Biography
Biography: Jianhua Luo
Abstract
Chromosome changes are one of the hallmarks of human malignancies. Chromosomal rearrangement is frequent in human cancers. One of the consequences of chromosomal rearrangement is gene fusions in the cancer genome. We have previously identified a panel of fusion genes in aggressive prostate cancers. In the present study, we found that these fusion genes are present in 7 different types of human malignancies with variable frequencies. Among them, the CCNH-C5orf30 and TRMT11-GRIK2 gene fusions were found in breast cancer, colon cancer, non-small cell lung cancer, esophageal adenocarcinoma, glioblastoma multiforme, ovarian cancer, and liver cancer, with frequencies ranging from 12.9% to 85%. In contrast, four other gene fusions (mTOR-TP53BP1, TMEM135-CCDC67, KDM4-AC011523.2, and LRRC59-FLJ60017) are less frequent. Both TRMT11-GRIK2 and CCNH-C5orf30 are also frequently present in lymph node metastatic cancer samples from the breast, colon, and ovary. Thus, detecting these fusion transcripts may have significant biological and clinical implications in cancer patient management. One of these fusion genes called MAN2A1-FER generated a constitutively activated tyrosine protein kinase. The fusion translocates FER kinase from the cytoplasm to Golgi apparatus. The fusion protein ectopically phosphorylates the N-terminal domain of EGFR and activates the EGFR signaling pathway in the absence of a ligand. MAN2A1-FER has been found in a variety of human malignancies. It transforms immortalized cell lines into highly aggressive cancer cells. Expression of MAN2A1-FER produces spontaneous liver cancer in animals. Cancer cells positive for MAN2A1-FER are highly sensitive to several tyrosine kinase inhibitors and can be targeted by genome therapy intervention. Thus, targeting at MAN2A1-FER or other oncogenic fusion genes may hold promise to treat human cancer effectively. To develop a cancer genome specific targeting strategy, we used Cas9-based genome editing to introduce the gene for the pro-drug converting enzyme ‘herpes simplex virus type 1 thymidine kinase (HSV1-TK) into the genome of cancer cells that carry unique sequences resulting from genome rearrangements. Specifically, we targeted the breakpoints of TMEM135-CCDC67 and MAN2A1-FER fusions in human prostate cancer or hepatocellular carcinoma cells in vitro and in mouse xenografts. We designed one adenovirus to deliver the nickase Cas9D10A and gRNAs targeting the breakpoint sequences and another to deliver an EGFP-HSV1-TK construct flanked by sequences homologous to those surrounding the breakpoint. Infection with both viruses resulted in breakpoint-dependent expression of EGFP-TK and ganciclovir-mediated apoptosis. When mouse xenografts were treated with adenoviruses and ganciclovir, all animals showed a reduction of tumor burden with no mortality over the observation period. Our results suggest that Cas9-mediated suicide gene insertion might be a viable genotype-specific therapy for cancer.