ABSTRACT
BACKGROUND: There is strong evidence that disease progression, drug response and overall clinical outcomes of CML disease are not only decided by BCR/ABL1 oncoprotein but depend on accumulation of additional genetic and epigenetic aberrations. DNA hydroxymethylation is implicated in the development of variety of diseases. DNA hydroxymethylation in gene promoters plays important roles in disease progression, drug response and clinical outcome of various diseases. Therefore in this study, we aimed to explore the role of aberrant hydroxymethylation in promoter regions of different tumor suppressor genes in relation to CML disease progression, response to imatinib therapy and clinical outcome. METHODS: We recruited 150 CML patients at different clinical stages of the disease. Patients were followed up for 48 months and haematological/molecular responses were analysed. Haematological response was analysed by peripheral blood smear. BCR/ABL1 specific TaqMan probe based qRT-PCR was used for assessing the molecular response of CML patients on imatinib therapy. Promoter hydroxymethylation of the genes was characterized using MS-PCR. RESULTS: We observed that promoter hydroxymethylation of DAPK1, RIZ1, P16INK4A, RASSF1A and p14ARFARF genes characterize advanced CML disease and poor imatinib respondents. Although, cytokine signalling (SOCS1) gene was hypermethylated in advanced stages of CML and accumulated in patients with poor imatinib response, but the differences were not statistically significant. Moreover, we found hypermethylation of p14ARF, RASSF1 and p16INK4A genes and cytokine signalling gene (SOCS1) significantly associated with poor overall survival of CML patients on imatinib therapy. The results of this study are in agreement of the role of aberrant DNA methylation of different tumor suppressor genes as potential biomarkers of CML disease progression, poor imatinib response and overall clinical outcome. CONCLUSION: In this study, we report that promoter hydroxymethylation of DAPK1, RIZ1, P16INK4A, RASSF1A and p14ARFARF genes is a characteristic feature of CML disease progressions, defines poor imatinib respondents and poor overall survival of CML patients to imatinib therapy.
Subject(s)
Leukemia, Myelogenous, Chronic, BCR-ABL Positive , Leukemia, Myeloid , Apoptosis/genetics , Cell Cycle , Chronic Disease , Cytokines , DNA/therapeutic use , Disease Progression , Drug Resistance, Neoplasm/genetics , Humans , Imatinib Mesylate/pharmacology , Imatinib Mesylate/therapeutic use , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/drug therapy , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics , Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology , Surveys and Questionnaires , Tumor Suppressor Protein p14ARF/therapeutic useABSTRACT
BACKGROUND: Peritoneal dissemination of cancer is a terminal condition with limited therapeutic options. Because the peritoneal cavity is a single enclosed space, regional treatment approaches for isolated peritoneal cancrinomatosis are appealing. There is a potential role for gene therapy in the management of peritoneal cancrinomatosis. MATERIALS AND METHODS: An adenoviral construct of the human p14ARF gene (a tumor suppressor) and a 22 amino acid sequence of the ARF gene product, which has cell membrane penetrating properties, were assayed for proapoptotic properties in a human colorectal cancer cell line (Clone A) cells in vitro. Peritoneal carcinomatosis derived from Clone A cells was also established in nude mice and then treated with intraperitoneal administration of an adenoviral construct of the human p14ARF gene. RESULTS: Treatment of ARF-negative Clone A cells with Ad-hARF in vitro reestablished ARF function. However, the cell penetrating ARF-related peptide did not restore ARF function in Clone A cells. Treatment of Clone A peritoneal xenografts with a single intraperitoneal dose of Ad-hARF (9 × 10(6) viral particles) suppressed the progression of peritoneal disease. Weekly (six times) administration of the Ad-hARF at a lower dose (3 × 10(6) viral particles) also suppressed tumor progression. CONCLUSIONS: Treatment of peritoneal carcinomatosis by intraperitoneal administration of adenoviral constructs of inactivated tumor suppressor genes may be a feasible clinical approach, and ARF may represent a suitable molecular target for tumors where the ARF gene is inactivated.
