I'm not convinced by the idea that mainstream art drives attitudes. To my eyes art is simply another form of conversation, and conversations reflect the current distribution of opinions in the melting pot. Pick one thread at random and it will be unusual in its own ways, pick a hundred and the majority will look roughly the same, sharing many commonalities. The more money involved and the larger the conversation the more it will blend to the average, seeking success through being palatable (or at least unoffensive) to as many people as possible, or successful through having already become broadly palatable.
So we should look at mass art for more of what people are thinking now, or at least what people want you to think they think in order to blend in to what they believe are the majority opinions. The largest cultural currents are full of chameleons trying to blend in, even when that goes against their vested interests: we humans like our hierarchies and social acceptance, perhaps too much for our own good. Consider support for longevity science and extending the healthy human life span, for example. The chameleon who supports healthy life extension today can really only blend in by denying it. This is unfortunate on many levels, not least of which being that support is needed to help make rejuvenation therapies a reality sometime soon, and can only be changed by the slow process of convincing people the old-fashioned way: one by one, with articles, with conversation. Advocacy is a matter of changing the environment to become a new normal, repainting the room one small brushstroke at a time.
It is increasingly recognised that community attitudes impact on the research trajectory, entry and reception of new biotechnologies. Yet biogerontologists have generally been dismissive of public concerns about life extension. There is some evidence that biogerontological research agendas have not been communicated effectively, with studies finding that most community members have little or no knowledge of life extension research. In the absence of knowledge, community members' attitudes may well be shaped by issues raised in popular portrayals of life extension (e.g. in movies). In order to investigate how popular portrayals of life extension may influence community attitudes I conducted an analysis of 19 films depicting human life extension across different genres. I focused on how the pursuit of life extension was depicted, how life extension was achieved, the levels of interest in life extension shown by characters in the films, and the experiences of extended life depicted both at an individual and societal level.
Mainstream movies will likely be the last of the great mass media to survive our present explosion of diversity in culture. The economics of the business are so gargantuan that it will take greater tides to wash them away that we'll see in the next few decades. But since the population at large are more or less opposed to living longer - at least in public, where the chameleons have to stay dressed up - you can expect to see that same level of opposition expressed in the movies. So it's usually the case that life extension is punished as hubris, given crippling disadvantages, made a curse, and so forth. When you write the story you can do what you want, regardless of the plausibility: it only has to find a receptive audience who have the same incorrect intuitions about the way the world works.
This isn't propagation of ignorance and mistaken attitudes, it's only a reflection of what already exists. If the average fellow in the street was in favor of longevity science, then the average movie plot would support that view.
Monolithic cultural blocks are disintegrating at an increasing pace given the greater ability for people to communicate and organize through the internet. Walk beyond the mass media and you'll find any number of positive portrayals of radical life extension, assumed and issued as a matter of course. In modern written science fiction great longevity is often a non-event - characters live for centuries or millennia because that is the logical outcome of advanced medical technology. We are biological machines, we can be improved, repaired, and rejuvenated, and this is remarked upon to the same degree as the color of the walls: no big deal, a long-accepted trope, let's move on to talk about the interesting new stuff. For examples, you might look at the works of Greg Egan, the late Iain M. Banks, Alastair Reynolds, Vernor Vinge, and so forth.