亚硝基胍诱发大鼠胃腺癌发生发展过程中p53、ras基因表达和突变的研究

目的探讨ｐ５３、ｒａｓ基因在亚硝基胍（ＮｍｅｔｈｙｌＮ′ｎｉｔｒｏＮｎｉｔｒｏｓｏｇｕａｎｉｄｉｎｅ，ＭＮＮＧ）诱发大鼠胃腺癌发生发展过程中的作用。方法用免疫组织化学、聚合酶链反应单链构象多态性分析（ＰＣＲＳＳＣＰ）技术对大鼠正常腺胃粘膜、癌前病变和胃腺癌组织中ｐ５３，ｒａｓ基因的表达和突变进行检测。结果ｐ５３蛋白在癌组织中的阳性表达率为５０％（２０／４０只），正常和癌前病变组织中为阴性；ｒａｓ蛋白（ｐ２１）癌前病变组织中阳性率为４４％（２３／５２只），在癌组织中为２３％（９／４０只）。癌组织中ｐ５３基因突变率为４５％（１８／４０只），非癌组织为阴性。癌组织及癌前病变组织中均未发现ｒａｓ基因突变。结论在ＭＮＮＧ诱发大鼠胃腺癌发生发展过程中，ｒａｓ基因的激活是一早期事件，可能参与了癌的发生过程，而ｐ５３突变则主要与胃癌的进展有关。     

膀胱移行细胞癌P21,P185,p53蛋白表达及ras,p53基因突变的检测

为探讨基因的改变在膀胱移行细胞癌发生过程中的意义，应用免疫组织化学及聚合酶链反应－限制性片段长度多肽性法，检测１５０例膀胱移行细胞癌Ｐ２１、Ｐ１８５、ｐ５３蛋白表达以及５０例ｒａｓ、ｐ５３基因突变。结果表明：膀胱移行细胞癌Ｐ２１、Ｐ１８５、ｐ５３蛋白表达阳性率分别为５９．３％（８９例）、５５．３％（８３例）、２９．３％（４４例）。Ｐ２１、ｐ１８５蛋白表达阳性率与膀胱移行细胞癌分级呈负相关（Ｐ＜０．０５），ｐ５３蛋白表达与膀胱移行细胞癌分级呈正相关（Ｐ＜０．０１）。Ｐ２１、ｐ５３蛋白表达阳性率与预后呈显著相关，Ｐ２１与预后呈负相关。７３例膀胱移行细胞癌存在两种以上蛋白共同表达。膀胱移行细胞癌Ｈａ－ｒａｓ癌基因第１２位密码子突变１６例（３２％），ｐ５３基因突变９例（１８％），均为２４８位点突变。Ｈａ－ｒａｓ第１２位点突变随病理分级增高而增高，与膀胱移行细胞癌分级显著相关（Ｐ＜０．０５）。ｒａｓ基因、ｐ５３基因突变与预后显著相关（Ｐ＜０．０５）。ｒａｓ基因、ｐ５３基因突变患者死亡率高于无突变患者。４例膀胱移行细胞癌存在ｒａｓ基因及ｐ５３基因共同突变。     

p53、ras p21、c-erbB-2和nm23在肺癌组织中的表达

目的：探讨癌基因与肺癌临床病理特征及预后的关系。方法：应用免疫组化ＳＰ法对５８ 例肺癌行ｐ５３、ｒａｓｐ２１、ｃｅｒｂＢ２和ｎｍ２３ 的检测。结果：癌组织中阳性反应检出率分别为４６－６％ 、２４－１ ％ 、５０－０ ％ 和５３－４ ％ ,腺癌和差分化癌ｒａｓ ｐ２１ 、ｃｅｒｂＢ２表达高于鳞癌和分化好的癌（ Ｐ＜ ０－０５） ,术后长期生存患者ｒａｓｐ２１ 、ｃｅｒｂＢ２ 表达低于短期死亡患者（Ｐ＜ ０－０５ ,Ｐ＜ ０－０１）,吸烟患者ｒａｓ ｐ２１ 表达高于不吸烟患者（Ｐ＜ ０－０５） ,淋巴结癌转移阴性组ｎｍ２３ 表达高于淋巴结癌转移阳性组（ Ｐ＜ ０－０１）,ｐ５３ 与ｒａｓ ｐ２１、ｃｅｒｂＢ２ 阳性表达具有协同性（ Ｐ＜ ０－０５） 。结论：肺癌发生发展和转移与ｒａｓｐ２１ 、ｃｅｒｂＢ２ 的激活和ｐ５３ 、ｎｍ２３ 的失活密切相关,部分基因的改变存在协同性,ｒａｓ ｐ２１ 基因的激活与吸烟有关,ｒａｓ ｐ２１、ｃｅｒｂＢ２ 的检测对判断肺癌预后有价值。     

大肠腺瘤与腺癌P21,P53,P185蛋白表达及ras,p53基因突变的检测

应用免疫组化及ＰＣＲ－ＲＦＬＰ法检测３０例大肠腺瘤、７４例大肠腺癌及癌旁粘膜Ｐ２１、Ｐ５３、Ｐ１８５蛋白表达及ｒａｓ、ｐ５３基因突变。结果表明，大肠腺瘤Ｐ２１、Ｐ５３蛋白阳性率（５３．３％，２７．６％）高于癌旁粘膜（Ｐ＜０．０１），二者过度表达与腺瘤恶性倾向有关。大肠腺癌Ｐ２１、Ｐ５３及Ｐ１８５蛋白阳性率（７２．９％，３７．８％，４７．２％）皆高于腺瘤Ｉ级不典型增生（Ｐ＜０．０１，Ｐ＜０．０５及Ｐ＜０．０５）。９例腺瘤，４０例腺癌存在两种以上蛋白表达，共同表达与腺瘤恶性倾向及腺癌预后有关。大肠腺瘤及腺癌ｒａｓ基因突变率分别为２６．７％及４１．９％，ｒａｓ基因突变与腺瘤恶性倾向有关。大肠腺瘤及腺癌ｐ５３基因２４８位点突变率分别为３．３％及１４．９％。６例腺癌存在两种基因突变，两种基因协同突变与大肠癌预后有关。提示ｒａｓ、ｐ５３及ｃ－ｅｒｂＢ－２基因改变均参与了大肠癌的发生、发展过程。     

肝癌组织中N—ras基因突变和p53蛋白表达

目的：研究Ｎ－ｒａｓ和ｐ５３基因与肝癌发生，发展的关系。方法：应用多聚酶链反应－单链构象多态性分析法（ＰＣＲ－ＳＳＣＰ）和免疫组化法，检测２９例肝癌中的Ｎ－ｒａｓ基因突变和ｐ５３蛋白的表达。结果，１３例肝癌ｐ５３蛋白阳性（４４．８％），表明广西地区肝癌中曾普遍存在ｐ５３基因的突变，肝癌及癌旁组织中Ｎ－ｒａｓ基因在第２～３７密码子间的突变率分别为７９．３１％和８０．７７％，２２例有２个以上突变位点（     

p21ras,p53,c—myc,PCNA在子宫内膜腺癌中的表达

目的：探讨癌基因与子宫内膜腺癌的关系。方法：应用免疫组化ＬＳＡＢ法对３３例原发性子宫内膜膜癌进行Ｐ２１ｒａｓ，ｐ５３，ｃ－ｍｙｃ和ＰＣＮＡ的检测。结果：Ｐ５３表达来７８．８％，Ｐ２１ｒａｓ表达为５１．５％，ｃ－ｍｙｃ表达为８１．８％，ＰＣＮＡ表达为９７％。均明显高于正常增殖期子宫内膜。Ｐ２１ｒａｓ和Ｐ５３在正常子宫内膜无表达，因此比ｃ－ｍｙｃ在子宫内膜腺癌的表达更特异。本研究显示Ｐ５３与子宫内膜腺     

c─erbB─2、ras p21及p53在大肠癌表达的免疫组化研究

对４８例大肠癌连续切片进行ｃ─ｅｒｂＢ─２、ｒａｓｐ２１及ｐ５３３种癌相关基因产物的免疫组化ＡＢＣ法及ＡＰＡＡＰ－ＩＧＳＳ双重标记研究，结果表明：（１）癌相关基因ｃ─ｅｒｂＢ─２、ｒａｓｐ２１和ｐ５３阳性表达率在癌组织分别为５０．２％（２５／４８）、４３．８％（２１／４８）和５４．２％（２６／４８）；癌旁粘膜分别为２５％（１２／４８）、１８．８（９／４８）和２０．８％（１０／４８）；而在＂正常＂结肠粘膜则分别为１２．５％（６／４８）、６．３％（３／４８）和０．（２）有２种以上癌相关基因产物同时表达者在癌组织中有２６例（５４．２％）．在癌旁粘膜有５例（１０．５％），而在正常粘膜则未见有２种癌相关基因同时表达，（３）癌组织中ｃ─ｅｒｂＢ─２＋ｐ２１、ｃ─ｅｒｂＢ─２＋ｐ５３、ｐ２１＋ｐ５３及ｃ─ｅｒｂＢ─２＋ｐ２１＋ｐ５３同时表达者分别为２．１％、１２．５％、１６．７％及２２．９％，（４）ＡＰＡＡＰ－ＩＧＳＳ双重免疫标记结果表明，单一癌细胞可同时表达２种癌基因产物。上述结果提示：ｃ─ｅｒｂＢ─２、ｒａｓｐ２１及ｐ５３可能与大肠病的发生有关，三者在大肠病的发生中可能起协同作用。     

免疫组化和PCR—SSCP检测p53基因异常的一致性探讨

目的：探讨免疫组化检测ｐ５３蛋白表达和ＰＣＲ－ＳＳＣＰ检测ｐ５３基因突变的一致性。方法：单克隆抗体ＤＯ－７检测８５例非小细胞肺癌（ＮＳＣＬＣ）的ｐ５３蛋白表达，ＰＣＲ－ＳＳＣＰ检测其中３１例腺癌的ｐ５３基因突变。结果：８５例ＮＳＣＬＣ中ｐ５３蛋白表达阳性率为６８％（５８／８５），３１例腺癌中ｐ５３蛋白表达阳性率为６１％（１９／３１），１４例（４６％）出现ｐ５３基因５～８外显子突变，ｐ５３蛋白免疫组化和ＰＣＲ－ＳＳＣＰ检测ｐ５３基因突变无显著相关（χ２＝０．１，Ｐ＝０．７６），其一致率为５２％。结论：ｐ５３蛋白表达并不能很好地反映ｐ５３基因突变。     

胃癌基因表达的免疫组化研究

应用免疫组化方法对４２例胃癌和相位癌旁组织以及１１例良性胃病组织的ｐ５３、ｃ－ｍｙｃ和ｒａｓ基因编码产物进行检测。结果发现；３种基因在胃癌中的阳性率分别是３３．３％、２３．８％和４２．９％；在相应癌旁组织的阳性率依次分别是１６．７％、１１．９％和１６．７％；ｐ５３和ｃ－ｍｙｃ在在良性胃病组织中无表达，ｒａｓ基因在良性胃病组织中阳性率２．４％。     

大肠腺癌p53基因cDNA突变与突变型p53基因蛋白表达的相互关系和意义

目的：探讨大肠腺癌突变型ｐ５３基因蛋白表达与ｐ５３基因ｃＤＮＡ突变间的相互关系和意义。方法：对１００例新鲜大肠腺癌组织采用ＰＡｂ２４０单克隆抗体免疫组织化学染色（ＬＳＡＢ法）检测突变型ｐ５３基因蛋白表达、ＲＴ－ＰＣＲ－ＳＳＣＰ检测ｐ５３基因ｃＤＮＡ突变，并比较它们间相互关系。结果：１００例大肠腺癌中，７６例ＰＡｂ２４０单抗阳性（７６％），５１例ｐ５３基因ｃＤＮＡ突变阳性（５１％）；ＰＡｂ２４０单抗反应与ｐ５３基因ｃＤＮＡ突变比较，两者皆阳性４９％，两者中一者阳性２９％，两者皆阴性２２％（Ｐ＜０．０００１）。结论：ｐ５３基因ｃＤＮＡ突变与其基因蛋白产物结构改变高度吻合，大肠腺癌ｐ５３基因ｍＲＮＡ（ｃＤＮＡ）突变是参与和影响突变型ｐ５３基因蛋白结构改变和生物学行为的主要因素     

乳腺增生病p53基因第5外显子突变及其蛋白表达

目的：探讨p53基因在乳腺癌发生早期的作用。方法：用免疫组化方法检测36例乳腺单纯性增生、31例不典型增生、14例原位癌和16例浸润癌中p53蛋白的表达，用PCR－SSCP检测了上述组织中p53基因第5外显子突变。结果：p53蛋白在单纯性增生、不典型增生、导管内癌、浸润癌中的表达率分别为0、22.6%(7/31)、42.8%(6/14)、50％（8／16），PCR－SSCP在各组中均未检测到该基因第5外显子突变。结论：乳腺癌发生早期阶段有p53基因的参与，但与第5外显子突变无明显关系。     

DukesC期大肠癌原发灶与淋巴结转移灶中p53基因突变的比较

目的探讨大肠癌转移与ｐ５３基因突变的关系。方法用ＰＣＲ－ＳＳＣＰ检测７３例ＤｕｋｅｓＣ期大肠癌及４０例相应的淋巴结转移灶ｐ５３基因第５至第９外显子的突变。结果７３例原发灶有２７例（３７％），４０例淋巴结转移灶中有１９例（４７．５％）检测到ｐ５３基因突变，总突变率为４４％。在原发灶和转移灶同时检测的４０例中，有２１例（５２．５％）两者均未见ｐ５３突变；另１２例（３０％）两者均可见完全相同的突变条带；余下的７例（１７．５％）两者ＰＣＲ－ＳＳＣＰ的结果不一致。这７例经ＤＮＡ直接测序确定了ｐ５３基因突变位点。其中５例原发灶未见ｐ５３突变，而转移灶ｐ５３有明确突变；７例中２例转移灶可见ｐ５３有二个外显子突变，而原发灶仅一个或无突变点。结论多数ｐ５３基因突变发生在转移之前并持续存在于大肠癌进展至转移的整个时期，大肠癌的转移可伴有ｐ５３基因的新突变，或转移对ｐ５３基因突变有一定选择，提示ｐ５３基因突变可能与大肠癌转移相关。     

胃癌及其癌前病变中细胞凋亡及其调控基因的表达

目的:通过观察胃癌及其癌前病变中细胞凋亡及其调控基因p53、bcl-2、c-myc的表达,探讨其在胃癌恶性转化进程中的作用。方法:利用DNA末端标记技术(TdT-mediateddUTP-biotinnickendlabeling,TUNEL法)和免疫组织化学(streptavidin/peroxidase,S-P法),原位观察了46例胃癌、20例癌前病变、24例正常粘膜中的凋亡细胞和p53、bcl-2、c-myc的表达。结果:癌前病变和胃癌中凋亡指数显著高于正常粘膜(P＜0.01),癌前病变组高于胃癌组(P＜0.01)。p53、bcl-2、c-myc蛋白在胃癌中阳性率分别为60.9%、67.4%、73.2%,均高于正常粘膜组(P＜0.01);在癌前病变中3种蛋白阳性表达率分别为40%、95%、58.8%(P＜0.01)。胃癌中p53、bcl-2蛋白阳性细胞凋亡指数分别低于阴性组(P＜0.05),c-myc蛋白阳性组细胞凋亡指数高于阴性组(P＜0.01)。结论:细胞凋亡调控异常在胃癌发生中可能起重要作用。p53、bcl-2蛋白分别抑制细胞凋亡,c-myc蛋白在胃癌中促进细胞凋亡。     

胃癌及胃液中p53、ras基因突变与临床病理的关系

目的：探讨胃良性病变向恶性转化过程中p53、ras基因突变的规律，并分析胃癌无损伤基因检测的可行性。方法：应用PCR－SSCP及免疫组织化学方法对比研究。结果：异型增生p53基因突变率10％（3／30）、ras基因突变率10％（3／30）、ras基因突变率16．7％（5／30）（二者总突变率26．7％）；早期胃癌p53基因突变率35％（7／20）、ras基因突变率60％（12／20）（二者总突变率85％，其中2例重复突变）； 中晚期胃癌p53基因突变率60％（18／30）、ras基因突变率43．3％（13／30）（二者总突变率90％，其中4例重复突变）；胃息肉ras基因突变仅1／10。30例胃溃疡边缘正常黏膜均未发现p53、ras基因突变。p53基因突变的25例胃癌的胃液中其相应的突变率32％（8／25）。19例胃癌患者的胃液中9例有ras基因突变47．1％（9／19）。异型增生p53蛋白过度表达阳性率13．3％（4／30),p^21ras蛋白阳性率16．7％（5／30）。胃癌p53蛋白阳性率56％（28／50），p^21ras蛋白阳性率60％（30／50）。正常胃黏膜上皮、溃疡边缘正常黏膜及胃息肉均呈p53及ras蛋白阴性表达。结论：胃癌的发生发展与癌基因ras与抑癌基因p53的突变有关，且两种基因同时检测，可覆盖绝大多数胃癌病例，提高了本项技术的可靠性，提供了胃癌无损伤基因检测的可行性的实验证据。     

ras Gene mutations and expression of Ras signal transduction mediators in gastric adenocarcinomas

OBJECTIVE: To investigate ras gene alteration in human gastric adenocarcinomas and its potential relationship to ras signal transduction mediators. DESIGN: Genomic DNA from 104 gastric tumors were analyzed by sequencing of polymerase chain reaction-amplified products for the presence of ras mutations. All the samples were further investigated with the use of immunohistochemical analysis for ERK1 and ERK2. SETTING: Tertiary care teaching hospital. PATIENTS: Seventy patients from a Korean population and 34 from a Midwestern US population composed of white Americans and African Americans. RESULTS: Fifteen tumors (14%) were positive for either H-ras or K-ras mutation: 9 (13%) of 70 Korean patients and 6 (18%) of 34 US patients. Seven (78%) of the 9 mutated tumors from Korean patients and all 6 (100%) from the US patients were intestinal-type lesions. Either ERK1 and/or ERK2 was overexpressed in 68 samples (65%). No association was established between ras mutations and overexpression of ERK1/2. However, the correlation between ERK1/2 and progression (early vs late) was statistically significant (P =.007). CONCLUSIONS: These data suggest that ras mutations are uncommon in gastric adenocarcinomas and that differing racial and/or geographic mechanisms may not underlie ras gene alteration. Most ras mutations were, however, observed in the group of intestinal-type samples, supporting the different genetic mechanisms of carcinogenesis between the intestinal- and diffuse-type tumors. It is noteworthy that enhanced ERK1/2 activity could be one of the characteristics of tumor invasiveness in gastric cancers.     

Genetic alterations of the Cdx2 gene in gastric cancer

Gastric atrophy and intestinal metaplasia are generally considered precancerous lesions of the stomach; Cdx2 plays an important role in intestinal metaplasia and gastric carcinogenesis. To elucidate the potential etiological role of the Cdx2 gene in gastric carcinogenesis, we analyzed genetic mutations and allelic loss in the Cdx2 gene of 95 sporadic gastric cancers. We found two somatic missense mutations in the Cdx2 gene, P63L in exon 1 and E204K in exon 2, encoding the caudal-like protein activation region (codon 13-180) and the homeobox domain (codon 188-243) of the gene, in the gastric cancers. In addition, 9 (25.0%) of 36 informative cases showed allelic loss at D13S220 and/or D13S260. In 11 cases with a genetic alteration, Cdx2 nuclear staining was observed only in 8 cases of gastric mucosa with intestinal metaplasia. Loss or reduced expression of the Cdx2 gene in cancer cells was found in two cases with a somatic mutation and in three cases with LOH. Interestingly, all of the cases were intestinal-type gastric cancers. Thus, these results suggest that genetic alterations of the Cdx2 gene may contribute to the loss of Cdx2 expression and to the development of gastric cancer, especially in the intestinal-type.     

Analysis of p53 tumor suppressor gene, H-ras protooncogene and proliferating cell nuclear antigen (PCNA) in squamous cell carcinomas of HRA/Skh mice following exposure to 8-methoxypsoralen (8-MOP) and UVA radiation (PUVA therapy)

Treatment with 8-methoxypsoralen (8-MOP) and ultraviolet radiation (primarily UVA), called PUVA therapy, has been used to treat different chronic skin diseases but led to a significant increased risk for skin cancer. The National Toxicology Program (NTP) performed a study in mice treated with PUVA that showed a significant increase in squamous cell carcinomas of the skin. In the present study, we evaluated the protein expression of p53 and PCNA and DNA mutations of p53 and H-ras genes in both hyperplastic and neoplastic squamous cell lesions from the NTP study. By immunohistochemical staining, protein expression of both p53 and PCNA was detected in 3/16 (19%) of hyperplastic lesions and 14/17 (82%) of SCCs in groups treated with both 8-MOP and UVA. The mutation frequency of p53 in SCCs from mice administered 8-MOP plus UVA was 15/17 (88%) with a predominant distribution of mutations in exon 6 (14/15 - 93%). No H-ras mutations were detected in the hyperplastic lesions/tumors. The mutagenic effect of PUVA on the p53 tumor suppressor gene may lead to a conformational modification and inactivation of the p53 protein, which are considered critical steps in PUVA-induced skin carcinogenesis. The p53 mutational frequency and patterns from our study were different from those reported in human PUVA-type tumors.     

Frequent expression of p53 protein without mutation in the atypical epithelium of human bronchus.

We investigated the correlation between p53 protein levels and mutations in the p53 gene of atypical bronchial epithelium (ABE). Protein levels were analyzed by immunohistochemistry, whereas mutations were assessed by polymerase chain reaction-single-strand conformational polymorphism (PCR-SSCP) and direct sequencing. A total of 78 formalin-fixed, paraffin-embedded bronchial biopsy specimens that had been diagnosed to be ABE were retrieved from the archives and examined. p53 protein was expressed in 44 of the 78 (56%) specimens overall. However, when pathologically classified, 38% of hyperplasias, 58% of metaplasias, and 73% of dysplasias were positive, indicating that an increased frequency of p53 expression correlated with the severity of ABE (P = 0.042). Among the 44 specimens that expressed p53 protein, 40 (91%) did not reveal mutations by PCR-SSCP. In the four specimens with abnormal PCR-SSCP bands, p53 gene mutation was identified by direct sequencing and revealed the same point mutation at codon 248 (CGG-to-CTG transversion) of exon 7 in all four specimens. These four specimens were dysplasias derived from patients with lung cancer. p53 protein expression in ABE was associated with the wild-type gene in most cases; therefore, wild-type p53 protein expressed in ABE might have a protective function from lung carcinogenesis, and mutation of p53 gene may be a late event in the sequential steps of lung carcinogenesis.     

肺癌p53蛋白表达和基因突变与临床病理的相关研究

目的 检测肺癌中ｐ５３蛋白表达和基因突变状况及其与临床病理和预后的相关性。方法：应用免疫组织化学（ＬＳＡＢ法）和聚合酶链反应－单链构象多态性分析（ＰＣＲ－ＳＳＣＰ）二种方法。结果 检测肺鳞癌４６例，共９５例。免疫组化ｐ５３蛋白总阳性率为５０．５％（４８／９５例），肺鳞癌阳性率为５６．５％（２６／４６例）、肺腺癌为４４．７％（２２／４９例）。ＰＣＲ－ＳＳＣＰ检测ｐ５３基因突变率为４１．１％（３９／９     

Optimized polymerase chain reaction-based single-strand conformation polymorphism analysis of p53 gene applied to Bulgarian patients with invasive breast cancer

Abstract. During the last few decades a substantial amount of evidence has accumulated proving that the abrogation of the normal p53 pathway is a critical step in the initiation and progression of tumors. Decoding the genetic mechanisms involved in carcinogenesis requires screening for consistent genetic tumor alterations, including those concerning the p53 gene. Thus, practical, efficient, and inexpensive techniques for accurate determination of p53 mutational status are needed. Polymerase chain reaction/single-strand conformation polymorphism (PCR-SSCP) analysis is considered to be a useful tool to investigate the role of the p53 gene in the development and progression of human cancers. The sensitivity of the method can be increased considerably by varying the experimental conditions. Here we demonstrate a scheme of PCR-SSCP optimization for detection of p53 gene mutations of patients with various cancers. Optimal conditions for PCRSSCP of p53 exons 4–9 are reported. Such PCR-SSCP optimization could allow an increase in the sensitivity and reproducibility of the technique and facilitates screening of large series of patients to assess the clinical significance of p53 mutations in human cancers. Using the optimized PCR-SSCP analysis we screened Bulgarian patients with invasive breast cancer for p53 gene mutations and registered a 33.33% frequency of mutations. To date, there are no data concerning the p53 status of Bulgarian breast cancer patients. Screening for p53 gene mutations enables an accurate and routine determination of the p53 status of patients with cancer and may be applied in clinical oncology to cancer diagnosis, prediction of prognosis and response to treatment.