Hi Breedge,

People use human CRC cell lines (HCT116, LS173T, KM12, HT29, ...) and inject them in immunodeficient mice, such as Balb/C nude, Swiss nude, NOD, NOD/SCID, NOG, NSG. These mice are typically hard to breed and can be purchased from commercial vendors and come with various price tags.

Intrasplenic injection is a common method to look at liver colonization, tail vein injection may be used to look at lung growths. In orthotopic models, cells are injected into the caecum (or colon) wall and this can be a good model for the multiple steps involved in CRC metastasis.

One step better than cell lines, or at least more fashionable, is to use patient derived cancer primary cultures (3D-cultured in matrigel) in the above-mentioned mice, with the hope of getting more relevant tumours and/or patient-specific metastatic mechanisms.

The reason for using immunodeficient mice for these xenograft models is of course that the immune system would reject foreign tissue, cancerous or not.

These models have been very important for oncology and continue to be vey useful to study cellular mechanisms, cancer signalling, and many other topics. However, this does not allow for the study of the contribution of the immune system in cancer progression. Also, the cross-talk between cancer cells and microenvironment between two species might get lost in translation.

Unfortunately, this seems to be the best we can do at the moment. Genetic models are complicated, not only because of the crossing of alleles (which can be done in much less than 12 breedings): their tumours are rarely invasive adenocarcinomas and if they are, they only sporadically achieve metastatic status. Because of low tumour aggressiveness or because of the mouse dying first. Not straight-forward to study or treat. 

Probably you mention the high number of crosses to get a homogenous genetic background (for which there are also tricks to reduce the number, i.e. selecting for markers). Indeed, backgrounds like C57BL/6, Balb/C, 129, FVB, ... generally appear to have differences in metastatic dynamics. C57BL/6 is one of the most common strains to study individual genes and combinations. It is relatively hard to get tumours to metastasise in, for many cancer types including CRC. 

There is a CRC cell line reported for Balb/C: CT26, it grows in syngeneic immunocompetent mice. However, the histology of these tumours is very different from most human pathology in that it looks mesenchymal instead of epithelial. These doubts notwithstanding, it is used to study immune checkpoint inhibitors and seems to be useful there.

I hope this helps.

Thank you very much for your detailed answer! You confirmed my thoughts.

Breedge,

Another option is to obtain the cre-lox AKP mice created by Tyler Jacks' group.  I believe they are available through jackson lab at this point.  These mice have apc 9truncation), p53 (truncation) and kras (oncogenic lox-stop-lox) inducible upon adenocre exposure.  Alternatively, there is are AB and ABP mice with oncogenic BRAF under lox-stop-lox control.  Ken Hung developed a protocol to induce colonic tumors using these mice that do occasionally spontaneously metastasize to liver and lung.  I generated a handful of tumor cell cultures from these mice (in mixed c57bl/6 background) that are capable of colonizing the liver upon splenic implantation.

Sorry to be so late in responding ... but it is better very in late than never ...

Here attached are articles that could be of interest.

Best regards

Robert

Hi again,

I know developing such models takes a lot of time, because it took us 3-4 years... We generated mice carrying conditional alleles of 4 of the most common CRC mutations. By triggering recombination in adult intestinal stem cells, we obtained very aggressive adenocarcinomas that mimic all the relevant aspects of poor prognosis (microsatellite-stable) CRC in humans: immune exclusion and TGF-beta-activated stroma. Moreover, these compound mutant mice developed spontaneous liver metastasis in about 2 months in 40% of cases.

From these murine cancers, I generated mouse tumour organoids (MTOs) that can be transplanted in syngeneic C57BL/6J mice to recreate the cancer including the rich tumour microenvironment seen in the genetic model. Exploiting this novel preclinical platform, as well as taking advantage of previous findings from our lab, we discovered that TGF-beta drives immune evasion in CRC metastasis and that ALK5/TGFBRI inhibitors can prevent metastasis initiation, as well as render established liver metastasis curable by additional checkpoint immunotherapy. These cured mice were immunized against the cancer (rejecting very robustly upon rechallenge) and are coming up on their second birthday this spring. Recurrence-free!

Published last week in Nature: https://www.nature.com/articles/nature25492

Video summary:

https://www.youtube.com/watch?v=FdSvydBWVk0

Thus, I think MTOs are a promising system to study CRC metastasis, especially if you are interested in the tumour microenvironment: you could inject them into any mouse model (BL/6) that you like. More info in my project page: https://www.researchgate.net/project/Targeting-the-Microenvironment-in-Advanced-Colorectal-Cancer

Our work comes on the heels of a number of other interesting models, see Fumagalli 2017 PNAS, O'Rourke 2017 NatBiotech, De Sousa e Melo 2017 Nature. So I think the field is finally advancing to more sophisticated models.

Best wishes,

Daniele

Thank You Prof. Robert Kiss , Breedge Callaghan , Daniele V F Tauriello .

Hi Breedge,

we had good results developing metastatic cancer after orthotopic implantation of human cancer in BALB/C nude mice. Orthotopic implantation was developed by Robert M.Hoffmann/San Diego years ago.

Especially in gastric cancer and pancreatic cancer this works very well. Colon cancer models are more difficult. Look for Thalheimer A./Illert B or Hoffmann R for more details.

Best regards,

Bertram