'to underline the problem' is correct and usable in written English.
You can use it when you want to emphasize the importance or severity of an issue. For example, "The report findings underline the problem of access to affordable housing in the city."
(As if to underline the problem, his previous film, from 1980, was called "Hardly Working").
Higgins tells his mother that Eliza will marry the vacuous and indolent Freddy Eynsford-Hill, and then laughs in repeated mockery at the stupidity of this arrangement - serving only to underline the problem that this outcome is not prepared for by the play, and that the consignment of his heroine to an unhappy, unintelligent and unworthy future leaves a sour taste.
Neither player has scored in the Premier League this season to underline the problem facing Gus Poyet's side.
These ads, unfortunately, feel neither clever nor funny, unlike their Apple predecessors, and they really serve only to underline the problems Microsoft continues to have with positioning its new, unusual device to consumers.
As if to underline the ethics problems involved with Vivendi's governance, on April 25 French authorities announced that Vincent Bolloré is under formal investigation for paying bribes to the presidents of two African countries.
And to underline the urgency of the problem, you reveal the startling news that you are seriously thinking about moving the whole nation somewhere else.
The governor said that his comments, made as he announced the formation of a commission on budget efficiency, were intended merely to underline the gravity of the problem and to encourage commission members to think expansively about possible solutions.
To underline the scale of the problem of UK nationals leaving to fight for Isis, Downing Street said 23 people had had their passports removed this year – 14 since June.
10.47am: Another statistic to underline the scale of the problems facing Greece - the credit default swap on its five-year government bonds has now reached 911.6 basis points.
Such scenarios would further underline the problem of trying to maintain public goods in large groups.
"Questions I never thought I'd have to answer". She added: "When he died there were comments that he was a 'soldier' - but there's nothing soldier-like about being run down in the street like an animal". As if to underline the immediacy of the gang problem, a 15-year-old boy was stabbed multiple times on the same street as the court that very day.
