Archive for the ‘genetic research’ Category

MD ANDERSON: MUTATED KRAS SPINS A MOLECULAR LOOP THAT LAUNCHES PANCREATIC CANCER

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Posted 31 Jan 2012 — by James Street
Category genetic research, Kras, Pancreatic
tct main 2010
MD ANDERSON: MUTATED KRAS SPINS A MOLECULAR LOOP THAT LAUNCHES PANCREATIC CANCER
Published 01/28/2012 – 2:17 p.m. CST
UT MD Anderson-led team identifies new potential treatment avenue to block an elusive target

HOUSTON — Scientists have connected two signature characteristics of pancreatic cancer, identifying a self-perpetuating “vicious cycle” of molecular activity and a new potential target for drugs to treat one of the most lethal forms of cancer.

The research, reported in the journal Cancer Cell and led by scientists at The University of Texas MD Anderson Cancer Center, connected the molecular dots between:

Mutated versions of Kras, a gene that acts as a molecular on-off switch but gets stuck in the “on” position when mutated.
Heightened activity of a protein complex called NF-?B that controls activation of genes.

“Kras is mutated in 80 to 95 percent of pancreatic ductal adenocarcinomas, and is the most frequent mutation among all cancers,” said senior author Paul Chiao, Ph.D., professor in MD Anderson’s Department of Molecular and Cellular Oncology.

About 42,000 new cases of pancreatic ductal adenocarcinoma are diagnosed in the United States each year. Estimates vary, but the 5-year survival rate has been 1 to 3 percent for decades and median survival after diagnosis is six months, the researchers note.

Interleukin-1a is a new potential drug target
“There have been many attempts to inhibit mutated Kras, but it’s an elusive target that so far has defied treatment,” Chiao said. “So if we can’t hit Kras, maybe we can target one of its downstream genes. This research identifies some of those genes and suggests that interleukin-1apha (IL-1a) is a potential therapeutic target.”

Chiao and colleagues identified IL-1a as a crucial player in a feed-forward loop that:

Begins with mutationally activated Kras triggering a chain reaction that induces IL-1a expression;
This in turn activates NF-?B via the protein kinase IKK2/ß, which blocks the inhibitor of NF-?B.
In the cell nucleus, NF-?B oversees gene transcription and regulates a number of inflammation-promoting genes, including IL-1a.
IL-1a and another protein called p62 activate NF-?B which in turn cycles back to perpetuate the loop by activating its activators.

“It’s a vicious cycle,” Chiao said. The overactive NF-?B fuels pancreatic cancer by activating genes that promote inflammation, the growth of new blood vessels and block programmed cell death.

Chiao has three research grants from the National Cancer Institute to study pancreatic cancer. “We study signaling transduction pathways to try to find out why it’s such a bad disease and to find a weak point for targeted therapy,” he said.

In the Cancer Cell paper, the authors conclude: “Our findings suggest that the prime mover responsible for cancer-related inflammatory response and the development of pancreatic intraepithelial neoplasia (precancerous lesions) and pancreatic ductal adenocarcinoma is the mutant Kras-initiated constitutive activation of NF-?B.”

This process, they further noted, creates a pro-tumor microenvironment by promoting inflammation, creation of new blood vessels and tissue repair that is similar to conditions found in inherited pancreatitis, inflammation of the pancreas that is linked to the development of cancer.

Kras mutation, IL-1a, NF-?B go together with poor survival
The team analyzed mouse and human tumors and mouse strains with mutated Kras expressed in their pancreases. In a series of experiments they found:

Active IKK2/ß – the activator of NF-?B – was required for the Kras-mutated mice to develop either pancreatic cancer or precancerous legions.
Deletion of IKK2/ß interrupted Kras-stimulated inflammation and cell proliferation, suggesting that chronic inflammation is a key factor in promoting pancreatic cancer development.
Microarray profiles of gene expression showed that several NF-?B-regulated inflammatory genes were present in high levels in mice with mutated Kras and active IKK2/ß but only found at lower levels in mice with IKK2/ß knocked out.
In human pancreatic tumors, high expression of the same inflammatory genes in the mutated Kras mice were associated with positive lymph node status, high-risk, late tumor stage and poor survival.
Expression of several genes regulated by NF-?B progressed from low levels in normal pancreases to higher levels in precancerous lesions and tumors, including IL-1a.
IL-1a was known to be both a target of and an inducer of NF-?B, but its expression had not previously been connected to mutated Kras. The team found that downstream targets of Kras, including IL-1a, are interrupted when IKK2/ß is inactivated.
Analysis of 14 human pancreatic cancer tumor samples showed that overexpression of IL-1a, the presence of Kras mutation and the activation of NF-?B are correlated and are associated with poor survival.
Continued activation of NF-?B and its gene transcription activity are sustained by IL-1a and p62.

Co-authors with Chiao are Jianhua Ling, Ph.D., Rulying Zhao, M.D., Ph.D., Qianghua Xia, Ph.D., Zhe Chang, Ph.D., and Mien-Chie Hung, Ph.D., of MD Anderson’s Department of Molecular and Cellular Oncology; Ya’an Kang, M.D., Ph.D., and Jason Fleming, M.D., of MD Anderson’s Department of Surgical Oncology; Huamin Wang, M.D., Ph.D., and Jinsong Liu, M.D., Ph.D., of MD Anderson’s Department of Pathology; Dung-Fang Lee, Ph.D., and Ihor Lemischka, Ph.D., of the Black Family Stem Cell Institute of Mount Sinai School of Medicine; Jin Li, Ph.D., of the Center for Applied Genomics of the Children’s Hospital of Philadelphia; and Bailu Peng, Ph.D. of the Guangdong Entomological Institute, Guangdong, China.

The team’s research was funded by grants from the National Cancer Institute, including MD Anderson’s Cancer Center Core Support Grant.

Scientists discover gene responsible for lung cancer

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Posted 07 Jan 2012 — by James Street
Category genetic research, Lung Cancer

SINGAPORE, Jan. 6 (Xinhua) — A team of Singaporean scientists have identified a gene responsible for lung cancer, the Agency for Science, Technology and Research said on Friday.

A small number of cells, known as cancer stem cells or tumor- initiating cells (TIC), are responsible for the promotion of tumor growth. The team of scientists found a marker, known as CD166, to identify these cells, it said.

The team, led by Bing Lim, associate director of cancer stem cell biology at the Genome Institute of Singapore, and Elaine Lim, medical oncologist affiliated with Tan Tock Seng Hospital and National Cancer Center Singapore, did more genomic study of the TICs, and discovered several genes that were important for the growth of cancer cells.

The scientists discovered that in abnormal instances when the level of a metabolic enzyme known as glycine decarboxylase rises significantly, it causes changes in the behavior of the cell, making it cancerous.

The glycine decarboxylase is a normal occurring enzyme in cells, present in small quantities.

The finding is reported in the online advance issue of Cell on Jan. 5 and is believed to be a huge step towards finding a cure for the disease.

Has an achilles’ heel for cancer been found?

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Posted 03 Jan 2012 — by James Street
Category Colon Cancer, DNMT1, genetic research, MBD2

RESEARCH into a gene called MBD2 could lead to new treatments for colon cancer, after experts discovered that switching it off prevents tumours from forming.

The breakthrough has been described as a “potential Achilles’ heel” by lead research Professor Alan Clarke.

It comes from the work at the Cancer Research UK Centre in Cardiff into how genes and proteins are involved in the formation of cancer.

Prof Clarke said: “The interesting thing about cancer is that one of its primary features is to turn off a number of defensive mechanisms. As the cancer develops, these defensive mechanisms are got around, usually because the genes are switched off or deactivated.”

 The first breakthrough came with the discovery of the DNMT1 gene, which, when switched off meant that cancers couldn’t develop.

But deactivating DNMT1 also had a significant effect on other bodily functions, meaning it would not make a good target for cancer therapies.

MBD2 belongs to a family of proteins which turn off other genes and research carried out in Cardiff has found that deactivating it prevents colon tumours from developing.

“It’s fantastic and does it with virtually 100% efficiency,” Prof Clarke said. “And, taking out MBD2 isn’t that damaging to other tissues and systems – it appears to be tolerated reasonably well.

“Therefore, if we were to have a therapy targeting MBD2, any off-target effects would be limited.”

The research team has been examining the impact of MBD2 by creating mice which lack the gene. But many questions remain unanswered.

Prof Clarke said: “We have to show that if you don’t have MBD2 then the likelihood of getting a tumour is much reduced. And we don’t know if you take out MBD2 from a tumour whether it will disappear.

“We’ve been trying to develop a drug that specifically targets MBD2 but, unfortunately, attempts have not been successful because it’s a very difficult protein.

“We think that MBD2 deficiency suppresses tumorigenesis by failing to turn off a number of genes – some these will be important. We’re trying to delve down and find out which of the genes it regulates are important.

“We have a potential Achilles’ heel here to stop tumours forming and we’re also trying to find a drug target.

“We can imagine that this will be useful for patients who have had a tumour and have had therapy but who have a chance of relapsing. But we’re also testing the notion that regulating MBD2 will cause tumours to regress.”

Prof Clarke added: “The remarkable thing about the way we treat cancer is that we’re stuck with pretty much ancient technology.

“We mostly use poisons but although we have made progress with virtually all forms of cancer in terms of improving treatment, if we are going to make a huge step change it will have to come from a better understanding of the mechanisms that lead to cancer.

“That will come from a molecular understanding of cancer – if we really understand the molecular basis we can create drugs that make a big difference rather than small, incremental differences.”

An ambitious plan for curing cancer in a businesslike way is in the works

Dec 31st 2011 | NEW YORK | from the print edition

 

Cancer, you have a problem

RON DEPINHO is a man on a mission. Oddly, though, he does not yet know exactly what that mission is. Dr DePinho is the new president of the MD Anderson Cancer Centre in Houston, Texas. (He took over in September, having previously headed the Belfer Institute, part of Harvard’s Dana-Farber Cancer Institute.) Mindful of his adopted city’s most famous scientific role, as home to Mission Control for the Apollo project, he says his own mission is akin to a moon shot. He aims to cure not one but five varieties of cancer. What he has not yet decided is: which five?

That it is possible to talk of curing even one sort of cancer is largely thanks to an outfit called the International Cancer Genome Consortium. Researchers belonging to this group, which involves 39 projects in four continents, are using high-throughput DNA-sequencing to examine 50 sorts of tumour. They are comparing the mutations in many examples of each type, to find which are common to a type (and thus, presumably, causative) and which are mere accidents. (The DNA-repair apparatus in malignant cells often goes wrong, so such accidents are common.)

The consortium’s work is progressing fast, and preliminary results for many tumours are already in. But such knowledge is useless unless it can be translated into treatment. That is where Dr DePinho comes in—for his career has taken him into the boardroom as well as the clinic. He is a serial entrepreneur: he helped found Aveo Pharmaceuticals, which is developing a drug to block the growth of blood vessels in tumours, Metamark Genetics, which works on diagnosing cancers, and Karyopharm Therapeutics, which is trying to regulate the passage of molecules into and out of the cell nucleus, and thus control the nucleus’s activities. His aim in coming to MD Anderson, he says, is to “industrialise” other aspects of biological research in the way that genetics has been pushed forward by high-throughput sequencing.

That will cost billions of dollars. Fortunately, the state of Texas—no pushover when it comes to spending taxpayers’ cash—is creating a $3 billion cancer-research fund to help pay for it. Local philanthropists, including T. Boone Pickens and Ross Perot, are chipping in, too. Their model is the original Human Genome Project, during which the cost of sequencing a single genetic “letter” (a DNA base pair) fell from $10 in 1991 to ten cents in 2001—and is now 3,000 base pairs a cent. They hope their dollars will encourage people working with what are now, essentially, craft technologies to think about how they might industrialise them.

Several techniques look ripe for such industrialisation. Dr DePinho sets great store, for example, by the use of genetically modified mice (he calls them “little patients”) in which mutations found in human cancers can be replicated precisely, but one at a time, to discover the shape of each piece of the jigsaw. If this process can be scaled up it will, as he puts it, allow cancer’s genetic generals to be distinguished from the foot soldiers.

Another field that has great potential is imaging technology—in particular, a combination of positron-emission tomography (which uses radioactive sugar to measure how metabolically active tissue is) and computerised tomography (which uses X-rays to map the body’s internal anatomy). Together these can show whether a treatment is reducing a cancer’s energy consumption, and thus its metabolism. This gives a good indication of how well that treatment is working.

A family business

Dr DePinho himself will have more duties at MD Anderson than just dealing with the five chosen tumours. The donkey work of creating the Institute for Applied Cancer Science, as the new mission control is to be known, will be done by Lynda Chin. Dr Chin, too, worked at the Belfer Institute. She is part of the International Scientific Steering Committee of the cancer-genome project. And she is also Dr DePinho’s wife. Dr Chin will be assisted by some 55 other scientists from the Belfer, who are making the journey to Texas with her and her husband. That sort of team poaching is common in investment banking but rarer in academic research. Dr DePinho refers to it, jokingly, as metastasis, since a clone of his primary creation will be taking root elsewhere in the country.

As to which five cancers to attack, that decision will be made by the middle of 2012. A crucial consideration will be how likely it looks that research into the tumour in question could get rapidly to the “proof of concept” stage—the point at which it could be taken forward by a business that relied on commercial sources of capital, rather than on the sorts of grants that usually propel academic research. At that moment a new firm might be spun out of the institute, or a deal might be done with an established pharmaceutical firm, to try to get a new drug developed.

In recent years many big drug companies have gutted their research departments. This is partly because those departments have failed to come up with new “blockbuster” drugs of the sort that created Big Pharma in the first place, and partly because the big firms’ bosses had hoped that smaller biotechnology companies, of the sort Dr DePinho has helped set up, would do the hard work of drug discovery instead, and then let themselves be bought by the big firms.

Unfortunately, it hasn’t quite worked out like that. The output of the biotech firms has been a trickle, rather than a torrent. They have been one of the worst-performing parts of the private-equity market since 2007, according to Dr DePinho. He hopes to change that—and in the matter of new anti-cancer drugs, the science is looking auspicious. For example, a drug called vemurafenib, which was approved for use in America in August 2011, gives months of extra life to people with metastasising melanoma, one of the deadliest cancers. Vemurafenib is so powerful that some people call it a “Lazarus” drug, after the chap Jesus is said to have raised from the dead.

Crucially for Dr DePinho’s project, the development of vemurafenib was stimulated by the identification of a mutated gene often present in melanomas. He and others like him hope that the cancer-genome consortium will throw up dozens of similar genes, and that they, too, will prove tractable targets for drug development.

Of course, if Dr DePinho had a penny for every time a “cure for cancer” headline proved premature, he wouldn’t need munificent donors. But if his bets on the science and on adopting business methods pay off, the drug industry and millions of patients will benefit. That would be one benign sort of metastasis.

Estela Jacinto, a scientist in pursuit of new ways to treat cancer

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Posted 26 Dec 2011 — by James Street
Category FRAP1, mTOR
Published: Sunday, December 25, 2011, 9:32 AM
Susan Todd/The Star-Ledger By Susan Todd/The Star-Ledger
jacinto.jpgNoah Murray/The Star-LedgerEstela Jacinto, an associate professor at Robert Wood Johnson Medical School, is carrying out reseach on how cells grow and multiply with the hopes of finding new ways to treat cancer.

This feature is part of “I Am New Jersey,” a Star-Ledger series profiling some of the people who make the Garden State special.

When Estela Jacinto, an associate professor at Robert Wood Johnson Medical School, lectures to her students on the biology of disease, she talks about the complexities involved in cell growth, how chromosomes may develop mysterious kinks and proteins can sometimes cause cells to go haywire. The damage that sets a disease in motion, Jacinto knows, can be caused by so many things — a flash of radiation, an exposure to chemicals, a bout with a virus.

The day after giving one of those familiar lectures last month, Jacinto’s 10-year-old daughter was diagnosed with acute lymphocytic leukemia, and the mother of two found herself tormented by the same questions she has discussed so often as a scientist.

“I tried to think how could I have damaged her genome,” Jacinto says, her voice growing softer. “I know as a kid she had a flu a couple of times, but was that enough to cause leukemia? It’s mind-boggling when you think about all of the things that can go wrong.”

Jacinto, a native of the Philippines with dark eyes and an easy smile, has spent more than a decade studying how normal cells grow and what causes the process to go wrong and allows cancer cells to proliferate.

Much of her research has focused around the activities of the TOR protein, which plays an important role in regulating cell growth. (The protein is the target of the immunosuppressant drug rapamycin resulting in its acronym of a name. When it appears as mTOR, it refers to mammalian cells.)

Jacinto’s efforts in the laboratory resulted in the discovery of a set of protein complexes created by mTOR. By focusing on mTORC2, the more mysterious of the two protein complexes, Jacinto has unlocked new understanding about its function, its relation to nutrients and identified another possible target for attacking a variety of cancers.

“It is still early and there is still a lot of work to be done,” said Jianjie Ma, who has worked over Jacinto for the past two years as her department chair, “but her work has great potential.”

In the field of drug development, some of the newest medicines are being created to inhibit the spread of disease by targeting specific proteins involved in cell growth and survival.

There are high hopes that Jacinto’s research will identify more new targets for treating cancer and other diseases. Earlier this year, she won some recognition — and money — to bolster those efforts. Stand up to Cancer, a group that combines the celebrity of Hollywood and the clout of top-notch scientists to raise money and fund innovative research, chose Jacinto from more than 100 other researchers to receive a $750,000 grant to help pay for her work.

Beyond the giant pharmaceutical companies that make billions selling new medicines, there are academic research laboratories around the world where scientists like Jacinto carry out meticulous experiments, de-assembling proteins and cells in an effort to better understand why the biological process sometimes goes awry, triggering bad cells — and disease.

The research done in these tight, brightly lit spaces scattered with laptops and glass instruments may lead to new insights about the biology of a disease or they may produce break-through medicines. When the research shows enough promise, it might be purchased by a large company or spun off to form the heart of a small, new drug-making firm. The goal is to move it into the clinical setting where it can be studied further and developed into a new treatment.

Terri Kinzy, a senior associate dean for research at Robert Wood Johnson Medical School, helped to recruit Jacinto for a professorship in the school’s department of physiology and biophysics nearly 12 years ago. “I think she really is that person who wants to take her research and translate it into the clinic,” Kinzy says. “She really wants to increase the impact of her work.

“It’s a big challenge,” Kinzy says, “and she likes challenges.”

Jacinto’s passion for her work is well-known among her colleagues. She is described as a collaborator and a mentor, who attracts some of the brightest, hardest-working graduate students to her laboratory.

Ma, who has chaired the department for the past two years, says he has, sometimes, come into the laboratory on weekends to find Jacinto writing a paper or working with a student. “For someone already established,” he says, “she doesn’t have to work that hard.”

Even so, most researchers attribute their successes to a combination of persistence and luck. Ma says Jacinto is someone who has proven she has both.

In some ways, it was an element of serendipity that put Jacinto on the path to becoming a cancer researcher.

“A lot of scientists, when you ask them, say it was their childhood dream to be a scientist. That wasn’t me,” Jacinto says. “I didn’t really know what I wanted to do when I grew up, but I liked science and I said, this is close enough to medicine, I’ll do research.”

Jacinto flirted with the idea of med school when her family immigrated to San Francisco from the Philippines in 1986. Fresh out of the University of the Philippines with a degree in zoology, she applied to both medical schools and graduate schools. She settled on a Ph.D. program in biomedical sciences at the University of California in San Diego.

In a laboratory managed by Michael Karin, a professor and a world authority on signal transduction pathways that regulate gene expression, Jacinto found herself in the midst of some of the most heady research of the time.

The excitement surrounding protein kinesis — ground-breaking work at the time — quickly overtook Jacinto’s interest in reproduction hormones. Today, she says the course of her career was strongly influenced by Karin’s laboratory.

Jacinto says the experience was both thrilling and stressful. There was such intense interest in the science at the time, she says, and such fierce competition among the students for Karin’s time and attention.

At the University of Switzerland in Basel, Jacinto found herself in a more comfortable environment, studying yeast genetics and working alongside Michael Hall, whose research led to the identification of TOR, which continues to influence the development of immunosuppressant medicines.

Jacinto’s own research in Hall’s laboratory led to the discovery that mTOR — again, the “m” refers to mammalian — creates two protein complexes, mTORC1 and mTORC2. While the two are considered a pair, they work differently: mTORC2 is not inhibited by the drug rapamycin.

“No one knew the function of mTORC2,” Jacinto said. “If mTOR is doing something important, then mTORC2 could have a critical role in cell growth and we could target that as well,” she said. “The job was to figure out what it does.”

In 2004, Jacinto left Switzerland to accept the position at the University of Medicine and Dentistry-Robert Wood Johnson Medical School. In her Piscataway laboratory, she has been able to advance her understanding of mTORC2’s function in the proliferation of cells.

Kinzy, who helped to recruit Jacinto during the school’s international search, remembers being impressed by the young scientist’s work. “She had this unique view of some unanticipated roles of the mTOR pathway,” Kinzy says.

Basic research is considered methodical, time-consuming and expensive and the scientists who do it usually divide their time between teaching and managing research in the lab. Jacinto oversees a research group of five.

“She is a person you bring into an institution,” Kinzy says, “and she becomes a catalyst because she brings great energy and ideas.”

While Kinzy describes Jacinto as an adept collaborator, she is also an advocate of her own ideas and someone who actively solicits feedback. “You’ve got the graceful art of self promotion when you can talk about your work and get others excited about it,” she says.

It may be a particularly good asset for a scientist to have when she is also responsible for raising money to help advance her research. Earlier this year Jacinto applied for a portion of the $9 million in grant money that Stand up to Cancer makes available to young scientists doing cutting-edge cancer research.

Stand up to Cancer, a charitable program of the Entertainment Industry Foundation, focuses its efforts on helping to advance research from the lab to the clinic, where it can be tested to determine if it works as a therapy. The program awards its grants after a grueling, months-long review process.

Jacinto, who ultimately won $750,000 in grant money, began as one of 188 applicants whose letters were reviewed by a 38-member committee, which includes prominent scientists and physicians. The committee chose 43 semi-finalists who were asked to submit full research proposals and then invited 18 to come in for interviews. Thirteen grants were awarded.

Richard Kolodner, one of the scientists who participated in the review of Jacinto’s grant application, acknowledges the intensity of the process. “(The interview) could have been the most serious interview she’s had in her life,” he says. “She had to come into a room and submit to questions from some very serious scientists.”

“She floated to the top of a very tough competition,” he says.

Targeted therapy is one of the latest strategies in the fight against cancer, but there are no guarantees that regulating one protein will make enough of a difference, just as there isn’t a guarantee that a treatment will work effectively for everyone.

Jacinto’s devastation over her daughter’s illness may be more profound because of what she knows about cancer and how it proliferates.

Her daughter’s doctors have assured her that their young patients often fare well with the standard treatment — a combination of chemotherapy drugs. Yet Jacinto is like any other parent of an ill child who is left clinging to hope that the doctors are correct.

“Hopefully, she responds,” Jacinto says. “Knowing what I know about cancer and how things can go wrong and so badly, I just hope they found it early enough.”

The hope underlying Jacinto’s work was always that she did not find something that would help cure a disease, then she might discover a piece of the puzzle that could help create a clearer picture of what triggered it. “As scientists we’re interested in understanding things. Finding a cure is considered a plus,” Jacinto said.

“All of a sudden, since my daughter’s diagnosis, it’s made me think more about how it’s all very urgent,” she says. “A lot of cancer patients are out there relying on us to make discoveries.”

Possible Anti-Cancer Target: Enzyme That Flips Switch on Cells’ Sugar Cravings

research has shown that cancer cells tend to take up more glucose than healthy cells.

Researchers are increasingly interested in exploiting this tendency with drugs that target cancer cells’ altered metabolism.

Cancer cells’ sugar cravings arise partly because they turn off their mitochondria, power sources that burn glucose efficiently, in favor of a more inefficient mode of using glucose. They benefit because the byproducts can be used as building blocks for fast-growing cells.

Scientists at Winship Cancer Institute of Emory University have shown that many types of cancer cells flip a switch that diverts glucose away from mitochondria. Their findings suggest that tyrosine kinases, enzymes that drive the growth of several types of cancer, play a greater role in mitochondria than previously recognized.

The results also highlight the enzyme PDHK (pyruvate dehydrogenase kinase) as an important point of control for cancer cell metabolism.

The results were published online Thursday by the journal Molecular Cell.

“We and others have shown that PDHK is upregulated in several types of human cancer, and our findings demonstrate a new way that PDHK activity is enhanced in cancer cells,” says Jing Chen, PhD, associate professor of hematology and medical oncology at Emory University School of Medicine and Winship Cancer Institute. “PDHK is a very attractive target for anticancer therapy because of its role in regulating cancer metabolism.”

Chen and Sumin Kang, PhD, assistant professor of hematology and medical oncology at Emory University School of Medicine, are co-corresponding authors. Postdoctoral fellows Taro Hitosugi, Jun Fan and Tae-Wook Chung are co-first authors of the paper. Co-authors at Emory include Georgia Chen, PhD, Sagar Lonial, MD, Haian Fu, PhD, and Fadlo Khuri, MD. Collaborators at Yale University, Novartis and Cell Signaling Technology contributed to the paper.

Chen and his colleagues started out studying the tyrosine kinase FGFR1, which is activated in several types of cancer. Tyrosine kinases attach a phosphate to other proteins, making them more or less active. They found that FGFR1 activates the enzyme PDHK, which has a gatekeeper function for mitochondria.

“We used FGFR1 as a platform to look at how metabolic enzymes are modified by oncogenic tyrosine kinases,” Chen says. “We discovered that several oncogenic tyrosine kinases activate PDHK, and we found that many of those tyrosine kinases are found within mitochondria.”

This was a surprise because tyrosine kinases are usually thought to drive growth by being active next to the cell membrane, Chen says.

Introducing a form of PDHK that is insensitive to tyrosine kinases into human cancer cells forces the cells to grow more slowly and form smaller tumors in mice, they found. This indicates that PDHK could be a target for drugs that specifically target cancer cells’ altered metabolism.

The experimental drug dichloroacetate (DCA), which inactivates PDHK, is being used in new clinical trials for cancer. Chen is collaborating with Haian Fu, professor of pharmacology and director of the Emory Chemical Biology Discovery Center, to find other, more potent inhibitors of PDHK.