Binding studies indicated the presence of 2,980 +/- 170 receptors per cell, each with an apparent Kd of (8.4 +/- 1.3) X 10(-11) M. Results from competitive binding studies suggested that Hs294T cells possess at least two types of IFN receptors: one which binds IFN-alpha A and IFN-beta 1 and another to which IFN-gamma binds.
The unique de novo and IFN-modified antigenic phenotype of cultures derived from different patients indicates that the antigenic phenotype displayed by melanoma cultures grown in vitro is genetically determined.
These data confirm the existence of a melanoma susceptibility gene on 9p and indicate that this locus most probably lies outside of the IFNA-D9S126 interval.
We previously reported that interleukin 4 (IL-4) and either tumor necrosis factor alpha (TNF) or interferon gamma (IFN) synergistically inhibit melanoma cell growth and induce cell differentiation.
We used two highly informative (CA)n repeats, D9S126 and IFNA, previously implicated in familial malignant melanoma (MLM), to conduct linkage analysis.
These results show that there is a specific disruption of IFN-alpha gene activation rather than IFN-beta in melanoma lines and suggest that this is due to disruption of a trans-acting IFN-alpha gene transcription factor.
We conclude that a defect in the level of STAT1 and possibly all three ISGF3 components in IFN-resistant human melanoma cells may be a general phenomenon responsible for reduced cellular responsiveness of melanomas to IFNs.
These results support a role for IFN-gamma priming in up-regulating ISGF3, thereby augmenting the responsiveness of IFN-resistant melanoma cell lines to type I IFN and providing a molecular basis and justification for using sequential IFN therapy, as proposed by others, to enhance the use of IFNs in the treatment of melanoma.
In a previous study on melanoma cell lines we found that greatest sensitivity to IFN was found in cell lines with the greatest number of copies of chromosome 9p, where the IFN gene family is located.
Direct intratumoral injection of 100 microg of a IFN-omega pDNA DMRIE/DOPE complex (1:1 DNA:DMRIE mass ratio) for 6 consecutive days resulted in a significant reduction in the tumor volume of NIH: OVCAR-3 ovarian carcinoma or A375 melanoma (P = 0.02).IFN-omega pDNA delivered by i.m. injection also had an antitumor effect.
These observations, together with our previous findings showing the importance of IFN-alpha-T cell interactions in the generation of an antitumor response in mouse models, underline the interest of using type I IFN in gene therapy strategies for the treatment of human melanoma.
Poly I:C was not able to induce melanocytes or melanoma cells to produce detectable amounts of IFN-alpha protein, but able to induce a significant amount of IFN-beta in melanocytes and two of the melanoma cell lines: MMAc and VMRC-MELG.
To further determine the significance of this observation, 17 melanoma cell lines sensitive or resistant to the antiproliferative effects of IFN-alpha2 and IFN-beta, as well as 30 melanoma patient samples, were analyzed for Stat1 levels by either Western blot analysis or immunohistochemistry.
LOH was detected in 10 out of 27 informative naevi (37%) at D9S171 and in eight out of 19 (42%) at IFNA in the dissected naevus cell clusters, and in nine out of 27 (33%) at D9S171 and seven out of 19 (36%) at IFNA in the associated melanomas.
In these contexts, targeted overexpression of hPNPase(old-35) might be a novel therapeutic strategy for c-myc-overexpressing and IFN-resistant tumors, such as melanomas.
We then developed IFN-lambda-resistant B16.IFN-lambda2 cells (B16.IFN-lambda2Res cells) and showed that their tumorigenicity was also highly impaired or completely abolished similar to B16.IFN-lambda2 cells, suggesting that IFN-lambdas engage host mechanisms to inhibit melanoma growth.
Seventeen SN tested for loss of heterozygosity (LOH) at 9p and 10q regions, known to be frequently deleted in melanoma, showed LOH at the 9p loci D9S942 and IFNA.
The data provide a plausible explanation why therapy of malignant melanomas with alkylating anticancer drugs failed even in trials where the repair of the critical toxic lesion O(6)MeG was blocked by MGMT inhibitors and suggest approaches to abrogate intrinsic drug resistance by IFN and VPA-mediated reactivation of the death receptor pathway.
Infection by measles virus (MV) induces type I IFN via the retinoic acid-inducible gene I/melanoma differentiation-associated gene 5/mitochondrial antiviral signaling protein (MAVS) pathway in human cells.