Colorectal Tumor Cells

Colorectal cancer is a significant global health concern, with the incidence and mortality rates steadily rising in recent years. Colorectal tumor cells are abnormal cells that originate in the lining of the colon or rectum, collectively known as the large intestine. These cells exhibit uncontrolled growth, evading the body's natural mechanisms that typically regulate cell division and proliferation. As they continue to multiply, they form a mass or tumor that can eventually spread to other parts of the body, a process known as metastasis.

The heterogeneous nature of colorectal tumor cells is a key factor in the complexity of this disease. These cells can exhibit various genetic and epigenetic alterations, leading to diverse morphological and functional characteristics. This diversity not only challenges the development of effective treatment strategies but also highlights the importance of a comprehensive understanding of the underlying mechanisms driving colorectal cancer progression.

Advantages of In Vitro Cell Line Models for Colorectal Cancer Research

• Experimental control. In vitro cell line models offer precise experimental control, allowing researchers to manipulate and monitor the growth, behavior, and molecular characteristics of colorectal tumor cells under defined conditions. This control is essential for studying specific cellular processes, signaling pathways, and responses to therapeutic agents.
• High reproducibility. Colorectal cancer cell lines provide consistent and reproducible results, enabling researchers to validate experimental findings across multiple studies and laboratories. This reproducibility enhances the reliability of research outcomes and contributes to the robustness of scientific discoveries.
• Cost-effectiveness. In vitro cell line models are generally more cost-effective and logistically feasible compared to in vivo models, enabling a broader range of experiments and high-throughput screening assays. This cost-efficiency allows for the screening of larger compound libraries and the rapid evaluation of potential drug candidates for colorectal cancer treatment.
• Scale and manipulation. Colorectal cancer cell lines can be expanded in large quantities, facilitating experiments requiring substantial cell numbers for molecular analyses, drug testing, and genomic studies. Additionally, these cells can be genetically manipulated to study specific genetic alterations, gene expression profiles, and signaling pathways relevant to colorectal cancer.

Cancer modeling and drug screening

One of the primary applications of colorectal tumor cells is their use in cancer modeling and drug screening. By culturing these cells in vitro, researchers can recreate the tumor microenvironment and study the effects of various therapeutic agents on cancer cell proliferation, migration, and invasion. This approach allows for the identification of promising drug candidates and the optimization of treatment strategies, ultimately paving the way for more effective and personalized cancer therapies.

Biomarker discovery and diagnostics

Colorectal tumor cells also serve as valuable tools for the discovery and development of biomarkers, which are molecules or characteristics that can be used to detect, monitor, and even predict the course of the disease. By analyzing the unique molecular signatures and cellular behaviors of these tumor cells, scientists have identified novel biomarkers that can aid in early cancer detection, risk stratification, and treatment selection.

Tumor microenvironment and immune interactions

Furthermore, research has delved into the intricate interplay between colorectal tumor cells and the surrounding tumor microenvironment. The role of various cellular and non-cellular components, such as immune cells, stromal cells, and extracellular matrix, in shaping the tumor's immune landscape and response to treatment. These insights have enabled us to explore novel immunotherapeutic strategies that harness the body's immune system to combat colorectal cancer.

Interference With Notch3 Signalling Attenuates Colon Tumour Growth

Macrophage infiltration in the tumor microenvironment participates in the regulation of tumor progression. Previous studies have found that the Notch signaling pathway is involved in regulating the progression of colorectal cancer (CRC), however, the specific mechanism is still unclear.

To test whether Notch3 was involved in regulating the recruitment of macrophages in vivo, an MC38 cell line with stable knockdown of Notch3 was constructed (Fig. 1a). The colony formation assay showed that interference with Notch3 expression in vitro had little effect on cell proliferation (Fig. 1b), which was also verified in 3D growth of MC38 cells (Fig. 1c). Next, control and Notch3 stable knockdown MC38 cells were injected on both sides of C57BL/6 mice. Surprisingly, interference with Notch3 significantly inhibited the growth of transplanted tumors (Fig. 1d-f). The above results indicated that Notch3 mainly promoted the development of CRC by regulating the tumor microenvironment. Furthermore, a flow cytometry experiment was conducted to detect macrophage in the tumor microenvironment of transplanted tumors. The results showed that interference with Notch3 significantly reduced the proportion of macrophage in tumor tissues (Fig. 1g, h). Meanwhile, the proportion of macrophage was analyzed in the peripheral blood of mice, and no significant changes were observed. Altogether, the results suggested that Notch3 participated in regulating the recruitment of macrophages in colon cancer, thereby regulating tumor progression.

Fig. 1 Interference Notch3 attenuates the colon tumor growth and decreases Macrophage infiltration in vivo. (Huang K, et al, 2023)

Effect of IFN-γ Stimulation on the Proliferation of CRC Cells

Interferon-γ (IFN-γ), also called immune interferon, is an important cytokine present in the tumor microenvironment (TME). In addition to playing a role in the defense against infection, IFN-γ also plays a prominent role in tumor diseases.

In the in vitro study, the proliferation of three CRC cell lines, CT26.WT, DLD-1, and SW480 were evaluated before and after IFN-γ stimulation using Cell Counting Kit-8 (CCK-8) assays and found that the absorbance value showed a decreasing trend in the IFN-γ stimulation group compared with the control group (without cytokine stimulation). These results showed that IFN-γ stimulation inhibited tumor cell proliferation in vitro (Fig. 2A).

In the in vivo study, IM-d-mice and IM-c-mice were selected for tumor growth assays using implanted CRC cells. First, the growth trend of subcutaneously implanted CT26.WT tumors were examined in IM-d mice. The IFN-γ stimulation group was compared with the control group, and the curves of both tumor volume (Fig. 2B) and final tumor weight (Fig. 2C) showed a decreasing trend in the IFN-γ stimulation group. These results suggest that IFN-γ stimulation can inhibit tumor growth in IM-d-mice, which is consistent with the results of the in vitro CCK-8 assay. However, in IM-c-mice, the tumors in IFN-γ-stimulated mice grew faster, and the final tumor volume (Fig. 2D) and weight were larger (Fig. 2E) than those in control mice. These results showed that IFN-γ stimulation promoted CRC tumor growth in IM-c mice. Therefore, IFN-γ may exert an immunomodulatory effect through the TME.

Fig. 2 IFN-γ stimulation of CRC cell proliferation depends on the immune microenvironment. (Jing ZL, et al., 2024)