regulation of the Fas receptor by transfecting OS cells with Fas plasmid inhibited the in vivo growth of metastases in the lungs.

METHODS:

In the current study, the authors treated OS cells with the histone deacetylase inhibitor SNDX‐275 and studied its cytotoxicity and its effect on Fas signaling in vitro and in vivo.

RESULTS:

Subtoxic doses of SNDX‐275 were able to activate the Fas pathway in OS cells by increasing the expression of Fas messenger RNA; however, the increased expression was not always followed by increased levels of Fas receptor expression on the cell surface. The treatment of cells with a combination of SNDX‐275 and Fas ligand (FasL) had a stronger cytotoxic effect on tested OS cells than either agent alone. Inhibition of the Fas pathway in cells by inhibition of the Fas‐associated death domain (FADD) molecule eliminated this combination effect, indicating that activity of FADD is important for the efficacy of this agent in the FasL‐expressing environment of the lungs. Intranasal administration of SNDX‐275 in mice with OS lung metastases revealed that SNDX‐275 may inhibit metastatic growth at a dose of 0.13 mg/kg, which is approximately 200‐fold lower than the therapeutically effective oral dose reported previously.

CONCLUSIONS:

The current findings indicated that SNDX‐275 can activate Fas signaling in OS cells in vitro and in vivo and that the administration of SDNX‐275 by inhalation is feasible as a treatment for OS metastases and warrants its further investigation. Cancer 2011. © 2011 American Cancer Society.     

Aerosol gemcitabine inhibits the growth of primary osteosarcoma and osteosarcoma lung metastases

Osteosacarcoma (OS) lung metastases are often resistant to chemotherapy. Most anticancer drugs are administered systemically. In many cases this is followed by dose-dependent toxicity, which may not allow the achievement of therapeutic levels in lungs to eradicate metastases. We determined the efficacy of gemcitabine (GCB) by administering it directly to the lungs via aerosol and studied the role of the Fas pathway in response to the therapy. We used 2 osteosarcoma lung metastases animal models: human LM7 cells that form lung metastases in mice following intravenous injection and murine LM8 cells, which grows subcutaneously in mice and spontaneously metastasize to the lung. Treatment was initiated when the presence of lung metastases had been established. Aerosol GCB inhibited the growth of lung metastases in mice. Intraperitoneal GCB administration at similar dosage had no effect on lung metastases. Besides its direct effect on lung metastases, aerosol GCB suppressed the growth of subcutaneous LM8 tumor. Histopathological examination of mice receiving aerosol GCB showed no evidence of toxicity. Lungs are distinguished from other tissues by the constitutive expression of FasL. Since exposure of tumor cells to GCB upregulated Fas expression, we hypothesized that the susceptibility of the tumor cells to ligand-induced cell death by resident lung cells may be increased. Therefore, the Fas pathway may contribute to the therapeutic effect of aerosol GCB.     

Interleukin-12 enhances the sensitivity of human osteosarcoma cells to 4-hydroperoxycyclophosphamide by a mechanism involving the Fas/Fas-ligand pathway.

Cyclophosphamide (CY) and its derivative ifosfamide are alkylating agents used to treat osteosarcoma (OS). The purpose of these studies was to determine whether alkylating agents affect the expression of Fas ligand (FasL) and whether interleukin 12 enhances the sensitivity of human OS cells to alkylating agents. 4-Hydroperoxycyclophosphamide (4-HC), the preactivated CY compound, and 4-hydroperoxydidechlorocloclophosphamide (4-HDC), its nonalkylating analogue, human OS LM6 cells, and a clone of cells derived by transfection with the interleukin 12 gene (LM6-#6) were used for these studies. Incubation of LM6 and LM6-#6 with 10 micro M 4-HC increased the expression of FasL mRNA (2.5- and 3.0-fold, respectively). By contrast, 4-HDC, Adriamycin (ADR), cisplatin (CDP), and methotrexate (MTX) had no effect on FasL mRNA expression. Increased FasL expression after treatment with 4-HC was also demonstrated by immunohistochemistry and flow cytometry. Drug-induced FasL was functional and mediated cell death. We examined the effect of FasL up-regulation by 4-HC on LM6 and LM6-#6 cells. Flow cytometry showed that LM6-#6 cells expressed 2.2-fold more Fas than LM6 cells. Cytotoxicity of 4-HC, 4-HDC, ADR, CDP, and MTX on LM6, LM6-neo, and LM6-#6 were quantified. Colony-forming assay revealed an IC(50) of 2.10 micro M for 4-HC in LM6-neo cells compared with 0.41 micro M in LM6-#6 cells. The IC(50) for 4-HDC, ADR, CDP, and MTX were not significantly different between the two cell lines. We concluded that the increased expression of Fas enhanced LM6-#6 sensitivity to 4-HC. These data indicate that Fas/FasL may be involved in the cytotoxic pathway of CY. Combining biological agents with chemotherapeutic agents that have complementary Fas/FasL pathway actions may offer new therapeutic alternatives.     

Fas expression inversely correlates with metastatic potential in osteosarcoma cells

A complex series of steps must take place to allow for a single cell to metastasize. Identifying factors responsible for these steps is essential in developing targeted therapy. We developed series of osteosarcoma cell lines with differing metastatic potentials. We used them to investigate mechanisms of metastasis and possible therapeutic targets for osteosarcoma metastasis to the lung in a nude mouse model. No correlation was found between epidermal growth factor receptor (EGFR), insulin-like growth factor receptor inhibitor (IGF-I-R), gelatinase, p53, metalloproteinase 9 (MMP 9), platelet derived growth factor receptor (PDGF-R), vascular endothelial growth factor (VEGF) and c-met expression and metastatic potential as measured by Northern analysis. By contrast, Fas expression inversely correlated with metastatic potential, and manipulation of Fas expression altered the metastatic phenotype of the cell. Our data indicate that fas gene expression may offer a new therapeutic target for the treatment of metastatic osteosarcoma in the lung.     

Production of VEGF165 by Ewing's sarcoma cells induces vasculogenesis and the incorporation of CD34+ stem cells into the expanding tumor vasculature

The Ewing's sarcoma cell line TC71 overexpresses vascular endothelial growth factor isoform 165 (VEGF165), a potent proangiogenic molecule that induces endothelial cell proliferation, migration, and chemotaxis. CD34+ bone marrow stem cells can differentiate into endothelial and hematopoietic cells. We used a transplant model to determine whether CD34+ cells migrate from the bone marrow to Ewing's sarcoma tumors and participate in the neovascularization process that supports tumor growth. We also examined the role of VEGF165 in CD34+ cell migration. Human umbilical cord CD34+ cells were transplanted into sublethally irradiated severe combined immunodeficient mice. Seven days later, the mice were injected subcutaneously with TC71 tumor cells. Tumors were excised 2 weeks later and analyzed by immunohistochemistry. The tumor sections expressed both human VE-cadherin and mouse CD31, indicating involvement of donor-derived human cells in the tumor vessels. To determine the role of VEGF165 in the chemoattraction of CD34+ cells, we generated two VEGF165-deficient TC71 clones, a stable anti-sense VEGF165 cell line (Clone 17) and a VEGF165 siRNA-inhibited clone (TC/siVEGF(7-1)). The resulting VEGF165-deficient tumor cells had normal growth rates in vitro, but had delayed growth when implanted into mice. Immunohistochemical analysis revealed decreased infiltration of CD34+ cells into both VEGF165-deficient tumors. These data show that bone marrow stem cells contribute to the growing tumor vasculature in Ewing's sarcoma and that VEGF165 is critical for the migration of CD34+ cells from the bone marrow into the tumor.     

Stromal cell-derived factor-1 stimulates vasculogenesis and enhances Ewing's sarcoma tumor growth in the absence of vascular endothelial growth factor

Stromal cell-derived Factor-1alpha (SDF-1alpha) stimulates the migration of bone marrow (BM) cells, similar to vascular endothelial growth factor (VEGF). We previously demonstrated that inhibition of VEGF(165) by small interfering RNA inhibited Ewing's sarcoma tumor growth, tumor vessel formation and recruitment of BM cells to the tumor. To determine the importance of BM cells in tumor vessel development, we investigated the effects of SDF-1alpha on VEGF-inhibited TC/siVEGF(7-1) Ewing's tumor neovasculature formation and growth. The effect of SDF-1alpha on CD34(+) progenitor cell chemotaxis was determined in vivo. Using a BM transplantation model with GFP(+) transgenic mice as BM donors and nude mice as recipients, we evaluated the effect of SDF-1alpha on the recruitment of BM-derived cells to VEGF(165)-inhibited TC/siVEGF(7-1) tumors, as well as its effect on neovasculature development, vessel morphology and tumor growth. SDF-1alpha stimulated the migration of CD34(+) progenitor cells to Matrigel plugs in vivo and promoted the retainment of BM-derived pericytes in close association with perfused, functional tumor vessels. Intratumor inoculation of Ad-SDF-1alpha into TC/siVEGF(7-1) tumors resulted in increased SDF-1 and PDGF-BB expression, augmented tumor growth, an increase in the number of large, lumen-bearing vascular structures, and enhanced vessel pericyte coverage, with no change in VEGF(165). SDF-1alpha stimulates BM cell chemotaxis and the association of these cells with functional tumor vessels. Furthermore, SDF-1alpha enhances tumor neovascularization and growth with no alteration in VEGF(165). Our work suggests that SDF-1-mediated vasculogenesis may represent an alternate pathway that could potentially be utilized by tumors to sustain growth and neovasculature expansion after anti-VEGF therapy.     

Downregulation of IFN-gammaR in association with loss of Fas function is linked to tumor progression

The host immune system functions as an intrinsic surveillance network in the recognition and destruction of tumor cells, and it has been demonstrated that lymphocytes and IFN-gamma are the primary tumor suppressors of the immune system. However, the immune system can concurrently select for tumor variants with reduced immunogenicity and aggressive phenotypes. We report here that tumor escape variants that have survived CTL adoptive immunotherapy exhibited decreased expression levels of both Fas and IFN-gammaR in vitro. Furthermore, examination of spontaneously arising mouse primary mammary carcinoma and lung metastases revealed that both Fas and IFN-gammaR protein levels were dramatically lower in lung metastases than in primary tumors in vivo. Functional disruption of either the Fas- or the IFN-gamma signaling pathway enhanced the colonization efficiency of preexisting metastatic tumor cells, whereas disruption of both Fas and IFN-gammaR pathways resulted in synergistic augmentation of the colonization efficiency of the preexisting metastatic tumor cells, as determined by experimental lung metastases assay. Gene expression profiling revealed that altered expression of genes involved in immediate IFN-gammaR signaling, the interferon primary response, apoptosis and tumor colonization is associated with loss of IFN-gammaR function and enhanced metastatic potential. Interestingly, disruption of IFN-gammaR function did not alter tumor cell susceptibility to CTL-mediated cytotoxicity, but is linked to enhanced infiltration of endogenous T cells in the tumor microenvironment in vivo. These findings suggest that coordinate downregulation of Fas and IFN-gammaR, 2 key components of cancer immunosurveillance system on tumor cells, leads to a more aggressive metastatic phenotype.     

VEGF(121), VEGF(165) overexpression enhances tumorigenicity in U251 MG but not in NG-1 glioma cells

Vascular endothelial growth factor (VEGF) is a multifunctional cytokine with important roles in angiogenesis. VEGF is overexpressed in human cancers, including highly vascularized and infiltrative brain tumors. In our previous study of seven glioma cell lines, VEGF expression levels correlated with blood vessel density and tumorigenicity, and U251 MG and NG-1 cells were recognized as low-tumorigenic glioma cell lines. We hypothesized that low-tumorigenic cells can become highly tumorigenic when high levels of VEGF are expressed. To test this hypothesis, we constructed VEGF expression vectors containing 564 bp or 696 bp of VEGF(121) or VEGF(165) cDNA, respectively, and transfected them into U251 MG and NG-1 cells. In comparison to parental cells, the 20 VEGF-expressing clones examined had on average 8-10-fold more VEGF mRNA and 12-88-fold more secreted VEGF proteins. Four VEGF-overexpressing clones (U251 MG/V121-C2, U251 MG/V165-C3, NG-1/V121-C6, and NG-1/V165-C3) were selected for additional study. As VEGF production increased with population growth, U251 MG/V121-C2 and U251 MG/V165-C3 cells accumulated 47.9 and 22.0 ng of VEGF during a 5-day culture of 10(4) cells, a 313- and 144-fold overexpression when compared with that in parental U251 MG cells. NG-1/V121-C6 and NG-1/V165-C3 cells secreted 30.4 and 9.4 ng of VEGF, respectively, or 138- and 43-fold more than did the parental NG-1 cells. Subcutaneous implantation of the VEGF-overexpressing U251 MG cells into nude mice caused huge, soft hemorrhagic tumors to form, whereas controls maintained very small tumors. Intracranial implantation of the VEGF-overexpressing cell lines significantly shortened survival of the mice when compared with controls, and it caused formation of solid brain tumors with variable sized hemorrhages, whereas the controls had no apparent brain tumors. Tumorigenicity of U251 MG cells was synergized by co-overexpression of VEGF(121) and VEGF(165). In addition, VEGF(165) seemed to be more potent to the brain endothelium than was VEGF(121). More interestingly, except when an admixture of cells was implanted s.c., VEGF overexpression in NG-1 cells did not promote hemorrhagic tumor formation. These data suggested that a switch from a phenotype of low tumorigenicity to one of high tumorigenicity is possible when VEGF overexpression occurs, although other factors may also be required.     

Intranasal therapy with an adenoviral vector containing the murine interleukin-12 gene eradicates osteosarcoma lung metastases.

The purpose of these studies was to determine the effect of adenovirus-mediated interleukin-12 (IL-12) gene transfer on the growth and development of osteosarcoma (OS) lung metastases in nude mice. A nude mouse model was produced by repetitive cycling of human SAOS OS cells through the lung. The resultant SAOS-LM6 cell line produced microscopic lung metastases by 5-6 weeks after i.v. injection of the tumor cells, with visible lung metastases present 8 weeks after injection. Transfection of SAOS-LM6 cells with a plasmid containing the murine IL-12 gene resulted in a decrease in metastatic potential. Animals injected with IL-12-transfected clones had fewer metastases compared with mice injected with SAOS-LM6 cells transfected with a control plasmid. Furthermore, nasal delivery of an adenoviral vector containing the murine IL-12 gene resulted in the inhibition of pulmonary metastases. Together, these data indicate that IL-12 may be an effective agent against OS and that nasal delivery may offer a unique way to deliver the gene to the local tumor environment, potentially decreasing systemic toxic effects.     

Decreased metastatic phenotype in cells resistant to aminolevulinic acid-photodynamic therapy

Photodynamic therapy (PDT) is a novel cancer treatment utilising a photosensitiser, visible light and oxygen. PDT often leaves a significant number of surviving tumour cells. In a previous work, we isolated and studied two PDT resistant clones derived from the mammary adenocarcinoma LM3 line (Int. J. Oncol. 29 (2006) 397-405). The isolated Clon 4 and Clon 8 exhibited a more fibroblastic, dendritic pattern and were larger than the parentals. In the present work we studied the metastatic potential of the two clones in comparison with LM3. We found that 100% of LM3 invaded Matrigel, whereas only 19+/-6% and 24+/-7% of Clon 4 and Clon 8 cells invaded. In addition, 100% of LM3 cells migrated towards a chemotactic stimulus whereas 38+/-8% and 73+/-10% of Clones 4 and 8, respectively, were able to migrate. In vivo, 100% of the LM3 injected mice developed spontaneous lung metastasis, whereas none of the Clon 8 did, and only one of the mice injected with Clon 4 did. No differences were found in the proteolytic enzyme profiles among the cells. Anchorage-dependent adhesion was also impaired in vivo in the resistant clones, evidenced by the lower tumour take, latency time and growth rates, although both clones showed in vitro higher binding to collagen I without overexpression of beta1 integrin. This is the first work where the metastatic potential of cells surviving to PDT has been studied. PDT strongly affects the invasive phenotype of these cells, probably related to a higher binding to collagen. These findings may be crucial for the outcome of ALA-PDT of metastatic tumours, although further studies are needed to extrapolate the results to the clinic employing another photosensitisers and cell types.     

Expression of Fas ligand (CD95L) in primary malignant melanoma and melanoma metastases is associated with overall survival

BACKGROUND: There is increasing evidence that the Fas/Fas ligand (FasL) system is involved in tumor-mediated immune suppression. The purpose of this study was to investigate the effect of Fas (CD95) as well as FasL (CD95L) expression in primary malignant melanoma and melanoma metastases on overall survival (OS). PATIENTS AND METHODS: 19 patients with metastatic malignant melanoma who were treated with different dacarbazine (DTIC)-based chemotherapy regimens were included in this study. From each patient, primary melanoma biopsies and biopsies from metastases were histologically evaluated. Immunohistology was performed with antibodies to Fas/CD95 and FasL/CD95L. Differences in OS were plotted using the Kaplan-Meier method and compared by the log rank test. RESULTS: Fas/CD95 and FasL/CD95L expression was detected in 73.7 and 63.2% of primary melanomas, respectively. In metastases, expression of both Fas/CD95 (63.2%) and FasL/CD95L (47.4%) was markedly decreased. Presence of FasL/ CD95L expression in primary melanoma resulted in significantly (p = 0.024) prolonged OS compared with FasL/CD95L-negative high-risk primary melanomas. In contrast, loss of FasL/CD95L expression in melanoma metastases resected before chemotherapy was associated with significantly prolonged median survival (p = 0.0139). CONCLUSION: Presence of FasL/CD95L expression in primary malignant melanoma and the loss of FasL/ CD95L expression in metastases seem to be positive prognostic factors.     

Vascular endothelial growth factor overexpression by soft tissue sarcoma cells: implications for tumor growth, metastasis, and chemoresistance

To better elucidate the role of vascular endothelial growth factor (VEGF)(165) in soft tissue sarcoma (STS) growth, metastasis, and chemoresistance, we generated stably transfected human STS cell lines with VEGF(165) to study the effect of VEGF(165) on STS cells in vitro and the effect of culture medium from these cells on human umbilical vascular endothelial cells. Severe combined immunodeficient mice bearing xenografts of transfected cell lines were used to assess the effect of VEGF overexpression and the effect of VEGF receptor (VEGFR) 2 inhibition on STS growth, metastasis, and response to doxorubicin. VEGF(165)-transfected xenografts formed highly vascular tumors with shorter latency, accelerated growth, enhanced chemoresistance, and increased incidence of pulmonary metastases. Blockade of VEGFR2 signaling using DC101 anti-VEGFR2 monoclonal antibody enhanced doxorubicin chemoresponse; this combined biochemotherapy inhibited tumor growth and decreased pulmonary metastases without overt toxicity. Combined therapy reduced microvessel counts while increasing vessel maturation index. VEGF overexpression did not affect on the sarcoma cells per se; however, conditioned medium from VEGF transfectants caused increased endothelial cell proliferation, migration, and chemoresistance. Addition of DC101 induced endothelial cell sensitivity to doxorubicin and suppressed the activity of matrix metalloproteinases secreted by endothelial cells. We therefore conclude that VEGF is a critical determinant of STS growth and metastasis and that STS chemoresistance, in our model, is a process induced by the interplay between STS cells and tumor-associated endothelial cells. STS growth and metastasis can be interrupted by combined low-dose doxorubicin and anti-VEGFR2, a strategy that attacks STS-associated endothelial cells. In the future, such therapeutic approaches may be useful in treating STS before the development of clinically apparent metastases.     

Fas/FasL 在肺癌中的表达与淋巴结转移的关系

 目的　探讨 Fas/Fas L在肺癌中的表达及其与淋巴结转移的关系。方法　用免疫组化方法同时检测 42例非小细胞肺癌组织及肺癌转移淋巴结的 Fas/Fas L表达。结果　肺癌的 Fas表达率为 52 .3% (2 2 /4 2 ) ,其中鳞癌为 58.3% (1 4/2 4 ) ,腺癌为 44.4% (8/1 8) ,二者无显著差异 (P>0 .0 5)。肺癌的 Fas表达与有否淋巴结转移无明显相关 (P>0 .0 5)。肺癌的 Fas L表达为 57.1 % (2 4 /4 2 ) ,其中鳞癌 58.3% (1 4/2 4 )与腺癌 55.5% (1 0 /1 8)之间无显著差别 (P>0 .0 5)。肺癌伴淋巴结转移的 Fas L表达为 72 .7% (1 6/2 2 ) ,无淋巴结转移的 Fas L表达为 40 % (8/2 0 ) ,有显著差别 (P<0 .0 5)。1 6例 Fas L阳性肺癌的转移淋巴结均呈表达 Fas L。结论　肺癌表达 Fas L,并可能在肺癌转移机制中起免疫逃避作用。     

miR-27a and miR-27a* contribute to metastatic properties of osteosarcoma cells

Osteosarcoma (OS) is the most common primary malignant bone tumor in adolescents and young adults. The essential mechanisms underlying osteosarcomagenesis and progression continue to be obscure. MicroRNAs (miRNAs) have far-reaching effects on the cellular biology of development and cancer. We recently reported that unique miRNA signatures associate with the pathogenesis and progression of OS. Of particular interest, we found that higher expression of miR-27a is associated with clinical metastatic disease. We report here that overexpression of miR-27a/miR-27a*, a microRNA pair derived from a single precursor, promotes pulmonary OS metastases formation. By contrast, sequestering miR-27a/miR-27a* by sponge technology suppressed OS cells invasion and metastases formation. miR-27a/miR-27a* directly repressed CBFA2T3 expression among other target genes. We demonstrated that CBFA2T3 is downregulated in majority of OS samples and its over expression significantly attenuated OS metastatic process mediated by miR-27a/miR-27a* underscoring CBFA2T3 functions as a tumor suppressor in OS. These findings establish that miR-27a/miR-27a* pair plays a significant role in OS metastasis and proposes it as a potential diagnostic and therapeutic target in managing OS metastases.     

Stable knockdown of S100A4 suppresses cell migration and metastasis of osteosarcoma

S100A4, a 10–12 kDa calcium-binding protein, plays functional roles in tumor progression and metastasis. The present study aimed to investigate the function of S100A4 in osteosarcoma (OS) metastasis, using a loss-of-function approach. Our previous expression profiling analysis revealed that S100a4 was preferentially expressed in the highly metastatic mouse OS cell line, LM8. Introducing a short hairpin ribonucleic acid (shRNA) targeting S100a4 using a newly established vector containing insulators and transposons, we established stable LM8 subclones with almost 100% silencing of endogenous S100a4 protein. These transfectants showed a significant suppression of cell migration in vitro as well as a marked reduction in their ability to colonize the lung and form pulmonary metastases in vivo following intravenous inoculation, whereas there was no significant change in cell proliferation or cell attachment to fibronectin, laminin, and type I collagen. Expression and phosphorylation of ezrin, an emerging OS metastasis-associated factor, and expression of MMPs, remained the same in S100a4-shRNA clones. In 61 human OS, immunohistochemical analysis showed that lesional cells in 85.2% samples expressed S100A4 protein, and the immunoreactivity was primarily cytoplasmic, but it also showed occasional nuclear localization. Chondroblastic and osteoblastic OS subtypes expressed more S100A4 than fibroblastic subtypes. The causative role of S100A4 in OS lung metastasis shown in the murine xenograft model, together with the high proportion of primary human OS expressing S100A4, suggest that S100A4 protein represents an important potential target for future OS therapy.