Natural and Synthetic Progestins Increase Transcriptional Expression of primiR-190 and primiR-199 in T47D Breast Cancer Cells: A Preliminary Study

Background Previous studies have shown that aberrant expression of different microRNAs potentially contributes to carcinogenesis, growth, and metastasis of several human cancers. Given that progestins have been reported to alter the expression of microRNAs in various human cancers, we hypothesized that progestins potentially influence the growth of hormone-responsive breast cancer through mechanisms involving the regulation of miRNAs functioning either as tumor suppressors or oncogenes. Using computer-based analysis, we identified two microRNAs that we investigated in this study, namely miR-190 and miR-199. Our main objective in this preliminary study was to determine the effect of different progestins on the expression of these two microRNAs in breast cancer cells. Methods Progesterone receptor (PR)-positive cell line, T47D breast cancer cells were exposed to progesterone and three different synthetic progestins for 24 hours, after which RNA was extracted and real-time polymerase chain reaction (PCR) was used to determine the expression of primiR-190 and primiR-199. For comparison, progestin effects were also tested in T47Dco-Y, a PR-negative cell line. Results Our results showed exposing T47D cells to both progesterone and synthetic progestins increased the transcriptional expression of primiR-190 and primiR-199a1 by as high as four to seven fold (P<0.0001). RU-486, a progesterone receptor antagonist, suppressed progestin induction of both primiR-190 and primiR-199a1. Progestin-induced effects were not observed in a PR-negative subline of T47D cells (P>0.05), further confirming the involvement of progesterone receptor-dependent pathways. Additionally, 17β estradiol and dimethyl sulfoxide did not alter the expression of both primiR-190 and primiR-199a1. Conclusion Different progestins increase transcriptional expression of both primiR-190 and primiR-199a-1 through progesterone receptor (PR)-dependent mechanisms. Both primiR-190 and primiR-199a1 can potentially be useful as biomarkers for PR-positive breast cancer.

Skeletal muscle BMAL1 is necessary for transcriptional adaptation of local and peripheral tissues in response to endurance exercise training

Objectives

In this investigation, we addressed the contribution of the core circadian clock factor, BMAL1, in skeletal muscle to both acute transcriptional responses to exercise and transcriptional remodelling in response to exercise training. Additionally, we adopted a systems biology approach to investigate how loss of skeletal muscle BMAL1 altered peripheral tissue homeostasis as well as exercise training adaptations in iWAT, liver, heart, and lung of male mice.

Methods

Combining inducible skeletal muscle specific BMAL1 knockout mice, physiological testing and standardized exercise protocols, we performed a multi-omic analysis (transcriptomics, chromatin accessibility and metabolomics) to explore loss of muscle BMAL1 on muscle and peripheral tissue responses to exercise.

Results

Muscle-specific BMAL1 knockout mice demonstrated a blunted transcriptional response to acute exercise, characterized by the lack of upregulation of well-established exercise responsive transcription factors including Nr4a3 and Ppargc1a. Six weeks of exercise training in muscle-specific BMAL1 knockout mice induced significantly greater and divergent transcriptomic and metabolomic changes in muscle. Surprisingly, liver, lung, inguinal white adipose and heart showed divergent exercise training transcriptomes with less than 5% of 'exercise-training' responsive genes shared for each tissue between genotypes.

Conclusion

Our investigation has uncovered the critical role that BMAL1 plays in skeletal muscle as a key regulator of gene expression programs for both acute exercise and training adaptations. In addition, our work has uncovered the significant impact that altered exercise response in muscle plays in the peripheral tissue adaptation to exercise training. We also note that the transcriptome adaptations to steady state training suggest that without BMAL1, skeletal muscle does not achieve the expected homeostatic program. Our work also demonstrates that if the muscle adaptations diverge to a more maladaptive state this is linked to increased inflammation across many tissues. Understanding the molecular targets and pathways contributing to health vs. maladaptive exercise adaptations will be critical for the next stage of therapeutic design for exercise mimetics.

Skeletal muscle BMAL1 is necessary for transcriptional adaptation of local and peripheral tissues in response to endurance exercise training

OBJECTIVE

In this investigation, we addressed the contribution of the core circadian clock factor, BMAL1, in skeletal muscle to both acute transcriptional responses to exercise and transcriptional remodeling in response to exercise training. Additionally, we adopted a systems biology approach to investigate how loss of skeletal muscle BMAL1 altered peripheral tissue homeostasis as well as exercise training adaptations in iWAT, liver, heart, and lung of male mice.

METHODS

Combining inducible skeletal muscle specific BMAL1 knockout mice, physiological testing and standardized exercise protocols, we performed a multi-omic analysis (transcriptomics, chromatin accessibility and metabolomics) to explore loss of muscle BMAL1 on muscle and peripheral tissue responses to exercise.

RESULTS

Muscle-specific BMAL1 knockout mice demonstrated a blunted transcriptional response to acute exercise, characterized by the lack of upregulation of well-established exercise responsive transcription factors including Nr4a3 and Ppargc1a. Six weeks of exercise training in muscle-specific BMAL1 knockout mice induced significantly greater and divergent transcriptomic and metabolomic changes in muscle. Surprisingly, liver, lung, inguinal white adipose and heart showed divergent exercise training transcriptomes with less than 5% of 'exercise-training' responsive genes shared for each tissue between genotypes.

CONCLUSIONS

Our investigation has uncovered the critical role that BMAL1 plays in skeletal muscle as a key regulator of gene expression programs for both acute exercise and training adaptations. In addition, our work has uncovered the significant impact that altered exercise response in muscle and its likely impact on the system plays in the peripheral tissue adaptations to exercise training. Our work also demonstrates that if the muscle adaptations diverge to a more maladaptive state this is linked to increased gene expression signatures of inflammation across many tissues. Understanding the molecular targets and pathways contributing to health vs. maladaptive exercise adaptations will be critical for the next stage of therapeutic design for exercise mimetics.