“Is it schadenfreude, or is it something else?”
It is a question Harvard professor David Sinclair asks himself a lot of late.
Just about everyone doing cell biology has something—and usually critical—to say of him these days. There are loudmouth bloggers calling fraud and normally circumspect colleagues spouting uncomfortable questions about his work.
All of this is something new for Professor Sinclair, a soft-spoken man whose calm visage belies his world-rocking discovery of just 10 years ago: that resveratrol, a compound made from an extract of common red wine, significantly expands the lifespan of laboratory mice. Fortunately, or unfortunately, the finding has fueled a powerful, if perhaps misplaced, 21st century obsession: immortality, and how to get it.
It has also made David Sinclair a rich man. In 2008, the pharmaceutical giant Glaxo paid $720 million for the rights to his research, which it hoped to use as a diabetes drug.
Some time later Sinclair signed a contract with the marketing giant Shaklee to use his name to sell resveratrol. (The deal was later unstrung when opprobrium set in.)
There was talk of a Nobel Prize.
Hence, the minor possibility that jealousy might lurk behind a roiling scientific brouhaha centered on one explosive charge: That Dr. Sinclair’s data and his laboratory methods are so flawed as to make resveratrol a doubtful elixir of youth - at worst completely unusable, and at best a highly troublesome drug candidate. The criticism, now churning everywhere from the blogosphere to the top scientific journals, has stung hard.
“Where does all that come from?” Sinclair says, his gentlemanly bearing ruffled. “They are prematurely piling on a young science that will potentially have enormous benefits.”
But those benefits are seriously under attack.
--Subsequent studies have shown that resveratrol does not extend lifespan in normal, normally fed mice
--Others have shown that at least one Sinclair compound does not improve diabetes—a key claim in the Glaxo acquisition
--still others show that the compound does not does not work in the targeted fashion initially reported, raising the prospect that it may be too “dirty” of a candidate for pharmaceutical development
That the criticism on the scientific blogosphere has been particularly rancid is unsurprising. But read between the lines of some of the field’s top research journals and you can see what really rankles. Citing a new study that may seriously undermine Sinclair’s most fundamental bench science last month, the editors of the Journal of Biological Chemistry noted, “[this] highlights the importance of performing careful and thorough biochemical methods with clear and unbiased analysis.”
It might be said that that was essentially a form of scientific bitch-slapping.
Now even his colleagues at Harvard have taken to ribbing him, sometimes not so gently. Presenting a PowerPoint to a group of university alumni recently, Gary Ruvkun, a fellow molecular biologist, has been getting laughs with one particular slide that proclaims: “Don’t believe anything you’ve heard about resveratrol!”
At the core of the controversy is a subject that rarely percolates down from the lab bench—the legitimacy of certain artificial chemicals used to determine how any given candidate molecule works. Does it trigger any known disease pathways? Does it suppress that activity or increase it?
David Sinclair at the 2008-2009 NIEHS Distinguished Lecture Series on August 11, 2009. Sinclair is professor of Pathology and co-director of the Paul F. Glenn Laboratories for the Biological Mechanisms of Aging at Harvard Medical School. Photo: Steve McCaw
In 2000, Dr Sinclair and his colleagues reported that resveratrol specifically triggered the SIRT family of enzymes that are critical to the regulation of energy, and hence, to aging, metabolic disease and diseases of uncontrolled growth, like cancer.
Resveratrol seemed to accomplish this in a very “clean” fashion. Such specificity is critical to the successful development and approval of any new drug; compounds that lack specificity and trigger lots of other mechanisms are hard to get past the FDA because they may cause side effects and adverse events. (Although Viagra, initially developed for angina, has been a just a little successful with something once considered a side effect.)
Sinclair’s discovery tool was a relatively new commercial assay, or “probe,” called Fleur de Lys. Like similar chemicals in use for at least a decade, Fleur de Lys inserts itself like a big thermometer into the outer membrane of a cell. There, it can react with whatever cellular enzyme or gene product it is designed to target. When it does, the top of the probe then glows under an ultraviolet light, allowing the researcher to see when a candidate molecule is hitting the right target. (The probe signals are known as florophores.)
That is exactly what happened in 2000, when Dr Sinclair exposed a cell to resveratrol, then exposed it to the probe for SIRT. Thus came the famous finding that resveratrol worked by regulating the sirtuin family of enzymes, mimicking the anti-aging properties of caloric restriction, to this day the only intervention that alters maximum lifespan in a mammal.
Since 2005, however, substantial concern about the Fleur de Lys probe led several researchers to doubt—if not entirely discount—its utility, especially as a probe for SIRT activation. Scientists at the University of Washington compared the florescent probe to other natural probes, known as native substrates. They found that, without the presence of the unnatural florophore, resveratrol did not activate SIRT.
“We couldn’t reproduce the in vivo data from Sinclair’s 2003 paper claiming 70 percent lifespan extension in yeast from resveratrol, nor did we observe activation of 2,” says Matt Kaeberlein, a geneticist at UW. “I don’t know if David knew about the substrate specificity of resveratrol before we published our paper, but I think it’s unfortunate that they never addressed the issue afterward.”
It’s not unethical to continue to use the assay because no Petri dish assay perfectly mimics what is occurring inside the body, he says, but, at the very least, “the editors and referees who handled the subsequent papers should have asked them to provide evidence that the compounds directly activate SIRT1.”
Last year, a study by researchers at Amgen showed something similar: That resveratrol only worked in the presence of another completely different enzyme system, again calling into question the compound’s critical ability to target a single clean drug pathway. And this year a study by researchers at Pfizer, a major Glaxo competitor, repeated the Fleur de Lys florophore test and found that four Sinclair compounds “are not direct activators of SIRT1.”
They also reported that one of the compounds, SIRT 1720, neither improves blood sugar levels nor increases energy—two key resveratrol claims. The conclusion: resveratrol’s ability to target SIRT was nothing but an artifact of the Fleur de Lys test— something completely unrelated to reality. It would be like getting a false positive on a pregnancy test strip that was way beyond its expiration date.
Sinclair bridles at that. “This is a new a complex science,” he says. “Historically people have called complexity an artifact, and often they are wrong.”
He points to some of the initial papers about another now-established finding: that mutations in the gene known as daf1 lead to lifespan expansion in many life forms. “Originally, people said this was an artifact, applicable only to worms. They were wrong. It extends from yeast to mice.” He notes that one of his present critics was the researcher who made that very mistake in the mid-1990s
Still, Professor Sinclair may be a little daunted, reviewing certain statements he made during resveratrol’s early glow.
line-height:115%;mso-bidi-font-family:Calibri;mso-bidi-theme-font:minor-latin">“The upside is so huge that if we are right,” he said after announcing the Glaxo deal in 2008, ”the company that dominates the sirtuin space could dominate the pharmaceutical industry and change medicine.”
UW’s Kaeberlein admits resveratrol “could certainly still turn out to be valid,” but remains convinced that it does not activate SIRT in yeast “because we have rock solid assays for that…we don’t have them for mammals.”
A growing body of work also raises a bigger question: Does resveratrol work at all to expand lifespan through SIRT?
Some evidence suggests not, or that, at best, it may do so in very idiosyncratic ways. When the compound was tested on mice that ate a normal diet (as opposed to his original cohort of mice on a high-fat diet), there was no expansion of lifespan. Again, the effect may have been an artifact of the high fat diet, laced with tropical oils. Even fly and worm studies have proven difficult to reproduce in disinterested laboratories.
And again, the issue lies in the usually skimmed realm of journal articles called “materials and methods.” But they have nevertheless added fuel to the artifacts charge.
It is nothing new, of course, that science — like Lady Gaga or Cher — can be a mean taskmistress. But Sinclair has been surprised by the heated nature of what he regards as an unwarranted attack. What, beyond jealousy, might be fueling it? He suggests one possibility: his patent on the basic processes underlying even more lucrative enzyme-based drug development. “Remember,” he says, “my detractors have something at stake in this kerfuffle too. They have old, established ways of developing compounds. They have an interest in beating up on new ways.”
Sinclair remains confident that the entire contretemps will turn out to be nothing but a “stupid” overreaction. He has been aware of the florophore concerns since 2005, he says, and they were disclosed to Glaxo during its extensive due diligence on the deal. (Glaxo has publically stood by their commitment to develop the Sinclair compounds, but has to date been unwilling to prove that they knew about the florophore issues at the time of the deal.) He is now working on a new probe, and plans to publish two articles in the coming months that will address those concerns.
And if the compounds turn out to be dirty, just as his critics contend? “Sure, it’s preferable for it to be narrowly targeted, but it’s not really essential,” he says.”Think of… aspirin.”
Greg Critser is the author, most recently, of Eternity Soup: Inside the Quest to End Aging (Harmony, 2010) Fat Land: Why Americans are the Fattest People in the World (Houghton/Mifflin, 2003), and Generation Rx (Houghton/Mifflin 2005).