Hi there and welcome.
The code in question is Article 300-3(c)(1) which states that 'Conductors of circuits rated at 600V nominal or less, AC and DC shall be permitted to occupy the same equipment wiring enclosure or raceway. All conductors shall have an insulation rating equal to at lest the maximum circuit voltage applied to any conductor in the raceway.
If you look at your 120V wiring, it is likely rated at 600V. Ditto your 277V wiring.
There are exceptions to this article which concern low voltage and signalling circuits amongst other things but if you're planning on running your 277V lighting circuits and your 120V power circuits in the same pipe, you can do so so long as you are using 600V wiring which you most likely are.
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