CANCER AND THE FOCAL POINT OF GENETICS - Drosophila melanogaster !
We all know that for nearly a century, Drosophila melanogaster has been on the focal point of genetics and developmental biology - genetically diverse, can be easily cultured in laboratory conditions, they produce large numbers of externally laid embryos, and of course the major reason being them having a much shorter life cycle.
Though humans and fruit flies don't possess similar morphological/anatomical characteristics, it became pretty much well known that most of the fundamental biological processes and pathways that control survival and development are conserved across evolution between these species. Drosophila genome is 60% homologous to that of humans, and about 75% of the genes responsible for human diseases have homologues in these fruit flies.
Research on Drosophila melanogaster already points to a new anti - cancer breakthrough different from the conventional goal of destroying a tumor. Tumors in fruit flies release a specific chemical that encompass the blood - brain barrier, paving the way for the two environments to mix - a recipe for disastrous situations in several diseases, including obesity, infection and trauma. Another research also suggested that some specific tumors in mice that release the same chemical - it's basically a cytokine called interleukin - 6 also makes the blood - brain barrier leaky like in the above case with fruit flies.
By blocking the effect of cytokine on the blood - brain barrier, the lifespan of both the fruit flies as well as the mice could also be increased. This interleukin - 6 cytokine is known to cause inflammation. The significant aspect to be noted here is that this tumor induced inflammation caused by the cytokine actually causes the blood brain barrier to open. If that opening process is disturbed, without conferring any disturbance to the tumor, then the host will be able to live longer and healthier with the same tumor. Blocking the activity of interleukin - 6 cytokine at the blood - brain barrier increased the lifespan of fruit flies with cancer by 45%!!
According to me, scientists need to discover one drug that blocks the effect of cytokine only on the blood - brain barrier, without altering its effect elsewhere. This drug will then be able to even extend the lifespan and health rate of cancer patients. Something which you cannot believe now also - tumors of these small small fruit flies release so much, well now I say they release a substance that blocks the effects of insulin too, that provides us with a perfect reasoning for cachexia - the inability to maintain weight, which leads to muscle wasting even when the patient is receiving intravenous nutrition. Cachexia kills some cancer patients :( This release of the substance that blocks insulin effects is still being explored by several labs worldwide.
One of the pros of helping the host ward off a tumor's effects on tissues far from the tumor site could actually decrease or even eliminate the need for toxic drugs typically used to subdue tumors. These toxic drugs harm the patient in disastrous ways, killing not only cancerous cells but even healthy cells. Since tumors have genetic variability, therefore targeting the tumor also selects for resistance in the tumor. However, if the host cells could be targeted, the host cells anyway have a stable genome and hence will not gain resistance against these kind of drugs.
There is still some amount of uncertainty that clouds the most common question of what actually causes death in many cancer patients. Taking an example of hepatic cancer (liver cancer), we can clearly say that this hepatic cancer destroys the function of the liver, an organ that is essential for the very being of life. However, certain other organs, like the ovaries, are less critical, though people die from cancer in these sites too. Although cancers most often metastasize other organs and not only the targeted organ - one of the major cause for death by cancer as reported by doctors has been multiple organ failure.
Most of the cancers are metastatic, but that still doesn't explain the question of what causes death in many cancer patients. If one's tumor metastasized to the lung, for example, is that person dying because of lung failure or is he/she dying from something else? This is one of the most common questions circulating cancer that looks forward to a satisfying answer.
The lifespan of fruit flies is normally 30 days (nearly 4 weeks), and with a leaky blood brain barrier, these fruit flies can still live for 3 or 4 weeks. However, if these fruit flies have a tumor, they die almost immediately after the barrier comes to terms. Additional cancer produced chemicals have been found by scientists in flies that has further been linked to edema and excessive blood clotting. Edema is bloating that is caused due to excess fluid retention. Both edema as well as excessive blood clotting frequently accompany cancer. Certain other studies link these tumor - produced fruit fly chemicals to anorexia (immune dysfunction and loss of appetite - linked to symptoms of several cancers).
Ok, so how is studying cancer on fruit fly models more advantageous than studying cancer on other animal models?
1. Researchers can follow up fruit flies till the moment of their death, for their lifespan is comparatively short and they reproduce quickly helping them to determine more easily what actually causes mortality in cancer patients.
2. Fruit fly experiments can involve hundreds of fruit fly individuals, which stimulates more accurate studies.
3. In the past, Drosophila melanogaster has played a significant role in analysing oncogenes and tumor growth factors. This implies that the fruit flies could also be significant in understanding the adverse effects of cancer.
Drosophila melanogaster - the key for the cancer treatment of tomorrow? Do let me know your views in the comments :) Stay scientifically tuned :)
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