can i run sierra on mac pro early 2008 which has el capitan 10.11.6

Can I update to Sierra 10.12 on my Mac Pro (early 2008) which is running El Capitan 10.11.6. My specs are:

Processor: 2 x 2.8 GHz Quad-Core Intel Xeon

Memory: 16 GB 800 MHz DDR2 FB-DIMM

Graphics: AMD Radeon HD 6870 1024 MB

Storage: Macintosh HD - 256 GB SS Sata Drive 129.3 GB free

Data Drive One - 1.97 TB free of 2 TB

Data Drive Two - 1.8 TB free of 2 TB

SuperDrive