Abstract
The NAD+-dependent deacetylase Sirtuin 1 (SIRT1) is down-regulated in triple-negative breast cancer. To determine the mechanistic basis by which reduced SIRT1 expression influences processes related to certain aggressive cancers, we examined the consequences of depleting breast cancer cells of SIRT1. We discovered that reducing SIRT1 levels decreased the expression of one particular subunit of the vacuolar-type H+ ATPase (V-ATPase), which is responsible for proper lysosomal acidification and protein degradation. This impairment in lysosomal function caused a reduction in the number of multi-vesicular bodies (MVBs) targeted for lysosomal degradation and resulted in larger MVBs prior to their fusing with the plasma membrane to release their contents. Collectively, these findings help explain how reduced SIRT1 expression, by disrupting lysosomal function and generating a secretome comprising exosomes with unique cargo and soluble hydrolases that degrade the extracellular matrix, can promote processes that increase breast-cancer-cell survival and invasion. Sirtuin 1 (SIRT1) expression is down-regulated in triple-negative breast cancer. Latifkar et al. show how reducing SIRT1 levels inhibit proper lysosomal function and, in doing so, results in the generation of a secretome with unique components, i.e., exosomes and resident lysosomal hydrolases, that promote the aggressiveness of breast cancer cells.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 393-408.e7 |
| Journal | Developmental Cell |
| Volume | 49 |
| Issue number | 3 |
| DOIs | |
| State | Published - May 6 2019 |
Funding
We would like to thank Cindy Westmiller for helping prepare the manuscript. This research was supported by grants from the NIH (R35 GM122575, R01 CA101402, and U54 CA210184) to R.A.C. (DK107868) to H.L. and NIH (F99 CA234921) and the Breast Cancer Coalition of Rochester to A.L. A grant from the NSF (1428922) funded the research performed using the Zeiss Elyra super-resolution microscopy, and NTA was performed at Cornell NanoScale Facility and was supported by NSF grant NNCI-1542081. A.L. L.L. A.H. E.J. A.C. X.Z. and J.H. performed the experiments. A.L. C.F. H.L. R.A.C. and M.A.A. designed the project. A.L. H.L. R.A.C. and M.A.A. wrote the manuscript. The authors declare no competing interests. We would like to thank Cindy Westmiller for helping prepare the manuscript. This research was supported by grants from the NIH ( R35 GM122575 , R01 CA101402 , and U54 CA210184 ) to R.A.C., ( DK107868 ) to H.L., and NIH ( F99 CA234921 ) and the Breast Cancer Coalition of Rochester to A.L. A grant from the NSF ( 1428922 ) funded the research performed using the Zeiss Elyra super-resolution microscopy, and NTA was performed at Cornell NanoScale Facility and was supported by NSF grant NNCI-1542081 . Transmission Electron Microscopy (TEM) on exosomes was performed as described in Desrochers et al., 2016b . Briefly, 5 \u03BCL of an exosome preparation derived from either control or SIRT1 KD MDA-MB-231 cells were diluted in PBS, added to a carbon-coated 300-mesh copper grid, and then stained with 1.75% uranyl acetate. Once dry, the samples were imaged using the FEI T12 Spirit 120\u2009kV Field Emission Transmission Electron Microscope at Cornell\u2019s Center for Materials Research (CCMR), supported by NSF MRSEC award number: NSF DMR-1120296.
Keywords
- cancer
- cathepsin
- deacetylation
- exosomes
- extracellular vesicles
- lysosome
- multi-vesicular body
- secretome
- sirtuin
- vacuolar-type H ATPase
ASJC Scopus subject areas
- Molecular Biology
- General Biochemistry, Genetics and Molecular Biology
- Developmental Biology
- Cell Biology
