The Expression Of KCNQ1 And P57～(KIP2) And Its Clinical Significance In Hydatidiform Mole

Background Hydatidiform mole (HM)is an abnormal gestation characterized by trophoblast hyperplasia and overgrowth of placental villi. Hydatidiform moles are one of the most common complications of pregnancy seen in Asian countries, The age distribution of hydatidiform mole patients was highest between 20 to 30 years,The worldwide incidence of HM occur in about 1 in 500-1000 pregnancies, Most cases will occur in less-developed countries.The incidence of HM in our country is about 1 per 1238,the highest is in Zhijiang and Jiangxi Province ,1 per 728 and 1.39 per 100;the lowest is in Shanxi Province,0.29 per 1000.Pathological studies have demonstrated that molar pregnancies may be either of two distinct subtypes, complete or partial hydatidiform mole . It has been generally recongnized that patient with a PHM have less of a tendency to develop PTD than do those with a CHMs.The incidence of PTD after CHM is approximately 15- 20%,( the after PHM is quite rare , about 4% to 6%.). Secondlyjt is thought the risk of second HM after CHM and PHM is about 1 in 60,But the BiCHM(Biparental complete hydatidiform moles ,BiCHM) is a special type of CHM,and about 20% of its.The affected woman hardly has a normal pregnancy, either abortion or stillbirth or HM in all her life.So differential diagnosis between the two subtypes of HM has an important clinical significance .morphologic examination still forms the main diagnostic tool in the differential diagnosis of molar pregnancies.CHM is characterized by the diffuse hydropic swelling and trophoblastic hyperplasia on the chorionic villous surfaces, Minimal embryonal development .PHM presents two populations of chorinic villi,one withnormal morphology , and the other with scattered hydropic villi and focal trophoblastic (syncytio and cyto)hyperplasia,which embryonal development occurs in association with trophoblastic hyperplasia. Ploidy analysis and molecular diagnostic techniques have been introduced to verify the genetic background of these two subthpes.so,Genetic analysis has been used to make the diagnosis of different type HM,such as DNA fingerprinting, restriction fragment length polymorphism,and ploymerase chain reaction amplification using microsatellite DNA polymorphism.but can not be a routine detected means because of its expensive and inconvenience and wasting time and strenuosity. Therefore, Looking for a useful biomarker has an important clinical implication for the differential diagnosis of CHM and PHM.The exact mechanism responsible for HMs is unknown yet. N.Sebire,R.A.Fisher,& speculate that in those cases where both complete moles and partial moles occurred,dispermy may be the underlying mechanism in both the complete and partial moles. Recently ,many learner think that the abnormal pregnancy ,hydatidiform mole (HM) represents a disorder of genomic imprinting ,a phenomenon whereby genes are monoallelically expressed from the maternally of paternally derived copy of the gene,the other being transcriptionally silent. Genomic imprinting plays a critical role in embryogenesis,imprinting may be implicated in the pathogenesis of anomalous gestations.evidence has recently been provided to support a role for genomic imprinting in the regulation of embryonic implantation and development and placental growth,as well as in the pathogenesis of proliferative trophoblastic disease. Complete moles are usually diploid and androgeneticjt may be monospermic arising by fertilization of an anucleate egg by a single sperm,which then doubles to provide a diploid chromosome complement, or dispermic , arising from fertilisatin of an anucleate egg by two sperms, in that all 46 chromosomes are paternal in origin ,maternal chromosomes are generally absent. Partial moles are usually paternally derived dispermic triploid conceptions , and PHMs are fertilization by one Ovum and two sperm.having two paternal and one maternal set of chromosomes.so the expression of maternal imprinting gene is expected to be absent in CHM.The P57^KIP2 gene, is a cyclin-dependent kinase inhibitor (CDKI) and tumor suppressor ,located on chromosome 11p15.5 and structurally related to the p21^CIP1 and p27^KIP1/CDKI,is known to be paternally imprinted and predominantly expressed from thematernal allele in most tissues. In normal placenta ,nuclear P57^KIP2 expression was observed at high frequency(up to 100%) in extravillous trophoblast,cytotrophoblast,and villous mesenchyme ,but was absent in syncytiotrophoblastjt was also expressed in the stromal cells of maternal decidua. PHM show expression comparable to those observed in nomal villious.Incontrast, P57^KIP2 expression in cytotrophoblast and villous mesenchyme was absent ormarkedly decreased in complete hydatidiform moles. In all gestations, P57^KIP2 was strongly expressed in deciduas and in intervillous trophoblast islands,which served as internal positive controls for immunostaining. Thus,P57^KIP2 immunohistochemistry is a useful diagnostic adjunct,complementary to histopathologic analysis in the diagnosis of hydatidiformmole.Next,it has compared the use of P57^KIP2 staining in the differential diagnosis of 68 morphologically challenging cases of early first-trimester hydropic placentas.Diagnosis basedon P57^KIP2 staining was compared with the original diagnosis based on morphology and DNAploidy analysis.Concordant results were obtained in 65 of 68 cases studied.so, P57^KIP2 havebeen recognized as highly sensitive and specific adjuncts to morphologic diagnosis of HM.KCNQ1 encodes a voltage-gated potassium channel, originally named KVLQT1(and later KCNQl),is a novel potassium channel gene. It has been identified on human chromosome 11p15.5. is another maternally expressed imprinted gene. It consists of 16 exons and spans approximately 400kb. It is a protein of 676 amino acid . It encodes the a-subunit of the KvLQT1 channel.It assembles with the minK-encoded b-subunit to form IKs channel underlying the slowly activating delayed rectifier potassium current in the heart. Like in other voltagegated K+ channels, each a-subunit is composed of six membrane-spanning alpha helices (S1-S6) separated by a pore domain and a long unique C-terminal cytoplasmic domain.The fourth membrane-spanning unit contains positively charged residues at approximately every third position and acts as a transmembrane voltage sensor. The residues between S5 and S6 form the ion selective pore. KVLQT1 is expressed not only in the heart but also in other human tissues,the such as pancreas, kidney, placenta and lung, but not in the liver, skeletal muscle or brain. The voltage-gated K+ channel KVLQT1 activity is essential for therepolarization phase of the cardiac action potential and for K+ homeostasis in the inner ear.Recently,it has been reported that the KCNQ1 gene is imprinted in most human fetal tissues,with the exception of the heart. It has been suggested that it could be involed in the development of the overgrowth malformaton disorder called Beckwith-Wiedemann syndrome, Besides of the Beckwith-Wiedemann syndrome,the gene is abnormally imprinted in some cancer . Mutations in the human KVLQT1 gene encoding the a-subunit of the KVLQT1 channel cause the long QT syndrome , Mutations truncating the carboxy-terminus of the KCNQ1 protein lead to the recessive variant of LQTS,called Jervell and Lange-Nielsen syndrome, Up to date ,more than 115 mutations have been found in the KCNQ1 gene.Now,many learner think that HM is a disease likely the result of abnormal dosage andconsequent misexpressin of imprinted genes. It is clear that KCNQ1 and P57^KIP2 are subjectto a maternally imprinted gene and mapped to the 11p15.5 region,are regulated by imprinting control region(KvDMRl).Recently, many studies presented immunohistochemicalevidence that P57^KIP2 is differentially expressed in CHM versus PHM. Most learner havethought P57^KIP2 immunohistochemistry can be a very useful tool for the differential diagnosis of CHM and PHM . but studies of the expression of KCNQ1 have not yet been reported on HM . and the relationship between P57^KIP2 and KCNQ1 in HM have not yet been reported too. This study assesses a group of samples of HM in order to evaluate the protein expression of P57^KIP2 and KCNQ1 in the two subtypes of HM and nomal villous byimmunohistochemistry, and to evaluated the relationship between P57^KIP2 and KCNQ1 inHM.Meterials and Methods we collected 112 speciments including CHM(56 cases),PHM(26cases)and normal early gestational placenta (30 cases) from the Department of pathology of theWomen's Hospital ,Zhejiang University.The former were suckered firstly in 2004-2005,thelater have been suckered because of all results from our hospital in 2005.12-2006.2. Theparaffin sections of samples were used to detect the expression of P57^KIP2(Maixin Biotechnology,Rab-0107) andKCNQ1(Santa Cruz Biotechnology,INC.sc-10646) protein byEnVision and ABC method immunohistochemical staining, and studied the relationship between protein expression and distinguishing CHM from PHM.Results 1. The expression of P57^KIP2 and KCNQ1 protein in different HM and normal earlypregnancy villous: In normal villous, KCNQ1 and nuclear P57^KIP2expression was observed at high frequency(up to 100%), triploid partial moles(19/26, 20/26) showed P57^KIP2 and KCNQ1 levels comparable to those observed in normal villous. But indiploid complete moles, P57^KIP2 and KCNQ1 expression was either absent(45/56, 39/56 cases) or low(11/56, 17/56 cases), The expressions of KCNQ1 and P57^KIP2 was significally lower in CHM,but it was higher in normal villous and PHM.( Z^a=7.907, 7.358P=0.000, Z^b=4.169, 4.841 P=0.000, Z^c=3.457, 2.424 P=0.015, 0.045). By statistical analysis,the difference of P57^KIP2 and KCNQ1positive immunostaining in CHM versus PHM,CHM versus normal villious was strongly discrimination and highly statistically significant(P<0.01);But the differenceof P57^KIP2 and KCNQ1 positive immunostaining in PHM versus normal villiouswas not distinction.(P>0.01).2: The expression of KCNQ1 and P57^KIP2protein in different cell:In normalvillous ,nuclear P57^KIP2 expression was observed at high frequency(up to 100%) in cytotrophoblasts(CTs) , villous mesenchymes(VMs) and extravillous trophoblasts(Ets). In triploid partial moles(19/26) showed P57^KIP2 levelscomparable to those observed in normal villous. In diploid complete moles,P57^KIP2 expression was either absent(45/56 cases) or low(11/56 cases) in CTs and VMs,but was observed in ETs.The expressions of P57^KIP2was significally lower in CHM,but it was higher in normal villous and PHM..By statistical analysis, In CTs and VMs ,the difference of P57^KIP2 positive immunostaining in CHM versus PHM,CHM versus normal villious in our cases was highly statisticallysignificant(P<0.01);Unlikeness the expression of P57^KIP2 protein, In CHM, KCNQ1 expression was either absent (39/56 cases)or low(17/56 cases) in syncytiotrophoblasts(STs) and CTs,In ETs ,KCNQ1 expression was either absent (37/56 cases)or low(19/56 cases). In normal villous ,KCNQ1 expression was observed at high frequency(up to 100%) in CTs,STs and ETs.Triploid partial moles(20/26) showed KCNQ1 levels comparable to those observed in normal villous. In CTs, STs, Ets,The expressions of KCNQ1 was significally lower in CHM,but it was higher in normal villous and PHM. By statistical analysis, In CTs, STs, Ets, the difference of KCNQ1 positive immunostaining in CHM versus PHM,CHM versus normal villious in our cases was highly statistically significant(P<0.01).3. The relationship between KCNQ1 and P57^KIP2 in HM :In all normal villous, Theexpressions of KCNQ1 were associated with the expressions of P57^KIP2.In CHM,there were 6 cases that had the corporate positive expression of KCNQ1 and P57^KIP2 and negative expression were 34 cases .But in PHM,positive expression were 16 cases and negative expression were 3 cases.The expressions of KCNQ1 and P57^KIP2 had positive correlation in 82 specimens of hydatidiform moles and 30 specimens nomal villous. (r=-0.551, P=0.000). Conclusions: 1. There are gradually decreased expression of P57^KIP2 , KCNQ1 from normalplacenta throught PHM to CHM,indicating that imprinting gene P57^KIP2, KCNQ1 play a role in the development of HM..2. The expressions of KCNQ1 and P57^KIP2 had positive correlation, suggestingthat KCNQ1 and P57^KIP2 has correlation in regulating of the development of hydatidiform mole.