In the Lab

In the Lab

The new camera

 

The Pediatric Brain Tumor Research Group Supported By Hannah's Heroes Foundation

The partial team in the lab.

The partial team in the lab.

Pediatric Brain Tumours

Brain cancer is an extremely aggressive disease that is difficult to cure and has a high mortality rate. Every year, more than 3,500 children in North America are diagnosed with this disease. Brain tumors are the most common solid tumors and the second leading cause (after leukemia) of cancer-related deaths in children. 

The majority of patients (80%) with the more aggressive forms of brain tumors will not survive more than 2 years. Surgery and chemotherapy are the mainstay of current treatments for brain cancers. Surgery for brain tumors are especially challenging because of the sensitive location of the tumors.

Children who have undergone brain tumor surgery often experience long-term difficulties in learning and memory. Complete surgical recession is often impossible due to the invasive nature of the tumours. Adding to that, in certain groups of patients the tumours become resistant to the current chemotherapeutic drugs, leaving no other treatment options.

Our Research Efforts 

Our new data shows that brain tumours cells must have a protein called Polo-Like Kinase 1 (PLK1) to divide. PLK1 levels are higher in cancer cells than in normal cells, and seem to be 'addicted' to this protein for survival. When we block this protein, cancer cells either die or their. growth is suppressed. Recently, we have shown in pediatric muscle cancer cells that when we removed this protein, cancer cells died, and leaving normal cells unharmed. The role of PLK1 is largely unexplored in pediatric brain cancers, and could be a crucial link in new treatments. 

We are also looking for the 'seeds' of brain tumors, which we now call 'brain tumor initiating cells' (STICs). There is evidence suggesting these tumor-initiating cells (TICs) not only cause tumors to form, but are also an underlying cause of drug resistance, and subsequently cancer relapse. The TICs are long-lived and can very effectively pump out the drugs administered to patients and survive radiation therapies. 

This research is dedicated to all the patients and their families who struggle against pediatric brain cancers.

Targeting Polo-Like Kinase 1 (PLK1) for the Treatment of Pediatric Brain Tumours

Lee, Cathy (Dunn Lab)

Cancer is a disease in which normal cells obtain genetic mutations that make them grow abnormally, forming tumours in different parts of the body. Brain cancer is an extremely aggressive disease that is difficult to cure and has a high mortality rate. Brain tumours are the most common solid tumours and the second leading cause (after leukemia) of cancer-related deaths in children. The majority of patients (80%) with the more aggressive forms of brain tumours will not survive more than 2 years.

Surgery and chemotherapy are the mainstay of current treatments for brain cancers. Surgery for brain tumours are especially challenging because of the sensitive location of the tumours. Children who have undergone brain tumour surgery often experience long-term difficulties in learning and memory. In addition, brain tumours are composed of extremely evasive cells that have a tendency to move into different regions of the brain, making complete removal of cancer cells virtually impossible. Patients with aggressive brain cancers are treated with a drug named Temozolomide (TMZ). However, in a subgroup of patients, this drug does not work effectively. These patients are, in fact, resistant to TMZ treatment. In addition, from our recent experimental results, we found that TMZ does not do a very good job of killing pediatric brain tumour cells. A few questions therefore emerged. 1) If TMZ does not effectively kill brain tumour cells, can we develop alternative therapeutics to kill these cancer cells more efficiently? 2) Like most chemotherapeutic drugs, TMZ does not eliminate all cancer cells. Certain ‘survivors’ in the tumour cell population become ‘seeds’, generating more cells that subsequently form a new tumour. Is there a way to eliminate these ‘seeds’ so that new tumours do not form and cancers do not recur?

We have exciting data indicating that brain tumours cells have an absolute requirement for PLK1 (Polo-like kinase 1), a protein required for cells to divide. As we know, most cancer cells divide in an uncontrolled manner and much more rapidly than normal cells do. Therefore we would expect that inhibiting PLK1 may exert a greater impact on cancer cells than on normal cells. Indeed, we have recently found that brain tumour cells are ‘addicted’ to PLK1 for survival. When we inhibit this protein, cancer cells either die or their growth is significantly suppressed in vitro (non-animal experiments). However, very interestingly, normal human astrocytes (a type of brain cells) do not seem to be much affected. Furthermore, PLK1 levels are between 100-400 times higher in brain cancer cells than in normal brain cells (specifically, astrocytes), suggesting that targeting PLK1 may exclusively eliminate brain tumour cells while leaving the normal brain cells unharmed. Of note, even the brain tumour cells that show upfront resistance to TMZ are extremely sensitive to PLK1 inhibition. This is a particularly exciting result because it implies that PLK1 inhibitor may be a potential alternative treatment for children who do not respond to TMZ.

The second question is addressed by specifically examining the ‘seeds’ of brain tumours, which we now call ‘brain tumour initiating cells’ (BTICs)’. In recent years, scientists have isolated cancer-initiating cells from leukemia and solid tumours of the breast and brain. There is increasing evidence to suggest that these tumour-initiating cells (TICs) not only cause tumours to form initially but are also an underlying cause of drug resistance. These TICs are believed to be the ‘ancestors’ of ≥99% of the cells within a tumour. In contrast to their descendents, the TICs are long-lived and can very effectively pump out the drugs administered to patients. TICs are hardy cells that can survive harsh conditions imposed by chemo/radiation therapy. The survival of these TICs allows propagation of tumour cells that eventually make up the bulk of a new tumour, resulting in disease relapse. The second aim of my project is to find out a way to prevent expansion of these TICs and ultimately to kill them. Over these two years, we have obtained various lines of BTICs from collaborators and have also been able to isolate BTICs from post-surgery patient specimens from the BC Children’s and Women’s Hospital. We have solid experimental evidence demonstrating that BTICs derived from all the patient samples we have examined showed sensitivity to PLK1 inhibition. The BTICs either died upon the drug treatment or their proliferation and expansion was largely suppressed.

In conclusion, we have demonstrated that blocking PLK1 function results in significant growth suppression and induction of cell death in pediatric brain tumour cells and/or BTICs. Given that clinical trials have begun to address the promise of PLK1 inhibitors in adult cancers, we proposed that molecular targeting of this protein may also be considered for the treatment of pediatric brain cancers, particularly for those that are TMZ-resistant.

This research is dedicated to all the patients and their families. We hope these studies will improve our understanding of pediatric brain cancers and allow future design of novel, alternative therapeutic strategies that will benefit patients’ health and improve the way we currently treat this devastating disease.

Alternative cancer use for common alcoholism therapeutic

Joanna Triscott, PhD Student, UBC Experimental Medicine

February 14, 2012      Supervised by: Dr. Sandra Dunn

Economic analysts estimate the cost to develop a new drug increased greater than 60% between 2000 and 2005. Six years ago this cost was on average $1.3 billion with many of these drugs failing to produce the “cure” they were intended [1]. The high cost and saturation of drugs available from pharmaceutical companies cause us to question whether there may be undiscovered therapeutic benefits in the battle against pediatric brain cancer.

In 1948, the Food and Drug Administration (FDA) approved the drug Disulfiram for the treatment of alcohol dependence. Disulfiram, or Antabuse, works by inhibiting a family of proteins called aldehyde dehydrogenase (ALDH). These proteins have detoxifying roles in the body and when an addict drinks an alcoholic beverage while taking Disulfiram, they feel flu-like symptoms, which discourage consumption.

Recently it has been found that ALDH activity is important in cancer cell growth and tumor formation. Cells with high ALDH activity have been used to identify highly drug resistant cells called tumor initiating cells (TICs) from greater populations of cancer cells. We have found that treating cells with Disulfiram drug, we are able to block cell growth in various types of brain cancers. In addition, we have used Disulfiram to block the self-renewal of TICs, which are thought to be responsible for repopulating brain tumors resulting in cancer relapse.

Disulfiram is an old drug that may have new and valuable uses in cancer treatment. It is being investigated for the treatment of melanoma and refractory malignancies that have spread to the liver (a process known as metastasis) [2,3]. This therapy would have a number of benefits for use in pediatric cancers, as there is over 60 years of documented safety in patients taking Disulfiram daily. Currently one of the few treatments available in the treatment of brain tumors is Temozolomide (TMZ). By combining Disulfiram with Temozolomide treatments we have demonstrated an even greater efficacy than using either one of the drugs alone in both cell growth assays and TIC formation experiments.

The cure to brain cancer may be a simple everyday product with undiscovered potential. In our quest to win the fight against brain tumors we hope to identify all means of eradicating this disease.

References:

 [1] J a Dimasi & h G Grabowski, “the Cost of Biopharmaceutical r&D: is Biotech Different?” managerial and Decision economics no 28 (2007): 469–79 ; J a Dimasi, r W hansen, and h G Grabowski, “the Price of innovation: new estimates of Drug Development Costs,” Journal of health economics 22 (2003): 151–185

[2] Phase I Study of Disulfiram and Copper Gluconate for the Treatment of Refractory Solid Tumors:  Involving the Liverhttp://clinicaltrials.gov/ct2/show/NCT00742911

[3] Disulfiram in Patients With Metastatic: Melanomahttp://clinicaltrials.gov/ct2/show/NCT00256230

Targeting the STAT3 Axis to Eliminate Glioblastoma Multiforme Brain Tumour

Laboratory of Oncogenomic Research, Departments of Pediatrics and Experimental Medicine, Child and Family Research Institute, University of British Columbia, Vancouver, BC

Mary Rose Pambid and Sandra E. Dunn

Glioblastoma multiforme (GBM) is the most common form of brain tumour in adults. While it is less common in children the disease is often life threatening independent of age.  Despite recent advances in surgery, radiation, and chemotherapy, GBM is highly aggressive and invasive, thus leading to dismal patient prognosis. Brain tumour-initiating cells (BTICs) are thought to be responsible for recurrence and resistance to conventional therapy. Signal transducer and activator of transcription 3 (STAT3) is a protein that is hyperactive in GBM, resulting in uncontrolled tumour growth. In light of this, we investigated the role of STAT3 as the driver of BTICs in pediatric and adult GBM. Silencing STAT3 causes its partner in crime, Twist, to decrease as well as increases BTICs to mature and stop growing. We are able to show that using natural compounds such as luteolin prevents STAT3 production and ultimately causes BTICs to mature and die. Overall, our data suggests that STAT3 is a promising therapeutic target.

Latest Update on the Research Funding (16th Jan 2012)

We just handed Dr. Dunn a cheque for $58,000 which went towards:

Fellowships total

  • Joanna Triscott (Y2 renewal) 15,500 4500 in current 20,000
  • Cathy Lee (Y3 project completion) 10,000 8,000
  • Mary Pambid (Y2 renewal)
  • Research expenses: cell culture, antibodies, publication fees 23,000

Total 48,500

Equipment

(Product Company Price)

  • Gilson Pipetman Neo starter kit Mandel $1,400 (P20, P200, P1000)
  • 8-Channel Multichannel pipette VWR $833.53
  • International Society of Pediatric Neuro-Oncology meeting $2,500
  • Gene Amp PCR System 9000 Thermocycler Applied Biosystems $7,270

Total $9,503.00

Total ask: 58,003

Future Asks:

  • Nanodrop Thermo Scientific $13, 256 (NOTE: Can get a cheaper PC Laptop from Staples or Futureshop)
  • PC Laptop (ND Dell Latitude E55000) Thermo Scientific $1,680
  • Extended service plan 1 year: $1275, 2 year: $2423

The American Association for Cancer Research Journal publishes research article about Glioblastoma (GBM)

(the type of tumour that Hannah suffered from)

Glioblastoma (GBM), the most common primary brain tumour in adults, is usually associated with a 2-year survival rate of only 10% to 25% (1). In children, primary brain tumors are the second most common type of cancer, following leukemia, with an incidence of 3.8 per 100,000 person-years (2, 3). Like adults, children who suffer from GBM have a low chance of long-term survival, thus, a better molecular understanding of these tumors may lead to new therapeutic targets.

Below is the Abstract of the article published in the American Associaton for Cancer Research Journal, titled

YB-1 Bridges Neural Stem Cells and Brain Tumor-Initiating Cells via Its Roles in Differentiation and Cell Growth.

The article is authored by Abbas Fotovati, Samah Abu-Ali, Pei-Shan Wang, Loic P. Deleyrolle, Cathy Lee, Joanna Triscott, James Y. Chen, Sonia Franciosi, Yasuhiro Nakamura, Yasuo Sugita, Takeshi Uchiumi, Michihiko Kuwano, Blair R. Leavitt, Sheila K. Singh, Alexa Jury, Chris Jones, Hiroaki Wakimoto, Brent A. Reynolds, Catherine J. Pallen, and Sandra E. Dunn (Dr. Sandra Dunn is a Scientist & High Content Screening Director on the Pediatric Brain Tumor Research Group supported by Hannah's Heroes Foundation).

Abstract

The Y-box binding protein 1 (YB-1) is upregulated in many human malignancies including glioblastoma (GBM). It is also essential for normal brain development, suggesting that YB-1 is part of a neural stem cell (NSC) network. Here, we show that YB-1 was highly expressed in the subventricular zone (SVZ) of mouse fetal brain tissues but not in terminally differentiated primary astrocytes. Conversely, YB-1 knockout mice had reduced Sox-2, nestin, and musashi-1 expression in the SVZ. Although primary murine neurospheres were rich in YB-1, its expression was lost during glial differentiation. Glial tumors often express NSC markers and tend to loose the cellular control that governs differentiation; therefore, we addressed whether YB-1 served a similar role in cancer cells. YB-1, Sox-2, musashi-1, Bmi-1, and nestin are coordinately expressed in SF188 cells and 9/9 GBM patientderived primary brain tumor–initiating cells (BTIC). Silencing YB-1 with siRNA attenuated the expression of these NSC markers, reduced neurosphere growth, and triggered differentiation via coordinate loss of GSK3-b. Furthermore, differentiation of BTIC with 1% serum or bone morphogenetic protein-4 suppressed YB-1 protein expression. Likewise, YB-1 expression was lost during differentiation of normal human NSCs. Consistent with these observations, YB-1 expression increased with tumor grade (n ¼ 49 cases). YB-1 was also coexpressed with Bmi-1 (Spearmans 0.80, P > 0.001) and Sox-2 (Spearmans 0.66, P > 0.001) based on the analysis of 282 cases of high-grade gliomas. These proteins were highly expressed in 10/15 (67%) of GBM patients that subsequently relapsed. In conclusion, YB-1 correlatively expresses with NSC markers where it functions to promote cell growth and inhibit differentiation. Cancer Res; 71(16); 5569–78. 2011 AACR.

A full copy of the article can be found at: http://cancerres.aacrjournals.org/content/71/16/5569.full.pdf+html