Clinical research isn’t something I’ve touched upon massively in this blog, but a new study by Kunogi et al¹ in April’s edition of the Journal of Medical Genetics touches upon the need to constantly re-evaluate and introduce new forms of diagnostic techniques.

In the study, 36 Japanese patients presenting with lung cysts of indeterminate cause underwent FLCN mutation analysis using a conventional approach: denaturing high performance liquid chromatography dHPLC analysis followed by direct sequencing of the exon suspected of harbouring the causative mutation. Germline FLCN mutations were identified in 23 patients using this method. When no mutation was identified by dHPLC, a second round of testing was initiated and involved quantifying the copy number of each exon of the FLCN gene using real-time qPCR. Subsequently, 2 of the remaining 13 individuals were shown to have large genomic deletions in FLCN and therefore, BHD Syndrome.

This study establishes that genetic testing of individuals with suspected BHD Syndrome should employ methods that detect large genomic deletions as well as point mutations. This is clinically relevant since BHD Syndrome is currently under diagnosed and any effort to improve on this is needed. Classically, this is achieved by increased public awareness and educating family health practitioners. Often correct clinical management of BHD Syndrome begins with a positive diagnosis through genetic testing and so increasing the efficacy of this process is greatly welcomed.

1.  Kunogi et al. Clinical and genetic spectrum of Birt-Hogg-Dube syndrome patients in whom pneumothorax and/or multiple lung cysts are the presenting feature. J Med Genet. 2010 Apr;47(4):281-7.

The principle remit behind www.BHDSyndrome.org, is for it to become the online reference site for anybody interested in BHD Syndrome.

I’d like to take this opportunity to highlight the BHD Article Library. Not only does it provide access to free research articles about BHD Syndrome, but it also provides access to articles about renal cancer and pneumoraces. These articles are great if you need to do some general reading and learn about BHD syndrome within a bigger context and it’s convenient because you don’t have to trawl through the web to try and find something relevant. If you haven’t already visited the BHD Article Library, take some time out today to see what you’ve been missing!

Have you registered for the Second BHD Symposium yet? There’s still time! Visit here for more info.

The Second BHD Symposium 2010 is less than a month away! The venue is booked, abstracts have been submitted and programmes have been finalised!

I’ve already blogged about how interesting I think the day is going to be, so I wont repeat myself, but suffice it to say, the only thing we can’t guarantee on the day is the weather!

BHD Syndrome is a rare disease and since this Symposium is intended specifically for BHD researchers, it’s unlikely that you’ll get another opportunity to find out what your peers are doing, so why miss out?

So…  all that’s left for you to do is register. It’s easy enough to do: head on over to the dedicated Second BHD Symposium 2010 page for more details about the day’s events (should you need them), and follow the links to register and to book your accommodation. What are you waiting for?

Professor Sir Liam Donaldson, Chief Medical Officer for the United Kingdom, highlighted the increased need for awareness and understanding of rare diseases in his annual report for 2009 published this week (On the state of public health: Annual report of the Chief Medical Officer 2009).

His findings were echoed in an article in The Times newspaper by Sam Lister, where Sir Liam warned of the plight of individuals diagnosed with rare conditions. In the piece, he states “This is about patchy and fragmented services, poor co-ordination and lack of clinical awareness about the diagnosis. It’s not just poverty of access, but poverty of visibility and representation.”

Highlights of Sir Liam’s report include the recommendation of a ‘national clinical director for rare diseases’ and the proposition of national registers to facilitate improved surveillance, planning and research into the field of rare diseases.

Both the annual report and the Times article highlight the need for increased translational research and perhaps more importantly, the encouragement of the pharmaceutical industry to develop medicines for rare diseases; unfortunately since the demand for these kinds of pharmaceuticals is relatively low the ‘encouragement’ appears to take the form of financial incentives.

It’s great to see rare disease highlighted in both the political arena and the media so honestly. Hopefully, both The Times article and Sir Donaldson’s annual report will bring attention to the oft ignored world of ‘orphan diseases’, raising much needed public and political awareness.

From a BHD perspective, it’s comforting to know that a significant amount of basic, clinical and translational research into BHD Syndrome is being carried out globally, and that whilst it is classified as a rare disease, that doesn’t mean it’s been forgotten about.

I’m sure it will come as no surprise, that on the week that programmes have been released for the Second BHD Symposium (both the scientific and patient-orientated sessions),  I have chosen to talk about the Symposium again! And if you haven’t already had the opportunity to go through them, they can be found here.

The scientific programme is a really tantalising because I see words like ‘regulation’, ‘understanding’, ‘insights’ and ‘functional characterisation’, all relating to BHD Syndrome and the protein Folliculin.

Back in 2008, when the inaugural BHD Symposium took place, researchers had the first opportunity to share insights into BHD Syndrome, like the availability of animal models and the identification of FNIP1 and FNIP2 as Folliculin interacting proteins, amongst other things, and really set the foundations for the excellent work that will be presented on April 22nd at the Second BHD Symposium.

It’s exciting to see that we’re getting to the real guts of the role of Folliculin and the mechanism(s) underlying BHD Syndrome. It would be extremely inappropriate of me to comment on specific presentations at this stage, in terms of potential highlights for the day, but I think the breadth and depth of work coming out of the BHD community speaks for itself when I say there truly is something for everyone, regardless of your area of expertise.

Also, the fact that two programmes have been issued also speaks volumes. We hope the parallel ‘Families Session’ will prove useful to individuals affected by BHD Syndrome since their specific needs will be discussed by health professionals with experience and knowledge of BHD Syndrome, and that the opportunity to listen to clinical presentations will put them in touch with the scientific community and conversely, give scientists the opportunity to meet the faces of BHD Syndrome.

The NCBI Database has proved itself to be the doyen of scientific resources and is often the first port of call for information regardless of your specific field. I’d like to highlight a resource I’ve found extremely useful over the last couple of weeks: the BioSystems page.

Searching for ‘Birt Hogg Dubé’ results in 12 different models of molecular pathogenesis underlying renal cell carcinoma (RCC) in several species. Three excellent schematics are provided illustrating which signalling pathways are deregulated in several types of RCC in homo sapiens.

The beginning of a BHD specific pathway is also provided, but has yet to be completed. I’ll provide a direct link to the page in question (here) so you can see for yourselves. I’ve found it’s useful when thinking about FLCNs role in renal tumourigenesis within the context of ‘the bigger picture’. The models provided are all RCC centric for the time being but that obviously reflects the quality of work done in the area. I hope that in the coming years we can flesh out the ‘BHD’ section a lot more!

Plans for the Second BHD Symposium on the 22^nd April 2010 (Washington, DC) are well under way and the Scientific Advisory Committee is busy finalising the programme for the day.

I’d like to take this opportunity to encourage as many researchers as possible to attend, as the day will be an interesting mix of talks and poster presentations addressing both the clinical and basic scientific aspects of BHD Syndrome (and I use the term ‘basic’ loosely).

Having previously worked in the lab for a number of years, I often attended a number of various conferences but almost always left underwhelmed since quite often, only one or two talks were applicable to my specific area of interest and even then, the further applications or insights into my own research were tenuous at best.

However, if your work is in anyway related to BHD Syndrome then the Second BHD Symposium 2010 really should be a date in your diary. Very rarely will you find a whole day dedicated to your area, and as a result of the BHD field being quite small you’ll get to hear from highly respected researchers from around the world. Since the last Symposium in 2008, so much more is understood about the molecular biology and biochemistry underlying BHD Syndrome and the number of groups involved in BHD research has increased. Further characterisation of Folliculin has been carried out as well as the collection of clinical data from larger BHD cohorts across the globe – can you afford to miss out?

Up to date information regarding the Second BHD Symposium, including how to register and accommodation details can be found here. Travel grants are available from the Myrovlytis Trust.

This Sunday (28th February 2010) is ‘Rare Disease Day‘, an annual event aimed at raising awareness of a multitude of rare diseases across the globe. The day is co-ordinated by Eurodis and is aimed at individuals from all walks of life – from members of the general public to public health authorities and drug developers.

This event is much needed and does a lot for the rare disease ’cause’ and I’d just like to take this opportunity to remind everyone that for some people, everyday is a rare disease day.

Undoubtedly, no comfort is gained in being diagnosed with the commonest of cancers, but prompt clinical management and treatment can not only be re-assuring but a real lifeline too. Often however, the positive diagnosis of a rare syndrome is often itself a struggle, let alone prompt and comprehensive treatment.

The organisers of Rare Disease Day correctly point out that there is ‘a lack of specific health policies, a scarcity of expertise and little research’ in the area of so-called ‘Orphan Diseases’ and that by increasing the awareness of ‘rare disease’ in the public consciousness, this matter can be addressed.

www.BHDsyndrome.org aims to be the primary online resources for individuals interested in, or affected by BHD Syndrome, a rare genetic disease.

Yang et al, (2010) describe the generation and characterisation of an immortalised hereditary leiomyomatosis renal cell carcinoma (HLRCC) cell line, derived from a human patient. HLRCC is a form of inherited kidney cancer in which affected individuals are at risk of developing cutaneous and uterine leiomyomas and kidney cancer, characterized by germline mutation of the Krebs cycle enzyme fumarate hydratase (FH; Launonen et al, 2001). Incidences of renal cancer in HLRCC are highly aggressive and often result in metastasis.

The dependence of HLRCC tumours on glycolysis as a means of obligate anaerobic respiration, coupled with their impaired mitochondrial respiration, mark this renal cancer as a unique example of Warburg’s hypothesis. This hypothesis suggests the tumours forgo the Kreb’s cycle as a means of ATP generation, instead, preferentially using glyclolysis (Ganapathy et al, 2009).

These findings suggest that interference of glycolytic flux may represent a targeted approach to therapy for HLRCC. BHD syndrome is phenotypically similar to HLRCC in that it is characterised by the growth of cutaneous and renal lesions (as well as pulmonary cysts) albeit less severely. Both syndromes share an element of HIF dysfunction: biallelic loss of FH results in aberrant signalling mediated through HIF dependent pathways (Sudarshan et al, 2007) and Weppler et al, (2008) presented data at the Inaugural BHD Symposium which showed that BHD patients may have aberrant HIF activity that was thought to contribute to the development of skin and kidney tumours.

A method similar to that used by Yang et al, (2010) could be used on the FLCN null cell line UOK257 (human RCC derived from a BHD patient), or any BHD animal model, to investigate the status of glycolysis and aerobic respiration could prove useful in expanding our understanding of the pathogenic mechanism underlying BHD syndrome.

References:

Ganapathy V,Thangaraju M, Prasad PD. 2009. Nutrient transporters in cancer: Relevance to Warburg hypothesis and beyond. Pharmacology & Therapeutics, 121(1); 29-40

Launonen V, Vierimaa O, Kiuru M, Isola J, Roth S, Pukkala E, Sistonen P, Herva R, Aaltonen LA. 2001. Inherited susceptibility to uterine leiomyomas and renal cell cancer. Proc Natl Acad Sci USA 98:3387–3392.

Sudarshan S, Linehan WM, Neckers L. 2007. HIF and fumarate hydratase in renal cancer.  Br J Cancer. 96(3): 403–407.

Weppler SA et al, 2008. Folliculin-dependent regulation of HIF2-alpha. Familial Cancer, 7 (Supplement 1)

Yang Y, Valera VA, Padilla-Nash HM, Sourbier C, Vocke CD, Vira MA, Abu-Asab MS, Bratslavsky G, Tsokos M, Merino MJ, Pinto PA, Srinivasan R, Ried T, Neckers L, Linehan WM. 2010. UOK 262 cell line, fumarate hydratase deficient (FH-/FH-) hereditary leiomyomatosis renal cell carcinoma: in vitro and in vivo model of an aberrant energy metabolic pathway in human cancer. Cancer Genet Cytogenet. 196(1):45-55.

Yang Y, Nash HM, Vira MA, Abu-Asab MS, Val D, Worrell R, Tsokos M, Merino MJ, Pavlovich CP, Ried T, Linehan WM, and Vocke CD.2008. The UOK 257 Cell Line – A Novel Model for Studies of the Human Birt-Hogg-Dubé Gene Pathway. Cancer Genet Cytogenet. 180(2): 100–109.

Recent research into the function of Folliculin has been carried out in the context of renal tumourigenesis using BHD animal models. Research has implicated Folliculin in the PI3K-AKT and mTOR signalling pathways and specifically interacting with AMPK, FNIP1 and FNIP2 (Baba et al, 2006; Hasumi et al 2008; Takagi et al, 2008). Is dysfunction of this role specific to renal tumourigenesis, or can it be applied to pulmonary cyst formation too?

We could speculate that the mechanism underlying renal tumourigenesis is a multi-step process where renal cysts develop initially and the accumulation of genetic instability results in tumourigenesis and the development of malignant renal tumours. However if this process is ‘universal’ how do we explain the absence of pulmonary tumours in BHD syndrome? So, the question of why pulmonary cysts do not develop into pulmonary tumours remains unanswered.

One suggestion would be that the lung cysts rupture once they are a certain size, preventing the transition to tumourigenic growth. Why cyst development is specific to the outer surface of the lungs is also an outstanding issue, since renal tumours are multifocal. One idea is that the mechanism instigating cystic growth through to tumourigenic development is the same in the lung and the kidney, but that pulmonary tumours never develop due to cyst rupture. Alternatively, could each organ have a specific mechanism which would result in the different phenotypes?

How do we shed light on what is happening in the BHD lung? One method could be to examine the underlying mechanism of pulmonary tumourigenesis in incidences known to have a genetic component in order to uncover dysfunctions in non-BHD related cell signalling pathways, or lung specific tumour suppressors or oncogenes, that might be potentially implicated in BHD syndrome.

Tobacco use accounts for up to 90% of lung cancer incidence, however the remaining 10% of cases are thought to have a genetic or familial component (Peto et al, 2006). A major familial lung cancer susceptibility locus was first identified in 2004 (Bailey-Wilson et al,) using genome wide linkage analysis to identify the major susceptibility locus. Fine-mapping of the region, subsequently, by You et al, (2009) determined that the RGS17 gene was over-expressed in familial lung cancer.

RGS17 encodes a member of the regulator of G-protein signalling family. This protein contains a conserved, 120 amino acid motif called the RGS domain and a cysteine-rich region. The protein attenuates the signalling activity of G-proteins by binding to activated, GTP-bound G alpha subunits and acting as a GTPase activating protein, increasing the rate of conversion of the GTP to GDP. As well as being associated with lung cancer, RGS17 has been shown to be over expressed in prostate cancer, associated with its ability to promote cyclic AMP (cAMP)-responsive element binding protein (CREB)-responsive gene expression, increase cAMP levels, and enhance forskolin-mediated cAMP production (James et al, 2009).

Ultimately, studies such as those by You et al, (2009) contribute further to our understanding of lung cancer susceptibility but since research into the pathogenic mechanism of RGS17 is fairly recent, how it contributes to pulmonary tumourigenesis is still unknown. However, by maintaining an awareness of RGS17 research, we might gain insights into potentially insightful elements of pulmonary tumourigenesis which may shed light on the mechanisms underlying the pulmonary phenotype of BHD Syndrome.

References:

Baba M, Hong SB, Sharma N, Warren MB, Nickerson ML, Iwamatsu A, Esposito D, Gillette WK, Hopkins 3rd RF, Hartley JL, Furihata M, Oishi S, Zhen W, Burke Jr. TR, Linehan WM, Schmidt LS and Zbar B. Folliculin encoded by the BHD gene interacts with a binding protein, FNIP1, and AMPK, and is involved in AMPK and mTOR signalling. Proc. Natl. Acad. Sci. USA 2006; 103, pp. 15552–15557.

Bailey-Wilson et al, 2004. A major lung cancer susceptibility locus maps to chromosome 6q23-25. Am J Hum Genet;75(3):460-74.

Hasumi H, Baba M. Hong SB, Hasumi Y, Huang Y, Yao M, Valera VA, Linehan WM. and Schmidt L.S., Identification and characterization of a novel folliculin-interacting protein FNIP2, Gene 2008; 415: 60–67.

James MA, Lu Y, Liu Y, Vikis HGand You M, (2009). RGS17, an Overexpressed Gene in Human Lung and Prostate Cancer, Induces Tumor Cell Proliferation Through the Cyclic AMP-PKA-CREB Pathway. Cancer Research 69, 2108.

Michael A. James, Yan Lu, Yan Liu, Haris G. Vikis and Ming You. 2009. RGS17, an Overexpressed Gene in Human Lung and Prostate Cancer, Induces Tumor Cell Proliferation Through the Cyclic AMP-PKA-CREB Pathway. Cancer Research 69, 2108.

Peto R, Lopez AD, Boreham J et al. (2006). Mortality from smoking in developed countries 1950–2000: Indirect estimates from National Vital Statistics. Oxford University Press. ISBN 0-19-262535-7

Takagi Y, Kobayashi T, Shiono M, Wang L, Piao X, Sun G, Zhang D, Abe M, Hagiwara Y, Takahashi K. and Hino O, Interaction of folliculin (Birt–Hogg–Dubé gene product) with a novel Fnip1-like (FnipL/Fnip2) protein, Oncogene 27 (2008), pp. 5339–5347.

You et al, 2009; Fine Mapping of Chromosome 6q23-25 Region in Familial Lung Cancer Families Reveals RGS17 as a Likely Candidate Gene. Clinical Cancer Research April 2009 15; 2666.