The HER2 gene encodes a transmembrane receptor tyrosine kinase that coordinates cell signaling pathways to promote cell division under normal physiological conditions. An activating mutation or amplification of the HER2 gene creates an oncogene, which can lead to tumour development in gastric tissue.
Suggest and explain how an activating mutation in the HER2 gene can cause a tumour to develop.
Overexpression of HER2 is strongly linked to aggressive gastric cancer. Scientists investigated the survival times of three groups of gastric cancer patients who also had chronic hyperlipidemia (high blood lipid levels):
The scientists performed a statistical test to compare the survival times of these groups against a control group of gastric cancer patients with no history of hyperlipidemia. Their results are shown in Table 1.
Table 1: Effects of hyperlipidemia treatments on the survival of gastric cancer patients
| Group | Mean survival time of gastric cancer patients / months | Probability value (PPP) |
|---|---|---|
| No history of hyperlipidemia | 32.4 | - |
| Group A | 19.8 | 0.002 |
| Group B | 48.6 | 0.008 |
| Group C | 35.1 | 0.385 |
Using the information provided in Table 1, what can you conclude about the effects of hyperlipidemia and the different drug treatments on the survival time of gastric cancer patients?
