Sex bias exists in the development and progression of non-reproductive organ cancers, but the underlying mechanisms are enigmatic. Studies so far have focused largely on sexual dimorphisms in cancer biology and socioeconomic factors. Here, we establish a role for CD8
+
T cell-dependent anti-tumor immunity in mediating sex differences in tumor aggressiveness, which is driven by the gonadal androgen but not sex chromosomes. A male bias exists in the frequency of intratumoral antigen-experienced
Tcf7
/TCF1
+
progenitor exhausted CD8
+
T cells that are devoid of effector activity as a consequence of intrinsic androgen receptor (AR) function. Mechanistically, we identify a novel sex-specific regulon in progenitor exhausted CD8
+
T cells and a pertinent contribution from AR as a direct transcriptional trans-activator of
Tcf7
/TCF1. The T cell intrinsic function of AR in promoting CD8
+
T cell exhaustion in vivo was established using multiple approaches including loss-of-function studies with CD8-specific
Ar
knockout mice. Moreover, ablation of the androgen-AR axis rewires the tumor microenvironment to favor effector T cell differentiation and potentiates the efficacy of anti-PD-1 immune checkpoint blockade. Collectively, our findings highlight androgen-mediated promotion of CD8
+
T cell dysfunction in cancer and imply broader opportunities for therapeutic development from understanding sex disparities in health and disease.
Background and Aims
Most tumor cells use aerobic glycolysis (the Warburg effect) to support anabolic growth and promote tumorigenicity and drug resistance. Intriguingly, the molecular mechanisms underlying this phenomenon are not well understood. In this work, using gain‐of‐function and loss‐of‐function in vitro studies in patient‐derived organoid and cell cultures as well as in vivo positron emission tomography–magnetic resonance imaging animal models, we showed that protein arginine N‐methyltransferase 6 (PRMT6) regulates aerobic glycolysis in human hepatocellular carcinoma (HCC) through nuclear relocalization of pyruvate kinase M2 isoform (PKM2), a key regulator of the Warburg effect.
Approach and Results
We found PRMT6 to methylate CRAF at arginine 100, interfering with its RAS/RAF binding potential, and therefore altering extracellular signal–regulated kinase (ERK)‐mediated PKM2 translocation into the nucleus. This altered PRMT6‐ERK‐PKM2 signaling axis was further confirmed in both a HCC mouse model with endogenous knockout of PRMT6 as well as in HCC clinical samples. We also identified PRMT6 as a target of hypoxia through the transcriptional repressor element 1‐silencing transcription factor, linking PRMT6 with hypoxia in driving glycolytic events. Finally, we showed as a proof of concept the therapeutic potential of using 2‐deoxyglucose, a glycolysis inhibitor, to reverse tumorigenicity and sorafenib resistance mediated by PRMT6 deficiency in HCC.
Conclusions
Our findings indicate that the PRMT6‐ERK‐PKM2 regulatory axis is an important determinant of the Warburg effect in tumor cells, and provide a mechanistic link among tumorigenicity, sorafenib resistance, and glucose metabolism.
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