Molecular mechanisms underlying IFN-{gamma}-mediated tumor growth inhibition induced during tumor growth inhibition induced during tumor immunotherapy with rIL-12 |
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Authors: | Yu, Wen-Gong Yamamoto, Noriniko Takenaka, Hiroshi Mu, Jie Tai, Xu-Guang Zou, Jian-Ping Ogowa, Makoto Tsutsui, Tateki Wijesuriya, Rishani Yoshida, Ryotaro Herrmann, Steven Fujiwara, Hiromi Hamaoka, Toshiyuki |
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Affiliation: | Biomedical Research Center,Osaka University Medical School,2-2 Yamada-oka,Suita,Osaka 565,Japan 1 Osaka Bioscience Institue Suita, Osaka 565, Japan 2 Genetics Institue Cambridge,MA 02140,USA |
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Abstract: | The present studnt Investigates the molecular by which IFN-produced as a result of in vitroIL-12 addministration exertsits anty-tumor,rIL-12 was administered three or five times intomice bearing CDA1M fibrosarcoma, OV-HM ovarian carcinoma orMCH-1-A1 fibosarcoma. This regimen induced complete regressionof CSA1M and OV-HM tumors but only transient growth inhibitionof MCH-1-A1 tumors. The anty-tumor effects of Il-12 were associatatedwith enhanced induction of IFN-becouse these effects were abrogatedby pretreatment of hosts with anti-IFN- antibody.Exposure inin vitro of the three types of tumor cells to rIFN- resultedin moderate to potent inhibition of tumor cell growth.IFNstimulatedthe expression of mRNAs for an inducible type of NO synthasa(INOS)in CSA1M cells and indoleamine 2,3-dioxygenasa (IDO),an enzyme capable of degrading tryptophan, in OV-HM cells ,but induced only marginal levels of these mRNAs in MCH-I-ALcells. In association withiNOS gene expression, INF--stimulatedCSA1M cells produced a large amount of NO which functioned toinhibit their own growth in vitro. Although OV-HM and MCH-1-A1cells did not produce NO, they also exhibited NO susceptibility.Whereasthe tumor masses from IL-12-treated CSA1M-bearing mice inducedhigher levels of INOS (for CSA1M) or IDO and iNOS (for OV-HM)mRNAs,the MCH-1-A1 tumor mass expressed lower levels of iNOS mRNAalone.Moreover, massive infiltration of CD4+and CD8+ T cellsand Mac-1+ cells was seen only in the CSA1M and OV-HM tumors.Thus, these results indicate that IFN- produced after IL-12treatment induces the expression of various genes with potentialto modulate tumor cells and growth by acting directly on tumorecells or stimulating tumor-infiltrating lymphold cells and thatthe effectiveness of IL12 therapy is assoiated with the operation if these mechanisms. |
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Keywords: | IFN- /math/gamma.gif" ALT=" {gamma}" BORDER=" 0" > IL-12 inducibel No synthase turmor immunity |
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