Cancer is a general term of a series of complex traits of the disease triggered by the body cells losing their normal regulation of excessive proliferation, which essentially is a genetic disease.Recombinant inbred strain (RI) mouse generated from one pair of founders has been widely used in traditional tumor model.However, RI has many limitations on the statistic efficiency because of the small scale and lacking of allele diversity.The Collaborative Cross (CC) was designed to generate hundreds of recombinant inbred lines by 8 divergent strains of mice.CC mice embody a tremendous amount of natural genetic variation in different sub-strains of mouse and the single nucleotide polymorphism is four times of the traditional experimental mice.The high-genetic diversity and large scale population enables CC mice simulates the differences of individual susceptibility to the pathogeny or the therapies,thus provides a better research tool and information platform for expediting discovery of genes and genes function in human complex traits diseases.This review summarizes our current knowledge of this field, including methodologic aspects, applications, challenges and limitations, and utilization for cancer research.

Cancer is a group of heterogeneous disease caused by diverse genomic alterations in oncogenes and tumor suppressor genes .Despite recent advances in high-throughput sequencing technologies and development of targeted therapies, novel cancer drug development is limited due to the high attrition rate from clinical studies .Patient-derived xenografts ( PDX) models are generated by implanting sectioned patient tumor fragments into immunodeficient mice .PDX models retain many of the key characteristics of patients ' tumors including histology , genomic signature , cellular heterogeneity , and drug responsiveness .These models cannot only serve as a platform for co-clinical trials by enabling the integration of clinical data , genomic profiles , and drug responsiveness data to determine precisely targeted therapies , but also be applied to the development of biomarkers for drug responsiveness and personalized drug selection .This review summarizes our current knowledge of this field , including methodologic aspects , applications in drug development , challenges and limitations , and utilization for precision cancer medicine .

Objective To determine whether Ca2+ activated Cl- current(Icl(Ca)) contributes to the functional remodeling of the failing heart.Methods Whole cell patch-clamp recording technique was employed to record the Icl(Ca) in cardiac myocytes enzymatically isolatedfrom rapidly pacing induced canine failing hearts at room temperature and compared that of the normal hearts (Nor).Results Thecurrent density of DIDS(200M)sensitive Icl(Ca) induced by intracellular Ca2+ release trigged by L-type Ca2+ current(Ica,L)wassignificantly decreased in heart failare(HE)cells compared to Nor cells.At membrane voltage of 20mV,the Icl(Ca) density was 3.02±0.54 pA/pF in Nor(n=6)vs.1.31±0.25 pA/pF in HF(n=8)cells,(P＜0.01),while the averaged Ica,L density did not show differencebetween two groups.The time constant of current decay of Icl(Ca) was similar in both types of cells.On the other hand,in intra cellularCa2+ clamped mode,where the[Ca2+];was maintained at 100nmol/L,Icl(Ca) density be increased significantly in HF cells when themembrane voltage at+30mV or higher.Conclusions Our results suggest that Icl(Ca) density was decreased in pacing induced failingheart but the channel function be enhanced.Impaired Ca2+ handing in HF cells rather than reduced,Icl(Ca) channel function itself may havecaused this abnormality.The Icl(Ca) density reduction might contribute to the prolongation of action potential in failing heart.The Icl(Ca)channel function up-rugulation is likely to cause cardiac arrhythmia by inducing a delayed after depolarization,when Ca2+ overloadoccurred in diastolic failing heart cells.

Objective To establish a patient-derived xenografts (PDX) mouse model of liver cancer (LC) and to explore its role in precision medicine.Methods PDX model was established by subcutaneous implantation of tumor tissues in NCG mice.The morphological structure of tumor tissue was exaimed using HE staining.Fifteen BALB/c nude mice were subcutaneously inoculated with tumor cell suspension from the PDX models.The xenograft mice were randomly divided into 5-fluorouracil (5-FU) group, sorafenib group and negative control group.The tumor volume and body weight of the tumor-bearing mice were measured regularly, the tumor inhibition rate was calculated and the curative effect was evaluated.Results The success rate was 33.3% (6/18) in the establishment of liver cancer PDX mouse model, and the model well retained the characteristics of the primary tumor.In one case of PDX mouse model, the tumor inhibition rates of 5-FU and sorafenib group were 63.7% and 29.6%, with a statistically significant differece between them (P< 0.05), and there was no significant difference between the sorafenib group and negative control group, consistent with clinical observation.Conclusions The PDX mouse model of liver cancer can maintain the histological structure of primary tumor, and can be applied to precision medicine for patients with liver cancer.

Objective To explore the mechanisms of ligament of Marshall (LOM) initiat and sustain atrial fibrillation (AF).Methods The electrophysiologic properties of canine LOM were investigated using multipolar catheter mapping(normal canines,n =4,group A;AF canines,n =5,group B).The programmed stimulation were performed in the LOM,PV-left atrium(LA)junction and LA,respectively.Activations maps of LOM were analyzed from episodes of spontaneous onset of AF and initiation of induced AF by a single extrastimulus.The effectives refractory period of each part was compared and statistically analyzed among three parts in each group and between the two groups.LOM were cutted with surgical incision technology.The inducing rate of AF and the mapping rate of double potential and fragmented electrocardiogram were compared and statistically analyzed pro and post isolation of LOM.Results The incidence of abnormal potential of LOM in the two groups was significantly different(P ＜0.01),re-entry cycle(group A 25％ vs.B group 80％),tachycardia(group A 25％ vs.B 100％),double potential(group A 25％ vs.group B 80％),fragmentation potential(group A 25％ vs.group 80％).There was a significant difference in the rate of LOM tachycardia induction before and after LOM intervention in group B (P ＜ 0.05,before 100％ vs.after 20％).Conclusion There are two possible mechanisms of LOM involved in the occurrence and maintenance of AF:one is that LOM induces AF through spontaneous excitation,the other is that LOM participates in the reentry of left atrium and pulmonary vein in the form of bypass to induce and maintain AF.