Cancer Principles Flashcards
(51 cards)
Cancer characterized by
general breakdown in lines of communication btwn cancer cell and its environment -> mutations -> alter expression and fx of genes that normally regulate cell proliferation, differentiation, and survival
cancer gene mutations can be
inherited, arise spontaneously in normal cells, and acquired during the evolution of the tumor
most cancer mutations occur in
somatic cells
age related incidence of cancer
cancer arises bc multistep process bc accumulate mutations in several genes including proto-oncogenes and tumor suppressor genes long latency period generally exists btwn first mutation and acquiring all others -> most cancers having late onset
tumor progression
accumulation of phenotypic trait characteristic of malignant neoplasia
hyperplasia -> dysplasia -> tumor -> metastasis
importnat colon cancer genes/ pathways
APC, PI3K, p53, TGF-beta pathway, ras; for diff types of cancers can ID genes that mutate at various stages of the cancer
APC
required for cell differentiation (acts as tumor suppressor)
ras
GTP protein involved in proliferative signaling acts as oncogene
PI3K
lipid kinase, acts as oncogene
p53
tumor supressor
TGF-B pathway
acts as tumor suppressor
epigenetic changes
ex DNA methylation pattern; alter normal gene expression and promote tumorigenesis
driver genes
responsible for development and progression fo individual tumor types
- oncogenes
- tumor supressor genes
What fosters tumor evolution and development of drug restiances
- Intra-tumor heterogeneity
2. Interactions between the tumor and tumor microenvionrment
intra-tumor heterogeneity
tumors are genetically and phenotypically heterogenous consisting of multiple subpopulations of cells with distinct properties; tumors are subject to harsh environments and only subpopulations of cells harboring mutations and epigenetic modifications with selective advantage will survive and proliferate and expand and populate tumor so tumor microenviorment major determinant of intra-tumor heterogeneity as it changes tumor adapts
what causes intra-tumor heterogenity
individual cells of tumor accumulate modifications
Gradually:
- as result of mutagen exposure and DNA replication erros
- Rapidly as consequence of genomic instability
- epigenetic changes may contribute
- splicing variants
tumor microenvironment plays critical role in
- development, evolution, and survival of primary tumor
- ability of tumor cells to invade surrounding tissue and metastasize to distant sites
tumor microenvionrment consists of
multiple cell types, ECM components, nutrients, and waste products
Tumor and TME connnection
dependent upon signals originating from the other; tumor cells recruit inflammatory cells, activate resident fibroblasts, and secrete factors that block immune fx promoting antiongenesis; they alter microenvionrmne to factor tumor cell
CAFs
cancer associated fibroblasts; these with recruited inflamatory cells secrete growth factors, cytokines, and other factors that promote angiogenesis along with secreting proteases (degrade ECM - activating ECM-associated growth factors) and promote tumor cell migration
Cancer stem cells niche
CAFs secrete appropriate conditions (niche) for generation and maintenance cancer stem cells
different microenvioments
tumor cells adapt to primary tumor, surrounding tissue, circulation, metazoic site
cancer stem cells
aka tumor initiation cells similar ro normal stem cells
- can undergo asymmetric cell division -> new CSC and proliferating transit amplifying cell that can differentiate
- > contributes to intra-tumor heterogeneity
- Most cells in tumor are not highly tumorigenic the cancer stem cells are the small subset that are**
- these are more resistant to traditional therapies
CSC identification criteria
- expression of stem cell specific markers and signaling patheays
- ability small # of these cells to form new tumors when translpanted into recipient mice
- following CSCs as they divide via lineage tracing experiments