Introduction in Oncology

8/7/2019 Introduction in Oncology

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CONTENTS:

Overview of the normal cell cycle Control of the growth and

multiplication of cells

Cellular Adaptation

ONCOLOGY

Definition

Fallacies

5 basic properties of cancer cells How cancer begins

Factors contributing to cancer cells

formation



Overview of the Normal Cell Cycle

� The normal cell growth and cycle several phases:

± Interphase: Contains 3 subphases ±

cellular production of RNA and proteinssynthesis of DNA and proteins and newchromosomes appear

RNA synthesis

± Mitosis



� Mitosis is divided into 4 stages:

± Prophase-

the chromatin condenses to form visible

chromosomes

Each chromosome consist of 2 chromatids joined

at the centromere

The centrioles moves to the opposite ends of thecell.

The nucleolus and nuclear envelope appear

± Metaphase

Chromosomes align at the center of the cell in

association with the spindle fibers.



� Anaphase

± Cromatids separate to form 2 sets of identicalchromosomes

± Chromosomes, assisted by spindle fibers,

moves towards the centrioles of the end of

the cell

� Telophase

± The chromosomes disperse

± The nuclei and nucleoli form± Cytoplasm begin to divide and form 2 cells.

new interphase begins





How the growth and multiplication of

cells is usually controlled?

Repair of daily wear and tear

Everyday, we loose many millions of cell in the

diff parts of our body. The cells that are lostare being replaced daily by new cell growthand multiplication.

Thats how the WEAR AND TEAR takes its toll- thereis always an appropriate supply of new cells ready

to replace damaged one. . .



Response to injuryIn an event of an injury or any trauma, cell

growth has to accelerate in order to repair the damage and to produce what werecognize as healing.

Control of GrowthEx. There is a gap in the tissues created by an

incision

The growing skin cells have to fill up the gapbefore they stop growing. At this point, theaccelerated growth slows down to the

normal (contact inhibition).



Cellular Adaptation

Hypertrophy

increase in the normal size ofcells

Atrophy

Shrinkage of cell size

HyperplasiaIncrease in the number of normalcells



Metaplasia

Conversion from the normal pattern of

differentiation of 1 type of cellinto another type of cell not normal

for that tissue.

Dysplasia Alteration in shape, size, appearance

and distribution of cells.

Anaplasia

Disorganized, irregular cells that

have no structure and have loss of

differentiation; the result is almost

always malignant.



ONCOLOGY

study of cancer: the branch of

medicine that deals with the studyand treatment of malignant tumors.





Cancer as««

� A single disease?

� An Alien invasion??!!� A mystery?

� A psychologicalproblem???

FALLACY!!!



= (medical term: malignant neoplasm) is a classof diseases in which a group of cells display:

uncontrolled growth (division beyond the normallimits),

invasion (intrusion on and destruction of adjacent tissues),

and sometimes metastasis (spread to other locations in the body via lymph or blood).



5 basic properties of cancer cells:

1.

CA cells go on

growing and multiplying when they should not.

CA cells

2.

Tissue boundary

CA cells are

capable of crossing the normal boundaries of the

tissue they start in.

CA cells Cells of neighboring

tissue



3.

CA cells can get

into the

bloodstream or

any other

channels or route.

CA cells

4.

CA cells can get

can establish secondary tumors

at distant areas.

5. Some Cancer may produce

substances that interfere withthe control of various body fnx,

and may affect nerves muscles,

salt regulation and other fnx.



Cancers are often referred to by terms that contain

a prefix related to the cell type in which the cancer

originated and a suffix such as -sarcoma, -

carcinoma, or just -oma. Common prefixes include:

� Adeno- = gland

� Chondro- = cartilage

� Erythro- = red bloodcell

� Hemangio- = bloodvessels

� Hepato- = liver

� Lipo- = fat

� Lympho- = white

blood cell

� Melano- = pigmentcell

� Myelo- = bonemarrow

� Myo- = muscle

� Osteo- = bone

� Uro- = bladder

� Retino- = eye

� Neuro- = brain



Cancer types can be grouped into broader

categories. The main categories of cancer

include:

� Carcinoma - cancer that begins in the skin or in tissuesthat line or cover internal organs.

� Sarcoma - cancer that begins in bone, cartilage, fat,muscle, blood vessels, or other connective or supportivetissue.

� Leukemia - cancer that starts in blood-forming tissuesuch as the bone marrow and causes large numbers of abnormal blood cells to be produced and enter theblood.

� Lymphoma and myeloma - cancers that begin in thecells of the immune system.

� Central nervous system cancers - cancers that beginin the tissues of the brain and spinal cord.





In a cancerous cell, permanent genealterations, or mutations, cause the cell to

malfunction. For a cell to become

cancerous, usually three to seven differentmutations must occur in a single cell.

These genetic mutations may take many

years to accumulate, but the convergence

of mutations enables the cell to becomecancerous.



T he body is made up of many types of cells. T hese

cells grow and divide in a controlled way to produce

more cells as they are needed to keep the body

healthy. When cells become old or damaged, they die

and are replaced with new cells.However, sometimes this orderly process goes wrong.

T he genetic material (DNA) of a cell can become

damaged or changed, producing mutations that affect

normal cell growth and division. When this happens,cells do not die when they should and new cells form

when the body does not need them. T he extra cells

may form a mass of tissue called a tumor.

� Cells are the building blocks of living things. Cancer grows out of normal cells in the body. Normal cellsmultiply when the body needs them, and die when the

body doesn't need them. Cancer appears to occur whenthe growth of cells in the body is out of control and cellsdivide too quickly. It can also occur when cells ³forget´how to die.

� Cancer begins in genes, bits of biochemical instructionscomposed of individual segments of the long, coiledmolecule deoxyribonucleic acid (DNA). Genes containthe instructions to make proteins, molecular laborers thatserve as building blocks of cells, control chemicalreactions, or transport materials to and from cells. The

proteins produced in a human cell determine the functionof each cell, and ultimately, the function of the entirebody.



A. Safety Systems Fail

While each human cell performs its own specializedfunction, it also exerts influence on the cells around it.Cells communicate with one another via receptors,protein molecules on the cell surface. A cell releases

chemical messages, which fit into the surfacereceptors of cells nearby, much as a key fits into alock. A cell may instruct other cells in itsneighborhood to divide, for example, by releasing agrowth-promoting signal, or growth factor . Thegrowth factor binds to receptors on adjacent cells,activating a message within each individual cell. Thismessage travels to the nucleus, where a cells genesare located.



1. Proto-oncogenes become oncogenes

Growth Factor Growth Factor Cell NucleusCell Nucleus Proto

oncogenes

Proto

oncogenes

These genesproduce

proteins that

stimulate the

cell to divide.

IN CANCEROUS CELLS:IN CANCEROUS CELLS:MutationsMutations

Malfnx of P.O.Malfnx of P.O.Oncogenes

A gene that

instructsthe cell to grow

and divide

repeatedly

without

stimulation from

neighboring cells

Cell

Division



2. Tumor Suppressor Genes Stop Working

CA

Neighboring cellsCome to the rescueNeighboring cellsCome to the rescueGrowth inhibitor Growth inhibitor

Malfnx

Cell

Malfnx

Cell

MutationsMutations

NOT YETNOT YET



Malfnx

Cell

Malfnx

CellGrowth inhibitor Growth inhibitor

Tumor

suppressor

genes

Tumor

suppressor

genes

NUCLEUSNUCLEUS

Continuation«Continuation«



3. Cell Cycle Clock Malfunctions

The cell nucleus contains a collection of interactingproteins that control cell division. Sometimes calledthe cell cycle clock, this group of proteins interpretsincoming messages at several checkpoints in the cell

division cycle. At these checkpoints, the clockevaluates the health of the cell. If conditions areright, the clock activates certain proto-oncogenes,which produce proteins that trigger the cell to enter

the next stage of the cell cycle. If conditions are notright, certain tumor suppressor genes produceproteins that prevent the cell from proceeding withcell division.



Cell cycle

clock

DNA

damage

p53

A tumor suppressorgene that prevents

the cell fromreproducing until thedamage is repaired.

Instructs the cell

to undergoapoptosis

Instructs the cell

to undergoapoptosis



In a cancerous cell, one or moremutations prevent these genes from doingtheir jobs. When mutated, p53 allows acell to continue to divide, even withdamaged DNA. This can lead to additionalmutations in proto-oncogenes or tumor

suppressor genes. In some cases,mutations occur in genes that produceproteins to repair damaged DNA. Suchmutations can lead to yet othermutations because the faulty DNA cannotduplicate properly during cell division.





4. Cells Achieve Immortality

A normal cell has a life span of about 40 celldivisions. This life span is controlled inpart by telomeres, protective segments at theends of the cells DNA. Telomeres shorten witheach cell division until they can no longerprotect the DNA. At this point cell division

severely damages the DNA, ultimately killingthe cell. This normal process ensures thatolder cells, which may have accumulatedmutations, no longer reproduce.

Cancer cells escape this protective mechanismby producing a protein called telomerase.Telomerase extends the length of telomeresindefinitely, rendering the cells immortal andcapable of never-ending cell division.



B. Cells break free and spread

� Normal cells adhere to each other

and to a fibrous meshwork called

an extracellular matrix. This matrix

exists throughout all tissues and

provides the structural support on

which cells grow and form organs

and other complex tissues. While a

normal cell will often die if it cannot

adhere to an extracellular matrix,cancer cells survive without this

matrix.



1. Tumor Forms A tumor is a mass of cells not dependent

upon an extracellular matrix. Thesecells can grow on top of each other,creating a mass of abnormal cells. Oftena tumor develops its own network of tinyblood vessels to supply itself with

nutrient-rich blood, a process calledangiogenesis.

There are two general types of tumors.Benign tumors do not invade other

tissues and are limited to one site,making surgical removal possible and theodds for a full recovery excellent. Somebenign tumors are quite harmless and arenot surgically removed unless they are

unsightly or uncomfortable.

2. Tumor Spread2. Tumor Spread



How 1 step can lead you astray?

(Factors) Age

Gender

Geographic Location

Genetics

Immune Disturbance

Chemical Agents

Race Smoking

Alcohol

Diet



The end«..

Reported by: P. G. De Juan BSN4A

SACR Batch 2011

Introduction in Oncology

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