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This Is How HPV Causes Cancer
HPV是如何致癌的
Human papilloma virus, or HPV, has a strange reputation. You might know of it as a sexually transmitted infection that causes uncomfortable warts, the papilloma, but you also may have heard that it can lead to a deadly form of cancer.
关于人乳头瘤病毒（HPV），有一些奇怪的传闻。你可能知道它是一种会引起疣，乳头状瘤的性传播感染病，也可能听说过它可能致癌。
Both are actually true, as is the possibility that you can have HPV and experience no symptoms whatsoever.
这两种说法都是正确的，因为感染HPV后，可能没有出现症状。
HPV isn’t just one virus. There are actually over 200 strains, and the different types of HPV can result in different outcomes (which we’ll get into a little bit later).
HPV不只是一种病毒。实际上，它有200多种，不同类型的HPV可引起不同的后果（稍后我们会稍作讲解）。
But first, before HPV can do anything, it has to find a way into your skin.
但是，首先，HPV危害人体前，它必须寻找一种进入皮肤的途径。
>>Hi, I'm Dr. Moscicki from the University of California Los Angeles, Department of Pediatrics. I'm chief of adolescent and young adult medicine, and I have been studying HPV for over 30 years now. So when you're looking at skin, you have several layers, and you have the very basal cell layer, that is, the layer that sits right on top of the basement membrane, and right under that is what we call the dermis, and on top of that, you have the spinous, and eventually, you get the very top cornified cell layers.
>>大家好，我是加州大学洛杉矶分校儿科的Dr. Moscicki，是青少年和青年医学主任，至今已经研究HPV 30余年。所以，观察皮肤时，你会发现它有很多层，如基底细胞层，它是基底膜上面的一层，基底膜下的一层是我们所说的真皮，再往上一层是棘细胞层，最上面的一层是角化细胞层。
HPV first attaches itself to the basement membrane, by entering the body through a wound or micro-abrasion. It usually does this through sexual intercourse, but there are other types of HPV that cause hand and foot warts that aren’t sexually transmitted. Reaching the basement layer is key because there is a receptor there that it must attach to first.
HPV首先通过伤口或小擦伤，进入人体基底膜。这通常通过性交实现，但是其他引起手足疣的HPV则不通过性交传播。到达基底膜层很关键，因为这一层有一种HPV必须要结合的受体。
>>It's referred to as a heparan sulfate receptor.
>>这种受体是硫酸乙酰肝素受体（heparan sulfate receptor）。
This receptor actually changes the virus so that it can then attach to the basal cells. Once it does this, it injects its DNA into the cell’s nucleus. As the basal cells matures, the infected cell makes its way to the very top....
该受体实际上会使病毒发生改变，然后改变的病毒可与基底细胞结合。结合后，病毒立即将DNA注入基底细胞核。随着基底细胞成熟，受感染的细胞会到达最顶端......
>>It kind of hijacks the cell. And what it does is it makes it start proliferating a lot so that it can replicate itself.
>>病毒会劫持细胞。目的是开始大量增殖，进行自我复制。
This all happens without your body mounting a real defense against the disease, because HPV avoids expressing genes that would initiate an immune response until later in its lifecycle.
所有这些都是在机体没有真正防御疾病时发生的，因为HPV会“避免”表达在生命周期后期启动免疫反应的基因。
>>It looks like it's a mechanism that HPV has developed in order for its own survival.
>>HPV可能发展出了一种利于自身生存的机制。
But, while HPV has found a clever way to avoid the immune system, the body can still get rid of the infection.
但是，尽管HPV非常聪明地避开了免疫系统的攻击，但是人体仍然能够清除感染。
>>Like, you know, when you're taking a shower, that top layer of skin kind of comes off....once it gets sloughed off, if there's no other place to invade, then that infection's just gonna burn out very quickly. That it was a one-time chance that it found access to the basement membrane.
>>例如，你知道，洗澡时，皮肤表层会脱落......一旦脱落，如果病毒没有发现其他可攻击部位，感染就会很快消失。病毒只有一次进入基底膜的机会。
In fact, even though 80% of people in the United States are thought to contract HPV, 90% of infections are cleared on their own. So, if the infection doesn’t usually last, what’s the big deal? Well, that’s where those different types of HPV become really important, specifically the ones that can cause cancer.
事实上，虽然美国80%的人被认为感染了HPV，但90%的感染都会被自行清除。所以，如果没有持续感染，那还有什么好惊慌的？当然，这就是了解不同类型HPV，特别是能致癌的HPV非常重要的原因。
>>There's only about 13 types that we have associated with cancer, and they all fall into the alpha types. The most famous ones are type 16 and 18. They're actually responsible for around 70% of cervical cancers.
>>我们发现，只有13种HPV与癌症相关，它们都属于α型。最主要的是HPV 16和18。70%的宫颈癌都是由这两种HPV引起的。
Types 16 and 18 are totally different from the types of HPV that cause warts, which aren’t pleasant but fortunately do not typically become cancerous.
HPV 16和18与引起疣的HPV完全不同，后者会引起不适，但所幸通常不会癌变。
>>What we believe, the way it causes cancer, is that it infects, probably, a stem cell within the basal cell layer. Therefore, those stem cells, as it maturates, what happens is, literally, HPV hijacks the host cell machinery, says, I want you to replicate, because every time you don't stop me, I can make more and more of my DNA.
>>我们认为，致癌的方式可能是感染基底细胞层的干细胞。因此，通俗地说法是，随着干细胞成熟，HPV可能会劫持宿主细胞的加工机器，告诉它们：“我需要复制，因为每次你们不阻止我，我就可以获得越来越多的自身DNA”。
While replicating in stem cells, these oncovirus types of HPV will express the genes called E6 and E7. These oncoproteins stop the body from killing and clearing out cells with damaged DNA, allowing the cancerous cells to continue replicating.
病毒在干细胞内复制时，HPV肿瘤病毒将表达E6和E7基因。这些癌蛋白阻止人体杀死并清除DNA受损的细胞，使癌细胞继续复制。
>>So when there's a damaged cell, it's a race. Their immune system is probably trying its best, but it's really pushing the system, that it's replicating way faster than the immune system can even access it.
>>当出现受损细胞时，竞赛就拉开了。免疫系统可能已尽全力，但是病毒攻击系统，它的复制速度远远大于免疫系统的清理速度。
Fortunately, we have ways to prevent HPV from getting to this point.
需要注意的是，我们有阻断HPV这种机制的方法。
First, there are screenings for cervical cancer that can catch the disease when it is still pre-cancerous. But there is an unfortunate lack of screening methods for the other cancers caused by HPV. For people who are young enough and have not been exposed to HPV, there is also a very effective vaccine has been available since 2006. And while some people might think it’s only given to girls because of the risk of cervical cancer.
首先，宫颈癌筛查可发现癌前病变。但是HPV引起的其他癌症则缺乏相应的筛查方法。自2006年以来，市面上已经出现了针对足够年轻且尚未感染HPV人群的行之有效的疫苗。有些人认为，该疫苗只适用于女孩，因为她们具有宫颈癌风险。
>>It's recommended for boys as well. So the prevention here, we're talking about anal cancer, penile cancers, and oropharyngeal cancers. So it's equally as important for boys to get this vaccine as it is for girls.
>>它也推荐给男孩使用，可以预防肛门癌、阴茎癌和口咽癌。因此，接种该疫苗对男孩和女孩同等重要！
相关单词学习
Papilloma
①发音和释义
pap·il·lo·ma/?p?p??l??m?/n. 乳头状瘤(通常为良性)
A benign tumor of the skin or mucous membrane consisting of hypertrophied epithelial tissue, as a wart.
单词 papilloma 由下列成分构成
papilla/p??p?l?/n.乳头，小乳头状突起
+
-oma（后缀）意为肿瘤或新生物
Heparan sulfate
hep·a·ran sul·fate/?hep?r?n ?s?l?fe?t/n. 硫酸乙酰肝素；硫酸类肝素
A glycosaminogly can found on cell surfaces and basement membranes in mammals that regulates a wide variety of biological processes, including angiogenesis and blood coagulation.
heparan sulfate 的近义词是 heparitin sulfate
Oropharyngeal
o·ro·pha·ryn·ge·al/'?:r??f?r?n'd?i:?l/adj. 口咽的
Pertaining to the mouth and the pharynx.
单词 oropharyngeal 由下列成分构成
oro-（前缀）口
+
pharyngeal/f??r?nd?i?l/adj.咽的；咽部
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