腫瘍間質相互作用のための三次元共培養モデル
Summary
Here we present a protocol to co-culture in three-dimensions, which is useful for investigating multicellular interactions and extracellular matrix-dependent modulation of cancer cell behavior. In this experimental model, cancer cells are cultured on collagen gels embedded with human cancer-associated fibroblasts.
Abstract
Cancer progression (initiation, growth, invasion and metastasis) occurs through interactions between malignant cells and the surrounding tumor stromal cells. The tumor microenvironment is comprised of a variety of cell types, such as fibroblasts, immune cells, vascular endothelial cells, pericytes and bone-marrow-derived cells, embedded in the extracellular matrix (ECM). Cancer-associated fibroblasts (CAFs) have a pro-tumorigenic role through the secretion of soluble factors, angiogenesis and ECM remodeling. The experimental models for cancer cell survival, proliferation, migration, and invasion have mostly relied on two-dimensional monocellular and monolayer tissue cultures or Boyden chamber assays. However, these experiments do not precisely reflect the physiological or pathological conditions in a diseased organ. To gain a better understanding of tumor stromal or tumor matrix interactions, multicellular and three-dimensional cultures provide more powerful tools for investigating intercellular communication and ECM-dependent modulation of cancer cell behavior. As a platform for this type of study, we present an experimental model in which cancer cells are cultured on collagen gels embedded with primary cultures of CAFs.
Introduction
Cancer tissue can be perceived as a type of organ, which evolves through close interactions between the cancer and the tumor stromal microenvironment, composed of cancer-associated fibroblasts (CAFs), immune cells, tumor vessels and the extracellular matrix (ECM). CAFs are the major source of soluble factors (cytokines, growth factors and chemokines) that exert mitogenic, pro-migratory and pro-invasive effects on cancer cells. They also stimulate tumor vessel formation and recruit precursor cells, such as bone marrow-derived cells (BMDC). Activated CAFs are involved in the production and remodeling of the ECM, thereby promoting the growth and spread of cancer cells1. CAFs also provide a niche that facilitates tumor cell colonization and metastasis and are capable of conferring stem cell phenotypes onto neighboring cancer cells. Pathological observations suggest that stromal reactions or fibrotic changes in cancer tissues are indicative of a poor prognosis. Recent studies have also demonstrated that tumor stromal features, such as the gene signature, can predict patient prognosis. Furthermore, CAF-derived factors can modulate sensitivity to chemotherapy, highlighting the role of CAFs in determining drug sensitivity and resistance2.
As CAFs play a multifaceted role in the promotion of tumor progression through signaling pathways that mediate interactions between CAFs and different cell types within the tumor microenvironment, they have attracted increasing attention as novel targets for cancer therapies. The heterogeneity of the cell populations within the cancer microenvironment presents an obstacle for targeting CAFs. Several markers for CAFs have been proposed, such as α-smooth muscle actin (α-SMA), fibroblast activation protein (FAP), and fibroblast specific proten-1 (FSP-1: also called S100A4); however, these molecular markers are not specific for distinguishing CAFs from other cells present in non-cancerous tissues3. Therefore, further studies are needed to obtain more knowledge about the specific properties of CAFs. To this end, it is informative to characterize primary cultured CAFs compared with patient-matched normal fibroblasts.
Recently, analyses on patient-derived CAFs have been reported in several cancer types, revealing unique gene expression patterns and cell behaviors compared with fibroblasts derived from non-cancerous tissues. Using isolated CAFs from human lung cancer tissues, we developed a three-dimensional co-culture method, enabling us to evaluate the properties of lung CAFs. In this model, we investigated the effects of the CAFs on lung cancer cell invasion, proliferation and collagen gel contraction, which experimentally recapitulated the tumor-promoting roles of lung CAFs4.
Protocol
Representative Results
Discussion
CAFSは、癌細胞の周囲のECMの主要な成分を形成し、腫瘍のための足場を提供するだけでなく、積極的に腫瘍の発達7に参加するだけでなく。証拠を蓄積すると、CAF媒介腫瘍進行8の重要な役割を強調し、最終的な予後上のCAFSまたはその関連分子の影響を解く。
以前の研究では、肺CAFS 4を単離するための成長方法を用いた。この実験では、皿の表面上…
Disclosures
The authors have nothing to disclose.
Acknowledgements
This work was supported by Grants-in-Aid for Scientific Research (KAKENHI) (26461185 and 25460137).
Materials
| Name | Company | Catalog Number |
| DMEM | Sigma-Aldrich | D5796 |
| FBS | GIBCO | 10437 |
| Collagen type IA | Nitta gelatin Inc. | CELL-1A |
| Reconstitution buffer | Nitta gelatin Inc. | |
| Cover slip | NUNC | 174934 |
| Silicone grease | Dow Corning Toray | High vacuum grease |
| Dispase I | WAKO | 386-02271 |
| 6-well plate | BD Falcon | 353046 |
| Cell strainer (70 μm) | BD Falcon | 352350 |
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