Targeting LxCxE Cleft Pocket of Retinoblastoma Protein in Immunosuppressive Macrophages Inhibits Ovarian Cancer...

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Ovarian cancer presents a significant health challenge with limited therapeutic options.
• The tumor microenvironment (TME) in ovarian cancer is immunosuppressive, largely due to tumor-associated macrophages (TAMs), which impede anti-tumor immunity and immunotherapy effectiveness.

Purpose of the Study:

• To investigate the therapeutic potential of targeting the retinoblastoma protein (Rb) in immunosuppressive TAMs within the ovarian cancer TME.
• To evaluate the impact of Rb targeting on TAM depletion, immune cell infiltration, and overall cancer progression.

Main Methods:

• Disruption of the retinoblastoma protein (Rb) LxCxE cleft pocket in M2-polarized or M2-like immunosuppressive TAMs.
• Induction of endoplasmic reticulum stress, p53, and mitochondria-related cell death pathways in targeted TAMs.
• In vivo and ex vivo assessment of TAM reduction, T-cell infiltration, and anti-tumor responses in ovarian cancer models and patient samples.

Main Results:

• Targeting the Rb LxCxE cleft pocket induced preferential cell death in Rb-high immunosuppressive TAMs.
• Reduction of immunosuppressive TAMs in the TME led to increased T-cell infiltration and enhanced anti-tumor responses, inhibiting cancer progression.
• Increased Rb expression in TAMs from ovarian cancer patients correlated with poorer prognosis; therapeutic Rb targeting ex vivo induced analogous cell death in patient-derived TAMs.

Conclusions:

• Therapeutic targeting of the Rb LxCxE cleft pocket represents a promising strategy for ovarian cancer treatment.
• This approach depletes immunosuppressive Rb-high TAMs, thereby reshaping the TME immune landscape and potentially improving treatment outcomes.