Multipolar spindles are spindle formations characteristic of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...

cells. Spindle formation is mostly conducted by the aster of the

centrosome In cell biology, the centrosome (Latin centrum 'center' + Greek sōma 'body') (archaically cytocentre) is an organelle that serves as the main microtubule organizing center (MTOC) of the animal cell, as well as a regulator of cell-cycle pro ...

which it forms around itself. In a mitotic cell wherever two asters convene the formation of a spindle occurs.

Mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maint ...

consists of two independent processes: the intra-chromosomal and the extra-chromosomal (formation of spindle) changes both of these being in total coordination of each other. In cancer cells, it has been observed that the formation of the spindles comes before when compared to the

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins ar ...

s. Because the

prophase Prophase () is the first stage of cell division in both mitosis and meiosis. Beginning after interphase, DNA has already been replicated when the cell enters prophase. The main occurrences in prophase are the condensation of the chromatin reti ...

stage is brief, metaphase begins earlier than in normal cells. Chromosomes unable to reach the

metaphase Metaphase ( and ) is a stage of mitosis in the eukaryotic cell cycle in which chromosomes are at their second-most condensed and coiled stage (they are at their most condensed in anaphase). These chromosomes, carrying genetic information, align ...

plate are stranded behind. These chromosomes still have asters attached to them and when met with other asters, form multiple spindles.

Characteristics

Cells with multipolar spindles are characterized by more than two centrosomes, usually four, and sometimes have a second metaphase plate. The multiple centrosomes segregate to opposite ends of the cell and the spindles attach to the chromosomes haphazardly. When

anaphase Anaphase () is the stage of mitosis after the process of metaphase, when replicated chromosomes are split and the newly-copied chromosomes (daughter chromatids) are moved to opposite poles of the cell. Chromosomes also reach their overall max ...

occurs in these cells, the chromosomes are separated abnormally and results in

aneuploidy Aneuploidy is the presence of an abnormal number of chromosomes in a cell, for example a human cell having 45 or 47 chromosomes instead of the usual 46. It does not include a difference of one or more complete sets of chromosomes. A cell with a ...

of both

daughter cell Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there ar ...

s. This can lead to loss of cell viability and chromosomal instability.

Presence in cancer cells

The presence of multipolar spindles in cancer cells is one of many differences from normal cells which can be seen under a

microscope A microscope () is a laboratory instrument used to examine objects that are too small to be seen by the naked eye. Microscopy is the science of investigating small objects and structures using a microscope. Microscopic means being invisibl ...

. Cancer is defined by uncontrolled cell growth and malignant cells can undergo

cell division Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there ar ...

with multipolar spindles because they can group multiple centrosomes into two spindles. These multipolar spindles are often assembled early in

mitosis In cell biology, mitosis () is a part of the cell cycle in which replicated chromosomes are separated into two new nuclei. Cell division by mitosis gives rise to genetically identical cells in which the total number of chromosomes is maint ...

and rarely seen towards the later stages. Research has shown possible causes of formation of multipolar spindles. A possible causes of multipolar spindle formation involve regulation of

protein kinase A protein kinase is a kinase which selectively modifies other proteins by covalently adding phosphates to them (phosphorylation) as opposed to kinases which modify lipids, carbohydrates, or other molecules. Phosphorylation usually results in a fu ...

family known as Aurora kinase. Aurora kinase has two forms which are designated Aurora kinase A and Aurora kinase B. These proteins play a key role in mitosis and are regulated by

phosphorylation In chemistry, phosphorylation is the attachment of a phosphate group to a molecule or an ion. This process and its inverse, dephosphorylation, are common in biology and could be driven by natural selection. Text was copied from this source, ...

and degradation. Deregulation of these proteins can lead to multiple centrosome formation and aneuploidy. In some human cancers, the expression and kinase activity of Aurora kinases have been up-regulated and has been looked into as a possible target for

anti-cancer drug Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs ( chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemoth ...

References

{{Reflist Cell cycle Oncology