bmb 460 final exam - paper 3

tophat and pptx questions

what are mesenchymal cells?

small, spindle-shaped cells with large nuclei, prominent nucleoli, and fine chromatin

what type of cell (multipotent, pluripotent, unipotent, totipotent) are mesenchymal stem cells?

multipotent - differentiate as progenitor cells for all types of ct, such as fibroblasts and osteoblasts

what do mesenchymal cells produce?

extracellular matrix (ECM) that consists of ground substance

what composes the mesenchyme?

mesenchymal cells and ECM

what is mesenchyme?

type of embryonic CT that gives rise to all other CT of the body during development

where do mesenchymal cells originate from?

the mesoderm germ layer

which statement is incorrect about mesenchymal cells?

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A. mesenchymal cells are small, spindle-shaped cells

B. mesenchymal cells produce ECM

C. mesenchymal cells are pluripotent

D. mesenchymal cells originate from the ectoderm

E. mesenchymal cells are multipotent

F. mesenchymal cells differentiate into CT such as fibroblasts

C. and D.

what is the epithelial mesenchymal transition (EMT)?

cell biological process that is required for remodeling of cells and tissues; occurs during embryogenesis, during wound healing, and during the acquisition of malignant traits by carcinoma cells

what cell type starts and ends the EMT?

epithelial to mesenchymal

select all that is true about EMT

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A. EMT is a biologic process allowing a mesenchymal cell to undergo multiple biochemical changes to assume a polarized epithelial cell status

B. during embryonic development, phenotypic plasticity is afforded by an EMT

C. EMT is signaled by degradation of the basement membrane and the formation of a mesenchymal cell that can migrate away from the epithelial layer where it originated

D. the c-Myc oncogene is a “master regulator” which controls many aspects of EMT

E. cultures of growth-arrested feeder cells have been used inducing EMT

b. and c.

what is the mesenchymal epithelial transition (MET)?

reverse of EMT; mesenchymal cells convert to epithelial derivatives

what process related to cancer does EMT help with

tumor metastasis

what are neoplastic tissues

self-renewing, stem-like cells within tumors, called CSCs

what is the experimental approach of paper 3?

induce EMT in nontumorigenic, immortalized human mammary epithelial cells (HMLEs) via ectopic expression of transcription factors twist and snail (selected for via puromycin)

what are HMLEs?

not cancerous, but cells that have been changed such that they can divide indefinitely (aka “immortalized”)

what is the point at which a normal cell stops dividing?

called the Hayflick Limit/Phenomenonw

what occurs when a cell undergoes mitosis?

telomeres shorten, and will eventually stop when they reach a certain length

what cells have an exception to the Hayflick limit?

stem cells and cancer cells

cells that acquired fibroblast-like, mesenchymal appearances look like what?

spread out, spindle shaped

what is an example of an epithelial marker?

E-cadherin

what are examples of mesenchymal markers?

N-cadherin, vimentin, and fibronectin

adding TGF-beta-1 to epithelial cells was a good way to achieve what step?

inducement of EMT

CD44 and CD24 are what?

cell surface markers

what configuration of CD44 and CD24 is associated with human breast CSCs and normal mammary epithelial stem cells?

high CD44/low CD24

mesenchymal-like cells generated by EMT showed what kind of CD configuration?

CD44 high/CD24 low

e-cadherin

epithelial marker

Snail

transcription factor known to induce EMT

vimentin

mesenchymal marker

hTERT

catalytic subunit of the human telomerase (the gene that encodes the catalytic unit)

mammospheres

mammary epithelial stem cell aggregates derived from primary breast tumors (associated with cancer stem cells)

more mammospheres present in the cell is indicative of what?

stem cell character

more mammospheres are formed in cells containing which transcription factors?

snail, twist, and TGF-B-1

undergoing EMT does what to the percentage of mammospheres?

increases presence by >30 fold

how can the authors tell that the cells over expressing snail or twist have undergone EMT?

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A. cells express more CD44 and less CD24 on average

B. E-cadherin is downregulated

C. Cells acquired fibroblast-like mesenchymal appearances

D. transforming growth factor beta-1 is expressed

A. B. and C.

some cells naturally express high CD44/low CD24. how did the authors distinguish between them and the EMT cells?

cells that underwent EMT expressed stem cell characteristics K18 and K8

which of the figures labelled in purple shows a CD44 high/CD24 low expression pattern?

B, C, and D

Study the figure and select the correct statements.

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A. Cell population labelled A have CD44high/CD24low

B. Cell population labelled B CD44high/CD24low

C. Cell population labelled A form mammospheres better than the population labeled B

A and C

tamoxifen

drug used to induce EMT; tests if EMT conversion promotes generation of cancer stem cells (it does)