Project description:Though mitogen activated protein kinase kinases (MKK or MEK) 1 and 2 are widely assumed to be functionally redundant some reports indicate they possess distinct biologic activities. To test the hypothesis that MEK1 and MEK2 signaling pathways are interchangeable we used two complementary approaches to determine the necessity and sufficiency of individual MEK1 and MEK2 signaling pathways for human melanoma SK-MEL-28 cell proliferation. To test the necessity we targeted MEK1 and/or MEK2 using specific siRNAs. An effect on proliferation was observed only when both MEK1 and MEK2 were knocked down indicating that neither of the individual MEK isoforms is necessary for SK-MEL-28 cell proliferation. To test the sufficiency we inhibited multiple MEK and MKK signaling pathways in SK-MEL-28 cells with anthrax lethal toxin (LeTx) a MEK/MKK-specific protease and rescued individual MEK signaling pathways by expressing a cleavage-resistant form of MEK (MEKcr). In this fashion ERK activation was retained only in MEK2cr-expressing cells but not in MEK1cr-expressing cells following LeTx treatment. Microarray analysis revealed groups of non-overlapping downstream transcriptional targets of MEK1 and MEK2 and indicated a substantial rescue effect of MEK2cr on proliferation pathways. Furthermore LeTx efficiently inhibited the cell proliferation and anchorage-independent growth of SK-MEL-28 cells expressing MKK1cr but not MEK2cr. These results not only indicate that in this cellular context MEK2 signaling pathway alone is sufficient for ERK activation melanoma cell proliferation and anchorage-independent growth but MEK1 is not but also demonstrate that MEK1 and MEK2 signaling pathways are not redundant and interchangeable for melanoma cell proliferation. We conclude that while MEK2 alone is sufficient for SK-MEL-28 cell proliferation MEK1 can conditionally compensate for loss of MEK2. SK-MEL-28 melanoma cells +/- cleavage resistant MKK1/MKK2
Project description:Though mitogen activated protein kinase kinases (MKK or MEK) 1 and 2 are widely assumed to be functionally redundant some reports indicate they possess distinct biologic activities. To test the hypothesis that MEK1 and MEK2 signaling pathways are interchangeable we used two complementary approaches to determine the necessity and sufficiency of individual MEK1 and MEK2 signaling pathways for human melanoma SK-MEL-28 cell proliferation. To test the necessity we targeted MEK1 and/or MEK2 using specific siRNAs. An effect on proliferation was observed only when both MEK1 and MEK2 were knocked down indicating that neither of the individual MEK isoforms is necessary for SK-MEL-28 cell proliferation. To test the sufficiency we inhibited multiple MEK and MKK signaling pathways in SK-MEL-28 cells with anthrax lethal toxin (LeTx) a MEK/MKK-specific protease and rescued individual MEK signaling pathways by expressing a cleavage-resistant form of MEK (MEKcr). In this fashion ERK activation was retained only in MEK2cr-expressing cells but not in MEK1cr-expressing cells following LeTx treatment. Microarray analysis revealed groups of non-overlapping downstream transcriptional targets of MEK1 and MEK2 and indicated a substantial rescue effect of MEK2cr on proliferation pathways. Furthermore LeTx efficiently inhibited the cell proliferation and anchorage-independent growth of SK-MEL-28 cells expressing MKK1cr but not MEK2cr. These results not only indicate that in this cellular context MEK2 signaling pathway alone is sufficient for ERK activation melanoma cell proliferation and anchorage-independent growth but MEK1 is not but also demonstrate that MEK1 and MEK2 signaling pathways are not redundant and interchangeable for melanoma cell proliferation. We conclude that while MEK2 alone is sufficient for SK-MEL-28 cell proliferation MEK1 can conditionally compensate for loss of MEK2.
Project description:Little is known about genes that promote melanoma cell growth and proliferation. siRNAs may be used to address the role of individual genesin these processes. RNAi library screens were used in the past to gain a comprehensive overview of all genes involved in cell growth, proliferation, migration and other cellular processes. A large-scale loss-of-function screen for eight different melanoma cell lines was performed using a pooled lentiviral shRNA library (GeneNet Human 50K lentiviral shRNA Library,cat#SI206B-1, System Biosciences) to identify genes relevant for melanoma cell growth and proliferation. shRNAs that lead to cell death or reduced growth of transduced melanoma cells are negatively selected and thereby underrepresented in the final cellular shRNA pool and vice versa. The shRNAs of the shRNA library (3-5 per gene) have complementary sequences to probes on the custom Affymetrix microarray HG-U133Plus2 and were analysed using this array. Well-known melanoma cell lines SK-Mel-103, A375, SK-Mel-147, SK-Mel-19, SK-Mel-28, SK-Mel-29, SK-Mel-5, WM3523cln6 were transduced with the lentiviral shRNA library and grown for 10 days under puromycin selection (day 10), control cells of respective cell lines were transduced and frozen immediately after transduction and genomic integration of shRNAs (day 0). Totel DNA was extracted and genomically integrated shRNAs were hybridized to Affymetrix microarrays (HG-U133Plus2.0 array).
Project description:Analysis of transcriptome kinetics of SW1736 thyroid cancer cell line vs SK-MEL-28 melanoma cell line at various times after addition of 2 µM vemurafenib. The hypothesis tested was that SW1736 cells (vemurafenib-refractory) differentially express genes compared to SK-MEL-28 cells (vemurafenib sensitive) that confer resistance to the RAF inhibitor.
Project description:Analysis of transcriptome kinetics of SW1736 thyroid cancer cell line vs SK-MEL-28 melanoma cell line at various times after addition of 2 µM vemurafenib. The hypothesis tested was that SW1736 cells (vemurafenib-refractory) differentially express genes compared to SK-MEL-28 cells (vemurafenib sensitive) that confer resistance to the RAF inhibitor. Total RNA was obtained from lysates of SW1726 and SK-MEL-28 cells treated with 2 µM vemurafenib for 0, 1, 6 and 48 h. Experiment was made by triplicate.
Project description:Cutaneous melanoma is the most aggressive skin cancer showing high mortality at advanced clinical stages. Platelet-Derived Growth Factor Receptor alpha (PDGFR-alpha) is known to strongly inhibit melanoma and endothelial cells proliferation, in vitro as well in vivo. PDGFR-alpha expression has been found to be reduced in metastatic human melanoma-biopsies, as compared to benign nevi-biopsies, thus implying a negative selection of PDGFR-alpha expressing cells, in melanoma. In the present study PDGFR-alpha was transiently overexpressed in endothelial (HUVEC) and melanoma (SK-Mel-28) human cells; a strong anti-proliferation effect was observed, along with profound effects on mRNA and miRNA expression. In detail, gene-expression profiling showed that PDGFR-alpha over-expression affects the expression of 82 transcripts in HUVEC (41 up-, 41 down-regulated), and 52 Transcripts in SK-Mel-28 (43 up-, 9 down-regulated). Finally, a miRNA profiling showed that 14 miRs are up-regulated and 39 are down-regulated in PDGFR-alpha overexpressing cells. Accurate validation with alternative techniques demonstrated that CXCL10 is one of the most significantly up-regulated at both gene- and protein level, in combination with a strong down-regulation of miR-503 in both HUVEC and SK-Mel-28 overexpressing PDGFR-alpha. We then demonstrate that CXCL10 is a validated miR-503 target, and that the anti-proliferation effect of PDGFR-alpha is reverted by specific CXCL-10 neutralization. In conclusion, PDGFR-alpha overexpression strongly inhibits endothelial- and melanoma- proliferation in a CXCL-10 dependent way, by significantly down-regulating miR-503 expression. This data set contains the results of the mRNA analysis.
Project description:Cutaneous melanoma is the most aggressive skin cancer showing high mortality at advanced clinical stages. Platelet-Derived Growth Factor Receptor alpha (PDGFR-alpha) is known to strongly inhibit melanoma and endothelial cell proliferation, in vitro as well in vivo. PDGFR-alpha expression has been found to be reduced in metastatic human melanoma-biopsies, as compared to benign nevi-biopsies, thus implying a negative selection of PDGFR-alpha expressing cells, in melanoma. In the present study PDGFR-alpha was transiently overexpressed in endothelial (HUVEC) and melanoma (SK-Mel-28) human cells; a strong anti-proliferation effect was observed, along with profound effects on mRNA and miR- expression. More in detail, gene-expression profiling showed that PDGFR-alpha over-expression affects the expression of 82 genes in HUVEC (41 up-, 41 down-regulated), and 52 genes in SK-Mel-28 (43 up-, 9 down-regulated). miRNA profiling showed that 14 miRs are up-regulated and 40 are down-regulated in PDGFR-alpha overexpressing cells. Accurate validation with alternative techniques demonstrated that CXCL10 gene expression is one of the most significantly up-regulated at both gene- and protein level, in combination with a strong down-regulation of miR-503 in both HUVEC and SK-Mel-28 overexpressing PDGFR-alpha. We then demonstrate that CXCL10 is a validated miR-503 target, and that the anti-proliferation effect of PDGFR-alpha is reverted by specific CXCL-10 neutralization. Several molecular pathways were identified in cells overexpressing PDGFR-alpha, according to KEGG and Gene Ontology analysis (p < 0.01). In conclusion, PDGFR-alpha overexpression strongly inhibits endothelial- and melanoma- proliferation in a CXCL-10 dependent way, by significantly down-regulating miR-503 expression. This dataset contains the results of the microRNA analysis.
Project description:Bmi-1 and Mel-18 are close structural homologues that belong to the polycomb group (PcG) of transcriptional regulators of homeotic gene expression in development. They are believed to stably maintain repression of gene expression by altering the state of chromatin at specific promoters. A number of clinical and experimental observations have also implicated Bmi-1 in tumorigenesis and stem cell maintenance. Bmi-1 overexpression or amplification has been observed in a number of human malignancies, particularly in B-cell lymphomas, medulloblastomas and breast cancer. We report here that shRNA-mediated knock-down of either Bmi-1 or Mel-18 in human medulloblastoma DAOY cells results in the inhibition of proliferation, loss of clonogenic survival and anchorage-independent growth, and suppression of xenograft tumor formation in nude mice. Furthermore, overexpression of both Bmi-1 and Mel-18 significantly increased clonogenic survival of Rat1 fibroblasts. In contrast, stable downregulation of Bmi-1 or Mel-18 alone did not affect the growth of SK-OV-3 or U2OS cancer cell lines or normal human WI38 fibroblasts. Gene expression analysis of shRNA-expressing DAOY cells has demonstrated a significant overlap in the Bmi-1- and Mel-18-regulated genes and revealed novel gene targets under their control. Taken together, these results suggest that Bmi-1 and Mel-18 might have overlapping functions in human tumorigenesis. Keywords: shRNA knock-down