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 DivisionNo Growth

Cell Division + Growth =Proliferation!

Growth with

No Cell Division

Growth withNo Cell Division:

A Differentiated Neuron

Cell Division with No Growth: Early Development

1 mm

spermtadpole 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: 108 cells

The size of a tumor first palpable: 109 cells

The size of tumor at death of patient: 1012 cells

Unregulated Proliferation: Cancer!

A Typical Solid Tumor…Needs to Grow

Budding Yeast Saccharomyces cerevisiae

Permissive (low) temperature Restrictive (high) temperature

Cdc Mutants Affect the Cell Cycle, Not Growth

Mammalian Cells Growing in Cell Culture

Amino Acids Vitamins Salts Miscellaneous

Arginine

Cystine

Glutamine

Histidine

Isoleucine

Leucine

Lysine

Methionine

Phenylalanine

Threonine

Tryptophan

Tyrosine

Valine

Biotin

Choline

Folate

Nicotinamide

Pantothenate

Pyridoxal

Thiamine

Riboflavin

NaCl

KCl

NaH2PO4

NaHCO3

CaCl2

MgCl2

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 21 fibroblast (Syrian hamster)

MDCK epithelial cell (dog)

HeLa epithelial cell (human)

PtK 1 epithelial cell (rat kangaroo)

L 6 myoblast (rat)

PC 12 chromaffin cell (rat)

SP 2 plasma 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 ProliferationGrowth + Cell Cycle Progression: But How?

Modified from The Biology of Cancer (© Garland Science 2007)

Growth Factors Induce Gene Expression

Growth Factors Induce Oncogene ExpressionAs 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 cyclins2 A-type cyclins3 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 TRANSLOCATIONT(11;11)(Q13;P15) THAT INVOLVES CCND1 AND THE PARATHYROID HORMONE (PTH) ENHANCER (PRAD1 ONCOGENE).

Translocations Cause One Geneto be Controlled by Another

Figure 8.4 The Biology of Cancer (© Garland Science 2007)

Cell Cycle CheckpointsThe Guardian Mechanisms of

the Genome

THEY ARE DISRUPTED IN CANCER!

Entering Mitosis Before the Completion of S phase isBad 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, 433 - 439 (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 22 2012 R966 - R980

Weaver BA, Cleveland DW. Does aneuploidy cause cancer? Curr Opin Cell Biol. 2006 Dec;18(6):658-667.

Mitotic Defects Leading to Aneuploidy

The Spindle Assembly Checkpoint Prevents Anaphase Errors

Lara-Gonzalez et al. Current Biology Volume 22, Issue 22 2012 R966 - R980

Very robust:e.g. A single unattachedkinteochore will activate the SAC

Weaver BA, Cleveland DW. Does aneuploidy cause cancer? Curr Opin Cell Biol. 2006 Dec;18(6):658-667.

Spindle Assembly Checkpoint Genes that are Mutated and/or Misregulated in Human Cancers