Sonic The Hedgehog might be a classic video game that defines a generation, but the gene of the same name dates further. In the past few decades, scientists have gathered data from fossils, DNA sequencing, and embryological development to assemble the lessons of Sonic Hedgehog into the story of building a human body. 

Initially discovered in fruit flies, the Sonic Hedgehog gene is highly conserved and found in species as diverse as mammals, reptiles, and birds. The mammalian version of the gene codes for a morphogen, a type of signalling molecule that elicits different cellular responses depending on its concentration. It is essential during embryonic growth, particularly in the development of the nervous and skeletal systems. Once considered to be generally silent after birth, this developmental pathway has recently been shown to be reactivated in adulthood. Several studies have demonstrated that Sonic Hedgehog signalling is also required for the survival and proliferation of certain cells such as tissue progenitor and stem cells. Alongside its function as a developmental morphogen, the gene is also involved in the injury-dependent regeneration of muscles and organs, such as the prostate and bladder.

Besides its effects on growth and development, other functions of the gene are actively being dissected, particularly its role in age-associated diseases including atherosclerosis, neurodegenerative diseases and sarcopenia where there is progressive loss of muscle mass. A decline in Sonic Hedgehog-mediated cell signalling during ageing was found to affect the regenerative potential of local stem cells, reducing an individual’s resilience to injury. Conversely, enhancing the gene’s activity has been found to prevent age-associated decline in stem cell functions.

From evolutionary science to developmental biology, Sonic Hedgehog indeed merits additional exploration and investigation for its potential applications in molecular therapy for certain groups of target patients.

Ms Low Shin Yi
Duke-NUS’ Programme in Cancer and Stem Cell Biology

Assistant Professor Tang Hong-Wen
Duke-NUS’ Programme in Cancer and Stem Cell Biology

The importance of vascular structures depends on the nature and stage of a tumour, so it is not always correct to say that veins are more important than arteries.

In most oncological surgeries, blood flow through the arteries is prioritised. Surgeons aim to decrease the blood inflow to reduce swelling of the organ and its surrounding? tissues. In this way, they can increase the operative surgical space to work in. In advanced cancer cases, this manoeuver also helps the tumour blood vessels retract into the organ.

However, in rare and extreme cases when the tumour blood vessel is too long, the involved veins and any branches will need to be considered as they present the highest source of excessive bleeding or haemorrhaging.

In endocrinologically functional tumors, where tumours in endocrine glands affect hormone production in the body such as adrenal pheochromocytomas, the vein may indeed be more critical. Controlling the amount of blood flowing through the vein reduces the release of adrenaline into the body which has an immediate impact on the patient’s blood pressure and heart rate. Alerting the anaesthesiologist before this step is also critical to ensure the patient’s safety.

In all cases, having intimate anatomical and functional knowledge of the artery and vein is the linchpin to surgical success.