Mitochondrial and chromosomal DNA alterations in human chromophobe renal cell carcinomas.

Renal cell tumours are characterized by the loss of chromosome 3p and trisomy of 5q segments (common, non-papillary renal cell carcinoma), or by trisomy of chromosomes 7 and 17 and loss of the Y chromosome (papillary renal cell carcinoma), or by random karyotype changes and mitochondrial DNA alterations (renal oncocytoma). We have studied by means of RFLP analysis the genomic and mitochondrial DNA in 11 chromophobe renal cell carcinomas, which have a unique morphology among kidney cancers. We found a loss of the constitutional heterozygosity at chromosomal regions 3p, 5q, 17p, and 17q, a combination of allelic losses that has not been found in other types of renal cell tumours. Three of the tumours showed a gross alteration in the restriction pattern of the mitochondrial DNA. A combined morphological and genetic analysis suggests that chromophobe renal cell carcinoma is a distinct entity.     

Chromophobe renal cell carcinoma,eosinophilic variant with papillary growth: a case report

We report the case of an 80-year-old man who presented with pathologically diagnosed chromophobe renal cell carcinoma composed of eosinophilic cells with partial papillary growth. The patient had a 2.5 cm diameter renal mass incidentally detected by abdominal ultrasound examination. Laparoscopic left partial nephrectomy was performed under a diagnosis of left renal tumor. Histopathology demonstrated uniform eosinophilic cuboidal cells growing with a partially papillary pattern: differential diagnosis of oncocytoma, papillary renal cell carcinoma, or oncocytic papillary renal cell carcinoma was necessary. Immunohistochemical staining with anti-monoclonal antibody 31 and -CD82 antibody, and choroid iron staining, were positive. Cytogenetic analysis by comparative genomic hybridization showed gains of chromosomes 1p, 9q, 19q, 20, and 21q, and losses of chromosomes 1p and q, 2q, 6q and 7q, leading to diagnosis of chromophobe RCC. We describe differential diagnosis for chromophobe renal cell carcinoma, eosinophilic variant, growing in a papillary fashion in the kidney.     

Allelic alterations in nontumorous liver tissues and corresponding hepatocellular carcinomas from chinese patients

Allelic imbalance may play an important in tumor progression in hepatocarcinogenesis, but the genetic background of the corresponding nontumorous liver in hepatocellular carcinoma (HCC) is not well defined. We studied the incidence of loss of heterozygosity (LOH) and microsatellite instability (MSI) by microsatellite analysis in both nontumorous livers and the corresponding tumors, by comparing them with the normal DNA from Chinese patients with resected primary HCCs. We also evaluated the pathologic significance of the alterations. We used 18 highly polymorphic microsatellite markers on chromosomes 1, 3, 4, 7, 8, 9, 13, 16, 17, and 18. Our results showed that 70.6% (24 of 34) of the HCCs exhibited LOH at 1 or more loci, and that the overall fractional allelic loss (FAL) was 0.169. MSI was observed in only 1 tumor. In contrast, the nontumorous livers of the HCCs showed a very low incidence of LOH, with only a single LOH detected in 1 of 34 (2.9%) of the nontumorous livers, with an overall FAL index of 0.005. Tumors with LOH at 1 or more loci had significantly more frequent venous invasion (P = 0.019). Allelic loss at locus D9S199 (9p23) was seen more frequently in larger tumors (P = 0.031), and, less significantly, allelic loss at locus D16S516 (16q24.1) was seen more frequently in larger tumors (P = 0.059). LOH was common in predominantly hepatitis B virus-associated HCCs from Chinese patients. However, LOH or MSI in the corresponding cirrhotic or noncirrhotic livers was uncommon.     

Hepatocellular carcinoma with lymphoid stroma: a tumour with good prognosis after liver transplantation

AIMS: Carcinomas with lymphoid stroma arising in non-liver-organs have a better prognosis than other carcinomas and may be associated with Epstein-Barr virus. We determined the frequency, characteristics and prognosis of hepatocellular carcinomas with lymphoid stroma. METHODS AND RESULTS: Histology of the livers of 162 patients with hepatocellular carcinoma, who underwent an orthotopic liver transplantation, was reviewed independently by three pathologists. Hepatocellular carcinoma with lymphoid stroma was diagnosed when all tumour samples contained more lymphocytes than tumour cells. Epstein-Barr virus was detected by in-situ hybridization and by polymerase chain reaction. Five patients (3.6%) were classified as hepatocellular carcinomas with lymphoid stroma. All patients were males. Cirrhosis was present in four/five patients. Serum alpha-fetoprotein levels were normal. Inter-observer histological reproducibility was good. Tumour cells did not contain Epstein-Barr virus. The five patients were alive without tumour at three years, although two of them had adverse prognostic factors at the time of transplantation (more than one tumour with a diameter > or = 40 mm). Only one patient had tumour recurrence, but he survived 7.6 years post-transplantation. The 5-year survival of patients with hepatocellular carcinoma with lymphoid stroma was better than that of the patients with other types of hepatocellular carcinomas (P = 0.04). CONCLUSIONS: Hepatocellular carcinoma with lymphoid stroma should be considered as a distinct clinicopathological and prognostic entity.     

Papillary renal cell carcinoma with clear cell cytomorphology and chromosomal loss of 3p

AIMS: Cytogenetic studies on renal cell carcinomas (RCCs) have disclosed a correlation between chromosome aberrations and histomorphological features. Nevertheless, it is still controversial whether the cytomorphology of the tumour cells (clear cell, chromophilic, chromophobe) or their growth pattern (nonpapillary, papillary) is more discriminative for the combined histomorphological-cytogenetic classification of RCCs. METHODS AND RESULTS: Three RCCs with papillary growth pattern and clear cell cytomorphology were analysed by classical cytogenetics using standard G-banding techniques. Each tumour displayed clonal aberrations leading to loss of terminal 3p chromosomal segments. Monosomy 14 was also consistently found. Trisomy 17 was not observed in any of the tumours. CONCLUSIONS: This series of three RCCs consisting of clear cells with papillary architecture revealed chromosomal aberrations characteristic for the conventional (clear cell) RCC. Irrespective of the predominant papillary growth pattern, none of the cases were characterized by trisomy of chromosomes 3q, 7, 8, 12, 16, 17 and 20 and loss of Y chromosome which are widely regarded as the most consistent genetic alterations for papillary RCC. Therefore, our cytogenetic findings provide evidence that papillary clear cell RCCs should be classified according to their cytomorphology rather than their growth pattern even when papillary architecture is prominent.     

Clinical features of renal cell carcinoma (RCC) found in 110 nephrectomized Japanese, of which 24 (22%) RCC cases showed 31 double or triple cancers

The causes of renal cell carcinoma (RCC) were investigated in 115 nephrectomized Japanese. Among them, 110 nephrectomized Japanese had RCC as follows: 86 clear cell RCC, 8 papillary RCC, 8 chromophobe RCC, 7 dialytic–multicystic RCC, and 1 liposarcoma, while 5 nephrectomized Japanese had benign renal tumors of oncocytoma (1), angiomyolipoma (2), and hemangioma (2). In the eight chromophobe RCC, three cases that resulted in death involved medullary RCC showing extensive oncogenic features. Double or triple cancers were found in 17 clear cell RCC, 5 papillary RCC, 1 chromophobe RCC, and 1 dialytic–multicystic RCC. Among 31 non-RCC found in 24 RCC cases, 23(74%) non-RCC were removed prenephrectomy. Prenephrectomy adenocarcinoma and postnephrectomy squamous cell carcinoma were their characteristic findings. Compared with those of clear cell RCC, double (triple) cancers of papillary RCC showed more aggressive malignancy. One clear cell RCC had triple cancer of thymoma and rectum cancer. One chromophobe RCC developed thymoma, while one oncocytoma had insulinoma >10 years before. A patient in his sixties with clear cell RCC, who had a past history of pneumothorax, had developed adenocarcinoma of colon polyps and liver adenocarcinoma almost at the same time as triple cancer. His lactate dehydrogenase (LDH) levels were under 300 IU/l. He was suspected of having Birt–Hogg–Dube syndrome. One patient with papillary RCC of Paget’s disease of the bone developed colon polyp adenocarcinoma, osteosarcoma, and additionally exhibited p97/valosin-containing protein downregulation in his sixties. His LHD was increased to 4,289 IU/l with cell lysis reactions. His radical nephrectomy accompanied by adrenalectomy reinforced clinical manifestations of p97 downregulation. For p97 functions, the kidney and adrenal gland had important roles. It was concluded that oxygen stress was stronger in RCC, especially in papillary RCC. Nonsense mutations of protein tyrosine phosphatase receptor delta might be one cause of double (triple) cancers in RCC.     

Genetic and epigenetic alterations during renal carcinogenesis

Renal cell carcinoma (RCC) is not a single entity, but comprises a group of tumors including clear cell RCC, papillary RCC and chromophobe RCC, which arise from the epithelium of renal tubules. The majority of clear cell RCCs, the major histological subtype, have genetic or epigenetic inactivation of the von Hippel-Lindau (VHL) gene. Germline mutations in the MET and fumarate hydratase (FH) genes lead to the development of type 1 and type 2 papillary RCCs, respectively, and such mutations of either the TSC1 or TSC2 gene increase the risk of RCC. Genome-wide copy number alteration analysis has suggested that loss of chromosome 3p and gain of chromosomes 5q and 7 may be copy number aberrations indispensable for the development of clear cell RCC. When chromosome 1p, 4, 9, 13q or 14q is also lost, more clinicopathologically aggressive clear cell RCC may develop. Since renal carcinogenesis is associated with neither chronic inflammation nor persistent viral infection, and hardly any histological change is evident in corresponding non-tumorous renal tissue from patients with renal tumors, precancerous conditions in the kidney have been rarely described. However, regional DNA hypermethylation on C-type CpG islands has already accumulated in such non-cancerous renal tissues, suggesting that, from the viewpoint of altered DNA methylation, the presence of precancerous conditions can be recognized even in the kidney. Genome-wide DNA methylation profiles in precancerous conditions are basically inherited by the corresponding clear cell RCCs developing in individual patients: DNA methylation alterations at the precancerous stage may further predispose renal tissue to epigenetic and genetic alterations, generate more malignant cancers, and even determine patient outcome. The list of tumor-related genes silenced by DNA hypermethylation has recently been increasing. Genetic and epigenetic profiling provides an optimal means of prognostication for patients with RCCs. Recently developed high-throughput technologies for genetic and epigenetic analyses will further accelerate the identification of key molecules for use in the prevention, diagnosis and therapy of RCCs.     

Clear cell renal cell carcinoma with wild‐type von Hippel‐Lindau gene: a non‐existent or new tumour entity?

The current World Health Organisation (WHO) classification of renal tumours is based on characteristic histological features or specific molecular alterations. von Hippel‐Lindau (VHL) alteration is the hallmark of clear cell renal cell carcinoma (RCC). After identification of the MiT translocation family of tumours, clear cell papillary renal cancer and others, the group of ccRCC with wild‐type VHL is small. TCEB1 mutation combined with chromosome 8q loss is an emerging tumour entity with wild‐type VHL. Inactivation of TCEB1 increases HIF stabilisation via the same mechanism as VHL inactivation. Importantly, recent molecular analyses suggest the existence of another ‘VHL wild‐type’ evolutionary subtype of clear cell RCC in addition to TCEB1 mutated RCC and clear cell papillary renal cancer. These tumours are characterised by an aggressive behaviour, high tumour cell proliferation rate, elevated chromosomal instability and frequent presence of sarcomatoid differentiation. Future clinicopathological studies will have to provide data to determine whether TCEB1 tumours and clear cell RCC with wild‐type VHL are separate tumour entities or represent variants of a clear cell RCC tumour family.     

Liver cell atypias: a comparative study in cirrhosis with and without hepatocellular carcinoma

Various criteria have been proposed for the identification of early neoplastic changes in the setting of both small hepatocellular carcinomas and macroregenerative nodules. In this study we have applied those criteria to cases of liver cirrhosis without tumour (group I) and hepatocellular-carcinoma-associated cirrhosis (group II) to assess their discriminatory value in these two situations. Group I included 50 liver biopsies with uncomplicated cirrhosis while group II encompassed 48 liver biopsies of cirrhotic nodules adjacent to hepatocellular carcinomas. The histological changes sought were large cell dysplasia, small cell dysplasia, cytoplasmic basophilia, small microacinar structures, peripheral distribution of nuclei, nuclear irregularities and thickened liver cell plates. These changes were also assessed in macroregenerative nodules (nine in group I and seven in group II). None of these changes was useful to discriminate between group I and group II cirrhotic nodules when assessed separately. On the other hand, cirrhotic nodules showing three or fewer changes were never associated with malignancy, whereas those exhibiting four or more alterations were often located in the vicinity of a tumour. Acinar structures, thickened cell trabeculae, peripheral distribution of nuclei and nuclear irregularities seem to be the most specific indicators of proximity to a hepatocellular carcinoma. Similar results were obtained for macroregenerative nodules. These results may be helpful as guidelines to the probability of having a hepatocellular carcinoma elsewhere in livers containing atypical cirrhotic nodules, and may also prove valuable in the selection of appropriate material for investigating early molecular events in hepatic carcinogenesis.     

Sarcomatoid hepatocellular-carcinoma showing rhabdomyoblastic differentiation in the adult cirrhotic liver

 An unusual case of a massive liver tumour composed of rhabdomyosarcoma with a small focus of hepatocellular carcinoma in a 52-year-old man is presented. He had hepatitis B virus (HBV) surface antigen in his serum. Macroscopically, a large tumour with satellite nodules occupied the right lobe of the cirrhotic liver. Microscopically, the tumours were composed of small and short spindle-shaped undifferentiated cells, mixed with desmin-positive round rhabdomyoblasts and elongated striated muscle cells, strongly suggestive of rhabdomyosarcoma of the liver. Elevated levels of alpha-fetoprotein in the serum led us to examine the liver tumour closely in multiple sections, which disclosed a hepatocellular carcinoma component measuring 2 cm in diameter within the massive tumour. Immunohistochemically, the hepatocellular carcinoma cells were alpha-fetoprotein positive. There was neither a tumour capsule, nor distinct demarcation, and cytokeratin-positive clusters of undifferentiated cells were intermingled with the hepatocellular carcinoma and rhabdomyosarcoma at the border. The invading tumour outside the liver and metastatic tumours were pure rhabdomyosarcomas. It is suggested that the present case should be diagnosed as rhabdomyosarcoma transformed from hepatocellular carcinoma. Received: 19 November 1998 / Accepted: 12 February 1999     

Microsatellite instability in preinvasive and invasive head and neck squamous carcinoma.

To investigate the extent and significance of microsatellite instability in head and neck carcinogenesis we analyzed DNA extracted from normal squamous epithelium, severe dysplasia, and corresponding carcinoma specimens from 20 patients by multiplex polymerase chain reaction. Loci on chromosomes 3p, 5p, 5q, 8p, 9p, 9q, 11q, 17p, 17q, 18p, 18q were selected for analysis. Our results show that three of the dysplasias (15.0%) and six of the invasive carcinoma (30.0%) manifested instability at multiple loci. Two of the dysplastic lesions had identical alterations in the corresponding carcinomas and one showed instability differences in only two of eight loci. Normal squamous epithelium lacked microsatellite instability. No apparent association between smoking, alcohol use, or family history of cancer and instability was found in this small cohort. Invasive carcinomas with instability were relatively more poorly differentiated and had a higher stage and a high proliferative fraction. Our study indicates that microsatellite instability is 1) noted in a small subset of dysplastic lesions of head and neck squamous epithelium and 2) present in approximately one-third of invasive lesions, usually with aggressive characteristics, and may clinically be a late event associated with tumor progression.     

Outcome prediction for renal cell carcinoma: evaluation of prognostic factors for tumours divided according to histological subtype

A wide variety of parameters have been investigated for their prognostic significance in mixed series of renal cell carcinoma (RCC). The classification of RCC into separate types with differing morphology, genotype and probable clinical outcome has led to a re-evaluation of many prognostic parameters with studies confined to a single RCC morphotype. Tumour stage remains the most important predictor of RCC outcome and recent investigations have focused upon tumour diameter and the prognostic significance of stromal, vascular and lymphatic invasion within the renal sinus. In large tumour series, morphotype has been correlated with patient survival, with clear cell RCC being associated with a less favourable outcome than chromophobe RCC and to a lesser extent papillary RCC, for organ confined tumours. The prognostic significance of nuclear grading remains controversial. Fuhrman grading has been shown to have prognostic utility for clear cell RCC in some series. Recent studies have shown that for papillary RCC, grading should be based upon nucleolar size and that Fuhrman grading is inappropriate for chromophobe RCC. Proliferative indices based upon a variety of markers have been correlated with outcome for clear cell RCC (Ki-67, AgNORs, p21(waf1/cip1) and p27(Kip1)) and papillary RCC (Ki-67, AgNORs), although in some series prognostic significance was lost on multivariate analysis. The presence of tumour necrosis has been shown to predict survival for clear cell and chromophobe RCC, and in clear cell RCC quantification of tumour vascular density has been correlated with outcome. Several molecular markers have been investigated for prognostic significance, mostly in clear cell RCC. Although some of these markers have been shown to be significantly associated with survival, these findings remain to be confirmed in large scale follow-up studies.     

Genetic and epigenetic alterations during renal carcinogenesis

Renal cell carcinoma (RCC) is not a single entity, but comprises a group of tumors including clear cell RCC, papillary RCC and chromophobe RCC, which arise from the epithelium of renal tubules. The majority of clear cell RCCs, the major histological subtype, have genetic or epigenetic inactivation of the von Hippel-Lindau (VHL) gene. Germline mutations in the MET and fumarate hydratase (FH) genes lead to the development of type 1 and type 2 papillary RCCs, respectively, and such mutations of either the TSC1 or TSC2 gene increase the risk of RCC. Genome-wide copy number alteration analysis has suggested that loss of chromosome 3p and gain of chromosomes 5q and 7 may be copy number aberrations indispensable for the development of clear cell RCC. When chromosome 1p, 4, 9, 13q or 14q is also lost, more clinicopathologically aggressive clear cell RCC may develop. Since renal carcinogenesis is associated with neither chronic inflammation nor persistent viral infection, and hardly any histological change is evident in corresponding non-tumorous renal tissue from patients with renal tumors, precancerous conditions in the kidney have been rarely described. However, regional DNA hypermethylation on C-type CpG islands has already accumulated in such non-cancerous renal tissues, suggesting that, from the viewpoint of altered DNA methylation, the presence of precancerous conditions can be recognized even in the kidney. Genome-wide DNA methylation profiles in precancerous conditions are basically inherited by the corresponding clear cell RCCs developing in individual patients: DNA methylation alterations at the precancerous stage may further predispose renal tissue to epigenetic and genetic alterations, generate more malignant cancers, and even determine patient outcome. The list of tumor-related genes silenced by DNA hypermethylation has recently been increasing. Genetic and epigenetic profiling provides an optimal means of prognostication for patients with RCCs. Recently developed high-throughput technologies for genetic and epigenetic analyses will further accelerate the identification of key molecules for use in the prevention, diagnosis and therapy of RCCs.     

Chromosomal imbalances in small cell carcinomas of the urinary bladder.

Small cell carcinomas (SCCs) represent a rare histological subtype of urinary bladder cancer. Little is known abut the genetic alterations in these tumours. To identify chromosomal aberrations that are typically present in SCC of the urinary bladder, ten tumours were analysed by comparative genomic hybridization (CGH). CGH allows screening for all relative DNA copy number gains and losses present in a tumour. SCCs of the bladder were characterized by a high number of genomic alterations (mean: 11.3 per tumour). Deletions were most frequent at 10q (7 of 10 tumours deleted), 4q, 5q (5/10 each), and 13q (4/10). These regions may carry tumour suppressor genes with relevance for this particular tumour type. Gains of DNA sequences were most prevalent at 8q (5/10), 5p, 6p, and 20q (4/10 each). High level amplifications were found at 1p22-32, 3q26.3, 8q24, and 12q14-21. These loci may pinpoint the localization of oncogenes with relevance for small cell bladder cancer. The analysis of one tumour having areas of both SCC and transitional cell carcinoma strongly suggests that SCC can develop from TCC through the acquisition of additional genetic alterations.     

Allelic imbalance at chromosome 11 in head and neck squamous cell carcinoma in an Indian patient population

BACKGROUND: Genetic instability of chromosome 11 is a frequent event in many solid tumours, including head and neck squamous cell carcinoma (HNSCC). AIMS: To perform allelic imbalance analysis of cytogenetically mapped altered regions of human chromosome 11 in patients with HNSCC from eastern India. METHODS: Genomic alterations were investigated using highly polymorphic microsatellite markers in both HNSCC and leukoplakia tissues. RESULTS: Microsatellite markers D11S1758 from 11p13-15 and D11S925 from 11q23.3-24 had the highest frequency (38% and 32%, respectively) of loss of heterozygosity among all the markers analysed. Allelic loss at the marker D11S925 was seen in both leukoplakia and in all stages of HNSCC tumour tissues suggesting that it is an early event in HNSCC tumorigenesis. Microsatellite size alteration was also found to be high (> 20%) in several markers. In leukoplakia samples microsatellite instability was seen at a higher frequency than loss of the allele, indicating such alterations might initiate the process of tumorigenesis in HNSCC. CONCLUSIONS: The high rate of chromosomal alterations at 11q21-24 in HNSCC suggests the presence of a putative tumour suppressor gene in this region.     

Rhabdoid differentiation of chromophobe renal cell carcinoma

AIMS: Rhabdoid change represents an aggressive form of divergent differentiation previously reported in conventional (clear-cell) and papillary renal cell carcinoma. This study aims to characterise rhabdoid differentiation in a case of chromophobe renal cell carcinoma (ChRCC) and to investigate its origin by genetic analysis. METHODS: A large tumour mass arising in the right kidney of a 76-year-old male was investigated using routine stains (H&E, Hale's colloidal iron), immunostains (vimentin, cytokeratin) and genetic analysis for loss of heterozygosity (LOH) on chromosomes 1, 2, 3p, 6q, 10q, 13q, 17q, 17p and 21q. RESULTS: The tumour mass was comprised of the following histological subtypes: (i) typical ChRCC, (ii) eosinophilic variant ChRCC and (iii) rhabdoid variant RCC. Tumour cells of all three different histological subtypes had a positive reaction to Hale's colloidal iron stain, negative immunostaining for vimentin and LOH on chromosomes 2, 10q, 13q and 17p. These results are consistent with a diagnosis of ChRCC and indicate a common genetic origin for all three histological cell types. CONCLUSIONS: This study confirms that the aggressive rhabdoid variant can arise from ChRCC, as has been previously demonstrated for conventional (clear-cell) and papillary RCC.     

High-resolution analysis of DNA copy number alterations and gene expression in renal clear cell carcinoma

We analysed chromosomal copy number aberrations (CNAs) in renal cell carcinomas by array-based comparative genomic hybridization, using a genome-wide scanning array with 2304 BAC and PAC clones covering the whole human genome at a resolution of roughly 1.3 Mb. A total of 30 samples of renal cell carcinoma were analysed, including 26 cases of clear cell carcinoma (CCC) and four cases of chromophobe renal cell carcinoma (ChCC). In CCCs, gains of chromosomes 5q33.1-qter (58%), 7q11.22-q35 (35%) and 16p12.3-p13.12 (19%), and losses of chromosomes 3p25.1-p25.3 (77%), 3p21.31-p22.3 (81%), 3p14.1-p14.2 (77%), 8p23.3 (31%), 9q21.13-qter (19%) and 14q32.32-qter (38%) were detected. On the other hand, the patterns of CNAs differed markedly between CCCs and ChCCs. Next, we examined the correlation of CNAs with expression profiles in the same tumour samples in 22/26 cases of CCC, using oligonucleotide microarray. We extracted genes that were differentially expressed between cases with and without CNAs, and found that significantly more up-regulated genes were localized on chromosomes 5 and 7, where recurrent genomic gains have been detected. Conversely, significantly more down-regulated genes were localized on chromosomes 14 and 3, where recurrent genomic losses have been detected. These results revealed that CNAs were correlated with deregulation of gene expression in CCCs. Furthermore, we compared the patterns of genomic imbalance with histopathological features, and found that loss of 14q appeared to be a specific and additional genetic abnormality in high-grade CCC. When we compared the expression profiles of low-grade CCCs with those of high-grade CCCs, differentially down-regulated genes tended to be localized on chromosomes 14 and 9. Thus, it is suggested that copy number loss at 14q in high-grade CCC may be involved in the down-regulation of genes located in this region.     

Chromosome 9 instability and alterations of p16 gene in squamous cell carcinoma of the lung and in adjacent normal bronchi: FISH and immunohistochemical study

Aims:  p16 , a tumour suppressor gene located at 9p21 chromosome and involved in cell cycle regulation, is often inactivated in lung carcinoma. Inactivation is also supported by the loss of p16 protein, a strong inhibitor of cyclin-dependent kinase (CDK) 4 and 6. The aim of this study was to examine alterations of p16 both in pulmonary squamous cell carcinoma (SCC) and in morphological normal bronchi contiguous with neoplasia.
Methods and results:  p16 gene and chromosome 9 alterations were examined by fluorescence in situ hybridization and the expression of p16 protein by immunohistochemistry in pulmonary surgical specimens from 31 patients with SCC. As controls, surgical specimens from 13 patients with non-neoplastic pathology were examined. Tumours showed molecular alterations for p16 gene and chromosome 9 abnormalities in, respectively, 29/31 and 19/31 cases respectively. p16 protein was unexpressed in 29/31 cases. In morphologically normal bronchi p16 gene and chromosome 9 alterations occurred in, respectively, 13/31 and 4/31 cases respectively; loss of protein immunoreactivity occurred in 14/31 cases. No alterations were seen in any of the control cases.
Conclusions:  Inactivation of p16 gene in histologically normal bronchi could aid the identification of individuals at risk of developing SCC of the lung.