Growth Factors act Prior to the Restriction Point Growth Factors Induce Cell Proliferation Modified from The Biology of Cancer (© Garland Science 2007)

Let’s think about the Difference Between Growth and Cell Division Cell Division No Growth Cell Division + Growth = Proliferation! Growth with No Cell Division

Growth with No Cell Division: A Differentiated Neuron

Cell Division with No Growth: Early Development 1 mm sperm tadpole feeds, grows and bcecomes an adult frog OOCYTE GROWS WITHOUT DIVIDING (MONTHS) FERTILIZATION FERTILIZED EGG DIVIDES WITHOUT GROWING (HOURS)

The size of a tumor first detectable by X-ray:10 8 cells The size of a tumor first palpable:10 9 cells The size of tumor at death of patient:10 12 cells Unregulated Proliferation: Cancer! A Typical Solid Tumor…Needs to Grow

Budding Yeast Saccharomyces cerevisiae

Permissive (low) temperatureRestrictive (high) temperature Cdc Mutants Affect the Cell Cycle, Not Growth

Mammalian Cells Growing in Cell Culture Amino AcidsVitaminsSaltsMiscellaneous Arginine Cystine Glutamine Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Tyrosine Valine Biotin Choline Folate Nicotinamide Pantothenate Pyridoxal Thiamine Riboflavin NaCl KCl NaH 2 PO 4 NaHCO 3 CaCl 2 MgCl 2 Glucose Penicillin Streptomycin Phenol red Whole serum Specific growth factors 1961Hayflick and Moorhead Showed that human fibroblasts die after a finite number of divisions in culture. This is called “The Hayflick Limit”

Some Commonly Used Cell Lines Cell Line*Cell Type and Origin 3T 3 fibroblast (mouse) BHK 21fibroblast (Syrian hamster) MDCKepithelial cell (dog) HeLaepithelial cell (human) PtK 1epithelial cell (rat kangaroo) L 6myoblast (rat) PC 12chromaffin cell (rat) SP 2plasma cell (mouse) *Many of these cell lines were derived from tumors. All of them are capable of indefinite replication in culture and express at least some of the differentiated properties of their cell of origin. BHK 21 cells, HeLa cells, and SP 2 cells are capable of growth in suspension; the other cell lines require a solid culture substratum in order to multiply.

Growth Factors act Prior to the Restriction Point Growth Factors Induce Cell Proliferation Growth + Cell Cycle Progression: But How? Modified from The Biology of Cancer (© Garland Science 2007)

Growth Factors Induce Gene Expression

Growth Factors Induce Oncogene Expression As Early Response Genes

Growth Factors Induce Cyclin D Expression They also act by inhibiting CKIs We actually have: 3 D-type cyclins 2 E-type cyclins 2 A-type cyclins 3 B-type cyclins And the D-type cyclins respond to different cues

Growth Factors Get the Cell Cycle Going

Growth Factors Induce Cyclin D Expression ONCOGENES!!!! So, is Cyclin D an oncogene?

YES! Cyclin D is also an Oncogene Disease: INVOLVED IN B-LYMPHOCYTIC MALIGNANCY (PARTICULARLY MANTLE-CELL LYMPHOMA) BY A CHROMOSOMAL TRANSLOCATION T(11;14)(Q13;Q32) THAT INVOLVES CCND1 AND IMMUNOGLOBULIN GENE REGIONS (BCL1 ONCOGENE). Disease: INVOLVED IN A SUBSET OF PARATHYROID ADENOMAS BY A CHROMOSOMAL TRANSLOCATION T(11;11)(Q13;P15) THAT INVOLVES CCND1 AND THE PARATHYROID HORMONE (PTH) ENHANCER (PRAD1 ONCOGENE).

Translocations Cause One Gene to be Controlled by Another

Figure 8.4 The Biology of Cancer (© Garland Science 2007) Cell Cycle Checkpoints The Guardian Mechanisms of the Genome THEY ARE DISRUPTED IN CANCER!

Entering Mitosis Before the Completion of S phase is Bad for Chromosomes and Therefore Bad for Cells

Caffeine Abrogates the Replication Checkpoint Molecular Biology of the Cell © 1994 by Bruce Alberts et al The point: the combination of cellular stress and an inactive Checkpoint is very detrimental to cells.

How do Cell Cycle Checkpoints Work? Zhou and Elledge Nature 408, (2000)

Remember Inhibitory CDK Phosphorylation? is a kinase is a phosphatase

G2 Arrest Induced by DNA Damage Signal Sensor Transducer Effector Nucleus Cytoplasm

Remember Kinetochore/Microtubule Attachments During Metaphase? Kinetochore Microtubule

Remember the Metaphase to Anaphase Transition? Lara-Gonzalez et al. Current Biology Volume 22, Issue R966 - R980

Weaver BA, Cleveland DW. Does aneuploidy cause cancer? Curr Opin Cell Biol Dec;18(6): Mitotic Defects Leading to Aneuploidy

The Spindle Assembly Checkpoint Prevents Anaphase Errors Lara-Gonzalez et al. Current Biology Volume 22, Issue R966 - R980 Very robust: e.g. A single unattached kinteochore will activate the SAC

Weaver BA, Cleveland DW. Does aneuploidy cause cancer? Curr Opin Cell Biol Dec;18(6): Spindle Assembly Checkpoint Genes that are Mutated and/or Misregulated in Human Cancers