| PC（Pancreatic cancer） is the most common type in pancreatic primary malignanttumors, which is one of the deadliest cancers and ranks as the fourth leading cause ofcancer death in North America. Survival statistics are poor because there are no reliabletests for early diagnosis and no effective therapies for the metastatic form. Although someapproaches to diagnosing earlier PC have been used and promoted, such as combinedtesting some marks of tumor (CA19-9and CA242. et al.), molecular biologicalexaminations (applications of technique of gene chips and tissue chips), Endoscopicultrasound-guided fine-needle aspiration (EUS-FNA) and radiological diagnosis withcontrast enhanced or perfusion scanning, all the above still can be limited by somepotential problems or with an outcome that may necessitate additional invasive procedures.Mesothelin is a differentiation antigen which high expresses in pancreatic diseases onlylimited to PC without expression shown in normal pancreas and other pancreatic diseases.This differential expression makes mesothelin an attractive candidate for targeted diagnosisor therapies. Nude mouse model with human tumor is suited for tumor researching. Thisstudy is to screen appropriate human pancreatic cancer cell line with stabler and strongermesothelin expression by various methods and to survey the process of building nudemouse model borne human PCs at multiple time-points. In addition, these subcutaneous PCmouse models were detected with3.0T MR and the images were compared to pathologicalsections. Based on these results, it is valued that the potential of diagnosis to earlierpancreatic cancer by molecular imaging.Part Ⅰ：Comparison of expression of Mesothelin among three kinds ofpancreatic cancer cell line and of development speed in their nude mousemodelsObjective To compare the difference of Mesothelin expression in3kinds of humanpancreatic cancer cell lines between in vitro and in vivo and the difference of developingspeed among the subcutaneous tumors implanted with3kinds of cell lines.Methods The human pancreatic cancer cell lines (SW1990, BxPC-3and PANC-1) werecultured and then were implanted subcutaneously into bilateral axillas of nude mice with 1ml injectors. The volumes of these subcutaneous tumors were recorded every week toreflex their developing speed. Finally, the mice implanted SW1990and BxPC-3cell lineswere surveyed for three weeks rather than five weeks to those implanted PANC-1cell lines.The tumors cropped from these mice killed were preserved in refrigerator (to WB analysis)or formalin solution (to histopathological and immunohistochemical analysis). The WBand the immunohistochemical staining to test the expression of Mesothelin in threevarieties of tumor would be done as soon as they were ready. Also, the WB to test theexpression of Mesothelin in three cell lines had been performed.Results The comparison of Mesothelin expression in these cell lines wasBxPC-3>PANC-1>SW1990and it in tumors was SW1990>BxPC-3>PANC-1(the resultsfrom WB and immunohistochemical staining were accordant). All the tumors grew outsuccessfully with they all being alive and the sequence of their average volume wasSW1990>BxPC-3>PANC-1.Conclusions The Mesothelin expression among3kinds of pancreatic cancer cell lineswas different whatever in vitro or in vivo, but the status of their difference between in vitroand in vivo was not accordant. The developing speeds of tumors originated from differentcell lines were different.Part Ⅱ：Establishing the nude mouse model bearing human PC atmultiple time-points and the3.0T MRI findingsObjective To establish nude mouse tumor models borne multiple human pancreaticcancers with different developing time and investigate the feasibility of multipletumor-bearing in these models; Then analyze the findings and detection rate of3.0Tmagnetic resonance image (MRI) in subcutaneous transplanted tumors.Methods A total of6nude mice were randomized into3groups (2mice per group). Atintervals of a week, one group was injected subcutaneously with the suspension ofSW1990cells at left axilla and right axilla and right groin in sequence; the other twogroups were injected at right axilla and groin, and right groin alone, respectively. Afterthree weeks of feeding, all the bearing-tumor mice were performed with MRI unenhancedand contrast-enhanced scanning and the subcutaneous masses were put intohistopathological analysis.Results All the6nude mice were alive during the feeding duration and an obviousmass was observed in every injected site. The longer of the growing time, the bigger of the masses. There were9tumors which could be detected by unenhanced MRI scanning andone more tumor detected by contrast-enhanced scanning. The major axis of the2undetected tumors in right groin was less than5mm. Despite the MRI findings of thetransplanted masses largely similar to that of human pancreatic adenocarcinoma, theydisplayed the characteristics of a clear rim. Outcomes of histopathological analysisrevealed human pancreatic adenocarcinoma cells and tissues in all the12masses.Conclusions It is feasible to transplant human PC cell at three different subcutaneoussites (injected at three different point of time) in the nude mouse, with a minimal survivaltime of three weeks. The findings of subcutaneously transplanted PC in MRI contribute toits identification. However, the detection rate of the earlier tumors(growing time in1week,major axis＜5mm) through the common MRI work-up remains low.PartⅢ：The MRI study with MSLN-USPIO in the nude mouse modelbearing human PC at multiple time-pointsObjective To study the potential and value of enhanced MR imaging with ultrasmallsuperparamagnetic iron oxide (USPIO) conjugated by mesothelin antibody to implantedhuman pancreatic carcinomas in nude mouse.Methods To establish nude mouse tumor models borne multiple human pancreaticcancers with different developing time and they were randomized into two groups. USPIOor MSLN-USPIO were used as contrast-enhanced agents in the3.0T MR detection to thecorresponding group of nude mouse, then the positive rates detected the smallest tumorsbetween the two groups were calculated and compared. Signal intensity of tumors in T2Mapping images of both unenhanced and contrast-enhanced scanning were measured, thenthe enhancement rate in the two groups of tumor were calculated and compared. After MRdetection, all the tumor specimens were performed Prussian blue stain and surveyed thedifference of ferrous ion deposition in the tumor tissue between the two groups of mouse.Results There is no statistical significance in the detection positive rate between the twogroups of the smallest tumor. In USPIO group, the enhancement rate of left or right axillatumors was12.29%or11.06%, there is statistical significance in the difference of signalintensity between unenhanced and contrast-enhanced images in left or right axilla tumors.In MSLN-USPIO group, the enhancement rate of left or right axilla tumors was33.88%or43.29%, there is statistical significance in the difference of signal intensity between unenhanced and contrast-enhanced images in left or right axilla tumors. There is statisticalsignificance in the difference of enhancement rate between two groups of tumors in thesame site, the enhancement rate in MSLN-USPIO group is obviously higher than in USPIOgroup. The ferrous ion deposition in tumors tissue in MSLN-USPIO group is obviouslymore than in USPIO group.Conclusions The enhanced effect of MSLN-USPIO is superior to USOPIO, soMSLN-USPIO could be a tumor-targeted MR contrast-enhanced agent for the diagnosis ofpancreatic cancer in nude mice. |
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