| Objective: The Cytokines are proteins that are secreted and mediate communication between cells. The biological functions of cytokines are achieved by binding with high affinity and specificity to cell-surface receptors, thereby triggering signal transduction cascades that regulate cellular activation, proliferation, differentiation, and survival. Many, if not most, cytokines use the Janus kinase (JAK)–signal transducer and activator of transcription (STAT) signaling pathway to mediate gene activation or repression. Jaks are protein tyrosine kinases that are pre-associated with membrane-proximal regions (termed box 1 and box 2) of cytokine receptors. It seems that only four mammalian Jaks exist: JAK1, JAK2, JAK3, and TYK2. Each contains a catalytically active kinase domain and a regulatory pseudokinase domain at the carboxyl terminus of the protein. JAK/STAT pathway is the principal signaling mechanism for many hematopoietic growth factors, stimulating cell growth ,proliferation,differentiation and, apoptosis, which is constitutively activated in leukemogenesis universally. There are two main mechanisms ( SHP-1,SOCS) regulating the jak-stat. The Src homology domain 2(SH2)-containing phosphatase -1(SHP-1) is primary expressed in hematopoietic cells and dephosphorylate the phosphotyrosine residues, proposed as a candidate anti-oncogene recently. SHP-1 negatively modulates the differentiation ,growth and proliferation of hematopoietic cells by dephosphorylating the downstream protein ,which subsequently either terminates or attenuates the activated signal or activates apoptosis pathway. As a negative regulator of janus kinase/signal transducer and activator of transcription(JAK/STAT) signaling pathway ,the expression of SHP-1 had been reported dismissing or abolishing in leukemia cell lines.SOCS, also termed JAB, SSI, or CIS molecules, are proteins that inhibit signaling by a large number of cytokines that use the Jak–STAT signaling pathway. So far, CIS (the original family member to be cloned), SOCS1, SOCS2, and SOCS3 have been shown to inhibit cytokine signaling, and the functions of SOCS4–SOCS7 are largely unknown. SOCS1 and SOCS3 interact with Jaks by means of an SH2–phosphotyrosine interaction, and SOCS1 is an effective inhibitor of Jak catalytic activity; SOCS3 is much less effective at inhibiting Jaks directly. SOCS proteins are short-lived and ubiquitinated, and it is possible that they also work by targeting receptors and other signaling components for degradation.SOCS proteins have a similar structure: an N-terminal domain of variable length, a central Src homology-2 domain, and a C-terminal SOCS box. Biochemical and genetic studies have revealed that SOCS family members play an important role in the termination of cytokine and growth factor signaling.Our study intends to observe the expression of TYK2, SHP-1 , SOCS6, SOCS7 mRNA in different types and phases of leukemia, to observe the changes of TYK2, SHP-1 , SOCS6, SOCS7 mRNA and primarily to investigate the impact of SHP-1,SOCS6,SOCS7 genes on JAK/STAT pathway in leukemogenesis and prognosis in leukemia .We hope to interpret the function and the possible mechanism of TYK2 ,SHP-1,SOCS6,SOCS7 genes in leukemogenesis, which would provide theoretic basis for studying the pathogenesis of leukemia and designing novel targeting therapeutic strategies.Methods: The expression of TYK2, SHP-1, and SOCS6,SOCS7mRNA were measured in 82 adult leukemia patients(including 36 de novo acute leukemia patients,6replased patients,20 chronic granulocytic leukemia patients and 20 complete remission patients),30 samples of normal controls(NC) by semi-quantity reverse transcription polymerase chain reaction(RT-PCR).Results: 1 Analysis of the expression of TYK2 ,SHP-1,SOCS6 and SOCS7 mRNA by RT-PCR 1.1 The expression of TYK2 mRNA in de novo AL patients (mean 0.3735,positive rate 83%) is significantly higeher than that in NC (mean 0.079, positive rate 33%), there is a statistical difference between them, P<0.05; There is no statistical difference between AML and ALL ; In relapse group, TYK2mRNA(mean0.4765,positive rate 100%) is higher than that in NC(P<0.05),there is a statistical difference between CR-patients (mean 0.2920,positive rate 60%) and NC(P<0.05).1.2 The expression of SHP-1 mRNA in de novo AL patients (mean 0.101,positive rate 25%) is significantly lower than that in NC (mean 3.121, positive rate 100%), there is a statistical difference between them, P<0.05; There is a statistical difference between AML (mean 0.197,positive rate 38%) and ALL (mean 0,positive rate 0%), P<0.05; In relapse group, SHP-1 mRNA(mean 0, positive rate 0%) is lower than NC(<0.05),also lower than de novo AL(P>0.05); there is a statistical difference between CR-patients (mean 0.301,positive rate 60%) and NC(P<0.05), but AL group is lower than CR group, P<0.05.1.3 The expression of SOCS6 mRNA in AL (mean0.9817,positive rate91.7%) is higher than that in NC (0.4576,57%), P<0.05; there is no statistical difference of expression between AML and ALL (P>0.05). Among 6 case of relapse patients, 5 cases are positive. The mean level is 1.2276,which is higher than in NC, but there is no difference from de novo AL (P>0.05). The mean level of SOCS6 mRNA in CR-patients is 0.529385,and positive ratio is 75%, with no statistical difference compared with NC (P>0.05).1.4 The expression of SOCS7 mRNA in AL (75%,0.379) is lower than NC (96.7%,1.0264) , difference statistically significant P<0.05).1.5 58.3% of CML-CP patients have TYK2 mRNA expression, with the mean level 0.3132, which is higher than in NC, there is statistical difference (P<0.05). 33.3% of CML-CP patients have SHP-1 mRNA expression, with the mean level 0.156 ,which is lower than NC, there is a statistical difference (P<0.05). 66.7%of CML-CP patients have SOCS6 mRNA expression, with the mean level 0.8816, which is higher than NC, there is statistical difference (P<0.05). 58.3%of CML-CP patients have SOCS7 mRNA expression, with the mean level 0.4974,which is lower than NC, there is statistical difference (P<0.05) In 8 case of blastic phase (BP) patients, the expression of TYK2 mRNA(75%,0.3334) is higher than in NC (P<0.05)., the expression of SHP-1 mRNA (0,0)is lower than those in NC(P<0.05), the expression of SOCS6 mRNA( 100%,0.9533) is higher than those in NC(P<0.05) ,and SOCS7 mRNA(62.5%,0.4109) is lower than those in NC (P<0.05). There havn't difference between ALL and CML in CP or BP.2 We have an outcome evaluation on 36 cases of de novo AML patients(2 died in early period).The remission rate is higher in SHP-1+ patients (7/9,77.78%) than that in SHP-1- patients (4/25,16%),χ2=11.540, P=0.001.In ALL patients, there is no expression of SHP-1+ patients and the remission rate is (2/9,22.22%). The CR rate in SHP-1 of negative patients were significant lower than that in positive patients(χ2=14.880,P<0.05). The CR rate of TYK2 negative is 100%,and 40% in positive patients. the CR rate of TYK2 negative patients was significant higher than in positive patients(χ2=3.96,P=0.047).The CR rate of SOCS6 negative patients is 0,and the CR rate of SOCS6 positive patients is 76%. the CR rate of SOCS6 negative patients was significant lower than in positive patients(χ2=5.303,P=0.021). The CR rate of SOCS7 negative patients is 84%,and the CR rate of SOCS7 positive patients is 31%. the CR rate of SOCS7 negative patients was significant higher than in positive patients(χ2=6.032,P=0.014). The CR rate of SHP-1 negative and SOCS7 positive was significantly different from SHP-1 positive and SOCS7 negative (χ2=24,P=0.001). The CR rate of SHP-1 positive and TYK2 negative patients was different with SHP-1 negative and TYK2 positive ones (χ2=12.18,P=0.001). The CR rate of SOCS6 positive and TYK2 negative patients was different with SOCS6 negative and TYK2 positive ones(χ2=5.0,P=0.025).Conclusions:1 The expression of TYK2,SHP-1,SOCS6,SOCS7 in AL1.1 The expression of TYK2 in AL is higher than in NC, and the paitent with the higher expression of TYK2 has the lower remission rate,Which both domonstrate that JAK-STAT is constitutively activated in leukemogenesis universally. 1.2 The findings, the highest expression of SHP-1 in NC and its lowest in AL, the patients with higher expression rate of SHP-1 has higher remission rate, the CR rate of SHP-1 positive and TYK2 negative patients is higher than in SHP-1 negative and TYK2 positive cases, suggest that SHP-1 functions as a candidate anti-oncogene .1.3 The SOCS6 is expressed constitutively in NC, and increases substantially in AL.The patients with higher expression has the higher CR rate, and the CR rate of SOCS6 positive and TYK2 negative patients is higher than that in SOCS6 negative and TYK2 positive patients.1.4 The expression rate of SOCS7 in NC is the highest and the lowest in AL, which suggests that SOCS7 works by targeting receptors of JAK-STAT for degradation .The CR rate in SOCS7 negative patients was significant higher than positive ones. The CR rate of SHP-1 negative and SOCS7 positive patients is significantly lower than that in positive and SOCS7 negative cases..2 The expression of TYK2,SHP-1,SOCS6,SOCS7 in CML In CML-CP, SHP-1 and SOCS7 are lower than in NC and the difference statistically significant. TYK2 and SOCS6 mRNA is higher than in NC and both of them reach statistical differences. In BP, they are the identical. Their expression in CP is not different from in BP on account of small number of cases. Because the trend of them in CML are identical with those in AL , it isn't necessary to explain them repeatedly. |
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