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Chemotherapy: Drug resistance
Chemotherapy
Recurrence
Drug Resistance
Gabriela M. Almeida
Cancer Biology Group
IPATIMUP
Encontro Ciência 2010
Lisboa, 4 Junho 2010
Principles of chemotherapy
Chemotherapy given with a curative intent, to prolong life or to palliate symptoms
Chemotherapy generally acts by killing cells that divide rapidly, characteristic of cancer
cells. However it will also affect normal cells that divide rapidly (e.g. bone marrow,
digestive tract, hair follicles).
Conventional chemotherapy regimens usually
involve several cycles of therapy with cytotoxic
agents, the purpose being to kill tumour cells but
allowing time for normal cells to recover from the
damage.
Most agents used in chemotherapy affect cell
division or DNA synthesis.
More recently targeted therapies (towards
specific
molecules
involved
in
cancer
progression) became available.
Pros and cons of chemotherapy
Pros: cure patients, prolong life or to improve quality of life (palliation of symptoms); able to
remove micro-metastasis far from the site of origin
Cons: Lacks selective toxicity - Toxicity towards normal cells/tissues (sometimes lifethreatening side effects); Long-term toxicity/carcinogenicity (particularly relevant when
treating young patients)
General toxic side effects of anticancer drugs
• Most suppress the bone marrow and immune
system
• Many cause nausea & vomiting
• Oral and GI ulceration, and diarrhea
• Hair may fall out (alopecia)
• Sterility
• Teratogenicity
• Carcinogenic
Selection of drug resistant clones that may lead to tumour recurrence
Mechanisms of chemoresistance,
platinum-based agents as an example
• Platinum based agents are widely used in chemotherapy;
• Cisplatin was first administered to patients in the early 70s and is still widely used in
chemotherapy (e.g. testicular, lung and ovarian cancer, etc);
• Carboplatin and Oxaliplatin, less toxic platinum based compounds, are used in many
chemotherapy protocols;
Mechanism of action of cisplatin
• Administered intravenously, inactive whilst in the
bloodstream;
• Becomes active upon entering the cell;
• Forms protein, RNA, and DNA adducts;
• DNA adducts are the key toxic lesions formed by
Cisplatin;
• Adducts cause inhibition of DNA replication, RNA
transcription, arrest at the G2 phase of the cell
cycle, and/or apoptosis.
Kartalou and Essigmann, 2001
Detecting platinum-induced crosslink formation and
repair in vitro and in the lymphocytes of cancer
patients receiving platinum-based chemotherapy
Gene ID Gene Name (official symbol)
Fold Change
Apoptosis
DNA repair
Ψ
581
Bcl2 associated X protein (BAX)
5366
phorbol-12-myristate-13-acetate-induced protein 1 Ψ
2.6
7508
xeroderma pigmentosum complem. group C (XPC) Ψ
1.7
1643
damage-specific DNA binding protein 2, 48kDa (DDB2) Ψ
5890
RAD51-like 1 (S. cerevisiae) (RAD51L1)
(PMAIP1)
11040
pim-2 oncogene (PIM2)
1.7
970
TNF ligand, member 7 (TNFSF7)
1.7
8744
TNF ligand, member 9 (TNFSF9)
2.1
2.1
2.1
- 1.9
Transcription
355
TNF receptor superfamily, member 6 (FAS)
4.2
467
activating transcription factor 3 (ATF3)
1.8
8795
TNF receptor, member 10b (TNFRSF10B)
1.6
57103
chromosome 12 open reading frame 5 (C12orf5)
1.9
9618
TNF receptor-associated factor 4 (TRAF4) Ψ
1.8
10432
RNA binding motif protein 14 (RNM14)
9540
tumor protein p53 inducible protein 3 (TP53I3) Ψ
1.6
- 1.7
Others
Cell Cycle and/or proliferation
8465
aurora kinase A (AURKA) Ψ
7832
BTG family member 2 (BTG2)
991
CDC20 cell division cycle 20 homolog (S. cerevisiae)
- 1.5
2.9
- 1.7
centromere protein A (CENPA)
Adenosine A2b receptor (ADORA2B)
1.6
220
H460
aldehyde A549
dehydrogenase 1 family,
member A3
1.7
0µM
(ALDH1A3)
50µM
0µM
50µM
1793
dedicator of cytokinesis 1 (DOCK1)
- 1.6
1806
dihydropyrimidine dehydrogenase (DPYD)
2232
ferredoxin reductase (FDXR) Ψ
(CDC20)
1058
136
9133
cyclin B2 (CCNB2)
- 1.6
899
cyclin F (CCNF)
- 1.8
10243
Gephyrin (GPHN)
900
cyclin G1 (CCNG1) Ψ
1.7
consen.
glucose-6-phosphate dehydrogenase
901
cyclin G2 (CCNG2)
1.6
3778
1026
cyclin-dependent kinase inhibitor 1A (p21, Cip1) Ψ
6.1
(CDKN1A)
1647
growth arrest and DNA-damage-inducible, alpha Ψ
(GADD45α)
5347
polo like kinase 1 (Drosophila) (PLK1)
8493
protein phosphatase 1D magnesium-dependent, delta Ψ
- 1.9
3.1
isoform (PPM1D)
27244
Sestrin 1 (SESN1) Ψ
4609
v-myc myelocytomatosis viral oncogene homolog (c-Myc)
2.5
- 1.5
Bax, 23 kDa
- 1.8
- 3.4
4.3
P21, 21 kDa
- 1.6
- 1.6
β- Actin, 43 kDa
potassium large conductance calcium-activated channel,
- 2.2
subfamily M, alpha member (KCNMA1)
6586
2.6
Bcl2, 26 kDa
slit homolog 3 (Drosophila) (SLIT3)
XPC, 130 kDa - 2.6
α-Tubulin, 55 kDa
Cisplatin Resistance by inadequate levels of cisplatin
reaching target DNA
• Reduced intracellular accumulation of cisplatin;
• Increased inactivation by intracellular proteins (e.g. glutathione);
Kelland, Nat Rev Cancer, 2007
Cisplatin Resistance mediated after DNA binding
• Increased repair of cisplatin adducts;
• Increased ability to replicate past cisplatin adducts;
• Defects in the apoptotic response pathway.
Kelland, Nat Rev Cancer, 2007
Cancer stem cells (CSCs)
• The cancer stem cell (CSC) hypothesis is an attractive model to explain the functional
heterogeneity that is commonly observed in solid tumours. It proposes a hierarchical organization of
cells within the tumour, in which a subpopulation of stem-like cells is responsible for sustaining
tumour growth.
• First evidence for CSCs came from acute myeloid leukaemia. There is now increasing evidence for
CSCs in a variety of solid tumours (both mouse and human).
• The frequency of CSCs in solid tumours is highly variable, reflecting biological variation as well as
technical issues.
“All roads lead to Rome”?
• The CSC phenotype could be
acquired by normal tissue stem,
progenitor or differentiated cells
through transforming mutations, which
activate/deregulate
certain
signalling
pathways;
Fábián et al. 2009, Cytometry Part A 75A:67-74
CSCs and Therapy Resistance
• CD133+ cells were significantly resistant to chemotherapeutic agents (e.g.
carboplatin, Taxol and etoposide) compared to autologous CD133- cells.
• CD133 expression was significantly higher in recurrent GBM tissue obtained from
five patients as compared to their respective newly diagnosed tumours.
Cancer stem cells: Key players in chemoresistance?
CSCs are believed to be, in part, responsible for therapy resistance as they are
generally more resistant than the cells that constitute the bulk of the tumour.
The chemoresistant phenotype of CSCs is believed to be due to:
1. Overexpression of drug efflux pumps
2. Alterations in apoptosis proteins: Overexpression of anti-apoptotic genes and members
of the inhibitor of apoptosis protein
3. Increased telomerase expression
4. Increased antioxidant capacity/enhanced resistance to oxidative stress
Cancer stem cells: Key players in chemoresistance?
Currently believed that chemotherapeutic
regimens are not able to effectively eradicate
CSCs (but only the cancer cells that constitute
the bulk of the tumour) and that this will
ultimately be responsible for recurrence.
Schatton et al. 2009, BioEssays 31:1038-1049
Crucial to effectively target and eradicate these cells in order to improve
the outcome of cancer patients
FCT Financed Project: PTDC/EBB-BIO/099672/2008 (Biotecnologia)
“Desenvolvimento de nanopartículas encapsuladas com siRNAs para
modular a resistência a agentes quimioterapêuticos em células estaminais
cancerígenas”
IPATIMUP,CEQUIMED-UP, IBMC
Circumvention of chemoresistance
in CSCs
Chemotherapy
Recurrence
Specific cell surface
markers
CSCs
% Cell Survival
Non-CSCs
Coupling with CSC
targeted nanoparticles
Mechanisms/Proteins
responsible for
chemoresistance?
Chemotherapeutic Drug
Targeting by siRNAs
Circumvention of chemoresistance
in CSCs
Chemotherapy
Chemotherapy
+
siRNA encapsulated
CSC targeted
nanoparticles
Recurrence
No
Recurrence
Research Team:
IPATIMUP:
GM Almeida,
MH Vasconcelos,
LF Santos-Silva,
RT Lima,
H Seca
The Economist, 2008
CEQUIMED-UP:
CM Barbosa,
M Teixeira,
R Pereira,
E Sousa,
E Tiritan
IBMC:
TL Duarte,
M Pinto