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New Tumor Suppressor Found--Twice Two research teams have separately homed in on a tumor suppressor gene, the loss or inactivation of which may be important for the progression of brain, prostate, and other cancers When Jing Li joined Ramon Parsons at Columbia Uni- versity's College of Physi- cians and Surgeons last year to hunt for breast cancer genes, he expected the work to be intense. But when news reached dxe lab that another team might have cloned the same gene his lab was work- ing on---a tumor suppressor, the inactivation of which seemed to contribute to the development of both pros- tate cancers and the highly malignant brain tumors "known as gliomas~Li got a tree taste of just how high tile stakes have become as academic and corporate labs scrambie to find important disease genes (see sidebar). Now, the race for this gene has ended in a dead heat. On page 1943, Li, Parsons, and their col- leagues rel~ort that they have cloned the tu- mor suppressor, which resides on chromo- sortie ].0. And in the April issue of Nature Genetics, cell biologist Peter Steck of M. D. Anderson Cancer Center in Houston and Sean Tavtigian of the biotech firm Myriad Genetics in Salt Lake City will announce that they have found the same gene. Called PTEN (for phosphatase and tensin homolog deleted on chromosome I0) by the Par- sons group and MMAC1 (for mutated in mul- tiple advanced cancers l) by Steck and his colleagues, the new gene joins some 16 other "known tumor suppressors. But while it's far from tile first such gene discovered, cancer researchers are enthusiastic, because tb.e early data indicate that PTEN might rank in importance with p53, retinoblastoma, and p 16, tumor suppressors that have been linked to several types of tumors. "[PTEN] seems to be a major gene in some pretty important cancers," says Kenneth Kinzler, a molecular geneticist at Johns Hopkins University. In addition to prostate cancer, which afflicts some 317,000 men every year in the United States, and gliomas, which strike another 15,000 people, these might include breast and kidney cancer. But equally intriguing, says molecular bi- ologist Stephen Friend of the Fred Hutch- inson Cancer Research Center in Seattle, is the apparent mode of action of the PTEN protein. Its amino acid sequence indicates that it resembles two different types of pro- teins: tyrosine phosphatases, which are en- Lost gene. Brain-tumor cells often lack a copy of chromo- some 10 (green) and gain a chromosome 7 (red). zymes that remove phos- phate groups from the amino acid tyrosine in other pro- teins, and tensin, a protein that helps connect the cell's internal skeleton of protein filaments to its external en- vironment. Cancer researchers sus- pected that tyrosine phos- phatases might be tmnor suppressors because they di- rectly counter the actions of another set of enzymes, the tyrosine kinases, which add phosphates to tyrosines and are part of the ceI['s growth- stimulating pathways. But there had been no direct evidence for that--until now. "This is proofofa long-held speculation that pho-s- phatases would be important," Friend says. In addition, the tensin resemblance suggests that PTEN might help ceils stay in their nor- mal locations within a tissue. Its loss, then, might be one of the steps that give tumor cells the ability to spread. Parsons began the current work about a Tumor progression. When a brain tumor, shown as a bright spot in the scan above, loses its PTENgenes, a low- grade cancer (lower left) is likely to turn highly malignant (upper left). year ago, when he joined forces with Michael Wigler of Cold Spring Harbor Laboratory on Long Island to apply a technique Wigler had developed earlier to the hunt for breast can- cer genes. Called representational difference analysis (RDA), the technique can identify abnormalities in DNA by comparing the equivalent sections of DNA from normal and diseased cells (Science, 12 February 1993, p. 946). By 1996, the technique had already helped researchers home in on BRCA2, the second of two genes that cause hereditary susceptibilities to breast cancer. Many of the gene changes that lead to cancer are not inherited, however, but sim- ply develop in specific cells, like those in the breast epithelia. To find such noninherited gene changes, Wigier had applied his method to ceils from 12 primary breast tumors, iden- tifying about a dozen possibilities for such cancer-causing gene changes, including a deletion on chromosome 10. Parsons was particularly interested in following up on that observation. Chromosome i0 is com- pletely or partially missing in a variety of cancers, especially the aggressive brain tu- mors called gliomas--a prime indication that it carries a tumor suppressor. Research- ers also suspected that it carries the gene responsible for a rare inherited disorder called Cowden disease, whose victims are pre- disposed to breast and other tumors. To narrow down the location of the sus- pected tumor suppressor, WigIer and the Par- sons team examined ceils from 65 human breast cancers to see whether their DNA lacked any of nine genetic markers located in the part of the chromo- some that tile RDA had identified as abnormal One marker was absent in two of those samples, and when it also proved to be missing in some prostate and glio- blastoma cell lines, Parsons and Wigler "lmew they were closing in on the gene. By October 1996, they were ready to try a technique called exon trapping to pull it out. This involves look- ing for messenger RNAs made by the deleted re- gion, then using them to find the corresponding ex- ons, which are the protein- coding regions of a gene. They found two exons. To get the rest of the gene, the group consulted the GenBank database, which includes not only the se- quences of full genes but also the short DNA pieces called expressed sequence tags (ESTs). More than a dozen ESTs in the database matched different parts of the ex- ons. Aided by a computer program called UNIGENE, which groups ESTs that seem to be part of the same gene, the researchers were 1876 SCIENCE • VOL. 275 • 28 MARCH i997 • http://www.sciencemag.org

of spin-off companies, Mikulski helped fun- nel $54 million in earmarked funds into the project over several years, tacking the money onto the appropriations of several federal agencies. With a guarantee of federal money, the state and city kicked in an additional $89 million, and the nonprofit Columbus Center corporation established by Heuisler attracted another $17 million in private funds. "The federal government provide[d], to some extent, what I call venture capital," Mikulski says. "We got in where nobody else had the resources to do it." But from the very start, there were signs of tension. An initial design for the facil- ity-by Richard Rogers, the creator of the Pompidou Center in Paris--called for pas- sages resembling tubes for caged gerbils to thread through the labs. The idea was to give visitors a closeup view of researchers, but the intrusiveness of the plan led to its quick rejection. In the final design, only the common facilities lab, which contains show- case equipment used by all the researchers, is on the same level as the museum exhib- its. To catch a glimpse of other work areas, museumgoers must crane their necks to peer through second2 and third-story windows above the museum floor. The design of the exhibits has also sparked controversy. After an extensive search, the center selected a company led by an Acad- emy Award-winning movie and stage de- signer, Bran Ferren, to create the exhibits. COMB researchers have spent hundreds of hours reviewing exhibit designs and scripts and consulting with film crews making loops describing their research. But some scien- tists say that the designers and filmmakers have not taken their suggestions seriously. "It has been a mixed experience," says John Hind, a postdoc at the lab. Others question whether the films and the exhibits have adequately captured the research being done at the center. "A lot of microbial research is not that obvious. So, it's hard to get it both accurate and striking," says Frank Robb, the acting director of COMB. Most researchers praise the exhibits as good initial presenta- tions but hope that some will be modified once the hall opens. These tensions over the design of the building and exhibits reflect deeper divisions among COMB staffers. At the top level, com- mitment to outreach is unequivocal. "There's a quid pro quo for everything," says Heuisler. "The city, the state, and the congressional delegation have secured over $100 million to build an institution that the 49 other states would kill for. That's the quid. The quo is that there probably will be on the face of the planet few other groups of scientists who will be as visible or as accountable for establish- ing a dialogue with the public." But while all the scientific staff publicly support the idea of outreach, privately some remain skeptical about the center's ap- proach. Some of the 14 tenured, tenure- track, and research faculty at COMB say they don't know how they will find the time to participate extensively in outreach. Oth- ers are concerned that museum activities will take their students and postdocs away from research. According to one staffer, such concerns have helped open a cultural divide within COMB: "One group has wanted to make sure that good science is presented, and another has figured it [is] somebody else's problem." Still, outreach proponents point to an Meet the scientist. Researchers and technicians con- duct teaching labs with groups of students. activity that they say should lessen doubts about success. Since the education facilities opened 2 years ago, school and community groups have been coming to the center for field trips. Typically, the groups split their time between the center's teaching and com- puter labs---both of which are overseen by the center's education staff with a half- hour interlude called "Meet the Scientist." At first, only a handful of people, mostly graduate students and postdocs, volunteered to meet with the groups--and several of them professed to be "terrified," says educa- tion director Judy Brown. So, she organized lunches with master teachers from Mary- land schools to build confidence and inter- est, and today a core of a dozen or so re- searchers meet regularly with visitors. In addi- tion, one of COMB's nontenured staff sci- entists, Bill Jones, is being supported by COMB to spend part of his time on out- reach activities. Brown also has hired sev- eral research technicians to conduct 3-hour teaching labs with students. So far, none of the tenured or tenure- track faculty members has gotten directly involved with the student groups, although Brown says they contribute by working with her and by allowing their students and postdocs to volunteer. And while those en- gaged in the educational activities would like to see more faculty participation, they recognize that, at present, faculty members have few incentives to get involved. Says Will Straube, director of the common facili- ties lab, "Until the time you spend with the public goes into your promotion and tenure file.., faculty [members] aren't going to feel that they can afford to participate." Faculty members are discussing the possibility of in- corporating public outreach into tenure de- cisions, but they feel constrained by policies governing other departments at the Uni- versity of Maryland. Many COMB researchers have worked with student groups before, but the opening of the Hall of Exploration this May repre- sents uncharted territory. As the staff strug- gles to define its involvement in ~the hall, some are asking whether g scientists are really the best people to explain science to the public. Carol Bossert, a former research geneticist who now works full- time for the Columbus Center as the director of the hall, believes they are: "It will be of greater ben- efit to the public if the person ex- plaining the exhibit is a COMB scientist." She argues that all sci- entists should have some experi- ence translating their work into lay terms. Still, Bossert and others also ac- knowledge that there may be a role for intermediaries who understand the sci- ence but are trained in public communica- tion as well. Colwell is working with her counterparts in other parts of the University of Maryland system to establish a graduate program in science education that would in- volve work at the center with schoolchildren and the public. She also is exploring whether graduate students elsewhere in the university system could serve as teaching fellows at the center, substituting work with high school students and the public for the usual experi- ence of teaching undergraduates. "It will pro- vide young scientists a new career track that they might not have considered but that they could enjoy very much," she says. Even as the last few exhibits go up in the Hall of Exploration, these and other issues remain up in the air. That's not surprising, say the center's supporters, given that no one has ever tried something like this before. What is surprising, they say, is how much attention their largely untested idea is at~- .tmcting. Almost every week, groups from the United States and abroad have been visiting the center to explore the possibility of setting up similar facilities. Says Heuisler: "When this is a success--well, I should say if it's a success~you're going to see a lot of these popping up." -Steve Olson Steve OIson is a science writer in Washington, D.C. http://www.sciencemag.org • SCIENCE • VOL 275 • 28 MARCH 1997 1875

.... Prepaper Publicity Ignites Race to Publish In mid-January, Ramon Parsons received a phone call that is every researcher's worst fear. Just weeks earlier, the molecular biologist,, who works at Columbia University's College of Physi-.~ clans and Surgeons, andhis research associate Jing Li had finally 'nailed the tumor-suppressor they had been hunting for the past year. It was potentially a major prize, but they still had to verifi/ that the gene was indeed a tumor suppressor--one whose loss or inactivation can lead to cancer development--and determine the . range of tumors, with which it might be involved. But just as they were anticipating the fruits of success, one of their collaborators, molecular biologist Michael Wiglet of Cold Spring Harbor Laboratory on Long Island, called to say that he had just read in a biotechnology newsletter that Myriad Genetics had.also found a tumor-suppressor. There was scant information in the press release, but what was there set offalarms. Myriad had linked its gene to malignant brain tumors called gliomas---just as Parsons had. The two genes, he feared, were the same. - • What happened over the next few weeks, as both the Parsons potential liability if information gets out in an uneven fashion." But when the release was mentioned in the biotech newsletter, B/otvor/d, it alsoalerted parsons to the competition at Myriad. "From reading the press release, [it seemed] we were farther along than they were~" says tXarsons. Nevertheless, he worried that ff the two groups had converged on the same gene, this announcement might jeopar- dize his chance to get credit for the discovery. "Do you know how hard it is tO publish in a small lab if you're second,v' Parsons asks. • Li and two graduate students worked around the clock for the next 4 days screening various tumor samples, mostly primary brain tumors, tO verify that the gene is indeed missing or aberrant, as would be expected for a tumor suppressor (see main text). But they skipped some of the tests they had planned to show that the gene is aberrant in more kinds of tumors, and also put off flling a patent on the gene until the paper was submitted. "My interest was to get a paper out the door," Parson says. Indeed, on 31 January, as soon as the paper was finished, Li flew to Washington, D.C., to hand- deliver it to Sc/ence. "It was pretty crazy," he says. and Myriad groups rushed to get papers in press und flle patents on Meanwhile, Myriad's academic collaborator on the project~ the gene, is testim.o~y to how complex life has~be~9~.e.~.foL~.or~_~e..t~ ~eck: of~.~.i~[,~D.~..An.der~on.Cancer Center'in. Houston,: i Searchers tracking down disease genes.~ With in~i.~_l._col_!gh0~;._ found him~lf~aught up in Myriad's commercial priorities. "The i : tidns~6n the tise~ the competition has grown more inte~ns~:, ~d ~: first e~phasis was patenting," he explains. In addition, he was .patenting and,stock-market wortri)es.~e.havmg an~qergreater racmgtOmeetarenewa!deadlmeforhtsgmnt.Hed~dntgettoh~s ~influ~qe 0~ h~ffi~i~n_t~t~ ~i~b~u~i~ir [~s!t~i~_i.~:~!~ ~:~.~i~i(~ Ui~lI i~ter, ~eni~thq~ghlhe began hea~ing through the . ~::!.~_Tl2.~e;jm~edi~te.~.~u~9~.~..a~sgns's ~anic ~ ~p~s~ ~i~_~e ~t ~ "in .._d!as. ttial~grapevine," as Steck calls it, that they had competi- : ._. M~ p~t ou~ On :22~a~. Tl~i~ r~!eas~ simply highlighted the~. : ti ~o~3.~ The paper was submitted in late February tO Nature.Genetics, ~i-~~fid ~ ~81b i~ gli0m~si:wi~thSut mention_'mg iy.~0s~q~_al..! ~c~a~ ~i:oaC~ted within a.week, and-published 3 weeks later, technically., : tion, Of gloving any ifiibrm'ati~n about its protein product or other ~ 4 days after Pars0ns's report. : ..... .. ':~!,?:~ :~ _.~i:,.' : :~:~i~_ :~ cancers the gene might be involved ir~ Also missing was any indi- . But whilePatrons beat St~eck ~and Myriad to publication, albeit i- cation that the work had been published, or wasat least submitted . hy a na~o~ margin, there's no telling yet which group will wind up for publication. "I thought itwas.bizarre, because, they were_an- withthepatent.Andperhapsneitherwill.Bothgroups'searchesled ~" nouncing a discovery without publishing it," Parsons recalls. : i :. them t~ the GenBanl~.c0mputer datable 9f gene sequences, which •. -:~;Ma~k Skolnick, Myriad's vice president of research, says the airead~ turned out.to contain several small DNA bits, called ex- company put Ouf the release to guard against possib!e i_ ~charges. of: presr~A sequencetags (ESTs), that fel! inside.thegene. A c0mputer insider.trading by the U~S.. Securities and Exchange Comm~!o~, :.~. program had eve~ grouped those F.STs into a tentati'~e gene, which - Sean.Tavtigian of Myriad notes that thecompany was about m. ~_contained a sequence indicating that its protein product is a de- enter one of the quarterly periods during which employees with, ph~phorylating enzyme. M ~y~'ad's Tavtigtan points out that this -stock opti0ns are allowed to trade their Myriad stocl~ia~d ~a~a~ed tO: .,~Id ~ea~ .that a ~a~-~. has generated many ESTs-- - make sure that th~ public knew what ~e em~loydeskn~r~it~i0i ~im,~a~ G~0~e"s~i~es in Ro~kvi!le, Maryland~may have' " had the giioma gd~e in hand..du~ng.that period~ ','We have ~ob~"~.:i b~te~ both S~ ~d~i~8 ~ P~t~n~ ~ce..That company ' unffo~ in ohr release df information," says Sko~ick. ~'~here's a declined comment on that ~possibil~. " " -E,P. then able to piece together the whole gene, using the ESTs as guides for sequencing it. In contrast to Parsons's 1-year blitz for the chrgmosome 10 gene, Steck's progress has been slow and steady, and he began his quest in gliomas rather than breast cancers. To try to find the crucial chromosome 10 gene that is missing in many of these brain cancers, Steck and his colleagues began adding pro- gressively smaller pieces of the chromosome back to cultured glioma cells. The idea was to demonstrate that one or more genes on the chromosome could reverse some of the can- cerous changes in the cells, and then to nar- row the search for those genes to ever smaller pieces of the chromosome. This approach got the researchers to within 5 million bases of the gene. To close in further, they determined whether glioma samples lacked a genetic marker located within that region, and by last summer had found four samples in which both copies oCchromo~ome 10 were missing that marker. There was a 75,000-base pair overlap in the missing DNA in these samples--a gap that presumably ex- tended over their rumor suppressor. However, the researchers still had a lot of DNA to sort through, and Steck thought it might be too big a project for his three- person lab group. He then went for help to Myriad, a company experienced in locating and sequencing genes, having done so for both BRCA1 and-2, andpI6. In November, Myriad's Sean Tavtigian stepped in; with Steck, he completed the hunt for the gene-- all in about a month, Tavtig~an says, using basically the same approach as the Parsons group. They also found signs that the gene is involved in some kidney, breast, and prostate cancers, as well as in gliomas. Although this team called the gene MMACI, its sequence shows that it is the same as PTEN. '%X/e started from two different places for two different reasons and got to the same place at the same time," says Steck, who was unaware of the Parsons effort until a few r~onths a.go. "We confirm each other's work." Both groups also attest to the importance of the gene. The Parsons group, for example, con- firmed the Sleek group's evidence that the gene is missing in many gliomas, as well as in some breast cancers. Their results hint that the gene is aho important for prostate cancer. It was missing or altered, for example, in all four http://www.sciencemag.org • SCIENCE • VOL. 275 ° 28 MARCH 1997 1877

be part of the system that helps cells know that they are in contact with neighboring cells. Normal cells tend to stop multiplying when they encounter their neighbors, but cancer cells often keep dividing, as if they never got the message to stop. PTEN's absence might be what blocks the message. PTEN may also somehow help anchor cells, in which case its loss may enable a cell to metastasise. "If [PTEN] does have a role in cell motility or cell structure, that might be quite interesting," says Eric Fearon, a cancer geneticist at the University of Michigan, Ann Arbor. How the protein's proposed roles as a phosphatase and a cytoskeletal protein might relate to each other is unclear, however. Even before researchers know how the gene works, it may prove useful to clinicians. Tavtigian points out that if this gene is the one mutated in Cowden disease, it could form the basis of a prenatal diagnostic test. And if the loss of the gene helps a cancer samples of the cancer that the Parsons group studied. Indeed, Johns Hopkins's Kinzler says, "there have been other candidate [prostate cancer] genes proposed, but I think this is the real McCoy." And he predicts, "the chances are, ir'.s going to be involved in other cancers2 Researchers still have a lot to do to find out just how the gene's loss could contrib- ute to these cancers, although its sequence provides some important clues. As a phos- phatase, thi~ PTEN protein may counteract the work of the growth-stimulating kinases, which can help make cells cancerous when they are mutated into an overactive form. The researchers have not yet shown directly that the protein is a phosphatase, however, nor have they identified any possible targets for its phosphate-removing activity. The cytoskeleml connection might also help explain the abnormal growth of cancer cells. Because of its links to the protein matrix outside the cell, the cytoskeleton is thought to MATERIALS SCIENCE Shape-Changing Crystals Get Shiftier The positive and negative charges balance out in each ofthe crystal's unit cells--its basic repeating units--but the positive charges, for instance, may be weighted toward the top of each cell. An electric field can dis- place the charges even farther, which dis- torts the overall shape of the unit cell and of the crystal as a whole. The process can also run in reverse: Squeezing or stretching the material shifts the charges relative to each other, redistributing electric charge around the surface of the crystal, which can produce a small electric current. The usual showcase for these properties is a cheap ceramic material called PZT, contain- ing millions of crystalline grains in different orientations. PZT, which is composed prima- rily of lead, zirconium, titanium, and oxygen, can deform by as much as 0.17% in a strong applied field. To boost this shape-shifting ability, researchers have tried to grow single crystals of PZT, in which all the unit cells would line up in the same direction. Their contributions to the piezoelectric effect would also line up, enhancing it. But because PZT's Zinc, Niobium, ~ 5fTit~nium .... Electric field Crystal growth. A weak field displaces atoms toward the cor- ners of the unit cells, but a stronger field rearranges the lattice. invade other tissues, then PTEN's status may help oncologists predict how malignant a glioma or prostate tumor will be--informa- tion that could help clinicians decide how aggressive they should be with surgery, che- motherapy, or other treatments. "If you had a molecular marker that could aid a clinician in that decision, that would be very signifi- cant," Steck suggests. And then there's the possibility that the PTEN work might provide guides to better cancer therapies by leading researchers to protein it normally dephosphorylates, put- ring the brakes on cell growth. A drug that either blocks the phosphorylation of the pro- tein or removes phosphates from it might cure a cell of any cancerous tendencies. Given all this potential, Li's life will not likely slow down any time soon, Parsons notes: "I think it's going to continue to be crazy here for at least another 6 months." -Elizabeth Pennisi components tend to separate during process- ing, the ceramic is extremely difficult to grow as a single crystal, says Shrout. To coax the material into forming single crystals, Shrout and Park tried varying its composition. They settled on a couple of dif- ferent mixtures, such as a combination of lead, zinc, and niobium spiked with varying amounts of lead-titanate (PT). The research- ers found that a small admixture of PT less than 9%myielded materials that not. only grew into single crystals, but also ended up with piezoelectric abilities that are enhanced more than they expected. Just why that is, "we still don't know for sure," says Shrout. But he and Park believe that at least part of the enhancement is due to the fact that an electric field applied to the new materials does more than just shift a few atoms around in the unit cell, as in PZT: "We think it causes the whole crystalline lattice structure to change from one form to another," says Shrout. The changed crystal structure, in turn, frees individual atoms to respond more strongly to the field, increasing the overall distortion of the material. Likewise, a me- chanical distortion probably produces a simi- lar lattice shift, enabling the material to gen- erate more current than standard PZT. Whatever the reason for the effect, it's likely to be very useful, says Robert Newnham, another piezoelectricity expert at Penn State. The new crystals will undoubtedly cost more than ceramics like PZT, says Park, because growing single crystals is a slow and painstaking process. But he adds that he and Shrout are working on ways to speed it up. If they suc- ceed, the new piezoelectric wunderkinds could grow up to live expansive lives indeed. -Robert F. Service A taler/te&family of materials has gained some even more gifted members. So-called ~iezo~lecm'.c crystals have the unique ability to swell or ~hrink when zapped with electric- ity, as well' as give off a jolt of juice them- selve~ when compressed or pulled apart. En- gineers la/ax;e exploited this trait for decades to convert mechanical energy to electricity and back a~ain in applications ranging from phonograp ,h needles to telephone speakers. NOW, a pair of researchers from Pennsylva- nia State University has bred new piemelectric wu~derk~ds, some of which display an effect 10 times greater than that of current family members. A-paper by the reseamhers, materials scientis~.Tl3.~omas Shrout and Seung-Eek Park, is scheduled to appear this spring in the inaugu- ral issue of the journal Mateda/s Research Inno- vations, but early word of the new work is ab ready mining a few heads. "It's an exciting breakthrough," says Eric Cross, another piezo- electric materials expert at Penn State, who is not afl~liated with the project. "Improvements by a factor of 10 are not easy to come by in a field that's 50 years old and considered mature." If the materials are commercial- ized, as Cross and others believe they Will be, they could usher in a new generation of piemelectric devices that would improve ev- erything from the resolution of ultrasound machines to the range of sonar listening devices. Piezoelectric materials owe their abilities largely to the asym- metrical arrangement of posi- tively and negatively charged atoms in their crystal structure. 1878 SCIENCE * VOL. 275 * 28 MARCH 1997 * http://www.sciencemag.org