Monthly Archives: March 2014

One in a thousand children in the United States is deaf, and one in three adults will experience significant hearing loss after the age of 65. Whether the result of genetic or environmental factors, hearing loss costs billions of dollars in healthcare expenses every year, making the search for a cure critical.

Now a team of researchers led by Karen B. Avraham of the Department of Human Molecular Genetics and Biochemistry at Tel Aviv University's Sackler Faculty of Medicine and Yehoash Raphael of the Department of Otolaryngology-Head and Neck Surgery at University of Michigan's Kresge Hearing Research Institute have discovered that using DNA as a drug -- commonly called gene therapy -- in laboratory mice may protect the inner ear nerve cells of humans suffering from certain types of progressive hearing loss.

In the study, doctoral student Shaked Shivatzki created a mouse population possessing the gene that produces the most prevalent form of hearing loss in humans: the mutated connexin 26 gene. Some 30 percent of American children born deaf have this form of the gene. Because of its prevalence and the inexpensive tests available to identify it, there is a great desire to find a cure or therapy to treat it.

"Regenerating" neurons

Prof. Avraham's team set out to prove that gene therapy could be used to preserve the inner ear nerve cells of the mice. Mice with the mutated connexin 26 gene exhibit deterioration of the nerve cells that send a sound signal to the brain. The researchers found that a protein growth factor used to protect and maintain neurons, otherwise known as brain-derived neurotrophic factor (BDNF), could be used to block this degeneration. They then engineered a virus that could be tolerated by the body without causing disease, and inserted the growth factor into the virus. Finally, they surgically injected the virus into the ears of the mice. This factor was able to "rescue" the neurons in the inner ear by blocking their degeneration.

"A wide spectrum of people are affected by hearing loss, and the way each person deals with it is highly variable," said Prof. Avraham. "That said, there is an almost unanimous interest in finding the genes responsible for hearing loss. We tried to figure out why the mouse was losing cells that enable it to hear. Why did it lose its hearing? The collaborative work allowed us to provide gene therapy to reverse the loss of nerve cells in the ears of these deaf mice."

Although this approach is short of improving hearing in these mice, it has important implications for the enhancement of sound perception with a cochlear implant, used by many people whose connexin 26 mutation has led to impaired hearing.

Embryonic hearing?

Inner ear nerve cells facilitate the optimal functioning of cochlear implants. Prof. Avraham's research suggests a possible new strategy for improving implant function, particularly in people whose hearing loss gets progressively worse with time, such as those with profound hearing loss as well as those with the connexin gene mutation. Combining gene therapy with the implant could help to protect vital nerve cells, thus preserving and improving the performance of the implant.

More research remains. "Safety is the main question. And what about timing? Although over 80 percent of human and mouse genes are similar, which makes mice the perfect lab model for human hearing, there's still a big difference. Humans start hearing as embryos, but mice don't start to hear until two weeks after birth. So we wondered, do we need to start the corrective process in utero, in infants, or later in life?" said Prof. Avraham.

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From mouse ears to human's? Gene therapy to address progressive hearing loss

PUBLIC RELEASE DATE:

24-Mar-2014

Contact: Jen Gundersen jeg2034@med.cornell.edu 646-317-7402 Weill Cornell Medical College

NEW YORK (March 24, 2014) Scientists from Weill Cornell Medical College and Houston Methodist have found that a gene previously unassociated with breast cancer plays a pivotal role in the growth and progression of the triple negative form of the disease, a particularly deadly strain that often has few treatment options. Their research, published in this week's Nature, suggests that targeting the gene may be a new approach to treating the disease.

About 42,000 new cases of triple negative breast cancer (TNBC) are diagnosed in the United States each year, about 20 percent of all breast cancer diagnoses. Patients typically relapse within one to three years of being treated.

Senior author Dr. Laurie H. Glimcher, the Stephen and Suzanne Weiss Dean of Weill Cornell Medical College, wanted to know whether the gene already understood from her prior work to be a critical regulator of immune and metabolic functions was important to cancer's ability to adapt and thrive in the oxygen- and nutrient-deprived environments inside of tumors. Using cells taken from patients' tumors and transplanted into mice, Dr. Glimcher's team found that the gene, XBP1, is especially active in triple negative breast cancer, particularly in the progression of malignant cells and their resurgence after treatment.

"Patients with the triple negative form of breast cancer are those who most desperately need new approaches to treat their disease," said Dr. Glimcher, who is also a professor of medicine at Weill Cornell. "This pathway was activated in about two-thirds of patients with this type of breast cancer. Now that we better understand how this gene helps tumors proliferate and then return after a patient's initial treatment, we believe we can develop more effective therapies to shrink their growth and delay relapse."

The group, which included investigators from nine institutions, examined several types of breast cancer cell lines. They found that XBP1 was particularly active in basal-like breast cancer cells cultivated in the lab and in triple negative breast cancer cells from patients. When they suppressed the activity of the gene in laboratory cell cultures and animal models, however, the researchers were able to dramatically reduce the size of tumors and the likelihood of relapse, especially when these approaches were used in conjunction with the chemotherapy drugs doxorubicin or paclitexel. The finding suggests that XBP1 controls behaviors associated with tumor-initiating cells that have been implicated as the originators of tumors in a number of cancers, including that of the breast, supporting the hypothesis that combination therapy could be an effective treatment for triple negative breast cancer.

The scientists also found that interactions between XBP1 and another transcriptional regulator, HIF1-alpha, spurs the cancer-driving proteins. Silencing XBP1 in the TNBC cell lines reduced the tumor cells' growth and other behaviors typical of metastasis.

"This starts to demonstrate how cancer cells co-opt the endoplasmic reticulum stress response pathway to allow tumors to grow and survive when they are deprived of nutrients and oxygen," said lead author Dr. Xi Chen, a postdoctoral associate at Weill Cornell, referring to the process by which healthy cells maintain their function. "It shows the interaction between two critical pathways to make the cells better able to deal with a hostile microenvironment, and in that way offers new strategies to target triple negative breast cancer."

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Gene implicated in progression and relapse of deadly breast cancer finding points to potential Achilles' heel in ...

Scientists from Weill Cornell Medical College and Houston Methodist have found that a gene previously unassociated with breast cancer plays a pivotal role in the growth and progression of the triple negative form of the disease, a particularly deadly strain that often has few treatment options. Their research, published in this week's Nature, suggests that targeting the gene may be a new approach to treating the disease.

About 42,000 new cases of triple negative breast cancer (TNBC) are diagnosed in the United States each year, about 20 percent of all breast cancer diagnoses. Patients typically relapse within one to three years of being treated.

Senior author Dr. Laurie H. Glimcher, the Stephen and Suzanne Weiss Dean of Weill Cornell Medical College, wanted to know whether the gene -- already understood from her prior work to be a critical regulator of immune and metabolic functions -- was important to cancer's ability to adapt and thrive in the oxygen- and nutrient-deprived environments inside of tumors. Using cells taken from patients' tumors and transplanted into mice, Dr. Glimcher's team found that the gene, XBP1, is especially active in triple negative breast cancer, particularly in the progression of malignant cells and their resurgence after treatment.

"Patients with the triple negative form of breast cancer are those who most desperately need new approaches to treat their disease," said Dr. Glimcher, who is also a professor of medicine at Weill Cornell. "This pathway was activated in about two-thirds of patients with this type of breast cancer. Now that we better understand how this gene helps tumors proliferate and then return after a patient's initial treatment, we believe we can develop more effective therapies to shrink their growth and delay relapse."

The group, which included investigators from nine institutions, examined several types of breast cancer cell lines. They found that XBP1 was particularly active in basal- like breast cancer cells cultivated in the lab and in triple negative breast cancer cells from patients. When they suppressed the activity of the gene in laboratory cell cultures and animal models, however, the researchers were able to dramatically reduce the size of tumors and the likelihood of relapse, especially when these approaches were used in conjunction with the chemotherapy drugs doxorubicin or paclitexel. The finding suggests that XBP1 controls behaviors associated with tumor-initiating cells that have been implicated as the originators of tumors in a number of cancers, including that of the breast, supporting the hypothesis that combination therapy could be an effective treatment for triple negative breast cancer.

The scientists also found that interactions between XBP1 and another transcriptional regulator, HIF1-alpha, spurs the cancer-driving proteins. Silencing XBP1 in the TNBC cell lines reduced the tumor cells' growth and other behaviors typical of metastasis.

"This starts to demonstrate how cancer cells co-opt the endoplasmic reticulum stress response pathway to allow tumors to grow and survive when they are deprived of nutrients and oxygen," said lead author Dr. Xi Chen, a postdoctoral associate at Weill Cornell, referring to the process by which healthy cells maintain their function. "It shows the interaction between two critical pathways to make the cells better able to deal with a hostile microenvironment, and in that way offers new strategies to target triple negative breast cancer."

Scientists still need to study how those strategies would help women with the disease.

"Obviously we need to know now whether what our group saw in models is what we'll see in patients," said coauthor Dr. Jenny Chang, professor of medicine at Weill Cornell and director of the Houston Methodist Cancer Center. "We are very excited about the prospect of moving this research forward as soon as possible for the benefit of patients."

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Newswise HOUSTON -- (March 24, 2014) -- Scientists from Houston Methodist and Weill Cornell Medical College have found that a gene previously unassociated with breast cancer plays a pivotal role in the growth and progression of the triple negative form of the disease, which can be particularly deadly, with few treatment options. Their research, published in the April 3 Nature (online today), suggests that targeting the gene may be a new approach to treat the disease.

"We are really beginning to understand what initiates the cancer and why cancer cells evade treatment," said coauthor and Houston Methodist Cancer Center Director Jenny Chang, M.D. "Our group learned this pathway was activated in about two-thirds of patients with this type of breast cancer, and we believe we may be able to treat the disease by manipulating elements of the pathway."

About 42,000 new cases of triple negative breast cancer (TNBC) are diagnosed in the United States each year, about 20 percent of all breast cancer diagnoses. Patients who relapse typically do so within one to three years of being treated.

Senior author Laurie H. Glimcher, M.D., the Stephen and Suzanne Weiss Dean of Weill Cornell Medical College, wanted to know whether the gene -- already understood from her prior work to be a critical regulator of immune and metabolic functions -- was important to cancer's ability to adapt and thrive in the oxygen- and nutrient-deprived environments inside of tumors. Using cells taken from patients' tumors and transplanted into mice, Glimcher's team found that the gene, XBP1, is especially active in TNBC, particularly in the progression of malignant cells and their resurgence after treatment.

"Patients with the triple negative form of breast cancer are those who most desperately need new approaches to treat their disease," said Glimcher, who is also a professor of medicine at Weill Cornell. "This pathway was activated in about two-thirds of patients with this type of breast cancer. Now that we better understand how this gene helps tumors proliferate and then return after a patient's initial treatment, we believe we can develop more effective therapies to shrink their growth and delay relapse."

The group, which included investigators from nine institutions, examined several types of breast cancer cell lines. They found that XBP1 was particularly active in basal-like breast cancer cells cultivated in the lab and in TNBC cells from patients. When they suppressed the activity of the gene in laboratory cell cultures and animal models, however, the researchers were able to dramatically reduce the size of tumors and the likelihood of relapse, especially when these approaches were used in conjunction with the chemotherapy drugs doxorubicin or paclitaxel. The finding suggests that XBP1 controls behaviors associated with tumor-initiating cells that have been implicated as the originators of tumors in a number of cancers, including that of the breast, supporting the hypothesis that combination therapy could be an effective treatment for TNBC.

The scientists also found that interactions between XBP1 and another transcriptional regulator, HIF1-alpha, spurs the cancer-driving proteins. Silencing XBP1 in the TNBC cell lines reduced the tumor cells' growth and other behaviors typical of metastasis.

"This starts to demonstrate how cancer cells co-opt the endoplasmic reticulum stress response pathway to allow tumors to grow and survive when they are deprived of nutrients and oxygen," said lead author Xi Chen, Ph.D., a postdoctoral associate at Weill Cornell, referring to the process by which healthy cells maintain their function. "It shows the interaction between two critical pathways to make the cells better able to deal with a hostile microenvironment, and in that way offers new strategies to target triple negative breast cancer."

Read more:
Triple Negative Breast Cancer's Progression and Relapse Pinned to a Gene