HCT116 cells represent a specific line of human cancer cells maintained and propagated in laboratory settings, forming what is known as an immortalized cell line. A cell line is essentially a population of cells derived from a single source that can be continuously grown and divided outside the body. These biological tools are foundational to oncology research, allowing scientists to study the mechanisms of cancer in a controlled environment. The ability to grow a consistent, large supply of these cells makes them essential for understanding disease progression and testing potential treatments.
Origin and Identity of HCT116 Cells
The HCT116 cell line was originally established from a patient diagnosed with colorectal carcinoma, a type of cancer that begins in the colon or rectum. The cells were isolated from the tumor and have been continuously cultured, meaning they have acquired the ability to divide indefinitely, a defining characteristic of an immortalized cell line.
This capacity for limitless replication is a significant advantage in the laboratory, as it ensures researchers have a stable and consistent model for repeated experiments over many years. HCT116 cells exhibit an epithelial-like morphology, resembling the shape of the cells that line the surfaces of the body. In a dish, they typically grow as a flat layer, known as a two-dimensional (2D) monolayer culture. This consistent growth and structure are why they are frequently selected for research studies focused on the fundamental biology of colon cancer and its treatment.
Unique Genetic Signature
The widespread use of HCT116 cells is largely attributed to specific genetic alterations that mirror those found in many human colorectal tumors. One of the most studied alterations is a heterozygous mutation in the KRAS proto-oncogene, meaning it is present on only one of the two copies of the gene, and results in a specific change at codon 13 (G13D).
The KRAS gene is a component of the RAS/RAF/MEK/ERK signaling pathway, which controls cell growth, division, and survival. The G13D mutation causes the KRAS protein to be constantly active, sending continuous signals that promote uncontrolled cell proliferation, which is a hallmark of cancer. Because this mutation is common in about 40% of colorectal cancers, HCT116 serves as an important model for studying therapies designed to target this specific hyperactive pathway.
The cells also possess a normal, non-mutated copy of the p53 tumor suppressor gene, unlike many other cancer cell lines. The p53 protein can stop cell division or trigger programmed cell death (apoptosis) if the cell’s DNA is damaged. Researchers often use the original HCT116 cells, which have a functional p53, to study how this protein influences cell response to stress or drug treatment. Scientists have developed isogenic variations of HCT116, where the p53 gene has been intentionally removed or altered, enabling direct comparison to understand the precise role of p53 in cancer progression and drug resistance.
Role in Drug Development and Screening
HCT116 cells are widely used in the early stages of drug discovery, primarily through high-throughput screening programs. This process involves rapidly testing thousands of compounds to identify those that show anti-cancer activity. Researchers expose the cells to various new chemotherapy drugs, targeted molecular agents, or extracts from natural products to quickly assess a compound’s efficacy and toxicity.
The cells are often used in assays that measure how a compound affects cell viability and metabolism, such as the MTS assay. These experiments help determine a drug’s half-maximal inhibitory concentration (IC50), which is the concentration needed to inhibit 50% of cell growth. By measuring cell proliferation rates, scientists can identify molecules that successfully inhibit the uncontrolled division driven by the mutant KRAS protein.
HCT116 cells are also instrumental in studying how potential drugs induce programmed cell death, or apoptosis. Researchers use this cell line to investigate the mechanisms of drug resistance, for example, by creating acid-adapted HCT116 cells that mimic the acidic environment of a tumor. Testing drugs against these resistant models provides insights into overcoming major challenges in cancer treatment.
Limitations and Future Use
Despite their utility, HCT116 cells grown in a flat, two-dimensional (2D) monolayer culture have significant limitations in representing a complex human tumor. The 2D environment lacks the physical and biochemical complexity of the body, which includes cell-to-cell connections and interaction with the extracellular matrix. This lack of physiological relevance can result in drugs appearing highly effective in a petri dish but failing in clinical trials.
To address these shortcomings, researchers are increasingly moving toward more advanced three-dimensional (3D) culture models, which often incorporate HCT116 cells. These 3D systems, such as spheroids or organoids, allow the cells to grow as compact, three-dimensional structures that better mimic the environment and architecture of a tumor. HCT116 spheroids develop gradients of oxygen and nutrients and show different gene expression profiles compared to their 2D counterparts. The evolution toward 3D modeling ensures that HCT116 cells remain relevant for preclinical testing, offering a more predictive platform for the next generation of cancer therapies.