Onconase responsive genes in human mesothelioma cells: implications for an RNA damaging therapeutic agent.
BACKGROUND
Onconase represents a new class of RNA-damaging drugs. Mechanistically, Onconase is thought to internalize, where it degrades intracellular RNAs such as tRNA and double-stranded RNA, and thereby suppresses protein synthesis. However, there may be additional or alternative mechanism(s) of action.


METHODS
In this study, microarray analysis was used to compare gene expression profiles in untreated human malignant mesothelioma (MM) cell lines and cells exposed to 5 microg/ml Onconase for 24 h. A total of 155 genes were found to be regulated by Onconase that were common to both epithelial and biphasic MM cell lines. Some of these genes are known to significantly affect apoptosis (IL-24, TNFAIP3), transcription (ATF3, DDIT3, MAFF, HDAC9, SNAPC1) or inflammation and the immune response (IL-6, COX-2). RT-PCR analysis of selected up- or down-regulated genes treated with varying doses and times of Onconase generally confirmed the expression array findings in four MM cell lines.


RESULTS
Onconase treatment consistently resulted in up-regulation of IL-24, previously shown to have tumor suppressive activity, as well as ATF3 and IL-6. Induction of ATF3 and the pro-apoptotic factor IL-24 by Onconase was highest in the two most responsive MM cell lines, as defined by DNA fragmentation analysis. In addition to apoptosis, gene ontology analysis indicated that pathways impacted by Onconase include MAPK signaling, cytokine-cytokine-receptor interactions, and Jak-STAT signaling.


CONCLUSIONS
These results provide a broad picture of gene activity after treatment with a drug that targets small non-coding RNAs and contribute to our overall understanding of MM cell response to Onconase as a therapeutic strategy. The findings provide insights regarding mechanisms that may contribute to the efficacy of this novel drug in clinical trials of MM patients who have failed first line chemotherapy or radiation treatment.
Altomare
Deborah A
DA
Cancer Genetics & Signaling Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA.
Rybak
Susanna M
SM
Pei
Jianming
J
Maizel
Jacob V
JV
Cheung
Mitchell
M
Testa
Joseph R
JR
Shogen
Kuslima
K
D000970:Antineoplastic Agents / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002470:Cell Survival; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007249:Inflammation; D008175:Lung Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D008654:Mesothelioma / Q000188:drug therapy* / Q000378:metabolism*; D020411:Oligonucleotide Array Sequence Analysis; D012313:RNA / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000494:pharmacology*; D013997:Time Factors; D015854:Up-Regulation
D000970:Antineoplastic Agents; D012313:RNA; D012260:Ribonucleases; C058703:ranpirnase