Synaptophysin: neuro-endocrine marker in breast tumors
Synaptophysin is a protein which is present in nearly all neurons in the brain and spinal cord. Its exact function is not known but it is involved in the process of synaptic transmission. Synaptophysin is a38-kDa integral membrane glycoprotein of the presynaptic vesicles in virtually all and neuroendocrine cells. As such, it is used as a marker of neuroendocrine differentiation in tumors, including breast cancer tumors.
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Synaptophysin can be detected through immunochemical staining, and it’s presence in a breast cancer tumor would indicate the prominent involvement of neuro-endocrine cells, and if significant quantities were found, the lesion might be identified as neuro-endocrine breast cancer.
Rate and prognostic significance of synaptophysin differentiation in breast tumors
Neuro-endocrine differentiation in a breast cancer tumor is usually determined a finding of high levels of either synaptophysin, chromogranin A, or both. Primary neuro-endocrine breast cancer is very rare, accounting for less than 0.1% of all breast carcinomas.
But, a certain amount of neuro-endocrine cell involvement in other, generic breast cancers is also not uncommon. The prognostic effect of neuro-endocrine cell involvement is very inconclusive. Recent studies on a variety of breast cancers have shown a positive detection rate for synaptophysin expression of about 5% to 10%.
It has been found that neuro-endocrine differentiation in breast cancers, determined through the positive expression of synaptophysin and chromogramin A, does not carry any special prognostic significance for the course of the disease at all.
Synaptophysin is not associated with breast cancer aggressiveness
Furthermore, synaptophysin appears to be commonly expressed in a whole range of neuro-endocrine breast neoplasms without any particular correlation with other neuro-endocrine markers, such as serotonin and neuropeptides.
The expression of synaptophysin also does not appear to be related to epithelial or cytoskeletal characteristics, or with the clinical aggressiveness of the breast cancer.
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