Use of monitoring levels of soluble forms of cytokeratin 18 in the urine of patients with superficial bladder cancer following intravesical Ad-IFNα/Syn3 treatment in a phase l study.

A phase l study using intravesical Ad-IFNαSyn3 for patients with bacillus Calmette-Guérin-resistant superficial bladder cancer showed a complete remission (CR) of 43% at 90 days after treatment with high levels of interferon-α (IFNα) being produced. Ad-IFNα kills bladder cancer cells by two apoptotic and one necrotic mechanism that can be measured by soluble forms of cytokeratin 18 (CK18) using M30 and M65 ELISAs, assays for caspase-cleaved (apoptotic) and uncleaved (necrotic) cell death, respectively. Therefore, we determined whether M30 and M65 levels in the urine after treatment could document all three mechanisms of cancer cell kill and also predict having a CR. High levels of both M30 and M65 were found in all patients within 24 h after treatment with all three types of cancer cell death occurring. Moreover, the return of both M30 and M65 levels in the urine to normal levels within 5 days or more after treatment was strongly associated with obtaining a CR (P=0.003). This is the first time that such assays have been used to study response to therapy in the urine of patients with bladder cancer and in the future may prove valuable in predicting clinical outcome.

Direct cytotoxicity produced by adenoviral-mediated interferon α gene transfer in interferon-resistant cancer cells involves ER stress and caspase 4 activation.

Over the past several years we have obtained considerable evidence indicating that adenoviruses-expressing interferon α (Ad-IFNα) can overcome resistance to the IFNα protein itself. Since cancer cells infected with Ad-IFNα also show high perinuclear cytoplasmic IFNα expression, we were interested in whether endoplasmic reticulum (ER) stress and cleavage of caspase 4 could have a major role in Ad-IFNα-produced cancer cell death. Indeed, procaspase 4 was upregulated and cleaved as early as 12 h after Ad-IFNα infection of the cancer cells, which co-localized with IFNα staining and ER tracker. In contrast, immortalized normal human urothelial cells, although exhibiting similar perinuclear IFNα staining, showed no cleaved caspase 4. Caspase 4 cleavage was not blocked by the caspase 8 specific inhibitor zIETD, indicating that caspase 4 activation was independent of caspase 8 activation. Blocking caspase 4 also inhibited activation of caspase 3 in Ad-IFNα containing cells. Finally, the cleaved form of caspase 4 (p10) was detected in Ad-IFNα-positive cancer cells from the urine of a patient following intravesical Ad-IFNα/Syn3 treatment. Therefore, ER stress and activation of caspase 4 appears to be an important mechanism involved in the direct cancer cell death produced by Ad-IFNα and also occurs in the clinical setting.

Direct gene transfer of adenoviral-mediated interferon α into human bladder cancer cells but not the bystander factors produced induces endoplasmic reticulum stress-related cytotoxicity.

We have previously shown that adenoviral-mediated interferon α (Ad-IFNα) is cytotoxic both to cells that are sensitive to recombinant interferon α (IFNα) and to cells which are resistant to IFNα. The cancer cell-specific cytotoxic effects of Ad-IFNα involve three different mechanisms: 1. The direct effect of IFNα production causing cancer cell death in IFNα sensitive cells (1); 2. The direct effect of Ad-IFNα infection and high levels of IFNα expression in IFNα resistant cancer cells (2); and 3. The indirect effect of the Ad-IFNα bystander factors produced (2-4). After Ad-IFNα infection, the cells produce a large amount of perinuclear localized IFN protein. This protein over-load could be a major factor in the direct cancer cell death of those cells infected with Ad-IFNα compared with the indirect cytotoxic effects of the bystander factors produced. Here, we investigated whether a component of Ad-IFN-induced cell death involves protein overload-induced endoplasmic reticulum (ER) stress, using an IFNα-resistant human bladder cancer cell line (KU7), and the normal human urothelial cell line, TERT-NHUC, as preclinical models. We found that the two ER stress response pathways examined were activated in KU7 cells. In contrast, following treatment of the normal TERT-NHUC cells with Ad-IFNα, no ER stress signals were observed. In addition, no ER stress related changes were seen, when KU7 cells were exposed to conditioned medium from Ad-IFNα-treated KU7 cells, indicating that bystander produced cytotoxicity did not involve ER stress. After 24 h of Ad-IFNα infection, the KU7 cancer cells produced spliced X-box binding protein 1 and activating transcription factor 6 protein (ATF6), evoking an ER stress response that could contribute to Ad-IFNα induced apoptosis in these cancer cells. In addition, GADD153/CHOP, GADD34 and BAX were also subsequently modified following activation of the ER stress pathways, thereby signaling downstream effectors in a pro-apoptotic manner.

Autophagy is induced by adenoviral-mediated interferon alpha treatment in interferon resistant bladder cancer and normal urothelial cells as a cell death protective mechanism but not by the bystander factors produced.

We have previously shown that adenoviral-mediated interferon alpha (Ad-IFNalpha) treatment is highly cytotoxic to tumor cells which are resistant to the IFNalpha protein. We now report that autophagy is produced after Ad-IFNalpha treatment of either IFN resistant bladder cancer cells (UC9 and KU7) or the normal urothelial cell line (TERT-NHUC). After Ad-IFNalpha infection autophagosomes, an early stage of autophagy, were seen in cancer cells whereas autophagolysosomes, a later stage of autophagy, were observed mostly in normal cells by electron microscopy. Conditioned medium from either normal or bladder cancer cells obtained after Ad-IFNalpha infection, however, produced no autophagy when placed on the bladder cancer cells, although again marked cytotoxicity was observed. This indicated that the autophagy seen was related to the direct effect of Ad-IFNalpha transfection and expression rather than to the bystander factors produced. In addition, autophagic changes were seen using LysoTracker Red DND-99 in both normal and cancer cells. We also documented that Ad-IFNalpha treatment produces the autophagic protein form, light chain 3 (LC3)-II, in cancer cells but not normal cells, which in turn was inhibited by the autophagic inhibitor, 3-methyladenine (3-MA). This inhibition of autophagy resulted in a significant increase in apoptotic cell death as measured by the sub-G1 population. We hypothesize that the autophagy seen in normal urothelial cells is a protective response and is allowed to be completed, providing a survival mechanism after Ad-IFN treatment, whereas the autophagy produced in IFN resistant cancer cells is not allowed to be completed and is insufficient to significantly suppress cytotoxicity.

Measuring soluble forms of extracellular cytokeratin 18 identifies both apoptotic and necrotic mechanisms of cell death produced by adenoviral-mediated interferon alpha: possible use as a surrogate marker.

Adenoviral transduction of human bladder cancer cells with human interferon alpha-2b (Ad-IFN) produces cancer-specific cell death through direct and indirect mechanisms. The indirect mechanisms involve the secreted IFN produced, which kill, IFN protein-sensitive cancer cells, as well as yet unidentified bystander factors, which are cytotoxic to neighboring cancer cells. The direct cell kill results from transfection and expression of Ad-IFN in the cancer cells. As the molecular forms of cytokeratin 18, either caspase cleaved or not, have been associated with apoptotic or necrotic cell death, respectively, we determined if increases in either or both cytokeratin 18 forms could be observed following IFNalpha protein or Ad-IFN treatment of bladder carcinoma cells. Quantification of M30 and M65 enzyme-linked immunosorbent assays (assays for cytokeratin 18 associated apoptotic and necrotic cell death, respectively) were used as surrogate markers of the cell death produced. In the IFN protein-sensitive RT4 bladder cancer cells, IFN produced primarily M30-related cell death, whereas Ad-IFN treatment resulted in high levels of both M30 and M65. In contrast, conditioned medium from Ad-IFN-treated cells whether from normal human urothelial cells or bladder cancer cells caused increases mainly in M30 levels when added to IFN protein resistant KU7 or UC9 bladder cancer cells, suggesting that the bystander factors present in the conditioned medium produced primarily apoptotic cell death. In addition, a significant increase in M65 levels above that observed for M30 was seen when the IFN protein resistant KU7 and UC9 cells were treated with Ad-IFN, again indicating there is additional necrotic-related cell death produced by Ad-IFN as well. Normal urothelial cells showed no cytotoxicity nor increases in M30 or M65 after Ad-IFN treatment. As intravesical Ad-IFN treatment is presently being evaluated for its efficacy in superficial bladder cancer measurement of M30 and M65 levels in the urine at various time points before and after Ad-IFN treatment may provide not only a biomarker of efficacy but also evidence for the different types and proportion of cell kill produced by the various mechanisms of cell kill in the tumors of individual patients.

Early RB94-produced cytotoxicity in cancer cells is independent of caspase activation or 50 kb DNA fragmentation.

RB94, which lacks the N-terminal 112 amino-acid residues of the full-length retinoblastoma protein (RB110) is a more potent inhibitor of cancer cell growth than RB110, being cytotoxic to all cancer cell lines studied, independent of their genetic abnormalities. Although we initially thought RB94-induced cell death was caspase-dependent, such caspase activation now appears to be a late event. Cells that remained attached 48 h after transduction with Ad-RB94 showed, among other changes, nuclear enlargement, peripheral nuclear chromatin condensation and often micronucleation. In addition, the cells were TdT-mediated dUTP nick end labeling (TUNEL) positive but showed no cleavage of caspase 3 or 9. Only after the cells detached was cleavage of both caspase 3 and 9 observed. These TUNEL-positive cells showed neither cytochrome c mitochondrial translocation usually found in typical apoptotic cells nor DNA laddering indicative of oligonucleosomal DNA fragmentation. In addition, although 50 kb DNA fragmentation was produced in these TUNEL-positive cells, which was dependent on apoptosis-inducing factor (AIF), inhibiting this fragmentation by siAIF did not inhibit TUNEL formation or cytotoxicity. As RB94 will soon be used for gene therapy further understanding the molecular basis of these early changes in killing cancer cells is one of our particularly important present goals.

Conditioned medium from Ad-IFN-alpha-infected bladder cancer and normal urothelial cells is cytotoxic to cancer cells but not normal cells: further evidence for a strong bystander effect.

We have reported earlier that a bystander effect is seen in cancer cells that are resistant to high concentrations of the interferon-alpha protein (Intron A) when treated with adenoviral-mediated interferon-alpha (Ad-IFN-alpha). We now provide further evidence for this bystander effect using conditioned medium (CM) collected from Ad-IFN-alpha-infected cancer and normal urothelial cells. The CMs collected from UC-9 and KU7 bladder cancer cells as well as normal urothelial cells following transfection with Ad-IFN produce cell death when added to various cancer cell types in culture but not to normal urothelial cells. The CM could be filtered, frozen and thawed, and diluted to at least one part Ad-IFN CM to five parts fresh control medium and the diluted CM still shows a similar cytotoxicity as a 100% concentration of Ad-IFN CM. This cytotoxicity was observed by both flow cytometry and MTT assays as well as by phase microscopy, and a significant sub-G1 population was seen whether the CM was collected 48, 72 or 96 h after initial Ad-IFN treatment. In addition, the CM could be partially inactivated by exposure to 65 degrees C for 30 min and totally inactivated by placement at 92 degrees C for 3 min, whereas Intron A was not inactivated under the same conditions. Importantly, although significant caspase 8 and caspase 9 cleavage occurred in Ad-IFN-treated cells as a direct effect of Ad-IFN transfection, the Ad-IFN CM produced no activation of caspase 8 and caspase 9, indicating that a different mechanism of cell death was produced by the bystander factor(s) than the direct effect of Ad-IFN. This bystander effect in turn may play an important role in the efficacy of the current Ad-IFN clinical trial for superficial bladder cancer now underway.

Enhancement of intravesical delivery with Syn3 potentiates interferon-alpha2b gene therapy for superficial bladder cancer.

Intravesical administration of interferon alpha-2b protein (IFN) has been successfully used in the treatment of patients with superficial bladder tumors. Local dosing of IFN minimizes well-known systemic side effects of the drug, but exposure to bladder tumors is limited by the duration of instillation and transient concentrations achieved in the urothelium. Intravesical delivery of the gene encoding interferon results in an alternative strategy for IFN-based therapy of the disease, enabling sustained exposure of IFN protein that results from production by tumor and non-tumor cells in the urothelium. Efficient gene delivery and expression of IFN has been achieved using a recombinant adenovirus gene delivery system (rAd-IFN) in conjunction with the novel small molecule excipient Syn3. Studies with rAd-IFN/Syn3 in animal models result in urine concentrations of IFN that persisted for weeks and correlated with potent anti-tumor effects. The objective of this review is to communicate the rationale and preclinical findings that support ongoing clinical investigation of intravesical rAd-IFN/Syn3 in superficial bladder cancer.

Adenoviral-mediated interferon alpha overcomes resistance to the interferon protein in various cancer types and has marked bystander effects.

We have previously shown that intravesical administration of adenovirus encoding human interferon alpha-2b (Ad-IFN) induced a marked regression of superficial human bladder tumors derived from cells that are resistant to over 1 million units/ml of IFNalpha protein in vitro. In addition, Ad-IFN appeared to produce strong bystander effects. In this study, we show that Ad-IFN causes marked inhibition of cell growth and apoptosis in cells of various tumor types, all of which are resistant to IFNalpha protein. In addition, strong perinuclear IFN staining was seen in all cell lines following Ad-IFN transfection and was never observed after exposure to the IFN protein. Ad-IFN induced proteolytic processing of caspases 3, 8 and 9, indicative of enzymatic activation. However, the caspase-8-selective inhibitor, IETDfmk, blocked apoptosis only in the cell lines that were sensitive to the IFNalpha protein and had minimal effect on Ad-IFN-induced caspase-3 or -9 processing and cell death, indicating that death receptor-independent mechanism(s) were involved in the cytotoxic effects observed for cancer cell lines resistant to the IFNalpha protein. Moreover, we document that a yet to be identified soluble factor(s) is responsible for causing the bystander effect observed following Ad-IFN treatment in IFN protein-resistant cancer cells.

Efficacy of a single intravesical treatment with Ad-IFN/Syn 3 is dependent on dose and urine IFN concentration obtained: implications for clinical investigation.

There is a need to improve the treatment of superficial bladder cancer. One area which holds promise is intravesical gene therapy. Recently, studies undertaken by us have shown that marked tumor regression of bladder cancers occurred after two daily intravesical administrations of an adenovirus encoding human interferon alpha (Ad-IFNalpha) using a mouse superficial bladder cancer model in which human bladder tumors are growing. A dose of 1 x 10(11) particles/ml (P/ml) was used along with 1 mg/ml of Syn3, a gene transfer-enhancing agent. Since clinical studies are being planned using this approach, it became critical to determine if one exposure and lower particle number could be equally effective. We report that indeed a single dose of Ad-IFNalpha in Syn3 at doses of 1 x 10(10)-1 x 10(11) P/ml is highly effective in reducing the size of the tumors, whereas 1 x 10(9) P/ml was not. Efficacy was also correlated with the level of IFN produced in the urine after treatment. Based on the results of the present studies, a Phase I trial is being planned for superficial bladder cancer, which will involve a single initial treatment with Ad-IFNalpha/Syn3 and measurement of IFN in the urine over time as an indicator of adequate gene transfer and expression.

Susceptibility of nonpromoter CpG islands to de novo methylation in normal and neoplastic cells.

BACKGROUND: Many cancers display alterations in methylation patterns of CpG islands--stretches of DNA rich in CpG dinucleotides often associated with gene promoters that are involved in initiation of gene transcription. This methylation may perturb expression of genes critical to the regulation of cell proliferation. Aberrant methylation is not limited to a few genes or to promoter regions but has been found on a genome-wide scale in a variety of neoplasias, including colorectal cancer and acute myelogenous leukemia. Our goal was to characterize, in a quantitative manner, the profiles of abnormally methylated genes that may be specific for different cancers. METHODS: Using a quantitative assay, methylation-sensitive single nucleotide primer extension (MS-SNuPE), we have analyzed the methylation levels of promoter and exonic (coding region) CpG islands of two cyclin-dependent kinase inhibitors [p15(INK4B) and p16(INK4A)] and the PAX6 gene, which encodes a transcriptional factor involved in neuronal proliferation, in DNA samples taken from patients with chronic myelogenous leukemia, acute myelogenous leukemia, myelodysplastic syndrome, and colorectal cancer. RESULTS: De novo methylation of all three exonic loci in tumors--relative to baseline levels found in nontumor tissue or blood--was observed in hematologic neoplasias and in solid tumors as well as in normal colonic tissue. However, methylation of promoter regions was more limited. Moreover, two different patterns of promoter methylation distinguished the leukemias from colorectal cancer: p15 promoter hypermethylation was found only in the leukemias, and p16 promoter hypermethylation occurred only in colon tumors. However, we did not address this issue prospectively; therefore, such an observation is only hypothesis generating. CONCLUSIONS: The methylation patterns that we observed suggest that exonic CpG islands are more susceptible to de novo methylation than promoter islands and that methylation may be seeded in exonic regions, from which it can spread to other islands, including promoter regions. Subsequent selection of cells with a growth advantage conferred by spread of methylation into and inactivation of a particular promoter might then contribute to the genesis of a specific type of cancer.

Correlation of immunohistochemical molecular staging of bladder biopsies and radical cystectomy specimens.

PURPOSE: To determine the relationship of p53, retinoblastoma (RB), and p16 expression between precystectomy transurethral resection bladder (TURB) biopsy and matched cystectomy specimens; and to determine the value of p53 immunoreactivity for predicting progression and survival in patients undergoing radical cystectomy. METHODS AND MATERIALS: We performed p53 immunohistochemical staining on matched archival TURB and cystectomy specimens taken from 40 patients. Twenty-seven and 26 of these patients were also evaluated for RB and p16 expression, respectively. RESULTS: Twenty-eight (70%) of the TURB and 22 (55%) of the cystectomy specimens stained positive for p53. RB and p16 protein expression were altered in 19 (70%) and 19 (73%) of the TURB specimens, respectively, and 19 (70%) and 19 (73%) of the cystectomy specimens, respectively. There was a strong correlation between p53, RB, and p16 expression and TURB and cystectomy specimens (all p < 0.001). In preoperative and postoperative multivariate analyses, biopsy p53 and cystectomy p53 were independently associated with disease progression (p = 0.049 and p = 0.034, respectively) and bladder cancer-related death (p = 0.044 and p = 0.037, respectively). CONCLUSION: p53, RB, and p16 expression patterns on TURB specimens correlate with cystectomy specimens. p53 immunoreactivity is an independent predictor of disease progression and bladder cancer survival. These data support the potential of prognostic staging using immunohistochemical analysis on bladder biopsy specimens prior to neoadjuvant or definitive therapy.

Gene therapy for superficial bladder cancer.

In this review, the basics of gene therapy and the strategies to increase the therapeutic effect of gene therapy for superficial bladder cancer are discussed. Strategies considered in detail are modification of the structure of vectors, modification of the promoters of viral vectors and the timing and route of vector administration. Although all of these modifications have shown some degree of improvement for gene transfer, the use of polyamides intravesically in conjunction with an adenoviral system shows the most promise and the greatest potential to supplement or even replace the current treatment modalities for superficial bladder cancer.

Retinoblastoma protein-initiated cellular growth arrest overcomes the ability of cotransfected wild-type p53 to induce apoptosis.

The retinoblastoma gene, RB, participates in the regulation of the G1/S-phase transition and in p53-mediated apoptosis. We have previously reported that stably transfected RB functions as a growth and tumour suppressor in HTB9 human bladder carcinoma cells, which carry a mutation of the p53 gene at codon 280 and lack RB expression. To elucidate the potential role of RB in the regulation of p53-mediated apoptosis, we transfected a wt p53 expression plasmid under the control of the human cytomegalovirus promoter into parental and RB-transfected HTB9 cells. The p53(+)/RB(-)cells were susceptible to apoptosis under various experimental conditions: 1) incubation in serum-free culture for 72 h, 2) short-term (6 h) or long-term (48 h) exposure to etoposide, and 3) culturing in soft agar. In contrast, p53(+)/RB(+)cells were significantly resistant to apoptosis under similar conditions and exhibited efficient growth arrest, as measured by laser scanning cytometry. Tumorigenicity in nude mice of parental HTB9 cells was lost by exogenous expression of wt p53. Likewise, none of mice injected subcutaneously with either p53(-)/RB(+)or p53(+)/RB(+)cells developed tumours, indicating that RB allows suppression of tumorigenesis, regardless of p53 status. These results suggest that the growth-inhibitory function of RB may overcome the ability of wt p53 to induce apoptosis.

TabBO: a model reflecting common molecular features of androgen-independent prostate cancer.

We established two human prostate cancer cell lines, MDA PCa 2a and MDA PCa 2b, the TabBO model system, that reflect common features of human androgen-independent prostate cancer that are not present in other model systems: bone origin, prostate-specific antigen production, androgen receptor expression, and androgen sensitivity. We therefore hypothesized that molecular pathways in our model system reflect common alterations responsible for the progression of a subset of human prostate cancer. Progression to androgen independence has been hypothesized to be largely associated with impairment of the regulation of cell growth or apoptosis of prostate cancer cells. Therefore, in this study, we examined molecular markers known or suspected to be important in prostate cancer progression and key regulators of cell growth and apoptosis: p53, p21WAF1/CIP1, Bcl-2, Bax, retinoblastoma (Rb), and p16INK4A/MITS1. We analyzed the expression of these markers in the cell lines, their tumor of origin, and tumors derived from the cell lines by s.c. inoculation into nude mice. DNA sequencing of the entire open reading frames of the p53 and p21 genes revealed no mutations. Additionally, accumulation of the p53 protein was not found by Western blot analysis, nor was overexpression of the Bcl-2 oncoprotein detected. Bax expression was detected in MDA PCa 2a cells, whereas it was absent in MDA PCa 2b. Rb and p16 protein expression was normal as measured by both Western blot and immunochemical analyses. Immunohistochemical studies of p53, p21, Bcl-2, and Rb in both samples from the original human cancer from which the lines were derived and mouse xenografts derived from the lines revealed similar levels of protein. These results are consistent with reports indicating that 40-50% of bone metastases of prostate cancer have wild-type p53, 50-70% do not overexpress the Bcl-2 protein, and mutations in the p21 gene are rare. Therefore, we conclude that MDA PCa 2a and MDA PCa 2b reflect molecular pathways in a common subset of human androgen-independent prostate cancer and that important molecular players in apoptosis (namely, p53 and Bcl-2) seem to be intact in this subset of androgen-independent prostate cancer. Understanding the signal-transduction pathways operating in these cell lines may help to identify therapeutic targets for prostate cancer.

Genetic modeling of human urinary bladder carcinogenesis.

We developed a model of human urinary bladder cancer progression from in situ precursor lesions to invasive carcinoma using whole organ histologic and genetic mapping. The model represents a high-density and detailed analysis regarding allelic losses on chromosomes 4, 8, 9, 11, and 17 as revealed by testing of 234 samples obtained from five cystectomy specimens. The samples corresponded to microscopically identified intraurothelial precursor conditions ranging from dysplasia to carcinoma in situ and invasive cancer. The initial analysis of paired normal and tumor DNA samples disclosed allelic losses in 72 of 225 tested hypervariable DNA markers. Subsequent use of these markers on all mucosal samples revealed that 47 had alterations with a statistically significant relation to urothelial neoplasia. The allelic losses clustered in 33 distinct chromosomal regions, indicating the location of putative tumor suppressor genes involved in the development and progression of urinary bladder cancer. Some of the markers with statistically significant allelic losses mapped to the regions containing well-characterized tumor suppressor genes but many were located in previously unknown loci. The majority of statistically significant allelic losses (70%) occurred early in low-grade intraurothelial dysplasia, and some of them involved adjacent areas of morphologically normal mucosa preceding the development of microscopically recognizable precursor lesions. The remaining 30% of markers developed allelic losses in the later phases of urothelial neoplasia, implicating their involvement in progression to invasive disease. Markers exhibiting allelic losses in early phases of urothelial neoplasia could be used for detection of occult preclinical or even premicroscopic phases of urinary bladder cancer, whereas markers that showed allelic losses in the later phases of the process could serve as indicators of progression to invasive disease. The approach used in this study facilitates genome-wide modeling of cancer progression and provides important chromosomal landmarks for more specific studies of multistep urinary bladder carcinogenesis.

Differential retinoblastoma and p16(INK4A) protein expression in neuroendocrine tumors of the lung.

BACKGROUND: Neuroendocrine neoplasms of the lung represent a wide spectrum of phenotypically and biologically distinct entities. Their histopathologic diagnosis, which carries therapeutic and prognostic significance, may sometimes be difficult because of their overlapping features. We previously demonstrated that large cell neuroendocrine carcinomas (LCNECs) and small cell lung carcinomas (SCLCs) failed to show positive nuclear staining of RB protein (RB-), whereas typical and atypical carcinoids (TCs and ACs) showed nuclear RB immunostaining (RB+). METHODS: In the current study, a series of 58 surgically resected lung tumors, of which 33 tumors were initially diagnosed as SCLCs and 25 as TCs or ACs, were studied for RB and p16 protein expression by immunohistochemistry. They were also reviewed for their pathologic diagnosis; the reviewers were blinded to the RB and p16 protein status. RESULTS: Nineteen tumors were diagnosed as TCs, 5 as ACs, 7 as LCNECs, and 27 as SCLCs. Three of seven LCNECs were RB+, whereas the other four were RB-. In contrast, all 19 TCs were RB+ and all 27 SCLCs were RB-. In addition, two of five ACs were RB+, whereas the other three were RB-. Interestingly, all 3 RB+ LCNECs and the 1 RB+ AC tested failed to show nuclear staining of p16 protein in any tumor cells (p16-), although some normal stromal cells showed nuclear staining of p16 protein (p16+) as positive internal controls, indicating loss of p16 function in these tumors. It is also noteworthy that the three RB+ LCNECs were initially diagnosed as SCLCs and one of the RB- ACs was initially considered a TC. With the exception of TCs, tumors were significantly more prevalent among heavy smokers with >20 pack-years compared with nonsmokers and light smokers with < or = 20 pack-years (P < 0.01). CONCLUSIONS: These findings suggest that all SCLCs and LCNECs have abnormalities in the p16:RB pathway, as do at least certain ACs, whereas the p16:RB pathway is normal in TCs.

An improved intravesical model using human bladder cancer cell lines to optimize gene and other therapies.

Orthotopic implantation of human bladder cancer cells into immunodeficient mice is an important tool for studying the biology and effects of therapy. Nevertheless, the incidence of tumor implantation and growth by transurethral instillation of the human bladder cancer cells into murine bladders has been low or not reproducible. However, using a modified intravesical technique and the human bladder cancer cell lines, KU-7 and UM-UC-2, we have been able to obtain a high and reproducible incidence of superficial bladder tumors. Furthermore, intravesical administration of the LacZ adenovirus vector resulted in significant beta-galactosidase expression in these bladder tumors as well as the normal urothelium, which was associated with the removal of the glycosoaminoglycan layer. Because this modified technique produces a high incidence of superficial human tumor growth and allows the efficacy of gene transfer to be evaluated, it should be a useful model for the study of intravesical gene therapy for human bladder cancer.

Expression of p16, Rb, and cyclin D1 gene products in oral and laryngeal squamous carcinoma: biological and clinical implications.

Cyclin D1, p16, and Rb genes play a critical role in the regulation of the G1-S transition of the cell cycle and are frequently altered in several neoplastic entities. Analysis of the protein products of these genes by molecular and immunohistochemical methods provides information on their functional status and allows for the phenotypic evaluation of tumor cells. We performed Western blotting and immunohistochemical analysis on tissues from 35 primary oral and laryngeal squamous carcinoma specimens with previous molecular analysis of the p16 gene and correlated the results with relevant clinicopathologic factors. Our study shows significant concordance between Western blotting and immunostaining results for cyclin D1 (P = .01), p16 proteins (P = .01), and Rb (P = .04). Heterogeneous staining of tumor cells and the positivity of non-neoplastic host elements for Rb by immunohistochemistry contributed to the discrepancy noted in some tumors by Western blotting. Significant reciprocal relationship between p16 and Rb proteins was observed (P < .001); in most tumors, absence of p16 (89%) and detectable Rb (94%) proteins were found. Two tumors had negative cyclin D1 expression, and one third overexpressed this protein. There was a lack of correlation between cyclin D1 overexpression and the clinicopathologic factors studied. Our results indicate that the absence of p16 in most of these tumors may constitute an early tumorigenic event and that the loss of the Rb function plays a minor role in HNSC.