CELL SIGNALLING PATHWAYS ASSOCIATED WITH THE REDUCTION IN MAMMARY CANCER BURDEN BY DIETARY COMMON BEAN – Matthews D. Thompson. et al.; Carcinogenesis, Vol 33, 2012.

Pranamee Sarma

INTRODUCTION- Phaseolus vulgaris (common, dry beans) and mammary cancer

Copyright 2008 PresentationFx.com | Redistribution Prohibited | Image © 2008 clix/sxc.hu | This text section may be deleted for presentation.

- It is a well known staple food, widely available and affordable

- Average consumption can reach 150-200g/day, BUT, typical US consumptions are below recommended levels*

This paper researches on the cancer risk associated with bean consumption and thus investigates specific Systemic factors known to contribute to the survival and proliferation of cancer cells.

*Please see Notes below.

1) Does consumption of beans, really help in reduction of cancer risk?

2) What systemic factors does it actually affect?

3) The signaling mechanism initiated by bean consumption is

dose-dependent or even traces of it can activate the cascade?

- Solving these issues would definitely bring to us a new solution to not treat mammary cancer (which is under the R&D world already) but will allow us to maintain our dietary structure to be ‘actually’ healthy.

And we always thought, only running and gyming would keep us fit, healthy and disease free!!!!

Copyright 2008 PresentationFx.com | Redistribution Prohibited | Image © 2008 clix/sxc.hu | This text section may be deleted for presentation.

HYPOTHESIS - So its Man vs Food; Cancer vs Beans

OBJECTIVES OF THE STUDY

-So to know the role of Beans in stimulating the health of our body; we need to study cancer progression focusing on:1) Systemic Factors(such as glucose-dependent pathways)2) Cell Autonomous Mechanisms(cellular energy and

networking pathways)3) Signaling pathways(such as mTOR; this one is the main

crux of beans and cancer risk) **Note

METHODS – A Detailed protocol (for all the curious heads )

Step I: Female Sprague-Dawley rats were obtained for this experiment; at 20 days of age(make a point of this) and maintained at 22⁰C with 50% relative humidity and a 12h light/dark cycle

Step II: At 21 days of age(here we go), the rats were injected with 1-methyl-1-nitrosourea(Carcinogen; cancer causing agent)

Step III: Seven days after the injection, all the rats were randomized based on diet groups (so that we can finally test beans against others). Bean was incorporated at 60% wt/wt and for Dose-Response at 7.5%, 15%, 30% and 60% wt/wt. Fed till 46 days post injection

Step IV: Following an overnight fast, rats were ‘euthanized’ over a 3 h time interval with Carbon monoxide. Blood was obtained, plasma was isolated by centrifugation at 1000g for 10mins.

Step V: Plasma Glucose, insulin, IGF-1, interleukin-6 and C-reactive protein (CRP) levels were measured using different assays, such as ELISA for Insulin, IL-6 and CRP.

Step VI: Cell proliferation and apoptosis was determined using Ki-67 immunohistochemical staining method for the mammary tissues isolated from the rats. Corresponding hematoxylin- and eosin-stained serial sections were acquired using Zeiss Axioskop II at 400x magnification.

Step VII: Western Blotting of the carcinomas (homogenized in lysis buffer) was performed. 40 ug of protein lysate per sample was subjected to 8-16% sodium dodecyl sulfate-PAGE gradient electrophoresis. After electrophoresis, proteins were transferred to a nitrocellulos membrane. The levels of Cyclin D1, E2F-1, Rb, p21, p27, Bcl2, X-linked inhibitor of apoptosis proteins, Bax, AMPK, pACC, ACC, Akt, Raptor were determined using specific primary antibodies.

Step VIII: Extraction of plasma metabolites using HPLC-Liquid chromatography and analysis of them using ANOVA was done.

RESULTS

Fig 1: Showing the difference in levels of factors after and before bean-treatment

e.g: We see a decrease in the levels of Cyclin D1 implying the fact that ratio of hyperphosphrylated Rb to hypo- decreases in bean-fed rats compared to control ones.***Note

Cont……

Figure 2: Dose-dependent effects of bean feeding on mTOR signaling components (as studied through the previous data) – Western Blots

As seen from the above data, at a higher dose there seems to be a considerable increase in the levels of these components of the mTOR pathway. This is also confirmed from the next data.

Graph A gives a good summarized dose-dependent curve showing the 60% wt/wt being the best for reduction of mammary cancer.****

mTOR is a conserved serine/threonine kinase that integrates external cellular stimuli with intracellular energy and nutrient-sensing pathways to regulate cellular metabolism and growth. (presence of Akt promotes mTOR’s cell growth activity)In this paper, two upstream regulators of mTOR pathway were investigated. AMPK (a nitrogen containing phytochemical derivative; BTW Common bean is a rich source of small nitrogen containing compounds , so here we go!) and Akt (a downstream effector of the insulin and IGF-1 receptors and both plasma insulin and IGF-1 were reduced dose-dependently with increasing dietary bean consumption).

mTOR affects lipid metabolism, lipid is required for cancer cell proliferation. So AMPK affects mTOR which decreases the lipid available and thus reduced Cancer risk .

Important word – AMPK (as it affects mTOR for a better effect)

Twist being: AMPK normally is activated under cellular stress and nutrient deprivation.. Hmm.. So that needs more study for the effect of dietary bean on AMPK. I am presuming that AMPK activation in our case in through LKB1 factor.

THUS,

- Common bean consumption appears to reduce mammary cancer burden through inducing apoptosis (increased Bax/Bcl2 ratio, p27, p21 increased levels, etc) and modifying key metabolic signaling networks linked to cell growth and survival (mTOR being the main one studied)

- We need to know : a) How AMPK is actually affected? b) Does the mTOR pathway have a relation with other factors such as p27 and Bax/Bcl2? c) What component of Bean and why only this variety? d) Has study been done also in Asians, who have a huge intake of dry beans in their regular diet? (Important as even the environmental effects and bean quality might differ and give varied results)

Lets research more and make this world a better place to enjoy and diseases just a mere thought THANK YOU!!!!