Abstract
Metastases are largely responsible for cancer deaths in solid tumors due to the lack of effective therapies against disseminated disease, and there is an urgent need to fill this gap. This study demonstrates an orthotopic colorectal cancer (CRC) mouse model system to develop spontaneous metastasis in vivo and compare its reproducibility against human CRC. IGF1R-dependent GEO human CRC cells were used to study metastatic colonization using orthotopic transplantation procedures and demonstrated robust liver metastasis. Cell proliferation assays were performed both in the orthotopic primary colon and liver metastatic tumors, and human CRC patient's specimen and similar patterns in H&E and Ki67 staining were observed between the orthotopically generated primary and liver metastatic tumors and human CRC specimens. Microarray analysis was performed to generate gene signatures, compared with deposited human CRC gene expression data sets, analyzed by Oncomine, and revealed similarity in gene signatures with increased aggressive markers expression associated with CRC in orthotopically generated liver metastasis. Thus, we have developed an orthotopic mouse model that reproduces human CRC metastasis. This model system can be effective in developing new therapeutic strategies against disseminated disease and could be implemented for identifying genes that regulate the development and/or maintenance of established metastasis.
Highlights
Colorectal cancer (CRC) is a major cause of cancer-related deaths in the United States [1]
Metastasis to the distant organs is the most common cause of cancer-related death in CRC, and understanding the molecular mechanisms of metastasis is critical to the development of effective therapies against metastasis for the improvement of patient survival with distant metastasis
Subcutaneous tumors generated by intraperitoneal injections of cancer cells generally grow faster and do not recapitulate the slower doubling times observed with most human solid tumors [24]
Summary
Colorectal cancer (CRC) is a major cause of cancer-related deaths in the United States [1]. The high mortality rate in CRC as well as other solid tumors stems out mainly from the metastatic dissemination of cancer cells to distant organ sites [1, 2]. The process of metastasis requires cancer cells originating from the primary tumor to overcome several layers of barrier to initiate secondary tumor deposits at a distant site which are often characterized by highly aggressive phenotypes [3, 4]. Certain subtypes of disseminating breast cancer cells which have demonstrated the ability to survive and colonize at distant organ sites are usually restricted to a small population of tumor-initiating cells [3, 5]. Relatively large populations of lung adenocarcinoma cells are able to survive the multistep metastatic process and frequently form aggressive secondary lesions [2, 3]. The molecular mechanisms involved in the multistep dissemination process are not completely elucidated
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