基調講演 3

CTOS as a model for studying tumor
heterogeneity and plasticity

Cancer is a disease characterized by its heterogeneity and plasticity. Cancer patients withthe same pathological diagnosis differently respond to the therapy, and cancer cells in a tumor

Masahiro Inoue, Jumpei Kondo
Department of Clinical Bio-resource Research and Development
Graduate School of Medicine Kyoto University[References]1.

Kondo J, Endo H, Okuyama H, Ishikawa O, Iishi H, Tsujii M et al. Retaining cell-cell contact enables

are genetically and phenotypically divergent. On the other hand, cancer cells change their

preparation and culture of spheroids composed of pure primary cancer cells from colorectal cancer.

characters, such as metastatic potential and drug resistance, during the clinical course. SuchProc Natl Acad Sci USA 2011; 108: 6235-6240.

heterogeneity and plasticity make the cancer treatment difficult. Interpatient heterogeneity2.

is a critical issue in molecular targeting drugs because they are very well effective on somepatients, but not effective at all on the others. Since the effects can be predicted by assessing

Kondo J, Ekawa T, Endo H, Yamazaki K, Tanaka N, Kukita Y et al. High-throughput screening incolorectal cancer tissue-originated spheroids. Cancer Sci 2019; 110: 345-355.

3.

Okuyama H, Kondo J, Sato Y, Endo H, Nakajima A, Piulats JM et al. Dynamic Change of Polarity inthe mutations of the genes related to the targeted pathway in some cases, genome sequencing

Primary Cultured Spheroids of Human Colorectal Adenocarcinoma and Its Role in Metastasis. Am J

is going to be widely applied in clinic. Since it is realistically difficult to predict the optimal drugPathol 2016; 186: 899-911.

for majority of the patients only by mutational analysis, additional approaches are required
to make the prediction better. Sensitivity assays using primary cultured cells has long been

4.

Kondo J, Inoue M. Application of Cancer Organoid Model for Drug Screening and Personalized
Therapy. Cells 2019; 8: 470.

expected to be a prediction platform but none of them are widely used so far.
We developed a novel primary culture system of cancer cells, cancer tissue-originatedspheroid (CTOS) method, in which cancer cells are prepared and cultured by maintaining cellcell contact throughout the process. CTOS preserves the nature of cancer cells in original
patient tumors. Some of the CTOS can be xenografted, and from the xenograft tumors, CTOS
can be easily and efficiently prepared and cryo-preserved. We call the CTOS as‘CTOS lines’
when CTOS can be passaged in vivo at least twice and a number of cryo-tubes are stocked forfurther studies. We generated CTOS panels, which consist of multiple CTOS lines preparedfrom different patient tumors. Using CTOS panels, we revealed wide range of drug sensitivity
among the lines depending on the drug. The sensitivity assay reflects the results of clinical
trials as well as the clinical response of individual patients.
As for the plasticity, CTOS dynamically changes their characteristics as a mass, not just asingle cell. One of the examples is the polarity switching. Most of the colorectal cancer is thedifferentiated adenocarcinoma, in which gland like structure, apico-basal polarity as a cell, ismaintained in various extents. We previously reported that polarity status of CTOS switchedaccording to different culture conditions; apical-out in suspension and apical-in in extracellularmatrix (ECM). Micropapillary carcinoma (MPC) is an aggressive variant of adenocarcinoma,
exhibiting reverse polarity, i.e. apical side facing to the ECM. The machinery of MPC has notbeen clarified yet. We established CTOS lines from MPC type colorectal cancers, MPC-CTOSs.
MPC-CTOS formed apical-out pattern even in ECM, recapitulating the polarity status in originaltumors. Treatment with ROCK inhibitor Y27632 enabled MPC-CTOS to accomplish polarity
switching in ECM. The polarity status of xenograft tumors of C166, one of the MPC-CTOSs,
changed to that of non-MPC when Y27362 was administered in vivo. These results suggest thatRhoA/ROCK signaling pathway might be involved in MPC phenotype.
Taken together, CTOS can be a model for studying tumor heterogeneity and plasticity.
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井上 正宏
京都大学大学院医学研究科
1987年
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クリニカルバイオリソース研究開発講座

特定教授

大阪大学医学部卒
臨床研修 大阪大学第一外科、小児外科など
大学院 大阪大学小児外科、大阪大学細胞工学センター
博士研究員 UC San Francisco
大阪国際がんセンター（旧 大阪府立成人病センター）生化学部 部長
大阪大学大学院薬学研究科 環境病因病態学分野 客員教授
京都大学大学院医学研究科 客員教授
大阪大学大学院医学研究科 客員教授
京都大学大学院医学研究科 クリニカルバイオリソース研究開発講座 特定教授

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