select_box - How to use join data as option label?

I have two tables; Pages and PagesTranslation which are joined. I can get all the data and translations; For example on single page I can get title via { page.pagestranslation.getTitle() }}

Now, I am listing all the pages in my controller:

    $pages = Pages::find();
    $this->view->pages = $pages;

And I want to use it in the select:

{{ select("parent_page", pages, 'using': ['id', 'title']) }}

The ID gets populated, but I can't find a way to get the title from pages.pagestranslation to the option label in the select. How can I use joined data values in the select box ?