The US consumption of beans was confirmed by a study done between Hispanic women and non-hispanic white women where Hispanic women showed reduced Cancer risk, who were also reported to be on a Native diet of high pulses intake (The Mexican food- such as Chiptole, is a proof of how much beans they consume) versus the non-hispanic white women who had a greater risk to cancer, reported to have rich (although considered healthy, protein rich diet) diet of meat, fish and processed foods. This paper would thus research the signaling pathways that bean intake affects to understand the proper mechanism.BTW- Chipotle is good, as per this study, but too much of food outside might bring out a new study, so bring beans at home .
**The mTOR network has been studied to be associated with diabetes, cardiovascular disease and CANCER. Our hypothesis, according to this paper, is based on the mTOR pathway and its related targets, to know the actual progression of signaling cascade on consumption of bean; either it is upregulated or downregulated – We shall see!!
*** We also see changes in E2F1 (Transcription factor necessary for cell cycle progression; usually bound by non-phosphorylatedRb protein); we see a Increased level of p21 and p27 which are a result of p53 activation and which inhibit CDK-cyclin complex formation in turn inhibiting cell cycle progression; Bcl2:Bax ratio was overall higher with an elevated rate of Apoptosis; mTOR network signaling pathway’s targets (that are in question in the paper) also seem to have affected levels on bean treatment e.g. pAMPK and AMPK seen in figure 1B has increased levels in bean-fed rats and we also see a downregulation of protein Akt which is also a part of the mTOR pathway. In fig 1C, Raptor, which is a direct regulator of mTOR pathway also seem to have been upregulated in bean-fed rats. Overall we can summarise from this data, that the factors that promote cancer progression and tumor growth seem to be decreased and downregulated in bean-fed rats compared to the control ones. After this first screening, the second data that we have will let us chose the best dose of this dietary regulation with beans.
**** Graph B, which also tells the dose-dependence of the reduction compared to the rate of Apoptosis (programmed cell death in layman terms), relates the previous data we discussed emphasizing the importance of Bax/Bcl2 ratio for Apoptosis dependent on Mitochondrial factors. Graph C and D goes back to the western blots we just saw comparing them with the dose-dependence wt/wt of bean showing, for instance, the much discussed mTOR target AMPK at a higher concentration with a higher bean dose therefore promoting mTOR pathway. Now what is this mTOR pathway? What is it got to do with Cancer?
Cancer research paper
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
OBJECTIVES OF THE STUDY-So to know the role of Beans in stimulating the health of ourbody; 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 thisexperiment; at 20 days of age(make a point of this) andmaintained at 22⁰C with 50% relative humidity and a 12hlight/dark cycleStep II: At 21 days of age(here we go), the rats were injectedwith 1-methyl-1-nitrosourea(Carcinogen; cancer causing agent)Step III: Seven days after the injection, all the rats wererandomized based on diet groups (so that we can finally testbeans against others). Bean was incorporated at 60% wt/wt andfor Dose-Response at 7.5%, 15%, 30% and 60% wt/wt. Fed till46 days post injectionStep IV: Following an overnight fast, rats were ‘euthanized’ overa 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 differentassays, such as ELISA for Insulin, IL-6 and CRP.Step VI: Cell proliferation and apoptosis was determined usingKi-67 immunohistochemical staining method for the mammarytissues isolated from the rats. Corresponding hematoxylin- andeosin-stained serial sections were acquired using Zeiss AxioskopII at 400x magnification.Step VII: Western Blotting of the carcinomas (homogenized inlysis buffer) was performed. 40 ug of protein lysate per samplewas subjected to 8-16% sodium dodecyl sulfate-PAGE gradientelectrophoresis. After electrophoresis, proteins were transferredto 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 specificprimary antibodies.Step VIII: Extraction of plasma metabolites using HPLC-Liquidchromatography and analysis of them using ANOVA was done.
RESULTSFig 1: Showing the difference in levels offactors after and before bean-treatmente.g: We see a decrease in the levels of Cyclin D1 implyingthe 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 onmTOR signaling components (as studied through theprevious data) – Western BlotsAs seen from the above data, at a higher dose there seemsto be a considerable increase in the levels of thesecomponents of the mTOR pathway. This is also confirmedfrom the next data.
Graph A gives a good summarized dose-dependentcurve showing the 60% wt/wt being the best forreduction of mammary cancer.****
mTOR is a conserved serine/threoninekinase that integrates external cellularstimuli with intracellular energy and nutrient-sensing pathways to regulate cellularmetabolism and growth. (presence of Aktpromotes mTOR’s cell growth activity)In this paper, two upstream regulators ofmTOR pathway were investigated. AMPK (anitrogen containing phytochemicalderivative; BTW Common bean is a richsource of small nitrogen containingcompounds , so here we go!) and Akt (adownstream effector of the insulin and IGF-1receptors and both plasma insulin and IGF-1were reduced dose-dependently withincreasing dietary bean consumption).mTOR affects lipid metabolism, lipid isrequired for cancer cell proliferation. SoAMPK affects mTOR which decreases thelipid 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 andnutrient deprivation.. Hmm.. So that needs more study for theeffect of dietary bean on AMPK. I am presuming that AMPKactivation in our case in through LKB1 factor.
THUS,-Common bean consumption appears to reduce mammarycancer burden through inducing apoptosis (increasedBax/Bcl2 ratio, p27, p21 increased levels, etc) andmodifying key metabolic signaling networks linked to cellgrowth 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 otherfactors 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 ahuge intake of dry beans in their regular diet? (Importantas even the environmental effects and bean quality mightdiffer and give varied results)Lets research more and make this world a better place toenjoy and diseases just a mere thought THANK YOU!!!!