The ultimate aim is to identify biomarkers of tumour response to drugs in the blood of children with high-risk neuroblastoma.
Challenge: Treatment regimens for patients with high-risk neuroblastoma involve intensive, multi-modal chemotherapy. Many patients response to initial therapy very well, but has only short-term effects, with most becoming resistant to treatment and developing progressive disease.
The project has two parts which complement each other.
We will study cell-to-cell communication using cell-based models. We will collect exosomes, small envelopes containing bioactive molecules, produced by drug-resistant cell lines to treat non-cancerous cells. We will measure the effect of exosomes on non-cancerous cells by counting cell growth, examining their shape and metabolism. We will also examine whether non-cancerous cells treated with exosomes become less responsive to chemo drugs.
We will treat neuroblastoma cells with a drug and collect exosomes before and after treatment. We will profile exosomes to identify any changes in their miRNA content. MiRNA are very small pieces of genetic material that can change the way cell feels and works. This step will help to find biologically active miRNA that can trigger cell resistance to drugs. These biologically active miRNA can represent biomarkers of tumour response to chemotherapy.
We will screen clinical samples for exosomal miRNA in response to drug treatment. We are planning to use a small sample of blood taken from neuroblastoma patients during routine examinations before, during and after chemotherapy.This step will help to find clinically relevant miRNA of tumour responsiveness to chemo drugs.
How does this project contribute to the biomedical community?
This study aims to contribute to the better understanding of the disease mechanisms and scientific knowledge in the area, and in particular how neuroblastoma cells communicate with other cells helping tumour to create a unique microenvironment and protect themselves from chemotherapy pressure. The new data will give insights in biologically active proteins and miRNAs involved in cell-to-cell communication and drug responsiveness.
What are potential benefits of the proposed research to neuroblastoma patients?
This project aims to develop exosomal biomarkers of tumour response to drugs that might be used to help select patients for treatment and identify novel targets for the development of more effective personalised therapy with the anticipated improvement in outcomes. This work will contribute to the more efficient design of re-initiation treatment, sparing patients unnecessary rounds of chemotherapy and ultimately increasing survival. These new circulating markers will benefit children with high-risk neuroblastoma whose tumours are relapsed leading to less harmful and more tailored treatment options and improving their quality of life.
This is the first time in the history of the IACR meetings when an entire plenary session is solely dedicated to challenges and advancements in childhood cancer.
This session will unite Internationally recognised leaders in childhood cancer research. They will speak about what we know about origin and evolution of childhood cancers (Prof. Tariq Enver), how blood biomarkers can help in stratification and treatment of children (Prof. Sue Burchill), what impact Down syndrome has in the white blood cell cancer development and progression (Prof. Irene Roberts), how epigenetic changes affect tumour pathogenesis and future of therapeutics targeting theses changes (Prof Raymond Stallings).
Childhood cancer is an umbrella term for a great variety of malignancies which vary by site of disease origin, tissue type, race, sex, and age.
The cause of childhood cancers is believed to be due to faulty genes in embryonic cells that happen before birth and develop later. In contrast to many adult’s cancers, there is no evidence that links lifestyle or environmental risk factors to the development of childhood cancer.
Every 100th patient diagnosed with cancer is a child.
In the last 40 years the survival of children with most types of cancer has radically improved owing to the advances in diagnosis, treatment, and supportive care. Now, more than 80% of children with cancer in the same age gap survive at least 5 years when compared to 50% of children with cancer survived in 1970s-80s.
Childhood cancer is the second most common cause of death among children between the ages of 1 and 14 years after accidents.
Unfortunately, no progress has been made in survival of children with tumours that have the worst prognosis (brain tumours, neuroblastoma and sarcomas, cancers developing in certain age groups and/or located within certain sites in the body), along with acute myeloid leukaemia (blood cancer). Children with a rare brain cancer – diffuse intrinsic pontine glioma survive less than 1 year from diagnosis. Children with soft tissue tumours have 5-year survival rates ranging from 64% (rhabdomyosarcoma) to 72% (Ewing sarcoma).
For majority of children who do survive cancer, the battle is never over. Over 60% of long‐term childhood cancer survivors have a chronic illness as a consequence of the treatment; over 25% have a severe or life‐ threatening illness.
This week can be rated for sure as feeling good, excited and accomplished. A UK based charity – Neuroblastoma UK has awarded a small grant to characterise a pre-clinical model of neuroblastoma which is a collaborative project between our lab and Tissue Engineering Research Group at RCSI. This project will study features of neuroblastoma cells growing on collagen-based scaffolds. The NBUK grant will contribute to one of the most expensive parts of the study – characterisation of cell secreting proteins using antibody-based profiling platforms.
Another research was accomplished yesterday – John Nolan had his Voice Viva examination and successfully defended his PhD Thesis. This 3 year PhD project was funded by the National Children’s Research Centre. As his supervisor, I am delighted for him and wish him best of luck in his research career.
This post is dedicated to parents of children with neuroblastoma. Some parents asked about DFMO – a re-purposing drug. In this post, I tried to collect and summarize information available from academic sources.
Q1: What is DFMO?
Difluoromethylornithine (DFMO, Eflornithine) is an anti-protozoan drug. It was originally developed and FDA approved for the treatment of Trypanosoma brucei gambiense encephalitis (“African sleeping sickness”). DFMO permanently binds to ornithine decarboxylase (ODC), an important enzyme in polyamine metabolism, and prevents the natural substrate ornithine from entering the active site.
By inhibiting ODC, DFMO reduces cellular polyamines and inhibits cell growth and proliferation of actively dividing cells, thus making DFMO an attractive candidate for cancer therapy. In neuroblastoma, a positive regulation of all aspects of polyamine metabolism by MYCN was reported (revived by Bassiri 2015, Gamble 2012). So, it is believed that MYCN amplified neuroblastomas would most benefit of the drug.
Q2: How intense is basic science behind DFMO in neuroblastoma?
To find out the intensity of basic science on DFMO in neuroblastoma search for ‘difluoromethylornithine/DFMO/Eflornithine’ and ‘neuroblastoma’ was run in PubMed, a web-based resource with 26 million citations for biomedical literature from MEDLINE, life science journals, and online books. The search returned 23 papers including 3 reviews and 20 primary research reports published from 1980 to present.
In comparison, I did another search for a novel drug Unituxin (dinutuximab) approved by FDA in 2015. It is monoclonal antibody against the glycolipid disialoganglioside GD2, a biomarker specific for neuroblastoma. Search for ‘anti-GD2 antibody’ and ‘neuroblastoma’ returned 181 papers including 25 reviews and 156 primary articles for the same period.
Q3: Is DFMO in cancer clinical trials?
“ClinicalTrials.gov is a Web-based resource that provides patients, their family members, health care professionals, researchers, and the public with easy access to information on publicly and privately supported clinical studies on a wide range of diseases and conditions. The Web site is maintained by the National Library of Medicine (NLM) at the National Institutes of Health (NIH).
Search for ‘difluoromethylornithine/DFMO/Eflornithine’ in ClinicalTrials.gov returned 36 registered trials across different health conditions.Two of these were withdrawn, the breakdown for the rest 34 is as follows: Adenomatous Polyp (1), Anaplastic Astrocytoma/Recurrent Anaplastic Astrocytoma (1), Bladder Cancer (1), Cervical Cancer/Precancerous Condition (1), Colorectal Cancer (3), Esophageal Cancer (1), Familial Adenomatous Polyposis (1), Gastric Cancer/Gastric Intestinal Metaplasia (1), Hirsutism (2), Human African Trypanosomiasis (5), Neuroblastoma (7), Non-melanomatous Skin Cancer/Precancerous/Nonmalignant Condition (4), Post-solid Organ Transplant/Skin Neoplasms (1), Precancerous Condition (1), Prostate Cancer (2), Pseudofolliculitis Barbae (1), Type 1 Diabetes (1) (Fig. 2). To see full details of 34 trials please click at this Table.
All of them have various statuses (Fig. 3) as well as study design. Importantly, 30 out of 34 studies are focused on safety and efficacy of this drug. Vast majority of studies of DFMO in adult cancers/benign conditions are randomized (16/18 or 89%). Randomization in assignment of patients in studied groups (control and new drug/combination) helps minimize researcher’s bias when comparing effect of the new treatment vs current/no treatment. All trials of DFMO in neuroblastoma are not randomized. Instead, studies use a single group assignment.
Three trails have been either completed/terminated and published results are available at ClinicalTrials.gov (NCT01059071, NCT00033371. NCT00118365).
Q4: What about clinical trials of DFMO in neuroblastoma?
The trial NCT01059071 was a Phase 1 clinical trial. A phase I clinical trial tries to find out whether a new treatment/drug is safe, what its side effects are, the best dose of the new treatment, if the treatment shrinks the cancer.
Twenty one patients were enrolled and eligible for treatment with DFMO and DFMO + etoposide. These patients were assigned into 4 groups of different DFMO doses (Fig. 4). The treatment was in cycles of 21 days. Cycle 1 – DFMO only followed by cycle 2 – combined treatment of DFMO+etoposide (14 days) and DFMO only (the last 7 days).
According to results of the trial: 14 patients did not complete the treatment due to different reasons. It was not clear what stage/cycle they left the trial.
As mentioned earlier this study used a single group assignment and a design called ‘3+3’. This design is straightforward and safe. Briefly, it means that for a dose (X) of the drug, 6 patients are selected. Of these, 3 receive the dose X and are monitored for a period of time. If no adverse effects are registered in these 3, then another new 3 patients start the same treatment. The effect of the drug is evaluated on the patent’s health condition before-, during – the treatment and after its completion. This approach is often used in vaccine tests and dose escalation methods in Phase I cancer clinical trials. This type of study can answer mainly two questions: 1) whether the tested drug is safe to use and 2) what doses are safe? The main drawbacks of this design are
Many patients treated at doses below therapeutic effect
Slow dose increase
Uncertainty about the recommended phase II dose (RP2D)
Only the result from the current dose is used for determining the dose of next cohort of patients. Information on other doses is ignored
Q6: What are main findings of the clinical trial NCT01059071?
The overflow of the study is presented in Fig 5 providing additional information on those who did not complete the trial. Out of 14 participants, disease has progressed in 11 patients – it is 52% of the enrolled participants. Authors highlighted that this phase I study was not designed to evaluateanti-tumour efficacy of DFMO. But tumour response and clinical response were monitored during the study.
According to the paper, 21 patients received at least one dose of DFMO only (Cycle 1, 21 days). During this cycle, 3 patients were withdrawn. All of them were assessed for safety of DFMO.
Eighteen of them completed cycle 1 and continued treatment with DFMO+etoposide for another 4 cycles followed with DFMO only therapy for a number of cycles. Their clinical response data were examined for efficacy of DFMO alone.
Three out of 21 participating patients in this clinical trial remain alive and disease free between 2–4.5 years after starting DFMO.
Authors concluded that
DFMO doses of 500-1500mg/m2/day are safe and well tolerated in children with relapsed NB
Research and review papers covering DFMO in neuroblastoma:
Evageliou NF, Haber M, Vu A, Laetsch TW, Murray J, Gamble LD, Cheng NC, Liu K, Reese M, Corrigan KA, Ziegler DS, Webber H, Hayes CS, Pawel B, Marshall GM, Zhao H, Gilmour SK, Norris MD, Hogarty MD. Polyamine Antagonist Therapies Inhibit Neuroblastoma Initiation and Progression. Clin Cancer Res. 2016 Sep 1;22(17):4391-404. doi: 10.1158/1078-0432.CCR-15-2539.
Bassiri H, Benavides A, Haber M, Gilmour SK, Norris MD, Hogarty MD. Translational development of difluoromethylornithine (DFMO) for the treatment of neuroblastoma. Transl Pediatr. 2015 Jul;4(3):226-38. doi: 10.3978/j.issn.2224-4336.2015.04.06. Review.
Saulnier Sholler GL, Gerner EW, Bergendahl G, MacArthur RB, VanderWerff A, Ashikaga T, Bond JP, Ferguson W, Roberts W, Wada RK, Eslin D, Kraveka JM, Kaplan J, Mitchell D, Parikh NS, Neville K, Sender L, Higgins T, Kawakita M, Hiramatsu K, Moriya SS, Bachmann AS. A Phase I Trial of DFMO Targeting Polyamine Addiction in Patients with Relapsed/Refractory Neuroblastoma. PLoS One. 2015 May 27;10(5):e0127246. doi: 10.1371/journal.pone.0127246.
Lozier AM, Rich ME, Grawe AP, Peck AS, Zhao P, Chang AT, Bond JP, Sholler GS Targeting ornithine decarboxylase reverses the LIN28/Let-7 axis and inhibits glycolytic metabolism in neuroblastoma. Oncotarget. 2015 Jan 1;6(1):196-206.
Samal K, Zhao P, Kendzicky A, Yco LP, McClung H, Gerner E, Burns M, Bachmann AS, Sholler G. AMXT-1501, a novel polyamine transport inhibitor, synergizes with DFMO in inhibiting neuroblastoma cell proliferation by targeting both ornithine decarboxylase and polyamine transport. Int J Cancer. 2013 Sep 15;133(6):1323-33. doi: 10.1002/ijc.28139.
Koomoa DL, Geerts D, Lange I, Koster J, Pegg AE, Feith DJ, Bachmann AS. DFMO/eflornithine inhibits migration and invasion downstream of MYCN and involves p27Kip1 activity in neuroblastoma. Int J Oncol. 2013 Apr;42(4):1219-28. doi: 10.3892/ijo.2013.1835.
Gamble LD, Hogarty MD, Liu X, Ziegler DS, Marshall G, Norris MD, Haber M. Polyamine pathway inhibition as a novel therapeutic approach to treating neuroblastoma. Front Oncol. 2012 Nov 16;2:162. doi: 10.3389/fonc.2012.00162. Review
Passariello CL, Gottardi D, Cetrullo S, Zini M, Campana G, Tantini B, Pignatti C, Flamigni F, Guarnieri C, Caldarera CM, Stefanelli C. Evidence that AMP-activated protein kinase can negatively modulate ornithine decarboxylase activity in cardiac myoblasts. Biochim Biophys Acta. 2012 Apr;1823(4):800-7. doi: 10.1016/j.bbamcr.2011.12.013.
Rounbehler RJ, Li W, Hall MA, Yang C, Fallahi M, Cleveland JL. Targeting ornithine decarboxylase impairs development of MYCN-amplified neuroblastoma. Cancer Res. 2009 Jan 15;69(2):547-53. doi: 10.1158/0008-5472.CAN-08-2968.
Koomoa DL, Yco LP, Borsics T, Wallick CJ, Bachmann AS. Ornithine decarboxylase inhibition by alpha-difluoromethylornithine activates opposing signaling pathways via phosphorylation of both Akt/protein kinase B and p27Kip1 in neuroblastoma. Cancer Res. 2008 Dec 1;68(23):9825-31. doi: 10.1158/0008-5472.CAN-08-1865.
Hogarty MD, Norris MD, Davis K, Liu X, Evageliou NF, Hayes CS, Pawel B, Guo R, Zhao H, Sekyere E, Keating J, Thomas W, Cheng NC, Murray J, Smith J, Sutton R, Venn N, London WB, Buxton A, Gilmour SK, Marshall GM, Haber M. ODC1 is a critical determinant of MYCN oncogenesis and a therapeutic target in neuroblastoma. Cancer Res. 2008 Dec 1;68(23):9735-45. doi: 10.1158/0008-5472.CAN-07-6866.
Wallick CJ, Gamper I, Thorne M, Feith DJ, Takasaki KY, Wilson SM, Seki JA, Pegg AE, Byus CV, Bachmann AS. Key role for p27Kip1, retinoblastoma protein Rb, and MYCN in polyamine inhibitor-induced G1 cell cycle arrest in MYCN-amplified human neuroblastoma cells. Oncogene. 2005 Aug 25;24(36):5606-18.
Bachmann AS. The role of polyamines in human cancer: prospects for drug combination therapies. Hawaii Med J. 2004 Dec;63(12):371-4. Review
Chen ZP, Chen KY. Differentiation of a mouse neuroblastoma variant cell line whose ornithine decarboxylase gene has been amplified. Biochim Biophys Acta. 1991 Dec 3;1133(1):1-8.
Piacentini M, Fesus L, Farrace MG, Ghibelli L, Piredda L, Melino G. The expression of “tissue” transglutaminase in two human cancer cell lines is related with the programmed cell death (apoptosis). Eur J Cell Biol. 1991 Apr;54(2):246-54.
Melino G, Piacentini M, Patel K, Annicchiarico-Petruzzelli M, Piredda L, Kemshead JT. Retinoic acid and alpha-difluoromethylornithine induce different expression of neural-specific cell adhesion molecules in differentiating neuroblastoma cells. Prog Clin Biol Res. 1991;366:283-91.
Stephanou A, Knight RA, De Laurenzi V, Melino G, Lightman SL.Expression of pre-opiomelanocortin (POMC) mRNA in undifferentiated and in vitro differentiated human neuroblastoma cell lines. Prog Clin Biol Res. 1991;366:173-80.
Melino G, Farrace MG, Ceru’ MP, Piacentini M. Correlation between transglutaminase activity and polyamine levels in human neuroblastoma cells. Effect of retinoic acid and alpha-difluoromethylornithine. Exp Cell Res. 1988 Dec;179(2):429-45.
Chen KY, Dou QP. NAD+ stimulated the spermidine-dependent hypusine formation on the 18 kDa protein in cytosolic lysates derived from NB-15 mouse neuroblastoma cells. FEBS Lett. 1988 Mar 14;229(2):325-8.
Karvonen E, Andersson LC, Pösö H. A human neuroblastoma cell line with a stable ornithine decarboxylase in vivo and in vitro. Biochem Biophys Res Commun. 1985 Jan 16;126(1):96-102.
Pösö H, Karvonen E, Suomalainen H, Andersson LC. A human neuroblastoma cell line with an altered ornithine decarboxylase. J Biol Chem. 1984 Oct 25;259(20):12307-10.
Chen KY, Nau D, Liu AY. Effects of inhibitors of ornithine decarboxylase on the differentiation of mouse neuroblastoma cells. Cancer Res. 1983 Jun;43(6):2812-8.
Chapman SK. Antitumor effects of vitamin A and inhibitors of ornithine decarboxylase in cultured neuroblastoma and glioma cells. Life Sci. 1980 Apr 21;26(16):1359-66. No abstract available.
Continue research into 3D neuroblastoma models, we imaged cells growing on collagen based scaffolds using confocal microscopy. This technique is very popular in cell biology providing depth in cell imaging.
Here you can see cells growing on scaffolds: white dots – cells, irregular fibers – collagen containing scaffold.
The results are fascinating! Cell nucleus is in blue (DAPI), cell actin is in red (phalloidin). You will be able also to see how two cells ‘having a handshake’. It is happening just in the middle.
For children who do survive cancer, the battle is rarely over. Over 60% of long‐term childhood cancer survivors have a chronic illness as a consequence of the treatment they received; over 25% have a severe or life‐ threatening illness. How much do we know about quality of life of childhood cancer survivors?
Researchers in health- and illness-related social sciences understand that the there is a life after the treatment completed. The life is full if diverse levels and issues from health related to social adaptation in different shapes and forms. Children and teenagers may experience fear when returning to school due to temporary or permanent changes to their physical appearance (1,2). They worry about their ability to socialise with their friends due to lengthy absences (3–5). Treatment can result in the development of learning disabilities in children and thus marking school as a major source of frustration (1,2). These learning difficulties can affect a child’s confidence and self-esteem, if left without attention and care (1,3). All studies come to the same conclusion. Challenges in education of children with cancer are complex, however most can be tackled efficiently through planning and good communication (1–5).
It is important not only to recognise the problems but to start changing the situation. Apparently much more could be done more efficiently if patients are involved in setting up future research agenda.
Gurney JG, Krull KR, Kadan-Lottick N, Nicholson HS, Nathan PC, Zebrack B, et al. Social outcomes in the childhood cancer survivor study cohort. J Clin Oncol. 2009;27(14):2390–5.
McDougall J, Tsonis M. Quality of life in survivors of childhood cancer: A systematic review of the literature (2001-2008). Supportive Care in Cancer. 2009. p. 1231–46.
Barrera M, Shaw AK, Speechley KN, Maunsell E, Pogany L. Educational and social late effects of childhood cancer and related clinical, personal and familial characteristics. Cancer. 2005;104(8):1751–60.
Langeveld NE, Stam H, Grootenhuis MA, Last BF. Quality of life in young adult survivors of childhood cancer. Support Care Cancer. 2002;10(8):579–600.
Klassen AF, Anthony SJ, Khan A, Sung L, Klaassen R. Identifying determinants of quality of life of children with cancer and childhood cancer survivors: A systematic review. Support Care Cancer. 2011;19(9):1275–87.
Yeh JM, Hanmer J, Ward ZJ, Leisenring WM, Armstrong GT, Hudson MM, et al. Chronic Conditions and Utility-Based Health-Related Quality of Life in Adult Childhood Cancer Survivors. J Natl Cancer Inst [Internet]. 2016;108(9):4–7.
Armstrong GT, Chen Y, Yasui Y, Leisenring W, Gibson TM, Mertens AC, et al. Reduction in Late Mortality among 5-Year Survivors of Childhood Cancer. N Engl J Med. 2016;374(9):833–42.
The conference on models and tumour microenvironment has brought together International experts in this field. Two keynote speakers (Peter Friedl, Radboud UMC/MD Anderson and Andrew Ewald, John Hopkins University) presented exhaustive experimental data on plasticity and microenvironmental control of cancer invasion and metastasis.
Their research teams independently found that
Tumour cells migrate collectively as a team from a piece of tumour like a group of people who changed their minds and decided to travel by bus when the majority stayed camping. However, Andrew Ewald acknowledged that they are not pioneers in this discovery. In 1976 Liotta observed migration of tumour cells in a group of 6-10 cells.
A migration group of cells has their leaders who crave the path through surroundings to the new locations.
Leader cells depend on cancer types. It can be any tumour cell in some cancer types or a specialised one.
Migrating cells take shape and follow the pattern of tissues to be invaded.
The experiments by Ewald’s research team on collective cell migration. In short, they co-implanted two lung tumour cell populations labelled differently into mice. One cell population had a green protein tag, another had red. After 6-8 weeks, researchers examined metastases and found that they had a mixed population of green and red tumour cells.
The very first human cancer cell line was developed from a patient with an aggressive cervical cancer in 1951. This cell line was called HeLa after the patient name – Henrietta Lacks. This is the most popular and robust cancer cell line in biomedical research. Since then, other cancer cell lines were developed including neuroblastoma.
The first successful neuroblastoma ‘cell lines’ were cell populations from tumours that were adapted to grow for a short period in the lab environment in 1947. These tumour cell populations were used as a tool for diagnosis. This success inspired other researchers to develop long-term or immortal neuroblastoma cell lines. To date different neuroblastoma cell lines exist.
Cancer cell lines are sensitive and delicate in handling. They can only grow in the safe environment. Researchers have to protect them against bacteria, low temperatures, and too acidic/alkaline conditions. We protect cancer cells from bacteria contamination by handling them in cabinets where all plastic and media are sterile.
Cancer cells like to grow in conditions similar to conditions in human body. They like temperature of 36.6 – 37C. To achieve it special ‘green cell houses’ – CO2 incubators are built, which maintain the constant temperature, humidity and CO2 concentration.
The cell growth and well being are checked regularly using microscopes. Healthy cells are to have similar shape, even distribution and grow attached to the plastic surface. Most microscopes have a camera attached to the top and linked to a computer. It helps to take picture of growing cells and record changes in cell behaviour.
Children with neuroblastoma undergo several cycles of intensive chemotherapy to stop disease progression with the final aim to eliminate the tumour. Chemotherapy includes carboplatin or cisplatin in various combinations with drugs such as cyclophosphamide, ifosfamide, doxorubicin, etoposide, topotecan and vincristine (1). Nevertheless, in average 1 in 5 children with stage 4 disease do not respond to therapy. Up to 50% of children that do respond experience disease recurrence with tumour resistant to multiple drugs and more aggressive behaviour that all too frequently results in death.
The development of drug resistance is the major obstacle in treatment of neuroblastoma. To tackle this problem, researchers need to study different models of disease using cell lines, 3D tumour cell models, mice models and have access to clinical samples.
The first stage in testing drugs is to understand their killing ability of cancer cells. At this stage, researchers test drugs using cell lines. Cell lines are derived from tumours which were surgically removed from children with neuroblastoma. Researchers usually take a small piece of tumour straight after surgery and bring it into the laboratory. Here, they place this piece into special solution that has enzymes to separate cells from each other. Then the suspension of all kind of tumour cells is placed into plastic dishes or flasks in a highly nutrient media to let cells grow. Cells that can adapt to these conditions start to grow, divide and produce a new generation of cancer cells. Researchers look after their growth, inspect their shape and behaviour; and test them on the presence of tumour markers. Once identity of these cells is confirmed they become a cell line and obtain a name. These cells keep majority of characteristics of the parental tumour and represent very useful tools in cancer research.
In our lab we use such cell lines to study neuroblastoma resistance to drugs. To understand changes in neuroblastoma biology during the development of drug resistance, we created drug resistant neuroblastoma cell lines (2). We treated three neuroblastoma cell lines CHP212, SK-N-AS and Kelly with cisplatin – a common drug in anticancer therapy. SK-N-AS and Kelly cells are sensitive to this drug, while CHP212 cells responded to this drug at much higher levels that the other two. Cells were grown in media containing cisplatin for several weeks. During this period most of the cells responded to cisplatin and died. Then we let cell survivors to recover in media without drug. This cycle was repeated several times until we got a population of cell survivors that can stand doses of cisplatin that can kill 50% of parental cells. It took us more than 6 months to generate cisplatin resistant neuroblastoma cell lines CHP212Cis100, SK-N-ASCis24 and KellyCis83.
At the next step, we studied differences between these cell lines. We first compared their behaviour and cell shapes. Two resistant cell lines KellyCis83 and CHP212Cis100 started to grow faster, but SK-N-ASCis24 – slower than their parental cell lines. Interestingly, these cells also became more resistant to other drugs such as doxorubicin, etoposide, temozolomide, irinotecan and carmustin. These results are very important as they demonstrate that one drug can activate the cell defense systems that allow to escape toxicity of other drugs. These cell lines can be used to test new drugs and find those that can overcome developed resistance.
Cisplatin resistant cells also changed their appearance. Most dramatic changes occurred in SK-N-ASCis24 cells (see Figure 1).
Figure 1. Microscopic images sensitive and drug resistant neuroblastoma cells (adapted from (2))
Two drug resistant cell lines SK-N-ASCis24 and CHP212Cis100 cells developed additional mobility skills – they became more invasive than their parental counterparts.
Then we asked a question: what type of changes allowed cells to adapt to cytotoxic environment? We examined changes in their genomic DNA first. We found that some genes increased their copy number, other went missing.
We identified changes in protein expression. More intriguingly, some proteins with the increased presence in the cells did not increase their presence in genomic DNA. We sorted these proteins on their role in cell processes such as migration, growth, cell cycle, etc. We found that each cisplatin resistant cell line developed a unique set of features that help them to escape cytotoxic stress (2). The similar patterns are found in clinic. Each patient responds to treatment differently.
What did we learn from this study?
One drug, in our study cisplatin, can activate the cell defense systems that allow to escape toxicity of other drugs.
The development of drug resistance gives cells new advantages and changes their behaviour and appearance, e.g. mobility skills, different cell shape, response to drugs, etc.
Each cisplatin resistant cell line developed a unique set of features that help them to escape cytotoxic stress.
These cell lines can be used to test new drugs and find those that can overcome developed resistance.