The weekly catch-up from Google Alerts for Breast Cancer and Cancer for the week ending 25 April 2014.
This week’s lead article is a study showing the link between gut bacteria and breast cancer.
It’s hard to believe that the breast, which is considered a sterile environment, can contain gut bacteria. And more significantly, that certain gut bacteria may exist in the breast, and play a role in preventing breast tumours.
I like the idea of hopefully one day being able to ingest a food product, like a yoghurt, knowing that it can help to prevent breast cancer. Unfortunately, there’s no mention in the study of where to get this “breast probiotic” – I don’t think it’s something that’s on the supermarket shelves yet.
In other developments this week, scientists find (yet another) way of sensitising cells that are resistant to chemotherapy; discover why some people are resistant to anti-estrogenic treatments and in yet another study show that Vitamin C can decrease breast cancer mortality risk.
1. Scientists may have found a link between bacteria and breast cancer
- A team of California researchers set out to determine if breast tumors contained bacteria and if this was reflective of dysbiosis.
- Earlier in 2014, the team released (“Microbial Dysbiosis Is Associated with Human Breast Cancer“) their findings: Not only did cancerous breasts contain microbes, so did healthy ones.
- The team identified a potential ‘breast probiotic’ organism in healthy tissue, Sphingomonas yanoikuyae, which is better known to degrade pollutants in the environment.
- Although no specific benefit to prevent cancer was suggested, members of this bacteria are able to use estradiols including 17-β estradiol, which is believed to be associated with this type of cancer.
- Not surprisingly, in cancerous samples, there was little to none of these bacteria found.
- The study’s quantitative survey of breast microbiota found that the amount of bacteria was not significantly different in paired normal tissue of breast cancer patients and healthy individuals. However, compared to both of these healthy tissues, breast tumour tissue had significantly reduced amounts of bacteria.
- Although there appeared to be a possible link between a lack of S. yanoikuyae and cancer, the authors could not determine if this was indicative of a possible cause.
- The study follows previous research suggesting a link between microbiota imbalance and various human diseases including obesity, diabetes and colon cancer.
For more information: PLoS One. 2014; 9(1): e83744, Microbial Dysbiosis Is Associated with Human Breast Cancer
2. Scientists find way to sensitise cells resistant to chemotherapy
- Cancer cells replicate rapidly, and chemotherapy drugs such as paclitaxel target mitosis as a way to kill these quickly dividing cells. But cancer cells can develop resistance to the drugs.
- Researchers at Manchester University found a particular protein known as ‘Bid’ in colon cancer cells, and looked at what happened when Bid was switched on.
- Their results show that Bid is turned on as cells prepare to divide.
- This primes the cells to die if cell division takes too long.
- Cancer cells that were resistant to chemotherapy still turned Bid on, but went through mitosis too quickly for it to kill the cell.
- However, these resistant cells could be made to die by directly targeting the part of the cell where Bid works.
3. Proteins conspire to make breast cancer cells resistant to antiestrogen treatments
- Scientists at Sanford-Burnham Medical Research Institute have shown that two proteins implicated in antiestrogen resistance and malignancy are breast cancer antiestrogen resistance proteins 1 and 3 (BCAR1 and BCAR3), which can bind together to potentially connect the signaling pathways they each regulate.
- In the study, the researchers also identified a signaling pathway that is crucial for drug resistance mediated by this protein complex.
- Antiestrogen resistance mediated by the BCAR1-BCAR3 complex depends on ERK1/2 signaling, which was previously implicated in breast cancer malignancy.
- ERK1/2 stands for extracellular-signal-regulated kinase 1 and 2, and carries out activation and signaling tasks between molecules and cells.
- Moreover, analysis of more than 400 tumors from an invasive breast cancer study revealed that higher levels of an ERK1/2-inhibiting protein called PEA15 were predictive of longer patient survival.
- Drug resistance is one of the most serious obstacles to breast cancer eradication.
- Inhibiting ERK1/2 activity through PEA15 may be a useful strategy to counteract breast cancer malignancy and resistance to chemotherapeutic agents
For more information: The Journal of Biological Chemistry, April 11, 2014, Association of the Breast Cancer Antiestrogen Resistance Protein 1 (BCAR1) and BCAR3 Scaffolding Proteins in Cell Signaling and Antiestrogen Resistance
4. Increased vitamin C intake reduced breast cancer mortality risk
- In women with breast cancer, an increased consumption of vitamin C in the diet was associated with reduced mortality risk, according to recent findings.
- Additionally, a post-diagnostic daily regimen of vitamin C supplementation may confer survival benefits.
- In the meta-analysis, researchers conducted a literature search of the PubMed database for relevant prospective studies through Feb. 6, 2014.
- The 10 studies selected for inclusion presented RRs with 95% CIs for at least two categories. The investigators constructed random-effects models to pool study-specific outcomes.
- “The association between dietary vitamin C intake and breast cancer survival is inconsistent and few studies have specifically examined vitamin C supplement use among women with breast cancer,” the researchers wrote.
- “Results from this meta-analysis suggest that post-diagnosis vitamin C supplement use may be associated with a reduced risk of mortality. Dietary vitamin C intake was also statistically significantly associated with a reduced risk of total mortality and breast cancer-specific mortality.”
5. Gold nanoparticles help target, quantify breast cancer gene segments in a living cell
- Purdue University researchers have developed a way to detect and measure cancer levels in a living cell by using tiny gold particles with tails of synthetic DNA.
- This is a simple yet sophisticated technique that can be used to detect cancer in a single cell and determine how aggressive it is.
- Being able to quantify these genetic molecules could ultimately help clinicians provide better and more individualized treatment to cancer patients.
- BRCA1 is a tumor suppressor gene that can transform a cell into a cancerous type under certain circumstances.
- Measuring the number of BRCA1 mRNA splice variants in a cell can indicate if the gene is being under-expressed, a possible sign of breast cancer.
- But current methods of detecting cancer rely on samples made up of hundreds or thousands of cells and cannot provide detailed information about how genes tied to cancer are being expressed in individual cells.
- The researchers are the first to detect and quantify BRCA1 mRNA splice variants – fragments of genetic material that are removed when mRNA is formed – in a single cell.
- Splice variants can determine the fate of a cell and how specific proteins are expressed. Errors in the splicing process have been linked to a variety of diseases.
- “With this method, we are basically able to spot a needle in a haystack – and we can determine if there are five needles in that haystack or if there are 50”
- “The technique also could increase our understanding of cell biology and paves the way for genetic profiling and diagnosis based on a single cell.”
For more information: Nature Nanotechnology, April 20, Quantitative imaging of single mRNA splice variants in living cells
6. Palbociclib shows promise in advanced ER-positive breast cancer patients
- Palbociclib, a first-in-class cyclin-dependent kinase 4/6 inhibitor, in combination with letrozole, significantly improved median progression-free survival in patients with advanced estrogen receptor–positive, human epidermal growth factor receptor 2–negative breast cancer in the first-line setting.
7. Trastuzumab associated with durable EFS in HER-2–positive breast cancer
- Patients with locally advanced or inflammatory HER-2–positive breast cancer who underwent neoadjuvant chemotherapy plus trastuzumab followed by adjuvant trastuzumab demonstrated durable EFS, according to updated phase 3 study results.
- “These results show a sustained benefit in EFS from trastuzumab-containing neoadjuvant therapy followed by adjuvant trastuzumab in patients with locally advanced or inflammatory breast cancer, and provide new insight into the association between pathological complete remission and long-term outcomes in HER-2–positive disease,” the researchers wrote.
- The study was funded by F. Hoffmann-La Roche.