I woke up this morning with a mammogram debate hangover. Enough with the new guidelines, already! But still, what do we do with the mammogram-shaped holes in our lives?
As it turns out, nature abhors a vacuum almost as much as I do, and there are already some interesting and, fingers crossed and lucky rabbit’s foot in hand, promising developments on the horizon. One of the most interesting is the recent research into microRNA. This type of protein molecule could lead to more accurate cancer screening than lousy mammograms or the crude bio-markers we have today, like PSA (for prostate cancer) and CA 15.3 (for breast cancer).
What’s miRNA?
Think back to your high school biology class… OK, too far? Then think back to the advent of biotechnology, and the massive Human Genome Project, and how companies like Genentech and Amgen were going to cure cancer and generate new organs and allow us to live forever. Heady days! Someone made a killing in the market, no doubt. As for the rest of us….
If you were anywhere but in a coma during the biotech bubble (about ten market bubbles ago), you heard a lot about genes and DNA. A light, quick, lemony refresher: DNA is a twisty molecule in the center (the nucleus) of the cells in your body, and it is organized into segments call genes. If you think of cells as little chemical factories that churn out proteins and other molecules all day long, then think of DNA as the ultimate molecule cookbook. DNA molecules are unzipped (DNA resembles a twisted ladder, and it “unzips” right up the middle of the rungs), and portions of it are copied. RNA molecules are the copies.
There are different types of RNA that serve different purposes, but the ones to care about right now are messenger RNA (or mRNA) and micro RNA (or miRNA). The mRNA molecules act as messages that cause parts of the cell to do something — to produce yet another protein, for example. MicroRNA molecules can intercept and bind to mRNA, changing its shape and making it ineffective. In essence, if you think of mRNA as a message, miRNA renders the message unreadable. Whether that’s a good thing or a bad thing depends on the nature of the message.
In a cancerous cell, there may be far too many mRNA messages that trigger growth. So, having miRNA molecules to intercept and destroy some of those messages would be a good thing. On the other hand, viral infections or DNA mutations can result in overproduction of miRNA molecules that turn off suicide messages — causing messed up cells to survive and grow into cancer. So, miRNA can act as the gas pedal or the brakes as far as cancer is concerned, depending on its function. There are hundreds of different miRNA molecules with hundreds of different functions, and researchers are looking at the overall mix of miRNA molecules in human tissues. What they’ve found is that the balance of different miRNA molecules can vary depending on what’s going on in your body.
Why I’m Wild About miRNA
This won't hurt a bit
A number of small studies (remember Size Matters? this is early stuff) have found that miRNA in the blood of test subjects could detect breast cancer, prostate cancer, diabetes, and other diseases. And, mixtures of miRNA appear to be a more consistent and direct measure of the presence of disease.
Existing biomarkers like PSA and CA 15.3 measure proteins that some tumor cells produce and some don’t, and which some healthy cells also produce. They can also be neutralized to some degree by the immune system until the number of tumor cells is extremely high. PSA and CA 15.3 can fail to rise even with significant cancer burden, and can be elevated in some cancer-free individuals. So, as screening tools, they stink. That’s why we’ve been stuck with breast self-exams and mammograms. The early miRNA research suggests that certain clusters of miRNA are a more specific and reliable test than either existing tumor markers (for breast and prostate) or mammograms, and contain more information about the characteristics of the cancer.
Cancer screening tests based on miRNA are in the pipeline for some cancers (including lung and colon), though not breast or prostate, yet. But it occurs to me that miRNA breast cancer diagnostics would be a fine way for the USPSTF (US Prevention Services Task Force — the folks who brought you the new mammography guidelines) to help fill the void they created. Perhaps they could recommend sugar-daddy funding for the research, or a dreamy tax break for the first ten companies to get their miRNA cancer detection kits through the FDA.
Some day, there may be a post-mammogram world where a simple annual blood test is all you need as an early screening tool. For now, stuck with prodding our girls and the occasional lousy mammogram. But hey, a girl can dream, can’t she?
A truth serum for cancer — microRNAs have major potential as cancer biomarkers (full text)
LJ Chin and FJ Slack (2008)
A commentary of microRNA-as-biomarker research, explaining the recent history, and what’s yet to be discovered before effective clinical tests exist; be sure to read the article by Mitchell and Parkin, which addresses some of the questions raised here.
women abhor a vacuum
who doesn't abhor a vacuum?
I woke up this morning with a mammogram debate hangover. Enough with the new guidelines, already! But still, what do we do with the mammogram-shaped holes in our lives?
As it turns out, nature abhors a vacuum almost as much as I do, and there are already some interesting and, fingers crossed and lucky rabbit’s foot in hand, promising developments on the horizon. One of the most interesting is the recent research into microRNA. This type of protein molecule could lead to more accurate cancer screening than lousy mammograms or the crude bio-markers we have today, like PSA (for prostate cancer) and CA 15.3 (for breast cancer).
What’s miRNA?
Think back to your high school biology class… OK, too far? Then think back to the advent of biotechnology, and the massive Human Genome Project, and how companies like Genentech and Amgen were going to cure cancer and generate new organs and allow us to live forever. Heady days! Someone made a killing in the market, no doubt. As for the rest of us….
If you were anywhere but in a coma during the biotech bubble (about ten market bubbles ago), you heard a lot about genes and DNA. A light, quick, lemony refresher: DNA is a twisty molecule in the center (the nucleus) of the cells in your body, and it is organized into segments call genes. If you think of cells as little chemical factories that churn out proteins and other molecules all day long, then think of DNA as the ultimate molecule cookbook. DNA molecules are unzipped (DNA resembles a twisted ladder, and it “unzips” right up the middle of the rungs), and portions of it are copied. RNA molecules are the copies.
There are different types of RNA that serve different purposes, but the ones to care about right now are messenger RNA (or mRNA) and micro RNA (or miRNA). The mRNA molecules act as messages that cause parts of the cell to do something — to produce yet another protein, for example. MicroRNA molecules can intercept and bind to mRNA, changing its shape and making it ineffective. In essence, if you think of mRNA as a message, miRNA renders the message unreadable. Whether that’s a good thing or a bad thing depends on the nature of the message.
In a cancerous cell, there may be far too many mRNA messages that trigger growth. So, having miRNA molecules to intercept and destroy some of those messages would be a good thing. On the other hand, viral infections or DNA mutations can result in overproduction of miRNA molecules that turn off suicide messages — causing messed up cells to survive and grow into cancer. So, miRNA can act as the gas pedal or the brakes as far as cancer is concerned, depending on its function. There are hundreds of different miRNA molecules with hundreds of different functions, and researchers are looking at the overall mix of miRNA molecules in human tissues. What they’ve found is that the balance of different miRNA molecules can vary depending on what’s going on in your body.
Why I’m Wild About miRNA
This won't hurt a bit
A number of small studies (remember Size Matters? this is early stuff) have found that miRNA in the blood of test subjects could detect breast cancer, prostate cancer, diabetes, and other diseases. And, mixtures of miRNA appear to be a more consistent and direct measure of the presence of disease.
Existing biomarkers like PSA and CA 15.3 measure proteins that some tumor cells produce and some don’t, and which some healthy cells also produce. They can also be neutralized to some degree by the immune system until the number of tumor cells is extremely high. PSA and CA 15.3 can fail to rise even with significant cancer burden, and can be elevated in some cancer-free individuals. So, as screening tools, they stink. That’s why we’ve been stuck with breast self-exams and mammograms. The early miRNA research suggests that certain clusters of miRNA are a more specific and reliable test than either existing tumor markers (for breast and prostate) or mammograms, and contain more information about the characteristics of the cancer.
Cancer screening tests based on miRNA are in the pipeline for some cancers (including lung and colon), though not breast or prostate, yet. But it occurs to me that miRNA breast cancer diagnostics would be a fine way for the USPSTF (US Prevention Services Task Force — the folks who brought you the new mammography guidelines) to help fill the void they created. Perhaps they could recommend sugar-daddy funding for the research, or a dreamy tax break for the first ten companies to get their miRNA cancer detection kits through the FDA.
Some day, there may be a post-mammogram world where a simple annual blood test is all you need as an early screening tool. For now, stuck with prodding our girls and the occasional lousy mammogram. But hey, a girl can dream, can’t she?
References
MicroRNAs as Novel Biomarkers for Breast Cancer (full text)
H. M. Heneghan, N. Miller et al (2008)
miRNA as a biomarker for prostate cancer:
Circulating microRNAs as stable blood-based markers for cancer detection (full text )
P. S. Mitchell, R. K. Parkin, et al (2008)
Characterization of microRNAs in serum: a novel class of biomarkers for diagnosis of cancer and other diseases (full text)
Xi Chen, Yi Ba, et al (2008)
A truth serum for cancer — microRNAs have major potential as cancer biomarkers (full text)
LJ Chin and FJ Slack (2008)
A commentary of microRNA-as-biomarker research, explaining the recent history, and what’s yet to be discovered before effective clinical tests exist; be sure to read the article by Mitchell and Parkin, which addresses some of the questions raised here.
Serum MicroRNAs Are Promising Novel Biomarkers (full text)
Shlomit Gilad, Eti Meiri, et al (2008)
Demonstrates use of microRNA as accurate test for pregnancy phase.