molecular biology of the cell - nhri · figure 19-1 molecular biology of the cell (© garland...

徐沺 Tien Hsu, PhD

Dean, College of Health Sciences and Technology

University Chair Professor

Department of Biomedical Sciences and Engineering

National Central University

[email protected]

Tel: 03-4256534

TUMOR MICROENVIRONMENT

Cancer is not a localized lump of cells; it's a

systemic disease.

癌症不是在定點位置的一團細胞，而是一個系統化的疾病。

Classic view of cancer:

Mutations in a cell —> uncontrolled proliferation —> Cancer

Systems biology of cancer:

Cellular transformation (genetic or epigenetic)

Systems changes in cell (metabolism,

global gene expression change)

Bidirectional interaction with

microenvironment:

angiogenesis, extracellular

matrix remodeling

Induction of myeloid response,

mobilization of immune responses

Cancer

LESSON I:

EPITHELIUM

Epithelium

Cancer and fibroblasts

上皮組織

E-cadherin

Lgl

Injured kidney, basement

membrane break down

BM

Epithelial tissues constitute most of the organs and skin

Three basic shapes of epithelial cells,

either single layer or stratified.

kidney tubules

lung alveoli (A)

villi of the

small

intestine

Columnarrespiratory

epithelium

esophagus

Simple cuboidal

Simple columnar

Simple

squamous

A: epithelium; B: cilia; C: nuclei

A: cells; B: nuclei

Stratified

squamous

A: epithelium; B: top layer flat

A: cells; B: nuclei; C: cell membrane

（立方型）

（柱狀）（鱗狀）

80% of the human solid tumors originate from

epithelial tissues.

The structure of the intestinal epithelia

An intestine villus （絨毛） is composed of epithelium

So the epithelium forms

a tight barrier that

separates the lumen （管腔） and the underlying

tissue, yet allows for

bidirectional exchange

of materials.

Figure 19-1 Molecular Biology of the Cell (© Garland Science 2008)

The defining characteristics of an epithelium are

(i) asymmetrical distribution of subcellular components

(ii) cell-cell adhesion

(iii) attachment to substratum (matrix)

(細胞外基質蛋白)

（細胞骨架纖維）


Types of cellular junctions (細胞連結）

粘著連接adherens junction

desmosome

間隙連接gap junction

緊密連接tight junction

遮檔型連接錨定型連接渠道型連接訊號轉播連接

Synaptic junction

filament

Table 19-1 Molecular Biology of the Cell (© Garland Science 2008)


（頂側）

（基底側）


Anchoring junctions

Table 19-2 Molecular Biology of the Cell (© Garland Science 2008)

Figure 19-9a Molecular Biology of the Cell (© Garland Science 2008)

Structure of E-cadherin

Homophilic adhesion

Figure 19-9c Molecular Biology of the Cell (© Garland Science 2008)

An adherens junction is composed of a cluster of E-cadherins


(e.g. a-catenin)

E-cadherin is connected to actin cytoskeleton via interacting

proteins.

b-catenin


Desmosomes (Greek, desmos = band)

Three types of cytoskeletons:

Microfilaments: actin （肌動蛋白）Intermediate filaments: cytokeratins （細胞角蛋白）Microtubules: tubulins （微管蛋白）

Figure 19-17b Molecular Biology of the Cell (© Garland Science 2008)

Desmosomes

Figure 19-17c, d Molecular Biology of the Cell (© Garland Science 2008)

Desmosomes


integrin a6b4 to

basement

membrane


Tight junctions

E-cadherin

(Claudin 2, 4

can allow ions

through)

Functions of tight junctions


Dye on the apical side

Dye on the basal side

Sawada et al. Tight junctions and human diseases. Med Electron Microsc. 2003 Sep;36(3):147-56.


actin filaments

Gap junctions

Gap junctions are a specialized intercellular connection between a multitude of animal

cell-types. They directly connect the cytoplasm of two cells, which allows various

molecules, ions and electrical impulses to directly pass through a regulated gate

between cells.

A gap junction is composed of six identical connexin proteins. Each of these

six units is a single polypeptide which passes the membrane four times.

Gap junction electron microscopyGap junction freeze-fracture

electron microscopy

Figure 3. Validation of the dye diffusion assay performed with the flattened cochlear preparation.

Chang Q, Tang W, Ahmad S, Zhou B, Lin X (2008) Gap Junction Mediated Intercellular Metabolite Transfer in the Cochlea Is

Compromised in Connexin30 Null Mice. PLoS ONE 3(12): e4088. doi:10.1371/journal.pone.0004088

http://journals.plos.org/plosone/article?id=info:doi/10.1371/journal.pone.0004088

耳蝸細胞


Figure 4. Time-lapse recordings of intercellular dye transfer in WT and Cx30 null mice after fluorescent dye

was injected into a single outer sulcus cell.

Chang Q, Tang W, Ahmad S, Zhou B, Lin X (2008) Gap Junction Mediated Intercellular Metabolite Transfer in the Cochlea Is

Compromised in Connexin30 Null Mice. PLoS ONE 3(12): e4088. doi:10.1371/journal.pone.0004088



Epithelial organoid (acinus) formation assay:

Single cell in 3-

dimensional matrix (2%

Matrigel)

Proliferation

epithelialization

Lumen formation

Acinus

How is epithelial polarity established?

Some mutant tubule cells fail to form epithelial organoids (acini) in 3D matrix

F-actin E-cadherin Merge+DNA

Wild-type

lumen

Mutant

20 mm


How is epithelial polarity established?

RAC is a RAS-like molecule that organizes the orientation of actin filaments.

Attachment to basement membrane

Localization of Par3/Par6/aPKC complex to apical surface

Recruitment of Rac, Cdc42 (actin filament regulator)

Recruitment of Crumbs/Discs-lost (Patj)/Stardust complex

Recruitment of Scribble/Discs large/Lethal giant larvae (Lgl)

complex

Establishment of adherens junctions


Apical complexes are evolutionarily conserved

Without these "apical complexes", adherens junctions cannot form

properly, and epithelium breaks down.

This explains why some of these proteins are known tumor

suppressors :

Breakdown of epithelial structure leads to a cellular event

called epithelial-to-mesenchymal transition (EMT). EMT is

believed to be the first step of tumor malignancy, and has been

shown to be a characteristic of cancer stem cells.

The ultimate phenotype of EMT is loss of adherens

junction (E-cadherin). Many EMT-inducing factors work via

blocking E-cadherin localization or reducing E-cadherin

expression.Dlg: breast cancer, colon cancer

Scrib: cervical cancer

Lgl: reduced or loss of expression found in 75% (n=94) of colon

cancer samples.

Domain architecture of the Dlg complex proteins. This architecture

is conserved from worms to vertebrates. (PDZ) PSD-95, ZO-1, Dlg

homology domain; (SH3) Src homology 3 domain; (GUK)

guanylate kinase-like domain; (LRR) leucine-rich repeats; (WD40)

tryptophan–aspartic acid 40 residue repeat; (S) serine residues that

are conserved phosphorylation sites targeted by aPKC.

(hDlg)

(SCRIB)

(Hugl 1, 2)

Disruption of tight junctions (ZO-1 mutation) can also lead to tumor formation.

w.t. lgl-/-

w.t. lgl-/-

Basal epidermal cells in vivo


(Basement membrane)


(層粘連蛋白)

(纖維連接蛋白)

(玻尿酸）


collagen

Laminin


Interaction between cell and basement membrane


Breakdown of basement membrane by proteases (matrix

metalloproteases) can cause disintegration of epithelium.

Hemidesmosome electron microscopy

Intestine

E-cadherin stain

Uterine

E-cadherin stain+DNA stain

LESSON II:

TUMOR STROMA

What is Stroma?

• Stroma is originally a Greek word meaning

“layer, bed, bed covering”.

• Used in biology, it refers to the connective,

supportive framework of a biological cell,

tissue, or organ. The stroma in animal tissue

is contrasted with the parenchyma.

Tissue architecture of prostate

molecular biology of the cell - nhri · figure 19-1 molecular biology of the cell (© garland...

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