الفهرس 
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Abstract
The hematological malignancies are clonal diseases which are thought to derive from a single cell in the bone marrow (BM) or peripheral lymphoid tissue. This cell has undergone a genetic alteration with accumulation of genetic mutations in cellular genes leading to malignant transformation. Successive mitotic divisions give rise to a clone of cells derived from the parent cell.
Hematological malignancies are caused by a complex interaction between genetic background and environmental influence..
Genetic causes of cancer are not the only source of cancer that is being investigated; epigenetic mechanisms also play an important role in the appearance and progression of cancers.
Activating oncogenic mutations, deletions of chromosomal material, inactivating mutations and aberrant promoter silencing of tumor-suppressor genes (TSG) have been recognized as important pathogenic mechanisms in hematological malignancies.
Several lines of evidence have shown that inactivation of tumor suppressor genes is closely associated with tumorigenesis in a wide variety of human tumors.
The retinoblastoma protein-interacting zinc finger gene (RIZ) was isolated in a functional screening for Rb-binding proteins. RIZ is also known as a positive regulatory domain methyl transferase (PRDM2).
The RIZ gene maps to short arm of chromosome 1p36, the gene encodes two products: RIZ1 that contains the PR domain and RIZ2 lacks the domain, RIZ1 but not RIZ2 has tumor-suppressive properties, so, it is considered a TSG.
RIZ1 methylates histone H3 lysine 9 a modification important for transcriptional repression, resulting in the modulation of chromatin structure and inhibition of transcriptional process as it arrest cell cycle at G2/M phase and induce apoptosis.
Deletion or loss of heterozygosity of RIZ1 gene has been reported in various human cancers, including both hematological as malignant lymphoma and blastic crisis of chronic myelogenous leukaemia.and non hematological malignancies as breast, liver, and esophageal carcinoma.
A decrease in the expression of RIZ1 has been noted due to inactivation of the RIZ1 gene by Methylation of CpG islands in gene promoter regions as reported as a major molecular mechanism of gene silencing and underlies both cancer development and progression.
Silencing or down regulation of a gene is best identified by Real Time Quantitative PCR (real-time qPCR) which has become a routine and robust approach for measuring the expression of genes of interest .
The role of down expression of RIZ1 gene in hematological malignancy was mentioned in many studies ago, but its levels after receiving induction therapy in these patients not evaluated, so the present study was designed.
The current study included patients with hematological malignancies who were attending the hematology oncology clinics of Menoufia University Hospital and National Cancer Institute Cairo University and patients with no hematological malignancies as control group. Thepatients have been subjected to Complete clinical history taking, Clinical examination: with careful notation and assessment of clinical signs relevant to leukemia as liver enlargement, spleen enlargement , lymphadenopathy, CNS infiltration, gums or skin infiltration Laboratory investigations including CBC using cell-counter (Advia 120). Morphological examination of leishman stained PB smears laying stress on blast % and BM aspiration and examination of leishman stained BM smear Immunophenotyping using Becton Dicinson (BD) Flow Cytometer., and RT-PCR for detection of relative quantitative expression of RIZ1 gene and GAPDH gene as internal control gene (housekeeping gene) using 7300 Real-Time PCR System .
Cytogenetic analysis and screening for the presence of the most frequent fusion transcripts [e.g. BCR-ABL, PML-RARA, FLT3 mutation] were kindly received from their department.
Regarding Group I of newly diagnosed hematological malignancies they were 15 males and 11 females with male to female ratio of 1.3:1 .their ages ranged between 2-65 years old with mean value of 19.74±17.6
As for Laboratory criteria in group I Hemoglobin level ranged from 3 to 9.8gm/dl With a mean of 6.95±1.68 and median value of 7.07.Platelet count ranged from 5 to 190 / with a mean of 77.42±58.08 and median value of 62.0 .WBCs count ranged from 1.78 to 245 × / with a mean of 44.77±64.78 and median value of 14.Blast percentage of peripheral WBCs ranged from 0 to 90 % with mean of 26.46±31.27 and median value of 7.5. Blast percentage of bone marrow ranged from 20 to 99 % with mean of 78.90± 22.58 and median
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of 90. Morphological FAB and Immunophenotyping classification showed that Ten ALL patients were found having common B ALL,twelve AML patients , one case was Bilineage acute leukemia,two cases were CML in blastic crises and One case was Burkitt lymphoma. RIZ1gene ranged from 0.15 to 25.65% with mean value of 5.83±7.18 and median value of 2.48.
Regarding Group II who were as samples were taken at the end of induction therapy( D 28) it comprised (12)patients they were 8 males and 4 females. With male to female ratio of 2:1 their ages ranged between 2-60 years with mean value of 21.08±15.67 years
As for Laboratory data Hemoglobin level ranged from 3 to 12.2 gm/dl With mean of 8.16 ± 3.10 and median value of 8.14.Platelet count ranged from 44 – 323 / μl with a mean of 143.29±80.8 and median value of 127.WBCs count ranged from 0.46 to10.5 × /μl with a mean of 3.62±2.86 and median value of 3.25.No blast could be detected in peripheral WBCs Blast percentage of bone marrow ranged from 0 to 58% with a mean of 8.92±15.88 and median of 4.
Morphological FAB and Immunophenotyping classification:
Five patient were ALL were common B ALL, 1 patient was Bilineage acute leukemia and 6 patients were AML
RIZ1gene ranged from 2.73 to 185.46% with mean value of 84.51±64.60 and median value of 80.05
Regarding Group III (control group) They were 7 male and 3 female. Their age ranged between 4-63 years with mean value of 43.10±16.19 years.
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As for Laboratory criteria of control cases Hemoglobin level ranged from 7 to 13 gm/dl With mean value of 10.48±1.66 and median value of 10.66.Platelet count ranged from 20 to 220 /μl with a mean of 115.30±53.70 and median value of 112.5.WBCs count ranged from 2.7 to12.5 × /μl with a mean of 7.70±3.46 and median value of 7.7.no blast could be detected in peripheral WBCs . Blast cell in bone marrow smear did not exceed 5%.
RIZ1gene by RT-PCR ranged from 58.28 to 148.67% with mean value of 104.29±13.11 and median value of 103.51.
Statistical analysis of the lab data revealed a highly statistically significant association between new cases and control group as regards RIZ1% as its percentage in D0 cases is significantly lower than control group. P value <0.001
There is a highly statistically significant association between D0 and D 28 cases as regards RIZ1% as its percentage in D 28 is significantly higher than D zero cases . P value <0.001
Statistical analysis revealed no significant association of( group II) to (Group III) as RIZ1 gene % after induction therapy is near to control group. P value =0.34
In Conclusion: RIZ1 gene is down expressed in leukemic patients and its levels increased after induction therapy, denoting its possible role in disease pathogenesis.