Laura Esperanza Valencia Asprilla

Juan Diego Villegas Alzate

The article is based on studies that suggest that alcohol intake promotes cell transformation and tumor formation, through the changes that it does on Pol III.

INTRODUCTION

Pol III synthesizes:

• 5S rRNA

• tRNA

• 7SL RNA

• 7SK RNA

POL III TUMORIGENESIS

↑ in both transformed and tumor cells.

Why RNA PolymeraseIII?

To explore the role of alcohol in Pol

III, theinvestigators…

Treated

normal HCC1937 cells with Ethanol

MCF-7 cells with Ethanol With the BRCA1

gene restored

What did they see?

• Ethanol induces deregulation of Pol III gene transcription via ERα in MCF-7 cells.

↑ 5s rRNA↑ tRNA

Pol III regulation

ER

The accumulation of Pol III gene transcripts makes the nucleolus

bigger

They also saw…

Overexpretion of BRCA1 reduces ethanol-induced tRNA and 5S rRNA transcription in the cells.

↓ 5s rRNA↓ tRNA

Pol III regulation

ER

BRCA1

BRCA1Repara DNA

Gen represor de tumores

Evita proliferación incontrolada

Regula el ciclo celular

Celula HCC 1937

BRCA1

GEN POL- III

Mutación

PCRSecuenciación

DNA

GEN RNA POL-III

Diferenciación celular, desarrollo o la oncogénesis.

TranscripciónRNA Pol-III

Oncogenic proteins

TFIIIB Complex(transcrpition factors)

ALCOHOL

La ingesta de alcohol estimula la transcripción del genpol-IIII, promoviendo así la transformación celular y laconsecuente formación de tumores.

Alcohol se asocia a riesgo de cáncer de mama ya queestimula la proliferación de receptores de estrógenos

ALCOHOL

Receptores Estrogénicos

Transformación celular…Formación de tumores

TRANSCRIPCIÓN

• Proceso de obtención de unARN mensajero (ARNm) apartir del ADNcorrespondiente a un gen.En cada tipo celular y encada estado funcional en elque se encuentre la célulase expresan unos genesdiferentes. Esto precisa unaregulación muy fina queconsiga orquestar unfuncionamiento complejode las células orientado aresponder adecuadamentea los estímulos externos einternos.

GENERAL OBJECTIVE

See how an alteration in BRCA1 expression may affect the transcription of RNA pol III dependent genes, in cells with and without ethanol effects

MATERIALES Y METODOS

Reactivos y anticuerpos

AnticuerposContra BRCA1 yB-actina

Ensayos de protección de RNAsa

Hacer unas transferencia de un gen a través de un plásmido (gen Pol III)

48 h

Aislamiento de RNA y RT qPCR

Obtener gran cantidad copias de un fragmento de DNA (Amplificación)

Función determinar su tamaño y seleccionar el apropiado

(dependiendo del análisis). Así puede comprobarse: clonación de un inserto o DNA pasajero en un

vector o plásmido.

RNA DNAcTranscriptasa inversa

SDS-PAGE y análisis inmunoblot

• Se usa para la identificación de antígenos por medio de antígenos

• y anticuerpos.

MCF-7

BCRA-1

Incubar con Etanol

Proteínas se determinaron por

electroforesis

Inmunoblot.Se usó Ac contra BCRA-1

Ag-AcSe detecta la unión

Introducción a la bilogía celular, ed 2, Editorial Medica Panamericana, pag 163.

Electoforesis

Técnica de separación y/o migración de moléculas en un

campo eléctrico, según la carga y el peso molecular

Resultados

Figura 1.

Figura 2.

Figura 3.

Figura 4.

Figura 5.

Discusión

Ford et al., 1998

Individuals harboring germline mutations in the breast cancer susceptibility gene BRCA1 carry an 80% lifetime risk of developing breast cancer

YES

Spillman and Bowcock, 1996; Marks et al.,1997

BRCA1 transcription isregulated by diverse environmentalstimuli including genotoxic agents,hypoxia and mitogenic hormonestimulation. The best-characterizedstimulant of BRCA1 expression isestrogen, which induces the highestelevationsin BRCA1 mRNA levels that routinelypeaks just before theonset of DNA synthesis

Discusión

Veras et al., 2009Although a studyshowed that BRCA1 decreased Pol III gene transcription in HCC1937cells

YES

Dumitrescu and Shields, 2005

These results support the idea thatalcohol increases ERαexpression to elevate Pol III genetranscription to bring about greaterphenotypic changes. Given thatalcohol down-regulates BRCA1expression

YES, no

permite la unión a su receptor

Conclusions

• We can realize that how occur the family incidents to the cáncer, in thiscase breast cáncer, all starts from a mutation in the BRCA1 gene, that is atumor supresor , the gene BRCA2 hasthe same function as the BRCA1, butits chromosomic location is different, with a medical and early analysis inthe people, we could detect the main effect in order to prevent all theother risk.

Nowdays the use of alcohol has been incresed and with this all the diseasesthat come with it, . Everytime even younger people is using alcohol withoutknowing the risks. In this case the breast and ovarian cáncer.

There are compaings against the uses of drug, but nowadyas one of the worstdrugs is sold freely.

This articule make us think in some sort of the about the risks of highuseage. If we stoped drinking alcohol, we would be able to decrease the rateof cerebrovascular, heart, gastrointestinal deseases and the death rate byalcohol poisoning.

As the article says, “people with mutation in the BRCA1 gene carry 80% lifetime risk of developing breast cancer”. Such things make you think if itwould be better to have BRCA1 gene therapy to help PREVENT or even CURE breast cancer. I belive that this article shows a pathway into the future of cancer tratment because it opens doors for Timely diagnosis (through gene identification), Prevention and Treatment.

Although every good thing this article has. I belive that is no good that theauthors don’t go deeper in the mechanism by which alcohol promotes thedevelopment of breast cancer and its relationship with other genes differentfrom BRCA1. Even if it is not the main topic of the article, I think that theauthors should have acknowledged that there are other genes responsible forbreast cancer and that further experiments should be also directed toidentify the relationship of these genes and other risks factors like alcohol.

Other genes with antitumoral activity that has not been as studied as BRCA1 are:

• ATM:that gene helps repair damaged DNA

• PTEN: that helps regulate cell growth.

Mapa

Inhibe transcripción

del Pol-III

Efecto fundador