Presenter: Venkat Rao Katkoori.,...
Transcript of Presenter: Venkat Rao Katkoori.,...
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Presenter:Presenter: Venkat Rao Katkoori., Ph.D.Venkat Rao Katkoori., Ph.D.
AuthorsAuthors:: Venkat R. Katkoori1, Xu Jia1, Tom Callens2, Ludwine Messiaen2, Wen Wan3, Sreelatha Meleth3, Harvey Bumpers4 and Upender Manne1.
Departments of Pathology1 and Genetics2 and Medicine3, University of Alabamaat Birmingham;
Department of Surgery 4, Morehouse School of Medicine, Atlanta, GA.
Prognostic Significance of p53 Codon 72Polymorphism Differs with Race in Colorectal
Adenocarcinoma
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Normal
Epithelium
Abnormal
Crypts Foci
Early
Adenoma
Late
Adenoma
In situ
Carcinoma
Invasive
Carcinoma
Metastatic
Carcinoma
APC,
5q Loss
DCC/Smad4
18q Loss
p53, BAT-26
17p Loss
Many genes
8p Loss
Many genesCell
Adhesion
Many decades 2 - 5 years
2 - 5 years
A:A: Chromosomal Instability (CIN) Pathway (Gene mutations, Chromosomal deletions)
K-Ras, β-CateninMMR (hMSH2)
B: Microsatellite Instability (MSI) Pathway(Mismatch Repair Inactivation)
Multi-Step Molecular Pathways of Colorectal Multi-Step Molecular Pathways of Colorectal CarcinogenesisCarcinogenesis
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Prognostic Molecular Markers of SporadicPrognostic Molecular Markers of SporadicColorectal AdenocarcinomaColorectal Adenocarcinoma
Promising Prognostic MarkersPromising Prognostic Markers: : Microsatellite Instability &Microsatellite Instability &18q deletions18q deletions
Candidate Prognostic Markers:p53, p27kip-1, Bcl-2, Bax, MUC1 & RPH3AL (Rabphillin-3A-like),
Potential Prognostic Makers: MUC4, MUC17, VEGF,EGFR, c-erb-2, TGF-α, COX-2,TP, TS, DPD, 17p deletions17p deletions
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STUDY RATIONALESTUDY RATIONALE
PREMISEPREMISE: Several studies from ourlaboratory as well as others have demonstratedthat prognostic value of molecular makers differbased on tumor location, tumor stage and/orpatient race/ethnicity in colorectal cancer(CRC).
AIMAIM: To identify race-specific prognosticmolecular markers in CRCs, first we evaluatedmutational patterns of the p53 gene andcorrelated with patient outcomes based onrace.
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Patient SelectionPatient Selection
CRC and corresponding normal tissues collected from373 patients (137 African-Americans patients & 236 non-Hispanic Caucasians patients).
Patients who underwent surgery with curative or palliativeintent at UAB Hospital during 1984-1995.
We selected only patients who have not received anypre- or –post surgery adjuvant therapy.
Patients with family or personal history were excluded. Patient demographics, pathologic, and clinical
information was extracted from medical records andphysicians charts
The follow-up information was collected from the UAB-Tumor Registry
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Microsatellite Instability AnalysisMicrosatellite Instability Analysis
Microsatellite instability was analyzed at BAT25, BAT26, D2S123,D5S346 & D17S250 loci in 373 CRCs and marching normal tissues
BAT-25 by ABI
Bat 25 InstableBat 25 Stable
Bat 25 InstableBat 25 Stable
BAT-25 by Light Cycler
BAT-26 by Light Cycler BAT-26 by ABI
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Microsatellite Instability & RaceMicrosatellite Instability & Race
Similar incidence of MSI-H has been observed betweenSimilar incidence of MSI-H has been observed betweenAfrican-American and Caucasian patientsAfrican-American and Caucasian patients
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+1 Coding Region
Exons 1 to 11
5’ 3’
+ 1179+1
Analysis of Analysis of p53p53 in CRCs based on Race in CRCs based on Race
A] Sequence Analysis exon 4 through 9
B] Frequency of p53 mutations Codon wise by race
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P53 mutations have been associated with poor survival of African-American(p= 0.001) and Caucasian (p= 0.028) patients with CRCs
African-American Patients Caucasian Patients
Survival Analysis based on p53 Status in CRCsby race
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Codon 72 polymorphism of p53Codon 72 polymorphism of p53
SNP at codon 72 of p53 results in thesubstitution of arginine for proline
Susceptible for p53 mutations and Increaseddegradation of p53 protein
Increased tumorigenecity and oncogenic effect Uncontrolled malignant process and Increased
invasiveness and metastasis Risk of cancer progression and poor prognosis and Resistance to anticancer therapy
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Analysis of genotype status at Codon 72 of p53By RFLP and Sequencing
M = Marker (100bp ladder)Lane 1 = G/G homozygous (Arg/Arg phenotype)
(160 and 119bp)Lane 2 = G/C heterozygous (Arg/Pro phenotype)
(279bp, 160 and 119bp)Lane 3 = C/C homozygous (Pro/Pro phenotype)
(279bp)
SequencingSequencing
PCR-RFLPPCR-RFLP
Genotype G/GHomozygous
Genotype G/CHeterozygous
Genotype C/CHomozygous
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Codon 72 Phenotypes of p53 and Race &Tumor Characteristics
Pro/Pro phenotype is correlated with nodal metastasis tumor gradeand higher incidence of p53 mutations in African American patients
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Hypothesis: The proline/proline phenotypes areassociated with aggressive tumor behavior.
Since higher frequency of proline/prolinephenotypes and these exhibited higher incidenceof p53 mutations, we analyzed their prognosticvalue in relation to other phenotypes(proline/arginine and arginine/arginine) based onrace .
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Survival Analysis based on phenotypes codon 72polymorphism of p53 in CRCs by race
African-American Patients Caucasian Patients
Pro/Pro phenotype of P53 at codon 72 is associated with poor survival Only in African-American patients (p= 0.005), but not in Caucasian ( p= 0.886)patients with CRCs
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Cox regression analysis to determine prognostic significance of p53 codon 72 phenotypes
Pro/Pro phenotype is an independent prognostic marker Only in AfricanAmerican patients with CRCs
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Mutational spectra of p53 in African-American and Caucasian patients in relation to Pro/Pro phenotype
Pro/Pro phenotype of P53 at codon 72 is associated with higher frequency of P53 mutations particularly disruptive type only in in African-American patients[Differential mutational spectra in relation to Pro/Pro phenotype]
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ConclusionsConclusions
p53 mutational pattern and prognostic value ofcodon 72 polymorphism differs with race incolorectal adenocarcinomas.
The incidence of Pro/Pro phenotype at codon 72of p53 is higher in African- American patients andassociated with higher incidence of p53mutations
Pro/Pro phenotype is associated with and poorclinical outcome of African-American but notCaucasian patients with CRCs.
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Mentor: Upender Manne, Ph.D.Colleagues : Xu Jia, MD
Chandra Kumar , MD
Collaborators: Wen Wan, Ph.D.Sreelatha Meleth, Ph.D
Harvey Bumpers, MD,FACS. William E. Grizzle, MD, Ph.D.
Grant Support: RO1-CA98932-01 (NIH/NCI)2U54-CA118948-03 (NIH/NCI)
AcknowledgementsAcknowledgements