S100A6, also known as Calcyclin, is a protein that belongs to the larger S100 family of proteins. This family is characterized by its members’ ability to bind to calcium. Found in the cytoplasm and sometimes the nucleus of many cell types, S100 proteins are involved in a variety of cellular activities.
The Normal Biological Role of S100A6
The S100A6 protein functions as a calcium sensor within cells. This means its shape and activity change when it binds to calcium ions. This binding ability allows it to interact with other proteins and influence their functions, effectively translating calcium signals into cellular responses.
This protein is involved in several routine cellular processes, including the regulation of the cell cycle. S100A6’s role can be compared to a traffic light, helping to control the timing of cell division. It participates in this process by interacting with other proteins that are part of the machinery that drives a cell from one phase of its life to the next.
S100A6 also participates in cell growth and differentiation, which is the process by which a cell changes from one cell type to another, more specialized type. The protein’s functions extend to influencing the cell’s internal scaffolding, known as the cytoskeleton, and helping the cell respond to various types of stress.
Connection to Cancer
The behavior and quantity of S100A6 can change significantly in a cancerous environment. Many types of cancer show an overexpression of this protein, meaning it is present in much higher amounts than in healthy cells. This increased presence is not just a byproduct of the disease but is understood to contribute to the cancer’s progression. These elevated levels have been observed in a range of cancers, including:
- Pancreatic cancer
- Colorectal cancer
- Lung cancer
- Gastric cancer
This overexpression is linked to several characteristics of cancer. It can promote the growth of tumors by affecting the cell cycle controls that normally prevent excessive division. The protein also contributes to invasion, the process where cancer cells move into surrounding healthy tissues, and metastasis, the spread of cancer cells from the primary tumor to other parts of the body.
In pancreatic cancer, higher levels of S100A6 are often considered a marker for the disease. For gastric cancer, the protein’s expression is sometimes influenced by epigenetic changes, which are modifications that alter gene activity without changing the DNA sequence itself. In some forms of lung cancer, S100A6 has been found to be underexpressed in small cell lung cancers compared to non-small cell types. The protein’s connection to melanoma has also been noted, with altered expression and chromosomal rearrangements of its gene implicated in this type of skin cancer.
Association with Non-Cancerous Diseases
The influence of S100A6 extends beyond cancer to a variety of other health conditions. In neurodegenerative diseases, such as Alzheimer’s, the protein’s role is an area of ongoing research. Its presence in the brain and its ability to bind calcium suggest it is involved in the cellular stress pathways that are characteristic of these disorders.
Cardiovascular conditions are another area where S100A6 is implicated. For instance, in atherosclerosis, a condition where plaque builds up inside the arteries, S100A6 is involved. Serum levels of S100A6 have been found to be associated with acute coronary syndrome, and the amount of the protein in both the blood and heart muscle appears to relate to the size of a heart attack.
The protein is also connected to inflammatory skin disorders. In conditions like psoriasis, which is characterized by the rapid buildup of skin cells, the regulatory functions of S100A6 in cell growth and differentiation are involved. Its presence in skin cells and its response to inflammatory signals indicate its contribution to the disease process.
S100A6 as a Clinical Biomarker
S100A6 serves as a clinical biomarker, which is a measurable substance that provides information about a disease. The level of S100A6 in the body can be an indicator of certain health issues.
Clinicians can detect the amount of S100A6 in a few different ways. One common method is through a blood test, which measures the level of the protein circulating in the bloodstream. Another method involves examining a tissue sample, often a biopsy, through a technique called immunohistochemistry. This technique uses antibodies to detect the presence and location of the protein within the cells of the tissue sample.
Elevated levels of S100A6 can have different implications depending on the clinical context. In some cancers, higher levels may be associated with the presence of the disease or provide information about the patient’s prognosis.