Magnetic Resonance Imaging for Translational Research in Oncology

The translation of results from the preclinical to the clinical setting is often anything other than straightforward. Indeed, ideas and even very intriguing results obtained at all levels of preclinical research, i.e., in vitro, on animal models, or even in clinical trials, often require much effort to validate, and sometimes, even useful data are lost or are demonstrated to be inapplicable in the clinic. In vivo, small-animal, preclinical imaging uses almost the same technologies in terms of hardware and software settings as for human patients, and hence, might result in a more rapid translation. In this perspective, magnetic resonance imaging might be the most translatable technique, since only in rare cases does it require the use of contrast agents, and when not, sequences developed in the lab can be readily applied to patients, thanks to their non-invasiveness. The wide range of sequences can give much useful information on the anatomy and pathophysiology of oncologic lesions in different body districts. This review aims to underline the versatility of this imaging technique and its various approaches, reporting the latest preclinical studies on thyroid, breast, and prostate cancers, both on small laboratory animals and on human patients, according to our previous and ongoing research lines.

Patient-derived xenografts as in vivo models for research in urological malignancies. Nat Rev Urol. 2017;14:267-283. [PMID: 28248952 DOI: 10.1038/nrurol.2017.19] [Cited by in Crossref: 49] Lack of appropriate models that recapitulate the complexity and heterogeneity of urological tumours precludes most of the preclinical reagents that target urological tumours from receiving regulatory approval. Patient-derived xenograft (PDX) models are characterized by direct engraftment of patient-derived tumour fragments into immunocompromised mice. PDXs can maintain the original histology, as well as the molecular and genetic characteristics of the source tumour. Thus, PDX models have various advantages over conventional cell-line-derived xenograft (CDX) and other models, which has resulted in an increase in the use of urological tumour PDXs in the analysis of tumour biology and, importantly, for drug development and treatment decisions in personalized medicine. PDX models of urological malignancies have great potential to be used for both basic and clinical research, but limitations exist and need to be overcome. In particular, several agents targeting the immune system have shown promising results in kidney and bladder cancer; however, establishing PDX models in mice with an intact immune system so that an immune response against the tumour is triggered is important to investigate these new therapeutics. Moreover, international collaboration to share PDX models is essential for research concerning fatal urological tumours

Lack of appropriate models that recapitulate the complexity and heterogeneity of urological tumours precludes most of the preclinical reagents that target urological tumours from receiving regulatory approval. Patient-derived xenograft (PDX) models are characterized by direct engraftment of patient-derived tumour fragments into immunocompromised mice. PDXs can maintain the original histology, as well as the molecular and genetic characteristics of the source tumour. Thus, PDX models have various advantages over conventional cell-line-derived xenograft (CDX) and other models, which has resulted in an increase in the use of urological tumour PDXs in the analysis of tumour biology and, importantly, for drug development and treatment decisions in personalized medicine. PDX models of urological malignancies have great potential to be used for both basic and clinical research, but limitations exist and need to be overcome. In particular, several agents targeting the immune system have shown promising results in kidney and bladder cancer; however, establishing PDX models in mice with an intact immune system so that an immune response against the tumour is triggered is important to investigate these new therapeutics. Moreover, international collaboration to share PDX models is essential for research concerning fatal urological tumours.

Biobanking of patient and patient-derived xenograft ovarian tumour tissue: efficient preservation with low and high fetal calf serum based methods

Using patient-derived xenografts (PDXs) for preclinical cancer research demands proper storage of tumour material to facilitate logistics and to reduce the number of animals needed. We successfully established 45 subcutaneous ovarian cancer PDXs, reflecting all histological subtypes, with an overall take rate of 68%. Corresponding cells from mouse replaced human tumour stromal and endothelial cells in second generation PDXs as demonstrated with mouse-specific vimentin and CD31 immunohistochemical staining. For biobanking purposes two cryopreservation methods, a fetal calf serum (FCS)-based (95%v/v) “FCS/DMSO” protocol and a low serum-based (10%v/v) “vitrification” protocol were tested. After primary cryopreservation, tumour take rates were 38% and 67% using either the vitrification or FCS/DMSO-based cryopreservation protocol, respectively. Cryopreserved tumour tissue of established PDXs achieved take rates of 67% and 94%, respectively compared to 91% using fresh PDX tumour tissue. Genotyping analysis showed that no changes in copy number alterations were introduced by any of the biobanking methods. Our results indicate that both protocols can be used for biobanking of ovarian tumour and PDX tissues. However, FCS/DMSO-based cryopreservation is more successful. Moreover, primary engraftment of fresh patient-derived tumours in mice followed by freezing tissue of successfully established PDXs is the preferred way of efficient ovarian cancer PDX biobanking.

The significance of clinicopathological aspects of tumor for the detection of liver micrometastasis in patients with colorectal cancer

BACKGROUND

Colorectal tumor is one of the main causes of death in our country. The aim of the present study was to determine the clinicopathological aspects of tumor and the presence of hepatic micrometastasis in patients with colorectal cancer (CRC).

MATERIALS AND METHODS

Forty two patients with CRC were evaluated in the study surgical treatment was performed and liver biopsy was taken for the evaluation of micrometastasis by immunohistochemistry and polymerase chain reaction. The variables that have been evaluated were: Patient's gender, patients age at the time of diagnosis, size and location of tumor, tumor-node-metastasis stage and grade of the primary tumor, lymph node involvement, lymphovascular and neural invasion, presence of macrometastasis and carcinoembryonic antigen level prior to surgery. After 1 year patients were called and asked to come back to the clinic for elective colonoscopy to evaluate the surgical site for recurrence of tumor and survival. All variables were compared between patients in whom liver micrometastasis were present in comparison with patients without liver micrometastasis.

RESULTS

Of the studied patients (6 with positive micrometatsis and 36 without micrometstasis), 38 were alive after 1 year (6 with positive micrometatsis and 32 without micrometstasis) and the difference was not significant between groups with or without micrometastasis (P = 0.52). In four of survived patients colonoscopy was abnormal, however this difference was not also significant between groups (P = 0.59).

CONCLUSION

Clinicopathologic aspect of tumor was not different in CRC patients with and without hepatic micrometastasis.

Microenvironment influence on human colon adenocarcinoma phenotypes and matrix metalloproteinase-2, p53 and β-catenin tumor expressions from identical monoclonal cell tumor in the orthotopic model in athymic nude rats

The present study aims to identify differences between left and right colon adenocarcinoma arising from identical clonal cell and to find out if microenvironment has any influence on matrix metalloproteinase-2 (MMP2), p53 and β-catenin tumor expressions. MATERIAL AND METHODS. Rats (RNU) were submitted to cecostomy to obtain the orthotopic model of right colon tumor (n = 10), while for the left colon model (n = 10), a colon diversion and distal mucous fistula in the descending colon was used. Cultivated human colon adenocarcinoma cells (WiDr) were inoculated in stomas submucosa. Histopathological analysis, real-time reverse transcription-PCR for β-catenin, p53 and MMP2, as well as immunohistochemical analysis for p53 and β-catenin expression were conducted. Central tendency, variance analysis and the Livak delta-delta-CT method were used for statistical analysis, adopting a 5% significance level. RESULTS. All tumors from the left colon exhibited infiltrative ulceration, while in the right colon tumor growth was predominantly exophytic (67%). In the left colon, tumor growth was undifferentiated (100%), while it was moderately differentiated in the right colon (83%). In right colon tumors, MMP2, p53, and β-catenin gene expressions were higher than compared to left colon (p = 4.59354E-05, p = 0.0035179, p = 0.00093798, respectively, for MMP2, p53 and β-catenin). β-catenin and p53 results obtained by real-time polymerase chain reaction were confirmed by immunohistochemistry assay (p = 0.01 and p = 0.001, respectively, for β-catenin and p53). CONCLUSION. Left and right human colon adenocarcinomas developed in animal models have distinct phenotypes even when they have the same clonal origin. Microenvironment has influenced p53, β-catenin, and MMP2 expression in animal models of colon cancer.

Histological and prognostic importance of CD44(+) /CD24(+) /EpCAM(+) expression in clinical pancreatic cancer. Cancer Sci. 2013;104:1127-1134. [PMID: 23679813 DOI: 10.1111/cas.12198] [Cited by in Crossref: 50] CD44(+) /CD24(+) /EpCAM(+) cells have been reported to be cancer stem cells in pancreatic cancer; however, the histological and clinical importance of these cells has not yet been investigated. Here we clarified the characteristics of CD44(+) /CD24(+) /EpCAM(+) cells in clinical specimens of pancreatic cancer using immunohistochemical assay. We used surgical specimens of pancreatic ductal adenocarcinoma from 101 patients. In view of tumor heterogeneity, we randomly selected 10 high-power fields per case, and triple-positive CD44(+) /CD24(+) /EpCAM(+) expression was identified using our scoring system. The distribution, histological characteristics, and prognostic importance of CD44(+) /CD24(+) /EpCAM(+) cells were then analyzed. As a result, the distribution of CD44(+) /CD24(+) /EpCAM(+) cells varied widely among the 101 cases examined, and CD44(+) /CD24(+) /EpCAM(+) expression was correlated with poor glandular differentiation and high proliferation. Survival analysis showed that CD44(+) /CD24(+) /EpCAM(+) expression was not correlated with patient outcome; however, CD44(+) /CD24(+) expression appeared to be correlated with poor prognosis. In conclusion, CD44(+) /CD24(+) /EpCAM(+) expression overlapped with poorly differentiated cells and possessed high proliferative potential in clinical pancreatic cancer. In particular, the presence of double-positive CD44(+) /CD24(+) expression seemed to have clinical relevance, associating with poor prognosis

CD44(+) /CD24(+) /EpCAM(+) cells have been reported to be cancer stem cells in pancreatic cancer; however, the histological and clinical importance of these cells has not yet been investigated. Here we clarified the characteristics of CD44(+) /CD24(+) /EpCAM(+) cells in clinical specimens of pancreatic cancer using immunohistochemical assay. We used surgical specimens of pancreatic ductal adenocarcinoma from 101 patients. In view of tumor heterogeneity, we randomly selected 10 high-power fields per case, and triple-positive CD44(+) /CD24(+) /EpCAM(+) expression was identified using our scoring system. The distribution, histological characteristics, and prognostic importance of CD44(+) /CD24(+) /EpCAM(+) cells were then analyzed. As a result, the distribution of CD44(+) /CD24(+) /EpCAM(+) cells varied widely among the 101 cases examined, and CD44(+) /CD24(+) /EpCAM(+) expression was correlated with poor glandular differentiation and high proliferation. Survival analysis showed that CD44(+) /CD24(+) /EpCAM(+) expression was not correlated with patient outcome; however, CD44(+) /CD24(+) expression appeared to be correlated with poor prognosis. In conclusion, CD44(+) /CD24(+) /EpCAM(+) expression overlapped with poorly differentiated cells and possessed high proliferative potential in clinical pancreatic cancer. In particular, the presence of double-positive CD44(+) /CD24(+) expression seemed to have clinical relevance, associating with poor prognosis.

Orthotopic xenografts of RCC retain histological, immunophenotypic and genetic features of tumours in patients

Renal cell carcinoma (RCC) is an aggressive malignancy with limited responsiveness to existing treatments. In vivo models of human cancer, including RCC, are critical for developing more effective therapies. Unfortunately, current RCC models do not accurately represent relevant properties of the human disease. The goal of this study was to develop clinically relevant animal models of RCC for preclinical investigations. We transplanted intact human tumour tissue fragments orthotopically in immunodeficient mice. The xenografts were validated by comparing the morphological, phenotypic and genetic characteristics of the kidney tumour tissues before and after implantation. Twenty kidney tumours were transplanted into mice. Successful tumour growth was detected in 19 cases (95%). The histopathological and immunophenotypic features of the xenografts and those of the original tumours largely overlapped in all cases. Evaluation of genetic alterations in a subset of 10 cases demonstrated that the grafts largely retained the genetic features of the pre-implantation RCC tissues. Indeed, primary tumours and corresponding grafts displayed identical VHL mutations. Moreover, an identical pattern of DNA copy amplification or loss was observed in 6/10 cases (60%). In summary, orthotopic engrafting of RCC tissue fragments can be successfully used to generate animal models that closely resemble RCC in patients. These models will be invaluable for in vivo preclinical drug testing and for deeper understanding of kidney carcinogenesis. The raw data of the SNP array analysis has been submitted to the GEO database (Accession No. GSE29062).

Detection of disseminated tumour cells in the liver of cancer patients

AIMS

The liver is a common site of metastasis from a variety of solid malignancies. This is due to disseminated tumour cells (DTC) that have spread prior to or during surgery from the primary carcinoma. This article gives a short overview of the data published on the detection of DTC in the liver and describes the commonly used detection methods and respective markers.

METHODS

A literature survey was performed in public medical databases comprising the last 15 years with focus on DTC detection in liver tissue of cancer patients.

KEY FINDINGS

Although the liver is a preferred site of metastasis, only a few studies have analysed the DTC incidence in inconspicuous liver tissue. The available reports include only patients with pancreatic and colorectal carcinomas. In patients with pancreatic cancer the DTC incidence varied from 5 to 76%. No follow-up data has been reported so far. In patients with colorectal carcinoma hepatic DTC were found in 5-69% of cases. A negative prognostic influence of hepatic DTC was reported in all but one studies with follow-up information.

CONCLUSIONS

The detection of DTC in the liver can contribute to identify patients with increased risk who could benefit from an intensified follow-up or new treatment strategies.

Xiaotansanjie recipe inhibits growth and metastasis of human gastric adenocarcinoma cell SGC-7901transplanted in nude mouse

AIM: To investigate the effects of the Xiaotansanjie recipe on the nude mouse model of human gastric carcinoma cells using orthotopic transplantation.

METHODS: Firstly we established the metastatic gastric carcinoma model of nude mice by orthotopic implantation. On the second day they were devided into four groups at random. The inhibitary rates of tumour growth were detected, and local invasiveness, the rates of metastasis in the local lymph node, lung, liver and peritoneum were compared between different groups. By Envision immunohistochemical method and semiquantitative reverse transcription polymerase chain reation, the expression of P21ras, P185, Ras, CerbB₂, VEGF and KDR in gastric carcinoma were determined.

RESULTS: The inhibitary rates of Xiaotansanjie recipe group, 5-Fu group and combined group were 72.0% , 51.3% and 70.1% respectively. Compared with the control group,the rates of local invasiveness, metastasis in the lymph node and distal organs in other three groups were significantly lower (P < 0.05). The positive rate of P21ras, P185, Ras, CerbB₂, VEGF and KDR in Xiaotansanjie recipe group obviously lower than those in control group (P < 0.05).

CONCLUSION: Xiao Recipe has a strong inhibitory effect on both growth and metastasis of gastric cancer, and the mechanism of that may related with the reduced expression of oncogene cerbB2, ras,VEGF and KDR.

Expression of PCNA and CD44mRNA in colorectal cancer with venous invasion and its relationship to liver metastasis

AIM: To investigate the expression of proliferating cell nuclear antigen (PCNA) and CD44mRNA in colorectal cancer with venous invasion and its relationship with liver metastasis.

METHODS: Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression of PCNA and CD44mRNA in 31 cases of colorectal cancer with venous invasion.

RESULTS: Positive expression rates of PCNA and CD44mRNA in colorectal cancer were higher than those without liver metastasis (P < 0.05 and P < 0.01). In case of colorectal cancer with liver metastasis, strongly positive rates of PCNA and CD44mRNA were 94.1% and 70.6%, respectively, significantly higher than those without liver metastasis. There was a positive relationship between the expressions of PCNA and CD44mRNA (r = 0.67, P < 0.05).

CONCLUSION: Detection of PCNA and CD44mRNA expression in colorectal cancer may be useful for evaluating liver metastasis of cancer cells.

Collagen fiber angle in the submucosa of small intestine and its application in gastroenterology

AIM: To propose a simple and effective method suitable for analyzing the angle and distribution of 2-dimensional collagen fiber in larger sample of small intestine and to investigate the relationship between the angles of collagen fiber and the pressure it undergoes.

METHODS: A kind of 2-dimensional visible quantitative analyzing technique was described. Digital image-processing method was utilized to determine the angle of collagen fiber in parenchyma according to the changes of area analyzed and further to investigate quantitatively the distribution of collagen fiber. A series of intestinal slice’s images preprocessed by polarized light were obtained with electron microscope, and they were processed to unify each pixel. The approximate angles between collagen fibers were obtained via analyzing the images and their corresponding polarized light. The relationship between the angles of collagen fiber and the pressure it undergoes were statistically summarized.

RESULTS: The angle of collagen fiber in intestinal tissue was obtained with the quantitative analyzing method of calculating the ratio of different pixels. For the same slice, with polarized light angle’s variation, the corresponding ratio of different pixels was also changed; for slices under different pressures, the biggest ratio of collagen fiber area was changed either.

CONCLUSION: This study suggests that the application of stress on the intestinal tissue will change the angle and content of collagen fiber. The method of calculating ratios of different pixel values to estimate collagen fiber angle was practical and reliable. The quantitative analysis used in the present study allows a larger area of soft tissue to be analyzed with relatively low cost and simple equipment.

K-ras gene mutation in the diagnosis of ultrasound guided fine-needle biopsy of pancreatic masses

AIM: To investigate the utility of K-ras mutation analysis of ultrasound guided fine-needle aspirate biopsy of pancreatic masses.

METHODS: Sixty-six ultrasound guided fine-needle biopsies were evaluated by cytology, histology and K-ras mutation. The mutation at codon 12 of the K-ras oncogene was detected by artificial restriction fragment length polymorphisms using BstN I approach.

RESULTS: The presence of malignant cells was reported in 40 of 54 pancreatic carcinomas and K-ras mutations were detected in 45 of the 54 FNABs of pancreatic carcinomas. The sensitivity of cytology and K-ras mutation were 74% and 83%, respectively. The speciality of cytology and K-ras mutation were both 100%. The sensitivity and speciality of K-ras mutation combined with cytology were 83% and 100%, respectively.

CONCLUSION: High diagnostic accuracy with acceptable discomfort of FNAB make it useful in diagnosis of pancreatic carcinoma. Ultrasound guided fine-needle biopsy is a safe and feasible method for diagnosing pancreatic cancer. Pancreatic carcinoma has the highest K-ras mutation rate among all solid tumors. The mutation rate of K-ras is about 80%-100%. The usage of mutation of codon 12 of K-ras oncogene combined with cytology is a good alternative for evaluation of pancreatic masses.

Arterial chemotherapy of 5-fluorouracil and mitomycin C in the treatment of liver metastases of colorectal cancer

AIM: Regional chemotherapy using hepatic artery catheters is a good method of treating patients with colorectal cancer liver metastases. We investigated the survival of patients with liver metastases from colorectal cancer using 5-fluorouracil (5-FU) and mitomycin C Cthrough implantable hepatic arterial infusion port.

METHODS: Seventy-five patients with inoperable liver metastases from colorectal cancer were included between March, 1992 and November, 2001. We placed implantable hepatic arterial catheter (HAC) port by laparotomy.5-FU, 1000 mg/m²/d continuous infusion for five days every four weeks, was delivered in the hepatic arterial catheter through the port. Mitomycin C, 30 mg/m²/d infusion in the first day every cycle through the port. Response to the treatment was evaluated by serial determinations of plasma CEA and imaging techniques consisting of computerized tomography and sonography of liver.

RESULTS: Sixty-eight were performed hepatic artery chemotherapy and fifty-six were followed up among seventy-five HAC patients. Twenty-six patients (46.4%) have responded and 4 complete remission were achieved. Eight patients (14.3%) had stable liver metastases. Twenty-two patients (39.3%) were progressed with increased tumor size and number. Twenty-nine patients (51.8%) had a decreased serum CEA level, while 10 patients (17.9%) were stable and 17 patients (30.4%) had an increased serum CEA level. There were no operative death in this series. Complications, which occurred in 18 patients (32.1%), were as followed: hepatic artery thrombosis in 11, Upper gastric and intestinal bleeding in 3, liver abscess in 1, pocket infection in 1, cholangitis in 1, and hepatic artery pseudo-aneurysm in one patient.

CONCLUSION: Combined infusion of 5-FU and mitomycin C by hepatic artery catheter port is an effective treatment for liver metastases from colorectal cancer. The high response and lower complication rates prove the adjuvant treatment of colorectal cancer with this treatment.

The role of KDR in the interactions between human gastric carcinoma cell and vascular endothelial cell

AIM: To study the interactions between human gastric carcinoma cell (HGCC) and human vascular endothelial cell (HVEC), and the role of KDR in these interactions.

METHODS: Antisense oligodexynucleotide (ASODN) specific to KDR gene was devised and added to the culture medium of HGCC and HVEC. After the action of ASODN, the proliferation of two cells was measured by MTT method. The role of KDR in regulating the proliferation of two kinds of cells was known through observing the effect of ASODN on them. The conditioned mediums (CMs) of HGCC and HVEC were prepared. The CM of one kind of cell was added acting on the other kind of cell, then the cell proliferation was measured by MTT. After the action of ASODN or CM, the cellular expression of KDR gene was detected with in situ hybridization (ISH) for mRNA level and with immunohistochemical staining for protein level. ABC-ELISA was used to detect hVEGF in the CMs of two cells.

RESULTS: KDR ASODN could specifically inhibit the proliferation of HGCC and HVEC significantly. The growth inhibitory rate amounted to 55.35% and 54.83%, respectively (P < 0.01). HGCC and HVEC could secret a certain level of hVEGF (92.06 ± 1.69 ng/L, 77.70 ± 8.04 ng/L). The CM of HGCC could significantly stimulate the growth (2.70 ± 0.01 times) and KDR gene expression of HVEC (P < 0.01) while the CM of HVEC could significantly inhibit the growth (52.97% ± 0.01%) and KDR gene expression of HGCC (P < 0.01).

CONCLUSION: KDR plays a key role in regulating the proliferation of HGCC and HVEC. There exist complicated interactions between HGCC and HVEC. HGCC can significantly stimulate the growth of HVEC while HVEC can significantly inhibit the growth of HGCC. KDR is involved in the interactions between them.