Increased expression of which of the following causes oncogenesis
**Core Concept**
The question is testing the understanding of oncogenesis, which is the process of cancer development. The correct answer is related to a key factor involved in the initiation and progression of cancer. Increased expression of this factor can lead to uncontrolled cell growth, genetic instability, and tumor formation.
**Why the Correct Answer is Right**
The correct answer is related to the PI3K/AKT signaling pathway, specifically the gene encoding the PI3K catalytic subunit, PIK3CA. Increased expression of PIK3CA leads to the activation of the PI3K/AKT pathway, which promotes cell survival, proliferation, and angiogenesis. This can result in oncogenesis by activating downstream targets that regulate cell cycle progression, apoptosis, and DNA repair. The PI3K/AKT pathway is often dysregulated in various cancers, including breast, lung, and colorectal cancer.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while **TP53** mutations are common in many cancers, increased expression of TP53 is not a direct cause of oncogenesis. Instead, TP53 is a tumor suppressor gene that is often inactivated or mutated in cancer cells.
**Option B:** This option is incorrect because **MDM2** is a negative regulator of TP53, and its overexpression can lead to TP53 inactivation. However, increased expression of MDM2 is not a direct cause of oncogenesis.
**Option C:** This option is incorrect because while **EGFR** overexpression is a common feature of many cancers, it is not a direct cause of oncogenesis. Instead, EGFR overexpression can activate downstream signaling pathways that promote cell proliferation and survival.
**Clinical Pearl / High-Yield Fact**
Remember that the PI3K/AKT pathway is a critical regulator of cell survival and proliferation, and its dysregulation is a common feature of many cancers. Increased expression of PIK3CA or other components of the PI3K/AKT pathway can lead to oncogenesis, highlighting the importance of targeting this pathway in cancer therapy.
**Correct Answer:** C.