A recent study from Jun Ho Yi and In-Gu Do reveals anti-tumor efficacy of fulvestrant in estrogen receptor positive gastric cancer

Their etrospective study showed that in a total of 932 patients with GC who had received curative resection followed by adjuvant chemoradiation, 40 patients (4.3%) were ER-α positive by IHC. ER-αexpression was associated with diffuse-type cancer and a poorer clinical outcome. Their in vitro study demonstrated that E2 enhances proliferation of an ER-α-positive GC cell line and that both fulvestrant and paclitaxel inhibited its proliferation; this result was not observed in ER-α-negative GC cells. Combination of fulvestrant and paclitaxel may show synergism. Both fulvestrant and paclitaxel enhanced E-cadherin expression, a crucial factor in diffuse-type carcinogenesis; this effect was mediated via the ER-α pathway.

The carcinogenic role of estrogen in breast and ovarian cancers is well understood, and in breast cancer, estrogen-directed therapy is a mainstream treatment. It has been suggested that E2 may play a role in the carcinogenesis of tissues other than female reproductive organs, including in lung, thyroid, or gall bladder cancers. It has also been suggested that estrogen is involved in development of non-small cell lung cancer, especially in adenocarcinoma of non-smoking women, and that there is functional cross-signaling between EGFR-ER pathways. Several in vitro studies have shown that combination treatment with fulvestrant enhances the anti-tumor efficacy of gefitinib and vandetanib.

Since the late 1980′s, estrogen and ER have been suspected to play roles in GC Owing to the male predominance of GC and the fact that males who were treated with estrogen for prostate cancer showed a reduced risk of GC, some investigators assumed that estrogen plays a preventive role against GC. However, as older menopause and null parity are associated with an increased risk of development of GC in women, in the same way as breast cancer, some investigators have regarded estrogen as pro-carcinogenic for GC. One population-based cohort study has reported that endogenous estrogen exposure was associated with a lower frequency of intestinal-type cancers and a higher frequency of diffuse-type cancers, giving rise to the idea that the role of estrogen may vary with GC histology.

In contrast to estrogen, the clinical implications of ER, especially the α subtype, have been relatively consistent for a long time. As described in the Introduction, approximately 20% of GC patients are positive for ER-α, and it is associated with poorly differentiated histology and a poor prognosis. In the present study, however, they found that less than 5% of patients were ER-α-positive. This may have resulted from our use of the usual ER-α IHC method for breast cancer, which differs in antibody concentration, incubation time, and temperature from the method employed by the former studies. As no validated ER-α IHC protocol or interpretation guidelines exist for GC, further study is needed. From a histological perspective, they also found that ER-α was significantly associated with diffuse-type GC. While 4 of 279 patients (1.4%) with intestinal-type cancer showed ER-α expression, 34 of 595 patients (5.7%) with diffuse-type cancer and 2 of 36 (5.6%) with mixed-type cancer showed ER-α expression; multivariate analysis of the results showed that the differences were significant. In regard to survival, patients with ER-α expression showed shorter median DFS than patients without ER-α expression (55.6 months vs. 143.2 months, P = 0.044); again, ER-α expression was shown to be associated with poor DFS following multivariate analysis.

In the in vitro analysis, ER-α expression, examined by protein and mRNA expression, was found to be associated with E2-dependent growth and inhibition. In SNU-216 cells, an ER-α positive cell line, E2 led to cellular proliferation which was suppressed by fulvestrant; these results were not observed in SNU-620 cells, an ER-α negative cell line. Kameda et al. have also shown that E2 induces proliferation of KATO-III and NCI-N87 cells, which was suppressed by fulvestrant and ER-α siRNA. They further analyzed the impact of paclitaxel in this setting. Keeping further analysis, including clinical trials in mind, they chose to use paclitaxel because it has been demonstrated to produce a synergistic impact with fulvestrant in breast cancer models, and because it is widely used as a standard treatment for metastatic GC patients, with a 4-week administration schedule that is compatible with that of fulvestrant. Although we could not draw any conclusions from the colony-forming assay, the combination of fulvestrant and paclitaxel showed synergistic effects in the viability assay. This synergism is concordant with their known modes of action; paclitaxel is a microtubule-stabilizing agent, and E2 enhances cell motility by destabilizing microtubules via deacetylation of α-tubulin, thereby causing paclitaxel resistance.

Absent or aberrant expression of E-cadherin is pivotal in both familial and sporadic forms of diffuse gastric carcinogenesis, probably via methylation of the promoter of the E-cadherin gene. Park et al. showed that ER-α regulates E-cadherin levels in ovarian cancer cell lines, and a study by Oesterreich found that ER-α and corepressors bind to the E-cadherin promoter and that overexpression of corepressors down-regulated E-cadherin in breast cancer cell lines. In the present study, suppressing ER-α with fulvestrant and siRNA resulted in increased E-cadherin levels. Because E-cadherin loss is not only involved in carcinogenesis but also in cancer invasion and metastasis, they hypothesize that restoring E-cadherin may have a beneficial influence on disease course. One of the motives that initiated this analysis was that they observed a considerable number of patients with diffuse-type GC. In their cohort, 65.4% were diffuse-type GC and in Asian trial, it is a quite common finding that diffuse-type GC being more predominant than intestinal-type. It becomes dramatically remarkable by an international AVAGAST trial, in which diffuse-type cancer predominated in Asian population while intestinal-type cancer predominates in European population. They think that there is an ethnic difference regarding the Lauren’s classification and probably the incidence of ER expressing GC.

The present study has several limitations. Regarding the retrospective analysis, patients with metastatic disease were not included. If ER-α and its correlated E-cadherin are associated with tumor progression, patients with metastatic disease may show more frequent ER-α expression. The population of the current study is all Asians and interestingly, most studies dealing with this issue came from East Asia. Although there is one study dealing with this issue in Western population, ethnic difference should be investigated in the future. Also, as described above, their IHC method requires further validation. Although poorly differentiated histology was associated with more frequent ER-α expression (5.4%), the fact that the remaining 94.6% of the patients did not show ER-α expression warrants further investigation to elucidate the pathogenesis of this disease. For the in vitro analysis, they used the methods described in Kameda’s study. Thus, fixed concentrations of E2 and fulvestrant were used throughout the analyses. However, E2 acts via 2 pathways: via the estrogen receptor (the genomic pathway) and via transcriptional cross-talk (the non-genomic pathway). They have only focused on the genomic pathway; the role of the non-genomic pathway should be clarified by further studies. At last, efficacy of paclitaxel in this subset should be investigated, as this agent demonstrated complete inhibition of cellular proliferation in colony-forming assay.

The present study implies that some portion of GC patients express ER-α and that they have distinct clinicopathologic features. Whether ER-α is simply another prognostic factor, or whether it may act as a therapeutic target, similar to HER-2, in GC patients require further investigation, including prospective clinical trials.

Reference:

Jun Ho Yi, Jiryeon Jang and In-Gu Do, Anti-tumor efficacy of fulvestrant in estrogen receptor positive gastric cancer, Scientific Reports, 4, Article number:7592 ︱doi:10.1038/srep07592

A new genetics project could help “unlock a series of secrets about devastating diseases”, the NHS says.

Under the scheme, 11 Genomics Medicine Centres are being set up in English hospitals to gather DNA samples to help devise targeted treatments for a wide range of diseases. It is focusing on cancer and rare genetic diseases. The aim is to sequence 100,000 genomes within three years in order to develop new tests and drugs. Doctors will offer suitable patients the opportunity to take part in the scheme. They will have to agree to have their genetic code and medical records – stripped of anything that could identify them – made available to drugs companies and researchers. Up to 25,000 cancer patients will have the genetic code of their healthy tissue compared to the genetic code of their tumour. A giant game of spot-the-difference will then take place to identify the precise mutations in DNA that are causing a patient’s tumour. This would allow targeted medicines to be developed.

Genetic code

Previous genetics research has shown how different cancers can be – for example that breast cancer is not one disease but at least 10 - each with a different cause and life expectancy and each needing a different treatment. And the development of targeted drugs such as Herceptin – given only if a patient’s breast tumour has a certain mutation – has been possible because of genetics research. Meanwhile, 15,000 patients with rare diseases will have their genome compared with those of their parents and grandparents. Thousands of genetic diseases – which are individually rare but combined affect large numbers of people – could be identified by finding mistakes in the three billion pairs of letters that make up our genetic code.

The resulting knowledge could give patients an explanation for a disease that has plagued their entire life. Prof Graeme Black, who will lead the project in Manchester, told the BBC: “It’s possible to sequence an individual’s entire genetic make-up, their genome, in merely a few days where five years ago that was completely unimaginable. “Therefore it’s possible for conditions where there’s a possibility that it’s genetic, that we can identify genetic causes much quicker than had been imagined previously.”

‘Devastating diseases‘

NHS England medical director Prof Bruce Keogh said the impact of genomic medicine will be on the same scale as other British successes including the smallpox vaccine and IVF. He said: “Our NHS is better equipped for the emerging science that will determine the future practice of medicine than any other Western healthcare system. “[It] puts us in a position to unlock a series of secrets about devastating diseases, that have remained hidden for centuries, for the whole of human kind.”

Life sciences minister George Freeman said: “We want to make the UK the best place in the world to design and discover 21st century medicines.” Angela Douglas, chairwoman of the British Society of Genetic Medicine, said: “The challenge of the project will be to embed its outcomes into routine health practice. “The genetics community looks forward to working with researchers, scientists, associated medical specialists and Genomics England to meet that challenge.”

A team of British cancer researchers is using 3D printing to create customized models of cancerous growths in the human body aimed at allowing doctors to target tumors for precise treatment.

They call them “phantoms,” 3D printed replicas of tumors and and organs which are constructed from CT scan data collected from patients during treatment. The plastic molds can be filled with liquid, and that lets doctors and technicians gauge the location and flow of radio pharmaceuticals within the body.

 Preliminary studies done by the team at ICR London can help map the exact position of a given tumor within a patient’s body, and initial tests have discovered that such models allowed the dose of radiation a patient has received to be calculated more accurately.

The tumor replicas were constructed of plastic and printed by researchers at the Joint Department of Physics at the ICR and The Royal Marsden. The researchers say the models were once made by hand before the teams turned to 3D printing technology to streamline the process.

For the most part, the models are used in the treatment of thyroid cancer, adult neuroendocrine tumors, cases of childhood neuroblastoma and bone metastases which arise from cases of prostate cancer.

Investigators at the UC Davis Schools of Medicine and Veterinary Medicine, dig out a complicated relationship between p53 and another protein, Rbm38, highlighting how the body calibrates protein levels. Too much Rbm38 reduces p53 levels, increasing the risk of cancer. The finding was published in the journal PNAS.

As known long, the p53 protein is necessary for tumor suppression.When Rbm38 suppresses p53, organisms develop tumors. Knocking out Rbm38 increases p53, which might be considered as a good thing. But too much p53 suppresses cell-cycle progression, causing cell death, premature aging and even cancer.

Scientists regarded the relationship between p53 and Rbm38 as a loop: p53 regulates Rbm38 expression, while Rbm38 suppresses p53. There are contradictory results that Higher Rbm38 levels have been found in certain breast and colorectal cancers and dog lymphoma. However, increased Rbm38 is also associated with better prognoses in glioblastoma, ovarian cancer and other forms of breast cancer.

What would happen if Rbm38 was removed?

They found that knocking out Rbm38, and thus increasing p53, caused problems with blood formation, increased sensitivity to ionizing radiation and premature aging. Also, they found that increased p53 levels cause apoptosis, which leads to shorter lifespans. Perhaps most surprising, the animals also had increased cancer risk, boosted by the accelerated aging.

These intricate interactions are cause for both caution and excitement. While too much p53 can be a bad thing, carefully manipulating these two proteins could have therapeutic benefits.

The mutual regulation between Rbm38 and p53 is critically important to both aging and tumorigenesis. It’s possible to make p53 levels go up in tumor cells via targeting Rbm38 , which could kill tumor cells and suppress cancer progression.

Reference:

Mice deficient in Rbm38, a target of the p53 family, are susceptible to accelerated aging and spontaneous tumors. PNAS, December 2014

Researchers from Centenary’s Molecular Hepatology unit found that blocking a widespread enzyme called DPP9 can slow down the movement of cells and potentially stop tumours from spreading and growing. The finding was published in the cell biology journal BBA Molecular Cell Research.

The enzyme was first discovered and cloned by researchers at the Centenary Institute and the Sydney Medical School in 1999. Ever since they’ve been studying what it does, with a view to its possible use as a cancer drug target.

Under the confocal microscopes, scientists can watch the enzyme at work and then block DPP9, and see the cells slow down. This gives the clearest evidence that this enzyme will be a good cancer drug target. Further, they render a conclusion from this study that this enzyme is absolutely critical to cell movement, and without cell movement, tumors can’t grow or spread.

Investigators discovered DPP9 accumulates at the leading edge of the moving cell when cells were stimulated to move. DPP9 was also associated with the adhesion protein complex that glues the cell to the external matrix though which it moves, acting as an anchor point to pull the cell along. When the action of DPP9 was inhibited in cells, such movement and adhesion diminished.

DPP9 is looking more and more like a cancer drug target. But at present we have no specific inhibitors for it, even though chemists have been trying for some years to make one, more investigators need to throw more resources at this problem.”

Reference:

Dipeptidyl peptidase 9 subcellular localization and a role in cell adhesion involving focal adhesion kinase and paxillin. Biochimica et Biophysica Acta (BBA) – Molecular Cell Research, 2015; 1853 (2): 470

A study found new drugs, posit that these inhibitors could provide first-line therapy for treatment-naive patients and second-line therapy for a range of patients with relapsed melanoma.

Acquired resistance and intrinsic resistance to BRAF inhibitors are persistent problems in the treatment of BRAF mutant melanomas.BRAF and MEK inhibitors are effective in BRAF mutant melanoma, but most patients eventually relapse with acquired resistance, and others present intrinsic resistance to these drugs. Resistance is often mediated by pathway reactivation through receptor tyrosine kinase (RTK)/SRC-family kinase (SFK) signaling or mutant NRAS, which drive paradoxical reactivation of the pathway. We describe pan-RAF inhibitors (CCT196969, CCT241161) that also inhibit SFKs. These compounds do not drive paradoxical pathway activation and inhibit MEK/ERK in BRAF and NRAS mutant melanoma. They inhibit melanoma cells and patient-derived xenografts that are resistant to BRAF and BRAF/MEK inhibitors. Thus, paradox-breaking pan-RAF inhibitors that also inhibit SFKs could provide first-line treatment for BRAF and NRAS mutant melanomas and second-line treatment for patients who develop resistance.

Reference:

Maria Romina Girotti, Filipa Lopes, et al.Paradox-Breaking RAF Inhibitors that Also Target SRC Are Effective in Drug-Resistant BRAF Mutant Melanoma [J].Cancer Cell, 2014.11.006.

Scientists from University of Copenhagen have identified a new molecular mechanism of cell division which could be very important in the process of canceration. This finding was published in Nature Communication.

Accurate chromosome segregation during mitosis is ensured by the spindle assembly checkpoint(SAC), which is a conserved mechanism requiring the Aurora B, Mad1, Mad2, Mps1, Bub1, BubR1(Mad3 in yeast) and Bub3 proteins. Improperly attached kinetochores activate the SAC and by an unknown mechanism catalyse the binding two checkpoint proteins, Mad 2 and BubR1, to Cdc20 forming the mitotic checkpoint complex (MCC).

In this study, researchers address the functional role of Cdc20 kinetochore localization in the SAC, they delineate the molecular details of its interaction with kinetochores. The research team finds that BubR1 recruits the bulk of Cdc20 to kinetochores through its internal Cdc20 binding domain (IC20BD). They also show that preventing Cdc20 kinetochore localization by removal of the IC20BD has a limited effect on the SAC because the IC20BD is also required for efficient SAC silencing.

Thus, scientists uncover an unexpected dual function of the second Cdc20 binding site in BubR1 in promoting both efficient SAC signaling and SAC silencing. The researchers hope to develop new anti-cancer therapy on the basis of this new finding and predict reactions of different drug therapies.

Reference:

Lischetti T, Zhang G, Sedgwick G G, et al. The internal Cdc20 binding site in BubR1 facilitates both spindle assembly checkpoint signalling and silencing[J]. Nature Communications, 2014, 5.

Scientists from US Marine Biological Laboratory have demonstrated that colorectal cancer tissues may have the feature of biofilms which are produced by bacteria. They identified invasive polymicrobial bacterial biofilms, structures previously associated with nonmalignant intestinal prathology, nearly universally on the right-sided tumors but only 12% of left-sided tumors. This finding was published in PNAS.

Environmental factors clearly affect colorectal cancer (CRC) incidence, but the mechanisms through which these factors function are unknown. One prime candidate is an altered colonic microbiota.

In this study, researchers firstly demonstrate that bacterial biofilms are associated with colorectal cancers. Colonbiofilms, dense communities of bacteria encased in a likely complex matrix that contact the colon epithelial cells, are nearly universal on right colon tumors. Most remarkably, biofilm presence correlates with bacterial tissue invasion and changes in tissue biology with enhanced cellular proliferation, a basic feature of oncogenic transformation occurring even in colons without evidence of cancer. Microbiome profiling revealed that biofilm communities on paired normal mucosa cluster with tumor mrcrobiomes but lack distinct taxa differences

This work introduces a previously unidentified concept whereby mrcrobial community structural organization exhibits the potential to contribute to disease progression.

Reference:

Dejea C M, Wick E C, Hechenbleikner E M, et al. Microbiota organization is a distinct feature of proximal colorectal cancers[J]. Proceedings of the National Academy of Sciences, 2014: 201406199.

Research from Ming Shi and Shan Wang showed the biological and clinical significance of epigenetic silencing of MARVELD1 gene in lung cancer.

In this study, they reported the correlation between MARVELD1 silencing and lung cancer. Immunohistochemical analysis and Western blotting experiments showed that the down-regulation of MARVELD1 was associated with malignant progression of lung cancer. Epigenetic silencing of MARVELD1 gene was observed in low MARVELD1-expressing lung cancer cell lines. Therefore, they deducted that MARVELD1 silencing may be required for tumorigenesis and has a potential to be developed as a biomarker for malignant phenotype of lung cancer, which possesses considerable value in prognosis prediction, progression monitoring and treatment evaluating. For future application, it is critical to design reasonable clinical trial for evaluation of this biomarker. Not only Overall survival (OS) and Disease-free survival (DFS) should be evaluated in randomized, controlled trials, some key factors with regard to lung cancer, such as smoking history information, will be considered.

Hypermethylation of tumor suppressor genes and demethylation of oncogenes contribute to tumorigenesis. Cancer-linked hypermethylation and hypomethylation of gene promoter is often associated with cell proliferation. MARVELD1 is a potential tumor suppressor, which negatively regulates proliferation of cancer cells. In this study, they observed that MARVELD1 is down-regulated in lung cancer tissues, especially small-cell lung cancer tissues. In lung cancer cell lines, the methylation states of the CpGs in MARVELD1 promoter region were found to be hypermethylated. Moreover, MARVELD1 gene was also re-expressed following treatment with 5-aza-CdR, a potent demethylating agent, suggesting that status of DNA demethylation was important for the active expression of MARVELD1. In addition, we also found histone acetylation and DNA demethylation synergistically activated MARVELD1 gene in lung cancer cells.

Previous results showed that MARVELD1 could suppress cell spreading and actin organization through regulation of pre-mRNA processing, a process parallel to NMD. Moreover, MARVELD1 associated with potential NMD factor Importin β1, suggesting the possible function of MARVELD1 in NMD pathway. A recent study further showed that MARVELD1 regulated NMD via modulating phosphorylation of UPF1. Considering the aberrant regulation of MARVELD1 gene in lung cancer, therefore, they discussed the gene silencing mechanism of MARVELD1 and the relationship between epigenetically masked MARVELD1 and NMD function in lung cancer cells.

Although NMD pathway has been extensively studied, the regulatory mechanism of NMD in cancer is still not well understood. In this study, they showed MARVELD1 co-localized and interacted with SMG1, the core kinase of the NMD machinery, in lung cancer cells. Moreover, they constructed the NMD reporter plasmid expressing PTC-containing truncated LRP1B-GFP mRNA (LRP1B exons 1–9 from lung cancer cell line QG56), and demonstrated that MARVELD1 bound PTC-mRNA as efficient as NMD core factor UPF1 and SMG1 by RNA-ChIP based reporter system. In addition, they also found MARVELD1 could enhance the association between NMD complex UPF1/SMG1 and PTC-containing mRNA, which suggested that MARVELD1 was involved in modulating the efficiency of NMD through interaction with SMG1. In summary, their study suggested the following working model(Figure1). The reduced MARVELD1 expression, due to promoter hypermethylation, attenuated NMD, which indicated aberrant mRNA surveillance mechanism in lung cancer.

Reference

Ming Shi, Shan Wang and  Yuanfei Yao,etc., Biological and clinical significance of epigenetic silencing of MARVELD1 gene in lung cancer, Scientific Reports 4, Article number: 7545︱doi:10.1038/srep07545

A study, published in Nature，reports that scientists from Queen Mary University of London have made a breakthrough in developing a new therapy for advanced bladder cancer where there have been no major treatment advances in the past 30 years.

They examined an examined an antibody (MPDL3280A) which blocks a protein (PD-L1) thought to help cancer cells evade immune detection. As indicated, the antibody show positive effectiveness in shrinking tumours in a phase one, multi-centre international trials.

As the subjects enrolled in this study, 68 patients with advanced bladder cancer -who had failed all other standard treatments such as chemotherapy – received MPDL3280A, a cancer immunotherapy medicine being developed by Roche. And patients were all tested for the protein PD-L1 and around 30 were identified as having PD-L1 positive tumours.

After 6 weeks of treatment, 43 per cent of PD-L1-positive patients found their tumour had shrunk. This rose to 52 per cent after 12 weeks of follow up. In two of these patients (7 per cent) radiological imaging found no evidence of the cancer at all following the treatment. Among PD-L1 negative patients, 11 percent responded positively to treatment too.

The early results of this trial are so promising, the MPDL3280A antibody drug has been given breakthrough therapy designation status by the U.S. FDA.  It gives hope to the thousands of people affected by advanced bladder cancer each year. As researchers see, this investigational drug had a striking response rate, and by screening its target protein PD-L1 they can offer the tailored treatments to patients with PD-L1 mutations.

Another citation, published in the same issue of Nature, reported broader results of this phase one study for the antibody MPDL3280A, with data from people with lung, kidney, colon or head & neck cancers authored by Roy Herbst, MD, PhD of the Yale Cancer Centre.

References:

MPDL3280A (anti-PD-L1) treatment leads to clinical activity in metastatic bladder cancer. Nature, 2014; 515 (7528): 558

Predictive correlates of response to the anti-PD-L1 antibody MPDL3280A in cancer patients. Nature, 2014; 515 (7528): 563