Expression of Raptor and Rictor and their relationships with angiogenesis in colorectal cancer

Area of Science:

• Oncology
• Molecular Biology
• Cell Signaling

Background:

• Mammalian target of rapamycin (mTOR) signaling, through mTORC1 (Raptor) and mTORC2 (Rictor), plays a role in cancer.
• The specific roles of Raptor and Rictor in colorectal cancer (CRC) concerning hypoxia-inducible factors (HIFs) and vascular endothelial growth factor (VEGF) remain unclear.

Purpose of the Study:

• To investigate the correlations between Raptor, Rictor, HIF-1α, HIF-2α, and VEGF expression in colorectal cancer.
• To analyze the relationship between these molecular markers and clinicopathological features, including microvascular density (MVD) and patient prognosis.

Main Methods:

• Immunohistochemistry, western blot, and RT-PCR were used to assess the expression of Raptor, Rictor, HIF-1α, HIF-2α, and VEGF in 120 CRC tissues and 60 normal colorectal mucosa samples.
• CD34 staining was performed to quantify microvascular density (MVD).

Main Results:

• Positive rates of Raptor, Rictor, HIF-1α, HIF-2α, and VEGF were significantly higher in CRC tissues compared to normal tissues.
• Raptor expression correlated positively with HIF-1α and VEGF, while Rictor expression correlated positively with HIF-2α and VEGF.
• Higher MVD was observed in patients with positive Raptor or Rictor expression. Raptor, Rictor, HIFs, VEGF, and lymph node metastasis were identified as independent prognostic factors.

Conclusions:

• Raptor and Rictor expression are associated with colorectal cancer initiation, development, and angiogenesis through distinct mechanisms.
• Combined assessment of Raptor and Rictor expression may aid in predicting prognosis and guiding optimal therapy for colorectal cancer patients.