Means and Ends

While reading Kant's Groundwork II, I was especially confused by the idea he expressed about rational beings work not just merely by means but ends as well. The quote from the reading that I focused on by far the most (since it took a while to understand in the first place) was the following:

So act that you use humanity, in your own person as well as in the person of any other, always at the same time as an end, never merely as a means.

After then reading the four following examples, I gathered that Kant is saying that rational beings cannot just be used as means or commit actions that are just means but also must be ends in themselves as well.

My only question with what I believe I understand is Kant's idea, is whether a person can use another person simply as a means without being an end in itself? If, for example, someone wanted to start a rumor about another person so they tell a lie about that person to a third individual who then proceeds to spread that lie to another and so on, would the people spreading the rumor not merely be means to the greater end of spreading the rumor?

It may be argued in this case that the person spreading the rumor is acting irrationally, but if that is the case, does his idea only come into play when a person is actually acting as a rational being?