NBCUniversal, the entertainment unit of Philadelphia’s Comcast Corp. (Nasdaq: CMCSA), is reportedly laying off 450 - 500 jobs, comprising roughly 1.5 percent of its workforce.

Unnamed sources told Bloomberg News and Deadline that the cuts, many of which have already taken place, are expected to affect NBC News group and NBCUniversal’s cable networks, which include USA, Bravo and the E! channel.

Reuters reports that Universal Studios has already cut about 20 jobs, most in the home entertainment division, as DVD sales continue to decline. Cuts have also taken place at the struggling G4 cable network and NBC’s “Tonight Show With Jay Leno,” which laid off about 12 employees. In September, Leno reportedly accepted a salary cut by as much as 50 percent to prevent further staff layoffs. Last month, G4 cancelled two of its long-running shows, “Attack of the Show” and “X-Play.”

Most of the staff cuts are in California, where the company has already logged 360 layoffs in 80 separate Notice of Reductions filings in September. NBC Entertainment creative executives are said to have been spared the ax, according to the Los Angeles Times.

Comcast Corp. reported a strong third quarter in October, with Olympics coverage and otherwise strong ratings boosting revenue at NBC. According to Bloomberg Industries research, however, ad revenue across NBCUniversal’s cable networks grew only 1 percent from a year earlier, following growth of about 5 percent in the first half of the year.

Comcast, the country’s largest cable provider, bought a 51 percent stake in NBCUniversal in 2011, with General Electric Co. (NYSE: GE) controlling the other 49 percent. The company’s unwieldy corporate culture is often spoofed on NBC’s “30 Rock,” the Tina Fey comedy set in a quasi-fictional universe in which the Peacock Network is owned by an unseen conglomerate called Cable Town.

NBCUniversal has a total workforce of about 30,000 employees.