Houston, TX - Researchers at The University of Texas MD Anderson Cancer Center have made a significant breakthrough in understanding the molecular underpinnings of the aggressive nature of colorectal cancer (CRC) in male patients with a KRAS mutation. The study, published in the journal Nature, sheds light on a gene called KDM5D on the Y chromosome, which becomes upregulated in KRAS-mutated CRC, leading to enhanced tumor cell invasiveness and compromised anti-tumor immune responses in male patients.
CRC is the second leading cause of cancer-related deaths worldwide, and males consistently exhibit higher incidences and poorer prognoses compared to females. While lifestyle factors and sex hormones have been considered as potential explanations for these disparities, the molecular mechanisms underlying sex-based differences have remained elusive.
Using genetically engineered mouse models that closely mimic human CRC progression, the research team, led by Dr. Ronald DePinho, uncovered sex-specific differences only in models with the KRAS mutation. Male mice displayed a higher incidence of metastasis and shorter overall survival than their female counterparts. These observations led the team to focus on KRAS as a potential driver of sex-based disparities in CRC.
Through cross-species and transcriptomic analyses, the researchers identified KDM5D as a highly upregulated gene in the KRAS-mutated models. Further investigations revealed that KDM5D plays a crucial role in suppressing genes associated with cell adhesion and anti-tumor immunity, thereby promoting metastatic behavior.
One of the early steps in metastasis is the disruption of cell-cell junctions, enabling cancer cells to acquire migratory capabilities. The team found that the KRAS-mutated metastatic cancer models exhibited downregulation of the cell junction gene AMOT. Moreover, in patient samples, a negative correlation was observed between AMOT and KDM5D expression in male tumor tissues. The experimental analysis demonstrated that KDM5D epigenetically represses AMOT, impairing cell junctions and facilitating the transition of cancer cells into a metastatic state.
Interestingly, the study also revealed that metastatic cancer cells displayed a reduced activity of genomic elements known as super-enhancers, which are involved in activating the transcription of gene clusters. Specifically, genes associated with antigen presentation through major histocompatibility complex I (MHC-I) were expressed at lower levels. MHC-I is crucial for tumor recognition by the immune system, and its deficiency can facilitate tumor immune evasion.
The researchers found that KDM5D represses the TAP1 and TAP2 genes, which are responsible for processing and presenting antigens that trigger T-cell responses against abnormal cells. By inhibiting TAP1 and TAP2, KDM5D enables cancer cells to evade detection and destruction by immune cells, promoting disease progression and metastasis.
Dr. DePinho highlighted the significance of these findings, stating, " Not only does this explain sex-specific differences, but our work uncovered an entirely new biochemical function for histone demethylases in regulating histone acetylation at super-enhancers controlling immune system genes."
The identification of KDM5D as a potential therapeutic target provides a promising avenue for future investigations aimed at improving outcomes in male patients with KRAS-mutated CRC. These research findings contribute to a deeper understanding of the molecular nuances driving more aggressive disease in men and may ultimately lead to the development of targeted therapies to combat metastatic colorectal cancer in male patients with a KRAS mutation.
CRC is the second leading cause of cancer-related deaths worldwide, and males consistently exhibit higher incidences and poorer prognoses compared to females. While lifestyle factors and sex hormones have been considered as potential explanations for these disparities, the molecular mechanisms underlying sex-based differences have remained elusive.
Using genetically engineered mouse models that closely mimic human CRC progression, the research team, led by Dr. Ronald DePinho, uncovered sex-specific differences only in models with the KRAS mutation. Male mice displayed a higher incidence of metastasis and shorter overall survival than their female counterparts. These observations led the team to focus on KRAS as a potential driver of sex-based disparities in CRC.
Through cross-species and transcriptomic analyses, the researchers identified KDM5D as a highly upregulated gene in the KRAS-mutated models. Further investigations revealed that KDM5D plays a crucial role in suppressing genes associated with cell adhesion and anti-tumor immunity, thereby promoting metastatic behavior.
One of the early steps in metastasis is the disruption of cell-cell junctions, enabling cancer cells to acquire migratory capabilities. The team found that the KRAS-mutated metastatic cancer models exhibited downregulation of the cell junction gene AMOT. Moreover, in patient samples, a negative correlation was observed between AMOT and KDM5D expression in male tumor tissues. The experimental analysis demonstrated that KDM5D epigenetically represses AMOT, impairing cell junctions and facilitating the transition of cancer cells into a metastatic state.
Interestingly, the study also revealed that metastatic cancer cells displayed a reduced activity of genomic elements known as super-enhancers, which are involved in activating the transcription of gene clusters. Specifically, genes associated with antigen presentation through major histocompatibility complex I (MHC-I) were expressed at lower levels. MHC-I is crucial for tumor recognition by the immune system, and its deficiency can facilitate tumor immune evasion.
The researchers found that KDM5D represses the TAP1 and TAP2 genes, which are responsible for processing and presenting antigens that trigger T-cell responses against abnormal cells. By inhibiting TAP1 and TAP2, KDM5D enables cancer cells to evade detection and destruction by immune cells, promoting disease progression and metastasis.
Dr. DePinho highlighted the significance of these findings, stating, " Not only does this explain sex-specific differences, but our work uncovered an entirely new biochemical function for histone demethylases in regulating histone acetylation at super-enhancers controlling immune system genes."
The identification of KDM5D as a potential therapeutic target provides a promising avenue for future investigations aimed at improving outcomes in male patients with KRAS-mutated CRC. These research findings contribute to a deeper understanding of the molecular nuances driving more aggressive disease in men and may ultimately lead to the development of targeted therapies to combat metastatic colorectal cancer in male patients with a KRAS mutation.