Leighton Meester sues - and is sued by - her mother

The mother of "Gossip Girl" actress Leighton Meester is suing the 25-year-old, claiming her daughter beat her with a bottle and refused to send her money she had promised to provide.

The lawsuit says that without the money, she couldn't properly take care of Leighton's younger brother, Alexander, a cancer survivor who recently underwent brain surgery.

But in her own lawsuit, Leighton Meester says her mother has substance abuse problems and that she spent money Leighton sent for Alexander's care on cosmetic procedures.

In a suit filed in Los Angeles County Superior Court Monday, Constance L. Meester also says that her estranged daughter had promised her a one-time payment of $30,000 and then $10,000 a month.

Constance Meester says that because her daughter didn't pay, the older Meester can't afford proper care for Leighton's brother.

In the actress's lawsuit, filed July 22, she claims that she sent money for her brother, but that "Constance has been using the money ... to pay for cosmetic procedures for herself, including plastic surgery on her face and stomach, Botox injections for her face, fillers for her hands and hair extensions."

The lawsuit continues, "sadly, Leighton is also informed and believes ... that Constance has an alcohol and substance abuse problem that is clouding her judgment. Leighton was recently informed that Constance has been taking pain medication prescribed to Lex following his recent brain surgery."

The suit says that Leighton stopped sending money to Constance but "will continue to pay for Lex's medical insurance and school tuition."

Constance Meester's lawsuit claims that "at 2:00 a.m. on December 11, 2010, Leighton intentionally assaulted Constance by throwing her to the ground and repeatedly hitting her with a bottle. Leighton had to be pulled off of Constance by her brother Alexander."

She asks for damages from the alleged beating, for breach of contract, fraud, intentional infliction of emotional distress and other charges.

The actress's lawsuit claims that "although she is healthy and physically able to work, Constance refuses to do so. Instead, Constance expects her daughter to support her financially." That lawsuit says that while Leighton Meester is willing to pay for her brother's insurance and other care, she doesn't owe her mother anything. It asks a judge to declare that she's not obliged to pay Constance Meester anything.

In addition to "Gossip Girl," Leighton Meester starred in "Monte Carlo," "The Roommate" and "Date Night," among other movies.

Pamela Chelin contributed to this report.