The terminal differentiation of malignant melanoma cells is known to be induced by activating cAMP signaling pathway with alpha-MSH or cAMP analogues. However, sustained activation of cAMP signaling system that induces the differentiation of melanoma cells, also induces the desensitization of the pathway at the receptor level. Nevertheless, the adaptation of adenylate cyclase (AC) expression by sustained activation of cAMP signaling system has not been clearly understood. This study was performed to examine whether the sustained activation of cAMP system induce changes in the expression AC isoforms as an adaptation mechanism. Treatment of B16/F10 murine melanoma cells with 100 mM forskolin for 6 days resulted in differentiation, melanin accumulation and increased expression of tyrosine hydroxylase mRNA. In the forskolin-treated melanoma cells, change in expression of various AC isoform at the transcription level was detected by reverse-transcription polymerase chain reaction (RT-PCR). Expression of AC isoform mRNA: ACI, III, VI, VII, and IX increased to the level of 196-392% of the control whereas the level of ACII was decreased by 30%. The cAMP concentration was increased both in basal and alpha-MSH stimulated cells, but the AC activity was decreased in the forskolin treated cells. Thus, these results suggest that sustained activation of cAMP system induces differential expression of AC isoforms, which results in increase of cAMP accumulation.
Adenylate Cyclase/*genetics ; Animal ; Cell Differentiation ; Cyclic AMP/*metabolism ; Forskolin/*pharmacology ; Isoenzymes/genetics ; Melanoma, Experimental/*enzymology/*pathology ; Mice ; Signal Transduction

OBJECTIVETo investigate the effects of endostatin and doxycycline on microcirculation patterns in melanoma and their molecular mechanisms.

METHODSTo establish mouse B16 melanoma model by subcutaneous injection of B16 melanoma cell suspension. The mice were divided into 3 experimental groups and 1 control group. To treat the mice in the 3 experimental groups with endostatin, doxycycline, endostatin and doxycycline, respectively, and the control group without any treatment. The tumor volume was measured and recorded to make comparison of their growth rate. To assess the expression of MMP-2, MMP-9 and TIMP-2 by immunohistochemical staining. The three microcirculation patterns of endothelium-dependent vessels, mosaic vessels and vasculogenic mimicry were counted. The activity of MMP-2, MMP-9 between different groups was examined by gelatin zymography.

RESULTSTumor growth in the three experimental groups was statistically significantly slower than that in the control group. The expression of MMP-2, MMP-9 and TIMP-2 in each treated group was significantly different with that in the control group. The amount of three microcirculation patterns in three experimental groups was less than that of the control group, and the amount of MV and VM in each experimental group was significantly less than that in the control group. By gelatin zymography, the enzyme activity of MMP-9, actived-MMP-2 and MMP-2/proMMP-2 in ES, DOX and ES + DOX group was lower than that in the control group, but the enzyme activity of pro-MMP-2 among the four groups was not significantly different.

CONCLUSIONThe combined use of doxycycline and endostatin in melanoma can inhibit the expression of MMPs, influencing the formation of different microcirculation patterns in melanoma.

Animals ; Antineoplastic Agents ; pharmacology ; Cell Line, Tumor ; Doxycycline ; pharmacology ; Drug Combinations ; Drug Synergism ; Endostatins ; pharmacology ; Female ; Male ; Matrix Metalloproteinase 2 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; Melanoma, Experimental ; blood supply ; enzymology ; pathology ; Mice ; Mice, Inbred C57BL ; Microcirculation ; drug effects ; Microvessels ; pathology ; Neoplasm Transplantation ; Tissue Inhibitor of Metalloproteinase-2 ; metabolism ; Tumor Burden ; drug effects

OBJECTIVETo study the effection of suppression murine melanoma growth by Intratumor injection of recombinant attenuated salmonella carrying heat shock protein 70 and herpes simplex virus thymidine kinase genes.

METHODSPlasmids PCMV-mtHSP70-IRES-TK were electro-transferred into salmonella typhimurium SL7207 to construct recombinant salmonella typhimurium. In vivo, Recombinant bacteria were injected into the mouse melanoma and the antitumor effection was observed. The survival period was recorded and safety analysis for this vaccine in each group.

RESULTSIn vivo, the mtHSP70/HSV-tk recombinant bacteria can suppress tumor growth significantly and extend survival. After recombinant Salmonella, 10(9) CFU/mL, was administered as an intratumoral injection, No diarrhea were observed. During therapy, body weight did not change markedly.

CONCLUSIONResults of the animal experiment suggests intratumor injection of recombinant attenuated salmonella typhimurium containing mtHSP70 and HSV-tk genes, has targeting ability against B16 tumor cell and could significantly inhibit tumor growth .

Animals ; Bacterial Proteins ; genetics ; immunology ; Cancer Vaccines ; genetics ; immunology ; pharmacology ; Genetic Therapy ; methods ; HSP70 Heat-Shock Proteins ; genetics ; immunology ; Melanoma, Experimental ; microbiology ; pathology ; therapy ; Mice ; Mice, Inbred C57BL ; Mycobacterium tuberculosis ; genetics ; Salmonella typhimurium ; genetics ; immunology ; Simplexvirus ; enzymology ; genetics ; Skin Neoplasms ; therapy ; Thymidine Kinase ; genetics ; immunology ; Vaccines, Attenuated ; genetics ; immunology ; pharmacology ; Vaccines, DNA ; genetics ; immunology ; pharmacology

Malignant melanoma still remains to be a serious health threat. Overexpression of focal adhesion kinase (FAK) in melanoma has suggested that FAK could be a promising target for therapeutic intervention. To further investigate the function of FAK in melanoma, FAK expression was down-regulated by stable transfection of plasmid harboring FAK small interfering RNA (siRNA) into melanoma cell line. Two stable cell lines, F10-siFAK and F10-control, have been constructed and screened. Compared with the F10-control, both the mRNA and protein levels of FAK decreased significantly, and the cell cycle of F10-siFAK was arrested at G1 phase. Furthermore, the tumor growth rate of F10-siFAK cells was notably slower than that of F10-control in in vivo tumor models. These results show that FAK is an important regulatory gene in melanoma. The stable FAK-knockdown melanoma cell line is an useful tool for further investigation of FAK's function in the progression of melanoma, and also an effective means of drug screening for anti-melanoma therapeutics.
Animals ; Cell Cycle ; Cell Line, Tumor ; Cell Proliferation ; Down-Regulation ; Focal Adhesion Protein-Tyrosine Kinases ; genetics ; metabolism ; G1 Phase ; Gene Knockdown Techniques ; Melanoma, Experimental ; enzymology ; pathology ; Mice ; Mice, Inbred C57BL ; Mitogen-Activated Protein Kinase 1 ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Plasmids ; RNA, Messenger ; metabolism ; RNA, Small Interfering ; genetics ; Transfection