My name is Ruth MacKinnon and I’m a researcher in the Victorian Cancer Cytogenetics Service at St Vincent’s Hospital, Melbourne. You can read more on the St Vincent’s Hospital webpage. Cytogenetics is the study of chromosomes. The VCCS is a diagnostic lab which analyses the chromosomes in cancer cells.

ABOUT THIS BLOG

Cancer survival is improving as better treatments become available, but there’s a catch. One of the risks of chemotherapy, radiotherapy, or even some environmental pollutants, is that they can cause another type of cancer, known as therapy-related leukaemia (specifically, therapy-related acute myeloid leukaemia, t-AML), or therapy-related myelodysplastic syndromes (t-MDS). MDS is a blood disease which can develop into leukaemia.

This project aims to help us understand these diseases better by studying their chromosomes.

Leukaemia is a blood cancer. All cancers have the same fundamental cause – something is wrong with the DNA. So sometimes I’ll talk about cancer, sometimes about genetics, and sometimes about my leukaemia project. I’ll probably go off topic too, occasionally.

gene probes - abnormal chromosomes

Coloured pieces of DNA can be made to attach to the chromosome – this shows where that DNA is in the chromosome.

WHAT ARE CHROMOSOMES? WHAT IS DNA?

You’ve probably heard of cancer that runs in families. Most cancers don’t. Even so, cancer is a disease of the genes, it’s just that in most cases the genes first become faulty in the tissue or organ that goes on to become cancerous.

The body is made up of tiny building blocks called cells. Each cell has a set of genes – these are the instructions that control the cell. Think of genes as the words that spell out these instructions. The language they are written in is called DNA. The genes are ordered very precisely into special packages called chromosomes –  the chapters.

READING THE BOOK

Sometimes a mistake slips into the genes. A word might be dropped, doubled up, or mis-spelt. These changes can be found relatively easily. In therapy-related leukaemia it can be as if all the pages have fallen out and been stuck back together, with many different sections mixed up. Somewhere among all the corrupted chapters there are a few sentences that tell the cell to become cancerous.

THE PROJECT

My research focuses on changes to chromosomes. Therapy-related leukaemias often have very complicated chromosome changes, but there are patterns, and I look for these. I’ve come up with an explanation for what causes some of these chromosome shuffles. But there’s a lot of work to be done to work out if I’m on the right track, and to work out how to use this information to treat or prevent therapy-related leukaemia.

A lot of the research funding dollars are going to reading the DNA to find errors that cause cancer. But finding and explaining the patterns of these chromosome changes will also provide important clues. We are one of the few labs doing leukaemia chromosome research, especially in Australia.

There are still many riddles to solve in cancer research, and the more angles we attack it from, the better understanding we will have. If we can learn how to use the abnormal chromosome patterns to help understand leukaemia, we will have a strategy that can be used to study other cancers – and many of these have even more mixed up chromosomes.

FURTHER READING

MacKinnon RN, Selan C, Wall M, Baker E, Campbell LJ 2010. The paradox of 20q11.21 amplification in a subset of cases of myeloid malignancy with chromosome 20 deletion. Genes Chromosomes and Cancer 49:998-1013.

MacKinnon RN and Campbell LJ 2011. The role of dicentric chromosome formation and secondary centromere deletion in the evolution of myeloid malignancy. Genetics Research International ID 643628 (open access).

MacKinnon RN, Duivenvoorden HM, Campbell LJ. 2011. Unbalanced translocations of 20q in AML and MDS often involve interstitial rather than terminal deletions of 20q. Cancer Genet. 204:153-61.

Chin LK, Cheah CY, Michael PM, MacKinnon RN, Campbell LJ. 2012. 11q23 rearrangement and duplication of MLLT1-MLL gene fusion in therapy-related acute myeloid leukemia. Leuk Lymphoa. 53:2066-8.

Wall M, Rayeroux KC, MacKinnon RN, Zordan A, Campbell LJ 2012. ETV6 deletion is a common additional abnormality in patients with myelodysplastic syndromes or acute myeloid leukemia and monosomy 7. Haematologica 97:1933-6 (open access).

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