Mitosis and Cytokinesis Lecture 1 The cell cycle

Mitosis and Cytokinesis Animal Cell Telophase/Cytokinesis

Mitosis and Cytokinesis Plant Cell Telophase/Cytokinesis

Mitosis and Cytokinesis Cells divide at different rates. • The rate of cell division

Mitosis and Cytokinesis • G 1 checkpoint: Cell will not enter into S phase

Mitosis and Cytokinesis The neurons not divided…………. . Going to cancer………… Believable…………

Mitosis and Cytokinesis Adult human neurons have insignificant capacity to divide. But at the

Mitosis and Cytokinesis Types of Tumors Primary brain tumors Secondary brain tumor • •

Mitosis and Cytokinesis Secondary brain tumors • Non-brain origin = Cancer metastasis – Most

Mitosis and Cytokinesis Primary brain tumors • Meningioma (35%) • Glioma (30%) – Astrocytoma

Mitosis and Cytokinesis Hyaluronic acid and cancer. -In some cancers, hyaluronic acid levels correlate

Mitosis and Cytokinesis By producing anti-adhesive HA, HAS can allow tumor cells to release

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Mitosis and Cytokinesis Lecture 1 The cell cycle Dr. Obeid Shanab

Mitosis and Cytokinesis

Mitosis and Cytokinesis Animal Cell Telophase/Cytokinesis

Mitosis and Cytokinesis Plant Cell Telophase/Cytokinesis

Mitosis and Cytokinesis Cells divide at different rates. • The rate of cell division varies with the need for those types of cells. • Some cells are unlikely to divide (G 0).

Mitosis and Cytokinesis • G 1 checkpoint: Cell will not enter into S phase unless appropriate signal is received – Many cells in adult mammals are in G 0 and thus do not divide (e. g. , nerve) • If not, enters non-dividing “G 0” phase

Mitosis and Cytokinesis The neurons not divided…………. . Going to cancer………… Believable…………

Mitosis and Cytokinesis Adult human neurons have insignificant capacity to divide. But at the same time, we must understand that apart from neurons, there are several other types of supporting cells, including various glial cells, blood vessel cells, pitutary gland cells, meningeal cells and those of the nerve sheaths and skull, which retain capability to replicate in adult mammalian brain, thus almost all tumors in adult people arise from these lineages. Only a fraction of brain tumors are of neuronal origin, usually arising in embryonic or foetal stages of the children or occasionally in neonatal life, when the neurons continue to divide at low rate. However, about 10 to 15 % of the brain neoplasms are metastases from primary tumors in other body sites than brain.

Mitosis and Cytokinesis Types of Tumors Primary brain tumors Secondary brain tumor • • Brain tissue origin Mostly in childhood Neuronal origin Not originated from metastasis Non-brain origin Mostly in adulthood Non neuronal origin From metastasis

Mitosis and Cytokinesis Secondary brain tumors • Non-brain origin = Cancer metastasis – Most common – 25 -45% of cancer patients - Lung: >50% of all; most common in men - Breast: Most common in women - Melanoma: Highest propensity for brain · 50% of melanoma patients develop brain metastasis; Multiple - Renal Cell - Colorectal • Any primary can metastasize to the brain

Mitosis and Cytokinesis Primary brain tumors • Meningioma (35%) • Glioma (30%) – Astrocytoma - Glioblastoma – Oligodendroglioma – Oligoastrocytoma – Ependymoma • Pituitary Adenoma (13%) – Within skull – Beneath brain Skull Meninges Brain Neuron Astrocyte Oligodendrocyte Ependyma

Mitosis and Cytokinesis Hyaluronic acid and cancer. -In some cancers, hyaluronic acid levels correlate well with malignancy and poor prognosis. Hyaluronic acid is, thus, often used as a tumor marker for prostate and breast cancer. - It also be used to monitor the progression of the disease Hyaluronic acid synthase (HAS) play roles in all of the stages of cancer metastasis. -During the processes of intravasation or extravasation, the interaction of HAS produced HA with receptors such as CD 44 promote the cell changes that allow for the cancer cells to infiltrate the vascular or lymphatic systems. - HA produced by HAS protects the cancer cell from physical damage.

Mitosis and Cytokinesis By producing anti-adhesive HA, HAS can allow tumor cells to release from the primary tumor mass, and if HA associates with receptors such as CD 44, can promote epithelial-mesenchymal transition (EMT is a process by which epithelial cells lose their cell polarity and cell-cell adhesion, and gain migratory and invasive properties to become mesenchymal stem cells ) of the cancer cells.

Mitosis and Cytokinesis