make a page template called portlet_mynews (put it in custom folder or on-disk skin folder or anywhere else)

<dl metal:define-macro="portlet" class="portlet">
  <dt>News!</dt>
  <dd tal:repeat="item python:context.portal_catalog(portal_type='NewsItem', state='published')">
    <p tal:content="item/Title">[title]</p>
    <p tal:content="item/Description">[descrip]</p>
  </dd>
</dl>

and then you can add this as a "classic portlet" -- the name is portlet_mynews, and the macro is "portlet"