Cell proliferation is the process by whicha cell grows and divides to produce two daughter cells.[1][2][3][4] Cell proliferation leads to anexponential increase in cell number and is therefore a rapid mechanism oftissue growth. Cell proliferation requires bothcell growth andcell division to occur at the same time, such that the average size of cells remains constant in the population. Cell division can occur without cell growth, producing many progressively smaller cells (as incleavage of the zygote), while cell growth can occur without cell division to produce a single larger cell (as in growth ofneurons). Thus, cell proliferation is not synonymous with either cell growth or cell division, despite these terms sometimes being used interchangeably.[5]
Stem cells undergo cell proliferation to produce proliferating "transit amplifying" daughter cells that laterdifferentiate to constructtissues during normaldevelopment and tissue growth, duringtissue regeneration afterdamage, or incancer.
The total number of cells in a population is determined by the rate of cell proliferation minus the rate ofcell death.
Cell size depends on both cell growth and cell division, with a disproportionate increase in the rate of cell growth leading to production of larger cells and a disproportionate increase in the rate of cell division leading to production of many smaller cells. Cell proliferation typically involves balanced cell growth and cell division rates that maintain a roughly constant cell size in the exponentially proliferating population of cells. Cell proliferation occurs by combining cell growth with regular "G1-S-G2-M"cell cycles to produce manydiploid cell progeny.
In single-celled organisms, cell proliferation is largely responsive to the availability ofnutrients in the environment (or laboratorygrowth medium).
Inmulticellular organisms, the process of cell proliferation is tightly controlled bygene regulatorynetworks encoded in thegenome and executed mainly bytranscription factors including those regulated bysignal transduction pathways elicited bygrowth factors duringcell–cell communication indevelopment. Recently it has been also demonstrated that cellular bicarbonate metabolism, which is responsible for cell proliferation, can be regulated by mTORC1 signaling.[6][4] In addition, intake ofnutrients in animals can induce circulating hormones of theInsulin/IGF-1 family, which are also considered growth factors, and that function to promote cell proliferation in cells throughout the body that are capable of doing so.
Uncontrolled cell proliferation, leading to an increased proliferation rate, or a failure of cells to arrest their proliferation at the normal time, is a cause ofcancer.
