The human body relies on countless proteins to carry out its complex functions, and among these is a protein known as CADM1. This protein is present throughout the body and plays a role in how cells interact, maintaining the integrity and communication within tissues.
Understanding CADM1’s Normal Functions
CADM1, or Cell Adhesion Molecule 1, is a protein in the immunoglobulin superfamily, a large group of proteins involved in cell recognition, binding, and adhesion. In healthy cells, CADM1’s primary role is cell-to-cell adhesion. This occurs through homophilic adhesion, where CADM1 on one cell binds to CADM1 on an adjacent cell. This binding is independent of calcium, distinguishing it from other cell adhesion molecules.
This cell-to-cell connection facilitated by CADM1 is important for maintaining the structural organization of tissues throughout the body. It helps cells stick together in an organized manner for proper formation and stability. Beyond physical attachment, CADM1 also transmits signals between cells, coordinating cellular activities and maintaining tissue function.
CADM1’s Role in Cancer
CADM1 functions as a tumor suppressor, meaning it helps prevent cancer development and progression. Its normal activity controls cell growth, inhibits uncontrolled cell division, and promotes programmed cell death (apoptosis). When CADM1 functions properly, it helps maintain the balance of cell proliferation and death, which is important for preventing tumor formation.
However, in many types of cancer, the expression of CADM1 is often reduced or completely lost. This reduction can occur due to promoter methylation, a process that silences the gene producing CADM1. Loss of CADM1 expression has been observed in various cancers, including non-small cell lung cancer, gastric cancer, prostate cancer, ovarian cancer, and colorectal cancer. In non-small cell lung cancer, its methylation has been linked to smoking-related factors.
In these cancers, the decreased or absent CADM1 expression contributes to disease progression by allowing uncontrolled cell growth, increased cell migration, and enhanced invasion and metastasis of tumor cells. Similarly, in melanoma, CADM1 overexpression inhibits cancer cell invasion and migration. In bladder cancer, reduced CADM1 expression has been linked to disease progression and recurrence, while increasing its expression inhibits tumor cell proliferation and invasion. Conversely, in some specific cancers like adult T-cell leukemia/lymphoma (ATLL), CADM1 can be overexpressed, associating with tumor growth and invasion, suggesting a context-dependent role.
CADM1’s Importance in Brain Health
Within the nervous system, CADM1 has distinct functions in brain health. It acts as a synaptic cell adhesion molecule, forming dendritic spines and assembling synapses, the specialized connections between neurons. These connections are important for communication within the brain. CADM1 is also involved in neuron migration during development, guiding their growth and pathfinding to establish proper neural networks.
CADM1 contributes to synaptic plasticity, the brain’s ability to adapt and change synaptic connection strength over time. This adaptability is important for learning and memory. Animal models show CADM1 regulates neuronal plasticity and synapse number in mature neurons, suggesting its continuous role in maintaining brain function.
When CADM1’s function is disrupted, it links to various neurological conditions. Mutations in the CADM1 gene associate with autism spectrum disorder (ASD). Studies in mice lacking CADM1 show reduced synapses and ASD-like behaviors. Imbalances in CADM1 may also contribute to other neurodevelopmental disorders, including schizophrenia and intellectual disabilities, which are often characterized by altered neuronal connections and communication within the brain.