Intro to Neoplasia Flashcards
General features of benign tumors
- -oma
- Adenoma
- Papilloma
- Cystadenofibroma
Malignant neoplasms of epithelial cell origin, derived from any of the 3 germ layers
Carcinoma
Malignant tumors arising in solid mesenchymal tissues
Sarcoma
Malignant tumors arising from blood-forming cells
Leukemia or lymphoma
Generic term for all malignant neoplasms
Cancer
Literally “new growth or form”
- “results from genetic alterations that are passed down to progeny of the tumor cells”
- These genetic changes allow excessive and unregulated
proliferation that becomes autonomous (independent of
physiologic growth stimuli.)
- Occurs in a spectrum from benign to malignant
Neoplasia
(swelling) first used as one of the characteristics of
acute inflammation. Now frequently used by physicians as a synonym for neoplasia
Tumor
Study of tumors (neoplasms); medical oncology, surgical
oncology, pediatric oncology …
Oncology
The entire population of a neoplasm arises from a single cell that has incurred genetic change… i.e., all neoplastic cells are clones of one original altered cell.
Clonal
Ectodermal Derivatives
- Skin
- Nervous System
- Teeth
- Eye
Mesodermal Derivatives
- Bone/cartilage
- Fat
- Muscle
Endodermal Derivatives
- Respiratory Tract
- GI tract
- Thyroid gland
Malignant
Can invade and destroy adjacent structures and spread to distant sites (metastasis) to cause death
Major Categories of Malignancy
• carcinomas
– squamous cell carcinoma
– adenocarcinoma
– secondary descriptors
• sarcomas
– primary descriptors
– secondary descriptors
• blood forming cells
– leukemias, lymphomas, etc
The most common general category of malignant tumor in US adults
Carcinoma
Types of Lung Cancer
- ADENOCARCINOMA (38%)
- Squamous cell carcinoma (20%) • Small cell carcinoma (14%)
- Large cell carcinoma (3%)
- Other (25%)
Difference between a mixed tumor and teratoma?
- Teratoma = more common in women and has at least 2 germ cell lineages
- Mixed Tumor= All come from the same germ cell lineage
What are the 2 basic tissue components of benign and malignant neoplasms?
- Parenchyma: Generally gives rise to the neoplastic cellular component, it is benign,
malignant or “other” - Stroma: the supportive cellular component (the
tissue “skeleton” upon which (or within which) the parenchymal component resides)
- Generally not neoplastic (in carcinomas)
- Typically consists of:
~ Connective tissue- supporting framework
~ Blood vessels
A group of cells, frequently arranged around a
lumen. The cells are typically specialized to secrete a substance.
Gland
Parenchyma, in terms of malignant transformation, is generally associated with?
Carcinoma
Stroma, in terms of malignant transformation, IF occurs, is generally associated with?
Saracoma
Difference between the structure of normal and cancer cells?
Normal:
- Large cytoplasm
- Single nucleus
- Single nucleolus
- Fine chromatin
Cancer
- Small cytoplasm
- Multiple nuclei
- Multiple and large nucleoli
- Coarse chromatin
The replacement of one type of cell with another type
Metaplasia
Literally means “disordered growth”
Dysplasia
Degree to which a neoplasm resembles the tissue from which it arises or is derived.
Differentiation
Two major determinants of differentiation
- The neoplastic cells nuclei and cytoplasm
2. The architectural relationship of the neoplastic cells to other neoplastic cells and non-neoplastic stroma.
The less differentiated a malignant neoplasm, the more ? its biologic behavior
Agressive
- Benign neoplasms are “well differentiated “ and may be
difficult to distinguish from normal tissue; e.g. lipoma.
2 Well Differentiated Benign Tumors
- Leiomyoma : benign, well-differentiated tumor contains interlacing bundles of neoplastic smooth muscle cells virtually identical to normal smooth muscle cells
- Thyroid Adenoma: unremarkable (well-differentiated) colloid-filled thyroid follicles
Grades of Differentiation
- Well differentiated: closely resembles parent tissue
- Moderately differentiated: features of the original tissue type identifiable, but it’s not the dominant pattern, with additional atypia
- Poorly differentiated: a small minority of cellular constituents allow identification of the parent tissue; associated with cellular anaplasia
- Undifferentiated: Tissue of origin cannot be discerned by histopathologic appearance of the neoplasm. Almost always associated with anaplasia.
Differentiation in Squamous Cell Carcinoma
- WELL differentiated tumor cells have prominent keratin production and intercellular bridges present.
- MODERATELY differentiated carcinoma has a significantly more distorted architecture
- POORLY differentiated tumor has little organization, and keratin present but it is frequently only detected with special techniques
Differences between Benign and Malignant Tumors
▪ Benign and malignant tumors can be distinguished from one another based on the degree of differentiation, rate of growth, local invasiveness, and distant spread.
▪ Benign tumors often resemble the tissue of origin and are well differentiated; malignant tumors are less well differentiated or completely undifferentiated (anaplastic).
▪ Benign tumors are more likely to retain functions of their cells of origin, whereas malignant tumors sometimes acquire unexpected functions due to derangements in differentiation.
▪ Benign tumors are slow growing and mitotic figures are rare and normal; malignant tumors generally grow faster and have numerous or abnormal mitotic figures.
▪ Benign tumors are circumscribed and may have a capsule; malignant tumors are poorly circumscribed and tend to invade surrounding normal tissues.
▪ Benign tumors remain localized at the site of origin, whereas malignant tumors have the capability to metastasize to distant sites.
The one unequivocal criterion of malignancy
Metastasis
second is invasiveness
Examples of Malignant Neoplasms that have inappropriate benign terminology
- Mesothelioma (Benign name: Benign fibrous tumor) = Mesothelium
- Seminoma = Testicular epithelium
- Malignant melanoma (Benign name: Nevus) = Tumors of Melanocytes
- Wilms Tumor = Renal anlage
- Immature teratoma (Benign name: Mature teratoma, dermoid cyst) = Totipotential cells in gonads or in embryonic rests
- Lymphoma
Local INVASION of Malignant Tumors
- Metastasis is defined by the spread of a tumor to sites that are physically discontinuous with the primary tumor, and unequivocally marks a tumor as malignant - by definition, benign neoplasms do not metastasize .
- The invasiveness of cancers permits them to penetrate blood vessels, lymphatics, and body cavities, providing the opportunity for spread. All malignant tumors can metastasize, but some do so very infrequently (ex. gliomas-
The most common tumors in men arise in the ?
- Prostate
- Lung
- Colon/rectum
In women, the most frequent cancers are in ?
- Breast
- Lung
- Colon/rectum
Cancers of the ? constitute more than 50% of cancer diagnoses and cancer deaths in the United States
- lung
- female breast
- prostate
- colon/rectum
In contrast, in the developing world the most common cancers involve the ? in men, and the ? in women.
- men: lung, stomach and liver
- women: breast, cervix, and lung
Tumors arising in the context of chronic inflammation are mostly ?, but also include ? and several kinds of ?. Immunodeficiency states predispose to ? cancers.
- carcinomas
- mesothelioma
- lymphoma
- virus-induced
?, the most common general category of cancer in adults, are extraordinarily rare in children
Carcinomas
Most carcinomas occur in the ?. Cancer is the main cause of death among women aged ? and among men aged ?; the decline in deaths after age ? is due to the lower number of individuals who reach that age.
- later years of life (>55 years)
- 40 to 79
- 60 to 79
- 80
Acquired conditions that predispose to cancer can be divided into ?
- chronic inflammations
- precursor lesions
- immunodeficiency states.
4 classes of regulatory genes – the principal targets of cancer-causing mutations, tend to be affected
- Growth-promoting proto-oncogenes
- Growth-inhibiting tumor suppressor genes
- Genes that regulate apoptosis
- DNA-repair genes
Conversion of one of the two alleles from a proto-oncogene to an oncogene is sufficient to promote ?. However, it requires loss of BOTH ? alleles to promote neoplasia, as one of the two gene (protein) products is sufficient to inhibit neoplasia
- neoplasia
- tumor suppressor
Include DNA methylation, which tends to silence gene expression, and modifications of histones, the proteins that package DNA into chromatin, which depending on their nature may either enhance or dampen gene expression.
Epigenetic modifications
? and ? dictate which genes are expressed, which in turn determines the lineage commitment and differentiation state of both normal and neoplastic cells.
- DNA methylation
- histone modifications
The study of changes in gene expression that occur without changes in DNA sequence
- These changes are reversible, but sometimes stable and heritable
Epigenetics
3 types of Epigenetic alterations
- Methylation of DNA
- Modification of histones
- RNA-mediated modifications
8 hallmarks of cancer
- Self-sufficiency in growth signals
- Insensitivity to growth-inhibitory signals
- Altered cellular metabolism
- Evasion of apoptosis
- Limitless replicative potential (immortality?)
- Sustained angiogenesis
- Ability to invade and metastasize
- Ability to evade host immune response
Molecular Hallmarks of Cancer
- Avoiding immune destruction
- Evading growth suppressors
- Enabling replicative immortality
- Tumor-promoting inflammation
- Activating invasion and metastasis
- Genomic instability (mutator phenotype)
- Inducing angiogenesis
- Resisting cell death
- Deregulating cellular energetics
- Sustaining proliferative signaling
Growth factor receptors
- EGF receptor family
- ALK (receptor tyrosine kinases)
Proteins involved in signal transduction
- RAS proteins
- ABL (non-receptor tyrosine kinase)
- BRAF
- SHH/WNT
A set of chemical reactions in a cell that occurs when a molecule, such as a hormone, attaches to a receptor on the cell membrane. The pathway is actually a cascade of biochemical reactions inside the cell that eventually reach the target molecule or site of reaction
Signal Transduction Pathway
Nuclear regulatory proteins
MYC
- ERBB1 encodes the ?, which is involved by point
mutations in certain cancers. - Of greatest clinical importance are several different ERBB1
point mutations that are found in a subset of ?. These mutations result in constitutive activation of the ?
- epidermal growth factor receptor (EGFR)
- lung adenocarcinomas
- EGFR tyrosine kinase
- ERBB2 encodes a different member of the receptor tyrosine kinase family, ?.
- Rather than being activated by point mutations, the ERBB2 gene is amplified in certain ?, leading to overexpression of the HER2 receptor and constitutive tyrosine kinase activity.
- HER2
- breast carcinomas
GENE REARRANGEMENTS activate other receptor tyrosine kinases, such the tyrosine kinase
?
ALK
Included in the ALK group of receptor tyrosine kinases are the ? neurotrophin receptor genes (A, B, C) which have a crucial role in the growth, survival and differentiation of neural cells.
- Clinically, they are notably useful as prognostic indicators in children with ? (and an important known association for MYC, as well)
- TRK
- neuroblastoma
Point mutations of ? family genes constitute the most common type of abnormality involving proto-oncogenes in human tumors.
RAS
3 RAS genes in humans
HRAS, KRAS, NRAS
The RAS genes, of which there are three in humans were discovered initially in ?
transforming retroviruses
- Mutations in ?, a member of the RAF family, have been detected in close to 100% of hairy cell leukemias, more than 60% of melanomas, 80% of benign nevi, and a smaller percentage of a wide variety of other neoplasms, including colon carcinomas and dendritic cell tumors.
- a serine/threonine protein kinase that sits at the top of a cascade of other serine/threonine kinases of the MAPK family. Like activating RAS mutations, activating mutations in ? stimulate each of these downstream kinases and ultimately activate transcription factors.
BRAF
?, the failure (of the embryonic prosencephalon to divide) to form cerebral hemispheres, is commonly linked to mutations in genes involved in the ? pathway.
- Holoprosencephaly
- hedgehog
?, the most common form of human cancer, has the closest association with hedgehog signaling
Basal cell carcinoma
Abnormal activation of the pathway probably leads to development of disease through transformation of ? stem cells into ? stem cells that give rise to the tumor.
- adult
- cancer
The ? signaling pathways are a group of signal transduction pathways distinct from but related to HH (hedgehog) pathways.
Wnt
- The most common malignant brain tumor of childhood, is an aggressive, diverse and heterogeneous cancer.
- Although it is most frequent in children between the ages 0 and 9, it can occur at any age.
Medulloblastoma
It is believed that ? induces neoplasia by aberrant effects on adult stem cells.
SHH
- ? (a proto-oncogene and the prototypical nuclear regulatory protein) is most commonly involved in human tumors.
- A major transcriptional regulator of cell growth
- expressed in virtually all eukaryotic cells and belongs to the immediate early response genes, which are rapidly and transiently induced by RAS/MAPK signaling following growth factor stimulation of quiescent cells.
MYC
Any organism whose cells contain a nucleus and other organelles enclosed within membranes.
Eukaryote
Single-celled organism that lacks a membrane- bound nucleus, mitochondria, or any other membrane- bound organelle.
Prokaryote
A small infectious agent that replicates only inside the living cells of other organisms.
Virus
MYC:
- Activates the expression of ? genes that are involved in cell growth
- In certain circumstances, MYC upregulates expression of ?
- Can act to reprogram somatic cells into ? stem cells
- MYC paralogs= ?
- In ?, MYC is deregulated by a variety of mechanisms (including mutation of MYC itself, and amplification in other neoplastic settings)
- associations with ? (and other B and T cell tumors), neuroblastoma, and many common carcinomas
- many
- telomerase
- pluripotent
- NMYC and LMYC
- cancer
- Burkitt lymphoma **
A gene that is related to another gene by descent from a single ancestral gene that was duplicated and that may have a different DNA sequence and biological function.
Paralog
Many tumor suppressors, such as ? and ?, are part of a regulatory network that recognizes genotoxic stress from any source and responds by shutting down proliferation.
- Rb and p53
Tumor Suppressor Genes:
Inhibitors of mitogenic signaling pathways
- APC (AD inheritance)
- NF1 (AD)
- NF2 (AD)
- PTCH
Tumor Suppressor Genes:
Inhibitors of cell cycle progression
RB (AD)
Tumor Suppressor Genes:
Inhibitors of pro-growth programs of metabolism and angiogenesis
VHL (AD)
Tumor Suppressor Genes:
Inhibitors of Invasion and metastasis
CDH1 (E-cadherin)
Tumor Suppressor Genes:
Enablers of genomic stability
TP53 (cell cycle checkpoint component) (AD)
Tumor Suppressor Genes:
DNA repair factors
- BRCA1, BRCA2
* MSH (AR)
Tumor Suppressor Genes:
Unknown Mechanisms
WT1
- “two hit” hypothesis of oncogenesis in retinoblastoma/the ? gene
- “The governor of proliferation”
RB
“the guardian of the genome” – the most frequently mutated
gene in human cancers
TP53
“gatekeeper of colonic neoplasia”
APC
A gene related to certain CNS tumors, renal cysts, neuroendocrine
tumors and renal cell carcinoma
VHL
Fusion gene
BCR-ABL
2 cell cycle checkpoint components
Rb and p53
Tumor suppressor “pocket” protein that binds E2F transcription factors in its hypophosphorylated state, preventing G1/S transition; also interacts with several transcription factors that regulate differentiation
Rb
- Tumor suppressor altered in the majority of cancers; causes cell cycle arrest and apoptosis.
- Acts mainly through p21 to cause cell cycle arrest. Causes apoptosis by inducing the transcription of pro-apoptotic genes such as BAX. Levels of ? are negatively regulated by MDM2 through a feedback loop.
- required for the G1/S checkpoint and is a main component of the G2/M checkpoint.
p53
- In FAMILIAL cases, children inherit one defective copy of the RB gene in the ? (the first hit), and the other copy is normal. Retinoblastoma develops when the normal RB allele is mutated in retinoblasts as a result of a spontaneous ? mutation (as the second hit).
- In sporadic cases both normal RB alleles must undergo ? mutation in the same retinoblast (two hits).
- germline
- somatic
- somatic
Loss of normal cell cycle control is central to malignant transformation and that at
least one of four key regulators of the cell cycle (?) is
dysregulated in the vast majority of human cancers.
- p16/INK4a
- cyclin D
- CDK4
- RB
- a tumor suppressor gene that regulates cell cycle progression, DNA repair, cellular senescence and apoptosis, is the most frequently mutated gene in human cancers.
- Loss of function mutations located on chromosome ?
- TP53
- 17p13.1
Tumors with ? TP53 alleles are more likely to be killed by such therapy (irradiation and conventional chemotherapy) than tumors with ? TP53 alleles
- wild type
- mutated
Inheritance of a mutated copy of TP53 predisposes individuals to malignant tumors because only one additional “hit” in the lone normal allele is needed to abrogate TP53 function.
- Such individuals, said to have the ? syndrome, have a 25-fold greater chance of developing a malignant tumor by age 50 than the general population.
Li-Fraumeni
pRB is associated with which high risk HPV protein?
E7
p53 is associated with which high risk HPV protein?
E6
Loss of function mutation on this gene is associated with Wilms tumor (pediatric kidney cancer)
WT1
The newest and most rapidly developing frontier in cancer treatment
Immunotherapy
a protein that in humans is encoded by the CD274 gene
PD-L1
A checkpoint protein on T cells. It normally acts as a type of “off switch” that prevents T cells from attacking other cells in the body.
PD-1
Monoclonal antibodies that target either ? or ? can block this binding and boost the immune response to
cancer cells.
- PD-1 or PD-L1
- A protein receptor that functions as an immune checkpoint to downregulate immune responses.
- Constitutively expressed in regulatory T cells but only upregulated in conventional T cells after activation – a phenomenon which is particularly notable in cancers.
- It acts as an “off” switch when bound to CD80 or CD86 on the surface of antigen-presenting cells].
CTLA4
- A monoclonal antibody that attaches to CTLA-4, blocking its expression.
- It has been utilized to treat melanoma of the skin and certain other cancers.
Ipilimumab (Yervoy)
- A major (perhaps predominant) enzyme that degrades the second messenger - cAMP - in many immune cells, including eosinophils, neutrophils, macrophages, T cells, and monocytes.
- Proinflammatory mediators released by those cells lead to activation of and tissue infiltration by other immune cells, as well as activation and hyperproliferation of keratinocytes; this process could play a role in the development of ? lesions
- Phosphodiesterase 4 (PDE4)
- psoriatic
- Evidence suggests that ? causes a downregulatory signal in immune cells, thus suppressing the production of proinflammatory mediators, including tumor necrosis factor (TNF)-α, interleukin (IL)-17, and interferon (IFN)-γ.
- It is also believed that cAMP promotes the production of anti-inflammatory mediators such as IL-10.
cAMP
The most common cancer in the United States.
-? patients had a 12 percent increased risk of developing it
non-melanoma skin cancer
- psoriasis
Additional, intrinsic features characteristic of malignancy due to identified molecular features
- Genomic instability
- Cancer-enabling inflammation
- Dysregulation of cancer-associated genes
- Epigenetic changes
- Non-coding RNAs and cancer
Chronic myelogenous leukemia (CML)
- Translocation = ?
- Gene = ?
- Translocation = (9;22)(q34;q11)
- Gene:
~ ABL 9q34
~ BCR 22q11
Acute myeloid leukemia (AML)
- Translocation = ?
Translocation:
- (8;21)(q22;q22)
- (15;17)(q22;q21)
Burkitt lymphoma
- Translocation = ?
(8;14)(q24;q32)
Mantle cell lymphoma
- Translocation = ?
(11;14)(q13;q32)
Follicular lymphoma
- Translocation = ?
(14;18)(q32;q21)
? changes have important roles in many aspects of the malignant phenotype, including the expression of cancer genes, the control of differentiation and self-renewal, and even drug sensitivity and drug resistance.
Epigenetic
2 types of non-coding RNAs
- Micro-RNA
2. Long noncoding RNA
- Do not encode proteins; instead, they function primarily to modulate the translation of target mRNAs into their corresponding proteins.
- Posttranscriptional silencing of gene expression by ? is a fundamental and well-conserved mechanism of gene regulation present in all eukaryotes (plants and animals).
Micro-RNA (miRNA)
bind to regions of chromatin, restricting RNA polymerase access to coding genes within the region.
Long noncoding RNA
Regulatory genes:
DNMT3A
- Function = ?
- Tumor = ?
- DNA methylation
- Acute myeloid leukemia (20%)
MLL1
- Function = ?
- Tumor = ?
- Histone methylation
- Acute leukemia in infants (90%)
MLL2
- Function = ?
- Tumor = ?
- Histone methylation
- Follicular lymphoma (90%)
CREBBP/EP300
- Function = ?
- Tumor = ?
- Histone acetylation
- Diffuse large B cell lymphoma (40%)
ARID1A
- Function = ?
- Tumor = ?
- Nucleosome positioning/chromatin remodeling
- Ovarian clear cell carcinoma (60%), endometrial carcinoma (30%-40%)
SNF5
- Function = ?
- Tumor = ?
- Malignant rhabdoid tumor (100%)
PBRM1
- Function = ?
- Tumor = ?
- Renal carcinoma (30%)