RPS6

RPS6 Full Name

ribosomal protein S6

RPS6 Introduction

Ribosomal protein S6 (RPS6) is an essential structural component of the eukaryotic 40S ribosomal subunit and serves as a critical downstream effector in the cellular translational machinery. As the primary substrate of p70 S6 kinases (S6K1 and S6K2) within the highly conserved PI3K/AKT/mTOR signaling pathway, RPS6 undergoes dynamic phosphorylation in response to various extracellular stimuli, including growth factors, mitogens, and nutrient availability. Physiologically, this phosphorylation event is crucial for regulating cell size, proliferation, and global protein synthesis. Historically, RPS6 activation has been associated with the translational up-regulation of a specific subset of mRNAs containing a 5'-terminal oligopyrimidine (5'-TOP) tract, which predominantly encode other ribosomal proteins and translation elongation factors. By modulating the efficiency of ribosome biogenesis and translation initiation, RPS6 acts as a fundamental molecular switch that aligns cellular metabolic activity with environmental nutrient status.

Figure 1. Constituent elements and inhibitors of PI3K/AKT/mTOR pathway in ESCC. (Source: Huang R, et al. 2022)

Given its central position in integrating growth and survival signals, the dysregulation of RPS6 and its upstream mTOR pathway is heavily implicated in the pathogenesis of numerous human diseases, most notably cancer. Aberrant hyperphosphorylation of RPS6 is a prominent hallmark of many malignancies, including breast, prostate, and non-small cell lung cancers, where it facilitates unchecked tumor cell proliferation and survival. Beyond oncology, disrupted RPS6 signaling contributes to metabolic syndromes, such as obesity, type 2 diabetes, and muscle hypertrophy, due to its involvement in insulin signaling feedback loops and cellular energy homeostasis. In modern clinical settings, the phosphorylation state of RPS6 is frequently utilized as a reliable pharmacodynamic biomarker to evaluate the efficacy of mTOR inhibitors and other targeted therapies in cancer treatment.

Alternate Names for RPS6

RPS6; ribosomal protein S6; S6; 40S ribosomal protein S6; phosphoprotein NP33;

• 1. Huang R, et al. A Review: PI3K/AKT/mTOR Signaling Pathway and Its Regulated Eukaryotic Translation Initiation Factors May Be a Potential Therapeutic Target in Esophageal Squamous Cell Carcinoma. Front Oncol. 2022 Apr 28;12:817916.
  2. Meyuhas O. Ribosomal Protein S6 Phosphorylation: Four Decades of Research. Int Rev Cell Mol Biol. 2015;320:41-73.