Posts Tagged ‘cancer’

Elephants’ secret to their low rates of cancer might be explained in part by a so-called zombie gene—one that was revived during evolution from a defunct duplicate of another gene. In the face of DNA damage, elephant cells fire up the activity of the zombie gene LIF6 to kill cells, thereby destroying any cancer-causing genetic defects, researchers reported in Cell Reports.

“From an evolutionary biology perspective, it’s completely fascinating,” Joshua Schiffman, a pediatric oncologist at the University of Utah who was not involved in the work, tells National Geographic.

The better-known LIF gene has a number of functions in mammals, including as an extracellular cytokine. In elephants, LIF is duplicated numerous times as pseudogenes, which don’t have the proper sequence to produce functioning transcripts. For the latest study, the researchers wanted to see whether the duplications might have anything to do with elephant cells’ unusual response to DNA damage: indiscriminant destruction.

The team found that one of the pseudogenes, LIF6, evolved after LIF was duplicated in a way that produces a transcript, and that the gene product is controlled by TP53, a tumor suppressor. When the researchers overexpressed LIF6 in elephant cells, the cells underwent apoptosis. The same thing happened with they introduced the gene to Chinese hamster ovary cells, indicating that LIF6 has a role in elephants’ defense against DNA damage.

More work needs to be done to determine whether the LIF6 revival is responsible for elephants’ low cancer rates. There are likely to be other contributors, says coauthor Vincent Lynch, an evolutionary biologist at the University of Chicago, in an interview with The New York Times. “There are lots of stories like LIF6 in the elephant genome, and I want to know them all.”

https://www.the-scientist.com/news-opinion/elephants-revived-a-zombie-gene-that-perhaps-fends-off-cancer-64643

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Lung cancer seen on chest X ray.

Researchers have identified a gene that when inhibited or reduced, in turn, reduced or prevented human non-small cell lung cancer tumors from growing.

When mice were injected with non-small cell lung cancer cells that contained the gene NOVA1, three of four mice formed tumors. When the mice were injected with cancer cells without NOVA1, three of four mice remained tumor-free.

The fourth developed a tumor, but it was very small compared to the mice with the NOVA1 tumor cells, said Andrew Ludlow, first author on the study and assistant professor at the University of Michigan School of Kinesiology.

The research appears online today in Nature Communications. Ludlow did the work while a postdoctoral fellow at the University of Texas Southwestern Medical Center, in the shared lab of Woodring Wright, professor of cell biology and internal medicine, and Jerry Shay, professor of cell biology.

The study found that in cancer cells, the NOVA1 gene is thought to activate telomerase, the enzyme that maintains telomeres—the protective caps on the ends of chromosomes that preserve genetic information during cell division (think of the plastic aglets that prevent shoelace ends from fraying).

Telomerase isn’t active in healthy adult tissues, so telomeres degrade and shorten as we age. When they get too short, the body knows to remove those damaged or dead cells.

In most cancers, telomerase is reactivated and telomeres are maintained, thus preserving the genetic material, and these are the cells that mutate and become immortal.

Telomerase is present in most cancer types, and it’s an attractive therapeutic target for cancer. However, scientists haven’t had much luck inhibiting telomerase activity in cancer, Ludlow said.

Ludlow’s group wanted to try a new approach, so they screened lung cancer cell lines for splicing genes (genes that modify RNA) that might regulate telomerase in cancer, and identified NOVA1.

They found that reducing the NOVA1 gene reduced telomerase activity, which led to shorter telomeres, and cancer cells couldn’t survive and divide.

Researchers only looked at non-small cell lung cancers, and NOVA1 was present in about 70 percent of them.

“Non-small cell lung cancer is the most prevalent form of age-related cancer, and 80 to 85 percent of all lung cancers are non-small cell,” Ludlow said. “But there really aren’t that many treatments for it.”

According to the American Cancer Society, lung cancer causes the most cancer deaths among men and women, and is the second most common cancer, aside from skin cancer.

Before researchers can target NOVA1 or telomerase splicing as a serious potential therapy for non-small cell lung cancer, they must gain a much better understanding of how telomerase is regulated. This research is a step in that direction.

Ludlow’s group is also looking at ways to directly impact telomerase splicing, in addition to reducing NOVA1.

Explore further: Blocking two enzymes could make cancer cells mortal

More information: Andrew T. Ludlow et al, NOVA1 regulates hTERT splicing and cell growth in non-small cell lung cancer, Nature Communications (2018). DOI: 10.1038/s41467-018-05582-x

https://medicalxpress.com/news/2018-08-nova1-gene-tumor-growth-common.html

As the result of a six-year long research process, Fredrick R. Schumacher, a cancer epidemiology researcher at Case Western Reserve University School of Medicine, and an international team of more than 100 colleagues have identified 63 new genetic variations that could indicate higher risk of prostate cancer in men of European descent. The findings, published in a research letter in Nature Genetics, contain significant implications for which men may need to be regularly screened because of higher genetic risk of prostate cancer. The new findings also represent the largest increase in genetic markers for prostate cancer since they were first identified in 2006.

The changes, known as genetic markers or SNPs (“snips”), occur when a single base in the DNA differs from the usual base at that position. There are four types of bases: adenine (A), thymine (T), guanine (G) and cytosine (C). The order of these bases determines DNA’s instructions, or genetic code. They can serve as a flag to physicians that a person may be at higher risk for a certain disease. Previously, about 100 SNPs were associated with increased risk of prostate cancer. There are 3 billion base pairs in the human genome; of these, 163 have now been associated with prostate cancer.

One in seven men will be diagnosed with prostate cancer during their lifetimes.

“Our findings will allow us to identify which men should have early and regular PSA screenings and these findings may eventually inform treatment decisions,” said Schumacher. Prostate-specific antigen (PSA) screenings measure how much PSA, a protein produced by both cancerous and noncancerous tissue in the prostate, is in the blood.

Adding the 63 new SNPs to the 100 that are already known allows for the creation of a genetic risk score for prostate cancer. In the new study, the researchers found that men in the top one percent of the genetic risk score had a six-fold risk-increase of prostate cancer compared to men with an average genetic risk score. Those who had the fewest number of these SNPs, or a low genetic risk score, had the lowest likelihood of having prostate cancer.

In a meta-analysis that combined both previous and new research data, Schumacher, with colleagues from Europe and Australia, examined DNA sequences of about 80,000 men with prostate cancer and about 60,000 men who didn’t have the disease. They found that men with cancer had a higher frequency of 63 different SNPs (also known as single nucleotide polymorphisms) that men without the disease did not have. Additionally, the more of these SNPs that a man has, the more likely he is to develop prostate cancer.

The researchers estimate that there are about 500-1,000 genetic variants possibly linked to prostate cancer, not all of which have yet been identified. “We probably only need to know 10 percent to 20 percent of these to provide relevant screening guidelines,” continued Schumacher, who is an associate professor in the Department of Population and Quantitative Health Sciences at Case Western Reserve School of Medicine.

Currently, researchers don’t know which of the SNPs are the most predictive of increased prostate cancer risk. Schumacher and a number of colleagues are working to rank those most likely to be linked with prostate cancer, especially with aggressive forms of the disease that require surgery, as opposed to slowly developing versions that call for “watchful waiting” and monitoring.

The research lays a foundation for determining who and how often men should undergo PSA tests. “In the future, your genetic risk score may be highly indicative of your prostate cancer risk, which will determine the intensity of PSA screening,” said Schumacher. “We will be working to determine that precise genetic risk score range that would trigger testing. Additionally, if you have a low score, you may need screening less frequently such as every two to five years.” A further implication of the findings of the new study is the possibility of precise treatments that do not involve surgery. “Someday it may be feasible to target treatments based on a patient’s prostate cancer genetic risk score,” said Schumacher.

In addition to the work in the new study, which targets men of European background, there are parallel efforts underway looking at genetic signals of prostate cancer in men of African-American and Asian descent.

http://thedaily.case.edu/researchers-identify-dozens-new-gene-changes-point-elevated-risk-prostate-cancer-men-european-descent/


Researching tuberous sclerosis from the left are Adelaide Hebert, M.D.; John Slopis, M.D.; Mary Kay Koenig, M.D.; Joshua Samuels, M.D., M.P.H.; and Hope Northrup, M.D. PHOTO CREDIT Maricruz Kwon, UTHealth

Addressing a critical issue for people with a genetic disorder called tuberous sclerosis complex (TSC), doctors at The University of Texas Health Science Center at Houston (UTHealth) reported that a skin cream containing rapamycin significantly reduced the disfiguring facial tumors affecting more than 90 percent of people with the condition.

Findings of the multicenter, international study involving 179 people with tuberous sclerosis complex appear in the journal JAMA Dermatology.

“People with tuberous sclerosis complex want to look like everyone else,” said Mary Kay Koenig, M.D., the study’s lead author, co-director of the Tuberous Sclerosis Center of Excellence and holder of the Endowed Chair of Mitochondrial Medicine at McGovern Medical School at UTHealth. “And, they can with this treatment.”

Tuberous sclerosis complex affects about 50,000 people in the United States and is characterized by the uncontrolled growth of non-cancerous tumors throughout the body.

While benign tumors in the kidney, brain and other organs pose the greater health risk, the tumors on the face produce a greater impact on a patient’s daily life by making them look different from everyone else, Koenig said.

Koenig’s team tested two compositions of facial cream containing rapamycin and a third with no rapamycin. Patients applied the cream at bedtime for six months.

“Eighty percent of patients getting the study drug experienced a significant improvement compared to 25 percent of those getting the mixture with no rapamycin,” she said.

“Angiofibromas on the face can be disfiguring, they can bleed and they can negatively impact quality of life for individuals with TSC,” said Kari Luther Rosbeck, president and CEO of the Tuberous Sclerosis Alliance.

“Previous treatments, including laser surgery, have painful after effects. This pivotal study and publication are a huge step toward understanding the effectiveness of topical rapamycin as a treatment option. Further, it is funded by the TSC Research Program at the Department of Defense. We are so proud of this research,” Rosbeck said.

Rapamycin is typically given to patients undergoing an organ transplant. When administered by mouth, rapamycin suppresses the immune system to make sure the organ is not rejected.

Rapamycin and tuberous sclerosis complex are linked by a protein called mTOR. When it malfunctions, tuberous sclerosis complex occurs. Rapamycin corrects this malfunction.

Rapamycin was initially used successfully to treat brain tumors caused by tuberous sclerosis complex, so researchers decided to try it on TSC-related facial tumors. Building on a 2010 pilot study on the use of rapamycin to treat TSC-related facial tumors, this study confirmed that a cream containing rapamycin shrinks these tumors.

As the drug’s toxicity is a concern when taken by mouth, researchers were careful to check for problems tied to its use on the skin. “It looks like the medication stays on the surface of the skin. We didn’t see any appreciable levels in the bloodstreams of those participating in the study,” Koenig said.

The Topical Rapamycin to Erase Angiofibromas in TSC – Multicenter Evaluation of Novel Therapy or TREATMENT trial involved 10 test sites including one in Australia.

Koenig said additional studies are needed to gauge the long-term impact of the drug, the optimal dosage and whether the facial cream should be a combined with an oral treatment.

Koenig’s coauthors include Adelaide Hebert, M.D.; Joshua Samuels, M.D., M.P.H.; John Slopis, M.D.; Cynthia S. Bell; Joan Roberson, R.N.; Patti Tate; and Hope Northrup, M.D. All are from McGovern Medical School at UTHealth with the exception of Slopis, who is with The University of Texas MD Anderson Cancer Center. Hebert is also on the faculty of the MD Anderson Cancer Center and Northrup on the faculty of The University of Texas MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences.

The study was supported in part by the United States Department of Defense grant DOD TSCRP CDMRP W81XWH-11-1-0240 and by the Tuberous Sclerosis Alliance of Australia.

“The face is our window to the world and when you look different from everyone else, it impacts your confidence and your ability to interact with others. This treatment will help those with TSC become more like everyone else,” Koenig said.

https://www.uth.edu/media/story.htm?id=37af25df-14a2-4c5e-b1ee-ac9585946aa0

As many as one in three women treated for breast cancer undergo unnecessary procedures, but a new method for diagnosing it could do a better job distinguishing between benign and aggressive tumors.

Researchers at the University of Michigan are developing a pill that makes tumors light up when exposed to infrared light, and they have demonstrated that the concept works in mice.

Mammography is an imprecise tool. About a third of breast cancer patients treated with surgery or chemotherapy have tumors that are benign or so slow-growing that they would never have become life-threatening, according to a study out of Denmark last year. In other women, dense breast tissue hides the presence of lumps and results in deaths from treatable cancers. All that, and mammograms are notoriously uncomfortable.

“We overspend $4 billion per year on the diagnosis and treatment of cancers that women would never die from,” said Greg Thurber, U-M assistant professor of chemical engineering and biomedical engineering, who led the team. “If we go to molecular imaging, we can see which tumors need to be treated.”

The move could also catch cancers that would have gone undetected. Thurber’s team uses a dye that responds to infrared light to tag a molecule commonly found on tumor cells, in the blood vessels that feed tumors and in inflamed tissue. By providing specific information on the types of molecules on the surface of the tumor cells, physicians can better distinguish a malignant cancer from a benign tumor.

Compared to visible light, infrared light penetrates the body easily—it can get to all depths of the breast without an X-ray’s tiny risk of disrupting DNA and seeding a new tumor. Using a dye delivered orally rather than directly into a vein also improves the safety of screening, as a few patients in 10,000 can have severe reactions to intravenous dyes. These small risks turn out to be significant when tens of millions of women are screened every year in the U.S. alone.

But it’s not easy to design a pill that can carry the dye to the tumor.

“To get a molecule absorbed into the bloodstream, it needs to be small and greasy. But an imaging agent needs to be larger and water-soluble. So you need exact opposite properties,” Thurber said.

Fortunately, they weren’t the only people looking for a molecule that could get from the digestive system to a tumor. The pharmaceutical company Merck was working on a new treatment for cancer and related diseases. They got as far as phase II clinical trials demonstrating its safety, but unfortunately, it wasn’t effective.

“It’s actually based on a failed drug,” Thurber said. “It binds to the target, but it doesn’t do anything, which makes it perfect for imaging.”

The targeting molecule has already been shown to make it through the stomach unscathed, and the liver also gives it a pass, so it can travel through the bloodstream. The team attached a molecule that fluoresces when it is struck with infrared light to this drug. Then, they gave the drug to mice that had breast cancer, and they saw the tumors light up.

The research is described in a study in the journal Molecular Pharmaceutics, titled, “Oral administration and detection of a near-infrared molecular imaging agent in an orthotopic mouse model for breast cancer screening.”

This work was done in collaboration with David Smith, the John G. Wagner Collegiate Professor of Pharmaceutical Sciences at the U-M College of Pharmacy. It was supported by the Foundation for Studying and Combating Cancer and the National Institutes of Health.
Bhatnagar, S., Verma, K. D., Hu, Y., Khera, E., Priluck, A., Smith, D., & Thurber, G. M. (2018). Oral Administration and Detection of a Near-Infrared Molecular Imaging Agent in an Orthotopic Mouse Model for Breast Cancer Screening. Molecular Pharmaceutics. doi:10.1021/acs.molpharmaceut.7b00994

A small, daily dose of Viagra significantly reduces colorectal cancer risk in an animal model that is genetically predetermined to have the third leading cause of cancer death, scientists report.

Viagra cut in half the formation of polyps, an abnormal and often asymptomatic clump of cells on the lining of the intestines that may become cancer, says Dr. Darren D. Browning, cancer researcher at the Georgia Cancer Center and Department of Biochemistry and Molecular Biology at the Medical College of Georgia at Augusta University.

Next steps should include a clinical trial for the drug in patients considered at high risk of colorectal cancer, such as those with a strong family history, multiple previous polyps and chronic intestinal inflammation like colitis, Browning says.

Viagra has been used safely for years in a wide range of doses and age groups, from premature infants with pulmonary hypertension to the elderly with erectile dysfunction, he notes.

When placed in the drinking water, Browning’s team found that Viagra reduced polyps in a mouse model with a genetic mutation that occurs in humans, causing them to produce hundreds of polyps starting as teenagers and essentially always resulting in colorectal cancer, says Browning, corresponding author of the study in the journal Cancer Prevention Research.

“Giving a baby dose of Viagra can reduce the amount of tumors in these animals by half,” Browning says.

Viagra is best known for its ability to relax the smooth muscle cells around blood vessels so the vessels can more easily fill with blood, which is how it helps both erectile dysfunction and pulmonary hypertension. But Browning’s lab is showing it also increases levels of the chemical cyclic GMP, which is known to affect the intestinal lining, called the epithelium.

While the details of just how remain unclear, Browning and his team have seen that the results of increased cyclic GMP include suppression of some of the excessive cell proliferation that occurs in the gut and an increase in normal cell differentiation as well as the natural elimination of abnormal cells, through a process called apoptosis.

“When we give Viagra, we shrink the whole proliferating compartment,” says Browning, in an area of our body that directly deals with whatever we put in our mouths and normally experiences high cell turnover “Proliferating cells are more subject to mutations that cause cancer.”

Existing polyps were not affected, more evidence that targeting cyclic GMP signaling appears to be a good prevention strategy in high-risk patients, he says.

Viagra is known to inhibit PDE5, a naturally occurring enzyme in colon cells – and other tissues – that breaks down cyclic GMP so there is more of it available to reduce cell proliferation and improve differentiation into cells like the goblet cells that secret protective mucus.

Guanylyl-cyclase C, or GCC, is the primary source of cyclic GMP in the intestinal lining. Mice like those in his study with the genetic predisposition for polyps, were found to have reduced levels of GCC-activating peptides, which are also commonly lost in human colon cancers.

The mice have mutations in the APC – adenomatous polyposis coli – gene, a known tumor suppressor. Like these mice, people with mutations in the APC gene can develop hundreds of polyps in the colon and rectum and are considered at highest risk for colorectal cancer, says Browning of the inherited disorder called familial adenomatous polyposis. The average age at which individuals develop colon cancer is 39, according to the National Institutes of Health.

The scientists also looked at the prescription drug linaclotide, which is used to treat constipation and irritable bowel syndrome with constipation and, like Viagra, is known to increase cyclic GMP. While linaclotide was also effective at significantly reducing polyp formation, the common side effect of diarrhea at pretty much any dose makes it unlikely that patients would find it tolerable to use long term, even to reduce their cancer risk, Browning says. The low doses of Viagra used by humans and in the lab, on the other hand, have no known side effects, Browning notes.

Browning’s lab published a paper in July in Cancer Prevention Research that showed Viagra cut polyp formation in half in a mouse model of colitis, an inflammation of the colon and risk factor for colorectal cancer. But in this model as well, they found the drug targeted problems from the genetic mutations, although inflammation also was reduced.

He notes that inflammation is the driver in less than 5 percent of colorectal cancers. About 80 percent form spontaneously when cells in this high-cell turnover area divide and develop a mutation that may support uncontrolled proliferation. Mutations occur most often when we consume carcinogens like those found in processed or over-cooked meats.

In one of the first successes of its kind, researchers from Case Western Reserve University School of Medicine and six other institutions have inhibited the spreading of cancer cells from one part of the body to another. In doing so, they relied on a new model of how cancer metastasizes that emphasizes epigenetics, which examines how genes are turned on and off.

In a study published in Nature Medicine, the investigators—including scientists from the National Cancer Institute and Cleveland Clinic—used innovative epigenetic-centered techniques to halt the spread of bone cancer (osteosarcoma) cells to the lungs in mice.

The large majority of deaths associated with osteosarcoma are due to the spreading of the cancer to the lungs, a process known as metastasis. Most human osteosarcoma cases occur in children and young adults between the ages of 10 and 30, with teens the most frequently affected age group. Clinical outcomes for patients with osteosarcoma have not improved for more than 30 years, and there are currently no approved targeted anti-metastatic therapies for the disease in wide clinical use.

“More than 90 percent of all cancer deaths are the result of tumor metastasis, not primary-site tumors,” said the study’s senior author, Peter Scacheri, professor of genetics and genome sciences at Case Western Reserve University School of Medicine and member of the Case Comprehensive Cancer Center. “While many of the genes responsible for metastasis have been identified, the mechanisms that control these genes are not well defined. Our findings demonstrate that altered gene-enhancer activity is fundamental to a cancer cell’s ability to metastasize.”

Gene enhancers are short segments of DNA that, when bound by specialized proteins called transcription factors, function like switches to activate genes. This process is critical for normal development, as when a single fertilized egg develops into the many different cell types that comprise the body.

There are tens of thousands of gene enhancers in each cell, far more than the number of genes; they will be in different “on” and “off” positions in, for example, eye and heart cells (or gradients thereof, like a dimmer switch’s effects on the brightness-level of a light). These distinctive “on and off” profiles lend cells their unique characteristics, even though they all have the same DNA.

But faulty enhancer regulation appears to contribute to tumor-formation and subsequent spreading of cancer cells. In addition, different cancers are distinguishable by different enhancer patterns.

In this new study, the authors show that the on-off switches of cancer cells that have metastasized are in different positions than in the cells of the source tumor.

“Metastasis results from a complex set of traits acquired by tumor cells, distinct from those necessary for tumors to form in the first place,” said the study’s lead author, James J. Morrow, a medical student in the Medical Scientist Training Program at Case Western Reserve University School of Medicine. “Unfortunately, searching for gene mutations that drive metastasis has not substantially improved outcomes for patients with metastatic disease. Five-year survival rates for cancer patients with regional or localized disease have significantly improved for many types of cancer. But with few exceptions, outcomes for patients with metastatic cancer have remained stagnant.

“It is well established that primary tumor formation is driven by a combination of genetic and epigenetic events,” he continued. “So based on the knowledge that enhancers drive both normal cell development and tumor-formation, we hypothesized that they may play a similar role in the transition of cancer cells from one developmentally distinct tissue to another during metastatic progression.”

Through epigenomic profiling experiments, the Case Western Reserve-led researchers consistently identified certain bunched clusters of enhancers—known as metastatic variant enhancer loci (Met-VELs)—near cancer genes in lung metastases of patients with osteosarcoma, indicating that they were central to the metastatic process. Using experimental mouse models, the researchers then showed that growth of osteosarcoma cells in the lung can be mitigated by using BET inhibitors (anti-cancer drugs currently in clinical trials), which broadly interrupt the function of Met-VELs in driving gene expression.

Second, they demonstrated that the metastatic capacity of osteosarcoma cells can be diminished by blocking expression of individual genes regulated by Met-VELs or the transcription factors driving that regulation. They verified that a particular Met-VEL-linked gene, Tissue Factor (F3), is essential for metastatic colonization. Specifically, interrupting the signaling and pro-coagulant (blood clotting) functions of F3 with antibodies inhibiting these functions was sufficient to prevent metastasis. Additionally, they showed that deleting a single Met-VEL regulating F3 expression via the TALEN gene-editing process achieved a similar effect.

“Our experiments show that removing a single enhancer of the F3 gene in tumor cells virtually eliminates their ability to metastasize in mice,” said Scacheri. “Collectively, our findings establish that enhancer elements endow tumor cells with metastatic capacity and that targeted inhibition of genes associated with enhancer alterations, or deleting altered enhancers themselves is sufficient to block metastatic colonization and proliferation. While our work focused on lung metastasis in osteosarcoma, the findings have implications for other types of metastatic cancer as well.”

The Case Western Reserve University School of Medicine focus on epigenetics in the new study represents a break with the prevailing model for metastasis, which largely explores mutations in the genes—not if or how certain genes are turned on or off. And the preponderance of current cancer research takes place on the early stages of disease, such as how tumors are formed and on what distinguishes cancer cells from normal cells, and not on metastasis. Additionally, most cancer medications and treatments today were developed to kill primary tumors, not cancer cells that have spread elsewhere.

http://thedaily.case.edu/researchers-inhibit-cancer-metastases-via-novel-steps/