What Is a Cancer Driver Gene? The Important Roles of KRAS and TP53 in Pancreatic Cancer

Data presented at the European Society for Medical Oncology Congress (ESMO 2024), held in Barcelona on September 13-17, 2024, highlight the diversity of driver genes in healthy and cancerous pancreatic tissue. These findings deepen our understanding of pancreatic tumor evolution and support important steps toward personalized treatment.

Understanding Driver Genes

DNA can be thought of as a book containing instructions that explain how living organisms are structured and function. The genes within DNA are like key sentences in this book, giving instructions on producing particular proteins. Each gene is a sequence of nucleotides , which can be thought of as the letters of the DNA book. For example, the human genome contains approximately 3 billion nucleotides (letters), forming between 20,000 and 25,000 genes (sentences) that determine how our bodies function and look.

A “driver” gene contains genetic changes that drive cancer cell growth and proliferation. Normally, these genes regulate cell division, cell death, and DNA repair. However, when they undergo mutations , they can cause uncontrolled cell division, initiating cancer and driving its progression. Driver genes play a key role in cancer development and progression and are therefore important molecular targets in treatment.

Differences in Driver Gene Profiles Between Healthy and Cancerous Tissue

A study showed that, compared with samples from patients with pancreatic ductal adenocarcinoma (conventional pancreatic cancer), healthy pancreatic tissue had a much lower mutation burden .

Researchers analyzed 181 pancreatic samples from 118 healthy donors and 62 biopsies from 4 patients with pancreatic cancer using techniques including laser capture microdissection, whole-exome sequencing, and NanoSeq.

Examining Driver Genes with NanoSeq

NanoSeq revealed the distribution of driver genes in normal pancreatic tissue and tissue from patients with pancreatic cancer in detail. Only a small proportion of cells in normal pancreatic tissue—approximately 0.81% to 3.6%—carried changes or mutations in driver genes. These included genes under positive selection, such as APC and PRSS1.

By contrast, in samples from untreated pancreatic cancer patients, a much larger proportion of cells (45% to 64%) carried driver gene changes or mutations. In these cells, KRAS and TP53 in particular were under positive selection, highlighting their critical roles in pancreatic cancer development.

In addition, incidental precancerous lesions were detected in 16 biopsies from nine apparently healthy donors, with KRAS under positive selection in 33% to 67% of cells. This suggests that KRAS mutations may be an important factor in pancreatic cancer development even at early precancerous stages.

The Role of Driver Genes in Malignant Transformation

New research analyzing mutations in healthy tissue shows that genetic changes called “driver mutations” play an important role in cancer. They cause uncontrolled cell division and the formation of malignant tumors. However, these mutations alone are not sufficient to make a cell cancerous; environmental factors also influence their selection and malignant transformation.

Frequent mutations in KRAS and TP53 are particularly notable in pancreatic cancers such as pancreatic ductal adenocarcinoma. These mutations are generally seen only in premalignant and malignant tissue. This suggests that KRAS and TP53 mutations may drive cancer development more strongly than genes observed in other normal tissues. Other genes found to be under positive selection in healthy pancreatic tissue have lower cancer-causing potential than KRAS and TP53. This highlights the role of driver genes as key triggers in cancer development and the importance of treatment strategies targeting them.

Conclusion

The study demonstrates cancer's complexity and the need to consider environmental and individual factors alongside genetic information in treatment. This understanding may enable more personalized approaches and improve their effectiveness.

These studies emphasize driver gene diversity and show that clinical and molecular factors beyond driver mutations contribute to tumor evolution and development, ultimately determining the course of pancreatic cancer.