Showing posts sorted by relevance for query tamoxifen. Sort by date Show all posts
Showing posts sorted by relevance for query tamoxifen. Sort by date Show all posts

Monday, November 23, 2015

Tamoxifen drug clears MRSA, reduces mortality


In continuation of my update on Tamoxifen
Tamoxifen2DACS.svg


Researchers at University of California, San Diego School of Medicine and Skaggs School of Pharmacy and Pharmaceutical Sciences have found that the breast cancer drug tamoxifen gives white blood cells a boost, better enabling them to respond to, ensnare and kill bacteria in laboratory experiments. Tamoxifen treatment in mice also enhances clearance of the antibiotic-resistant bacterial pathogen MRSA and reduces mortality.

The study is published October 13 by Nature Communications.

"The threat of multidrug-resistant bacterial pathogens is growing, yet the pipeline of new antibiotics is drying up. We need to open the medicine cabinet and take a closer look at the potential infection-fighting properties of other drugs that we already know are safe for patients," said senior author Victor Nizet, MD, professor of pediatrics and pharmacy. "Through this approach, we discovered that tamoxifen has pharmacological properties that could aid the immune system in cases where a patient is immunocompromised or where traditional antibiotics have otherwise failed."

Tamoxifen targets the estrogen receptor, making it particularly effective against breast cancers that display the molecule abundantly. But some evidence suggests that tamoxifen has other cellular effects that contribute to its effectiveness, too. For example, tamoxifen influences the way cells produce fatty molecules, known as sphingolipids, independent of the estrogen receptor. Sphingolipids, and especially one in particular, ceramide, play a role in regulating the activities of white blood cells known as neutrophils.

"Tamoxifen's effect on ceramides led us to wonder if, when it is administered in patients, the drug would also affect neutrophil behavior," said first author Ross Corriden, PhD, project scientist in the UC San Diego School of Medicine Department of Pharmacology.

To test their theory, the researchers incubated human neutrophils with tamoxifen. Compared to untreated neutrophils, they found that tamoxifen-treated neutrophils were better at moving toward and phagocytosing, or engulfing, bacteria. Tamoxifen-treated neutrophils also produced approximately three-fold more neutrophil extracellular traps (NETs), a mesh of DNA, antimicrobial peptides, enzymes and other proteins that neutrophils spew out to ensnare and kill pathogens. Treating neutrophils with other molecules that target the estrogen receptor had no effect, suggesting that tamoxifen enhances NET production in a way unrelated to the estrogen receptor. Further studies linked the tamoxifen effect to its ability to influence neutrophil ceramide levels.

Ref : http://www.nature.com/ncomms/2015/151013/ncomms9369/full/ncomms9369.html

Sunday, February 21, 2010

New strategy to overcome drug resistance (tamoxifen) in breast cancer ?

A solution to tamoxifen resistance is sorely needed, and if a strategy like this can work, it would make a difference in our clinical care of breast cancer,” says the study’s lead investigator. Yes, the researchers lead by Dr. Robert Clarke of Georgetown Lombardi Comprehensive Cancer Center have come with an interesting finding i.e., combining tamoxifen, the world’s most prescribed breast cancer agent  with a compound (Parthenolide,  see left structure source : ChemSpider) found in the flowering plant feverfew (right picture) may prevent initial or future resistance to the drug. 
 
As per the claim by the researchers tamoxifen resistance is regulated by the protein complex NF- κB (nuclear factor kappa B), which is often found to be over-expressed in ER+ breast cancer. NF- κB is known to help cells survive when damaged. Earlier the same researchers have also found that, the resistance to another tamoxifen-like drug, fulvestrant, was controlled by a protein (Bcl2) which is also regulated by NF- κB. These findings  encouraged  them to think that,  blocking NF- κB might affect tamoxifen resistance

Researchers conducted a variety of tests using parthenolide, which has been shown to act on NF- κB. They found that in resistant breast cancer cells, the chemical blocked the activity of NF- κB, making the cells sensitive once again to tamoxifen. Researchers then silenced NF- κB in tamoxifen resistant cells, and found that this had the same effect as using parthenolide. 

They further found that increased activation of NF- κB can alter sensitivity of tamoxifen by modulating the protein CASP8 (which is involved in programmed cell death), which affects Bcl2  and there by  helping  to  push a damaged cell to die.  
 
About Feverfew

Feverfew (Tanacetum parthenium) is edible and medicinal plant and   has a good reputation as alternative medicine and extensive research has proved it to be of special benefit in the treatment of certain types of migraine headaches and rheumatism or arthritis. The plant is rich in sesquiterpene lactones, the principal one being parthenolide. Parthenolide helps prevent excessive clumping of platelets and inhibits the release of certain chemicals, including serotonin and some inflammatory mediators. (other constituents are: pinene, pinene derivatives, bornylacetate, angelate, b-farnesine, spiroketalenol ethers, flavonoid glycosides and costic acid) .

Though the leaves and flowering heads are reported to possess antiinflammatory, antispasmodic, aperient,  sedative, stimulant, stomachic, vasodilator and vermifuge. activities, this type of activity has been reported  for the first time. 
 
Researchers conclude that the chemical, clearly has the potential to be able to figure out fairly  and it can help solve tamoxifen’s resistance problem with a caution that the science is much too early to make any recommendations. Let us wait for some more time.......

Sunday, January 20, 2013

Tamoxifen can counteract some pathologic features in mouse model of DMD

 In continuation of my update on Tamoxifen

Using the mdx5Cv mouse model of DMD, investigators found that tamoxifen, given orally for more than a year, "caused remarkable improvements of muscle force and of diaphragm and cardiac structure," according to lead author Olivier M. Dorchies, PhD, of the Department of Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences of the University of Geneva and University of Lausanne. For instance, in the heart, fibrosis was diminished by approximately 50%. In the diaphragm, the muscle of the dystrophic mouse thought to be most like that of human DMD, tamoxifen reduced fibrosis while increasing thickness as well as the number and average diameter of muscle fibers. The net effect was that tamoxifen raised the amount of contractile tissue available for respiration by 72%.


Patients with DMD show muscle degeneration, and their muscle fibers become abnormally susceptible to stress. In this animal study, tamoxifen improved the structure of leg muscles, slowed muscle contraction, increased overall muscle function, and made leg muscles more resistant to repetitive stimulation and fatigue. In fact, tamoxifen rendered dystrophic muscles even stronger than those of non-dystrophic control mice. "Our findings of a slower rate of contraction and an enhanced resistance to fatigue in muscles from tamoxifen-treated dystrophic mice are of significance for the pathophysiology of muscular dystrophy," say the authors.


More : http://www.journals.elsevierhealth.com/periodicals/ajpa/article/S0002-9440%2811%2901061-3/abstract
 

Friday, February 12, 2016

Study reveals why anti-hormone therapy tamoxifen works better in some women than others

Tamoxifen2DACS.svg
In continuation of my update on tamoxifen


The anti-hormone therapy tamoxifen can reduce breast cancer recurrence by about half in women with hormone-sensitive breast cancer. But it works better in some women than others. Researchers are not sure why.

"We do know that some tumors are inherently resistant to tamoxifen because of tumor genetic changes," says Daniel L. Hertz, Pharm.D., Ph.D., an assistant professor in the University of Michigan College of Pharmacy and member of the U-M Comprehensive Cancer Center.

"These tumor have found pathways to overcome anti-estrogen treatment. But we also believe some patients may be less likely to benefit from tamoxifen or endocrine therapy because of their genetics," Hertz says.

One theory is that in some patients, tamoxifen is not activated to the more potent estrogen inhibitor endoxifen. Patients with low levels of endoxifen may have worse outcomes on tamoxifen.

A meta-analysis by the International Tamoxifen Pharmacogenetics Consortium points to genetic variants. Researchers found patients with certain variants on the gene CYP2D6 had worse survival. Later analyses of prospective clinical trials, however, did not find the same link.

Wednesday, March 24, 2021

Team finds that their cancer-fighting compound fights obesity and diabetes, too

Eric Prossnitz, Ph.D., and his team hope to help 93 million obese Americans fight their fat.
In a paper published in Science Translational Medicine, they reported that G-1, a cancer-fighting compound they discovered some years ago, reduces fat in obese mice. Although G-1 is currently in phase 1 clinical trials for cancer, Prossnitz and his team are planning preclinical studies to use G-1 to fight fat in obese people.
Obesity affects 40% of adults in the United States, resulting in health conditions that include heart disease, high blood pressure, type 2 diabetes and some cancers. According to the U.S. Centers for Disease Control and Prevention, obesity and its related conditions far outweigh other causes of death. Current drugs for obesity don't effectively reduce it or have undesirable side effects.
Prossnitz and his team have been studying GPER, the G protein-coupled estrogen receptor that G-1 activates, because GPER affects certain breast cancer cells. When breast cancer drugs like tamoxifen and fulvestrant block estrogen receptors in a cell's nucleus, they also activate GPER, which is found in cell membranes.
Prossnitz's previous studies showed that GPER may play a role in resistance to tamoxifen and similar drugs, and that led him to wonder how G-1 affects non-cancerous cells when estrogen is lacking.
Estrogen is considered a female hormone, although men produce it at low levels. Low estrogen in women is a hallmark of menopause, and postmenopausal women also have higher rates of heart disease, high blood pressure, obesity and diabetes. So to understand whether G-1 might affect metabolism in postmenopausal women, Prossnitz and his team studied mice with low estrogen levels.
In their studies, low-estrogen female mice gained weight rapidly, even on a normal diet, and quickly became obese and diabetic. When the researchers treated these obese female mice with G-1, the mice lost weight and their diabetes went away.
The researchers determined that the weight loss wasn't due to the mice eating less or moving around more; it resulted from what their bodies did with the calories they ate. Instead of storing calories as fat, the mice used them as fuel.
"Their metabolism changed," Prossnitz says. "The mice showed an increased energy expenditure."
Prossnitz's team also studied male mice, which have naturally low levels of estrogen. The male mice were fed a high-fat diet, which made them obese and diabetic, and then some were treated with G-1. Although the treated mice did not lose weight, they did not gain additional weight either, like the untreated mice. More importantly, their diabetes improved.
"This result suggests that G-1 has separate effects on obesity and diabetes," Prossnitz says. "The G-1-treated male mice were metabolically healthier, even though they were still obese."
Finally, the team also fed a high-fat diet to low-estrogen female mice. These mice became obese very quickly, but just like their sisters on a normal mouse diet, they lost weight and their diabetes improved when they were treated with G-1. These results, says Prossnitz, could point to a sex difference in the effects of the drug or in the way GPER signals in the cells of males and females.
To learn about how G-1 increases energy expenditure, the team studied brown fat cells, which generate heat instead of storing excess calories as fat. What they found surprised them: when treated with G-1, the cells expended more energy.
"This fits nicely with what we saw in mice," Prossnitz says, "and suggests that G-1 may reduce obesity by targeting brown fat cells that burn extra calories."
In a future series of experiments, Prossnitz plans to study how signals from GPER induce the cellular changes that cause more energy to be used. He hopes that one day soon G-1 could revolutionize the treatment of metabolic disorders.
In the meantime, he and his team are starting the long path toward clinical trials that will test the ability G-1 to fight obesity and diabetes in people.
https://stm.sciencemag.org/content/12/528/eaau5956/tab-figures-data

Sunday, December 25, 2011

Notch inhibitor appears to treat breast cancer....

In a novel therapeutic approach to treating breast cancer, Loyola University Medical Center researchers are reporting positive results from a clinical trial of a drug that targets tumor stem cells. A pilot study at Loyola found that an experimental drug known as a "notch inhibitor" appears to block this process by turning off key genes. Prior to surgery, the patients received one of two commonly used drugs, tamoxifen or letrozole. These drugs work by blocking estrogen stimulation of breast cancer cells. In addition to tamoxifen or letrozole, patients also received the experimental notch-inhibitor drug, MK-0752 (see structure).


 "The notch inhibitor appears to be doing what it is intended to do," said Dr. Clodia Osipo....
There were minimal side effects from either the notch inhibitor or the estrogen-blocking drugs. One patient experienced puffy eyes and coughing and four patients experienced facial acne. No patients experienced diarrhea or surgical complications.


Ref : Loyola Medicine News Release

Friday, December 13, 2013

First in-human trial of endoxifen shows promise as breast cancer treatment



Estrogen receptor α (ERα) ligand; potent antiestrogen. Metabolite of tamoxifen (Cat. No. 0999). Primary metabolite responsible for the effectiveness of tamoxifen in ER-positive breast cancer...

Thursday, August 4, 2011

Taxoxifen combined with dasatinib reverses chemo-resistance in breast cancer cells

Researchers from Thomas Jefferson University Hospita,  found that taxoxifen combined with dasatinib, a protein-tyrosine kinase inhibitor, reverses the chemo-resistance caused by cancer-associated fibroblasts in the surrounding tissue by normalizing glucose intake and reducing mitochondrial oxidative stress, the process that fuels the cancer cells. 

In this study, researchers sought to better understand drug resistance by looking at the metabolic basis in an ER (+) cell line and cancer-associated fibroblasts.  Researchers claim that the  resistance to chemotherapeutic agents is a metabolic and stromal phenomenal  and the drug combination had an "antioxidant effect" in these types of cancer cells.  

Researchers showed that ER (+) cancer cells alone responded to tamoxifen but when co-cultured with human fibroblasts had little to no effect. Similarly, dasatinib, a chemotherapy drug used to treat leukemia patients who can no longer benefit from other medications, had no effect on fibroblasts alone or cancer cells. Together, however, the drugs prevented the cancer cells co-cultured with the fibroblasts from using high-energy nutrients from the fibroblasts. Researchers conclude that, 

"The drugs have no effect when they are used alone-it's in unison when they effectively kill the cancer cells in the presence of fibroblasts and combination resulted in nearly 80 percent cell death" 

Ref: http://www.jeffersonhospital.org/News/leukemia-drug-reverses-tamoxifen-resistance-in-breast-cancer-cells.aspx


Friday, February 20, 2015

Researchers identify 53 existing drugs that may block Ebola virus from entering human cells



Researchers found 53 existing drugs that may keep the Ebola virus from entering human cells, a key step in the process of infection, according to a study led by researchers at the Icahn School of Medicine at Mount Sinai and the National Institutes of Health (NIH), and published today in the Nature Press journal Emerging Microbes and Infections.

Among the better known drug types shown to hinder infection by an Ebola virus model: several cancer drugs, antihistamines and antibiotics. Among the most effective at keeping the virus out of human cells were microtubule inhibitors used to treat cancer.

"In light of the historic and devastating outbreak of Ebola virus disease, there is an urgent need to rapidly develop useful treatments against Ebola infection, and our study results argue that repurposing existing drugs may be among the fastest ways to achieve this," said lead author Adolfo García-Sastre, PhD, Director of the Global Health and Emerging Pathogens Institute within the Icahn School of Medicine at Mount Sinai. "Many of the compounds identified in this study promise to become lead compounds in near-future drug development efforts studies targeting this virus," said Dr. García-Sastre, also the Fishberg Chair and Professor of Medicine (Infectious Diseases) within the School.

A few are listed below...


Ref : http://www.nature.com/emi/journal/v3/n12/full/emi201488a.html

Nocodazole (IC50=0.4 µM), Toremifene (0.55 µM), Tamoxifen (0.76 µM), Raloxifene 1.84 (1.53 µM), Cepharanthine (1.53 µM), Clomiphene (1.72 µM), Dronedarone (2.2 µM), Amodiaquine (4.43 µM), Imipramine (13.7 µM), Chloroquine (15.3 µM), and Nilotinib (15.3 µM).




Sunday, December 13, 2009

Bisphosphonates play a role in reducing recurrent breast cancer....


We know that bisphosphonates (also called diphosphonates) are a class of drugs that prevent the loss of bone mass, used to treat osteoporosis and similar diseases. Bone has constant turnover, and is kept in balance (homeostasis) by osteoblasts creating bone and osteoclasts digesting bone. Bisphosphonates inhibit the digestion of bone by osteoclasts. Osteoclasts also have constant turnover and normally destroy themselves by a process called cell suicide (apoptosis). Bisphosphonates encourage osteoclasts to undergo apoptosis. Though other uses like in he treatments of osteoporosis, osteitis deformans, bone metastasis, primary multiple myeloma,hyperparathyroidism and osteogenesis imperfecta were known. A new data suggests that these agents may play a role in reducing recurrent breast cancer as well. Zoledronic acid (see the structure) is both safe and effective in preventing bone loss in postmenopausal women with breast cancer who are treated with aromatase inhibitors, according to data presented at the CTRC-AACR San Antonio Breast Cancer Symposium. Women who take aromatase inhibitors need some sort of bone protection, and this five-year data show that zoledronic acid is a viable option.

As per the claim by the researchers lead by Dr. Adam Brufsky , women who are on Medicare tend to go with tamoxifen because the cost of anastrozole puts them squarely in the donut hole of Medicare Part D, but once the cost barrier is removed there will likely be a mass switch to the aromatase inhibitor, which will necessitate the need for bone protection. More interestingly, in the same conference a research group lead by Rowan Chlebowski presented a study wherein "women who used bisphosphonates, had significantly fewer invasive breast cancers than women who did not use bisphosphonates. .......

http://www.upci.upmc.edu/news/upci_news/121009_study.cfm