Increased Growth Fraction Research Articles

Tumor-Infiltrated Immune Response Correlates with Alterations in the Apoptotic and Cell Cycle Pathways in Hodgkin and Reed-Sternberg Cells

To analyze tumor-microenvironment relationships in Hodgkin lymphoma (HL) as potential determinants in the decision-making process related to the alterations in cell cycle and apoptotic pathways of Hodgkin/Reed-Sternberg (H/RS) cells. Based on a cohort of 257 classic HL patients, we carried out a global descriptive correlational analysis and logistic regression study to identify tumor-infiltrated immune cell rate in HL that could be interconnected with genes involved in the regulation of apoptotic/proliferative pathways in H/RS cells. Our results reveal the existence of a connection between the reactive microenvironment and molecular changes in apoptotic/proliferative pathways in H/RS cells. A lesser incidence of infiltrated cytotoxic cells in the tumor (CD8(+) T lymphocytes, CD57(+) natural killer, and granzyme B(+) cells) was associated with overexpression of antiapoptotic proteins (Bcl-X(L), survivin, caspase-3, and nuclear factor-kappaB) in tumoral cells. Increased incidence of general infiltrated immune cells, such as CD4(+) T lymphocytes, CD57(+) natural killer cells, activated CTL, and dendritic cells, in the microenvironment of the tumor was associated with increased growth fraction of tumoral cells, including G(1)-S checkpoint (cyclin D and cyclin E) and tumor suppressor pathways (p16 and SKP2), and with the presence of EBV (signal transducers and activators of transcription 1 and 3 expression; STAT1/STAT3). A lower level of cytotoxic cells correlated with an increase of antiapoptotic mechanisms in H/RS cells, whereas the global infiltrated immune population correlated with the growth fraction of the tumor. Our collective data suggest a causal relationship between infiltrated immune response and concurrent changes of the different proliferative checkpoints, tumor suppressor, and apoptotic pathways of H/RS cells in HL.

Mcm2, Geminin, and KI67 Define Proliferative State and are Prognostic Markers in Renal Cell Carcinoma

The origin licensing factors minichromosome maintenance 2 (Mcm2) and Geminin have recently been identified as critical regulators of growth and differentiation. Here we have investigated the regulation of these licensing factors together with Ki67 to further elucidate the cell cycle kinetics of renal cell carcinoma (RCC). Furthermore, we have examined the role of Ki67, Mcm2, and Geminin in disease-free survival after nephrectomy in patients with localized RCC. Tissue sections from 176 radical nephrectomy specimens were immunohistochemically stained with Mcm2, Geminin, and Ki67 antibodies. Labeling indices (LI) for these markers were compared with clinicopathologic parameters (median follow-up 44 months). In RCC, Mcm2 is expressed at much higher levels than Ki-67 and Geminin, respectively [medians 41.6%, 7.3%, and 3.5% (P < 0.001)] and was most closely linked to tumor grade (P < 0.001). For each marker, Kaplan-Meier survival curves provided strong evidence that increased expression is associated with reduced disease-free survival time (P < 0.001). Additionally, an Mcm2-Ki67 LI identified a unique licensed but nonproliferating population of tumor cells that increased significantly with tumor grade (P = 0.004) and was also of prognostic value (P = 0.01). On multivariate analysis, grade, vascular invasion, capsular invasion, Ki67 LI >12%, and age were found to be independent prognostic markers. Although Ki67 is identified as an independent prognostic marker, semiquantitative assessment is difficult due to the very low proliferative fraction identified by this marker. In contrast, Mcm2 identifies an increased growth fraction that is closely linked to grade, provides prognostic information, and is amenable to semiquantitative analysis in routine pathologic assessment.

Hodgkin and Reed-Sternberg cells harbor alterations in the major tumor suppressor pathways and cell-cycle checkpoints: analyses using tissue microarrays

Tumoral cells in Hodgkin lymphoma (HL) display an increased growth fraction and diminished apoptosis, implying a profound disturbance of the cell cycle and apoptosis regulation. However, limitations of molecular techniques have prevented the analysis of the tumor suppressor pathways and cell-cycle checkpoints. Tissue microarray (TMA) is a powerful tool for analyzing a large number of molecular variables in a large series of tumors, although the feasibility of this technique has not yet been demonstrated in heterogeneous tumors. The expression of 29 genes regulating the cell cycle and apoptosis were analyzed by immunohistochemistry and in situ hybridization in 288 HL biopsies using TMA. The sensitivity of the technique was validated by comparing the results with those obtained in standard tissue sections. The results revealed multiple alterations in different pathways and checkpoints, including G1/S and G2/M transition and apoptosis. Striking findings were the overexpression of cyclin E, CDK2, CDK6, STAT3, Hdm2, Bcl2, Bcl-X(L), survivin, and NF-kappaB proteins. A multiparametric analysis identified proteins associated with increased growth fraction (Hdm2, p53, p21, Rb, cyclins A, B1, D3, and E, CDK2, CDK6, SKP2, Bcl-X(L), survivin, STAT1, and STAT3), and proteins associated with apoptosis (NF-kappaB, STAT1, and RB). The analysis also demonstrated that Epstein-Barr virus (EBV)-positive cases displayed a characteristic profile, confirming the pathogenic role of EBV in HL. Survival probability depends on multiple biologic factors, including overexpression of Bcl2, p53, Bax, Bcl-X(L), MIB1, and apoptotic index. In conclusion, Hodgkin and Reed-Sternberg cells harbor concurrent and overlapping alterations in the major tumor suppressor pathways and cell-cycle checkpoints. This appears to determine the viability of the tumoral cells and the clinical outcome.

P14ARF nuclear overexpression in aggressive B-cell lymphomas is a sensor of malfunction of the common tumor suppressor pathways

p14(ARF), the alternative product from the human INK4a/ARF locus, antagonizes Hdm2 and mediates p53 activation in response to oncogenic stimuli. An immunohistochemical study of p14(ARF) expression in 74 samples of aggressive B-cell lymphomas was performed, demonstrating an array of different abnormalities. A distinct nucleolar expression pattern was detected in nontumoral tissue and a subset of lymphomas (50/74). In contrast, a group of cases (8/74) showed absence of p14(ARF) expression, dependent either on promoter hypermethylation or gene loss. Additionally, 16 out of 74 cases displayed an abnormal nuclear p14(ARF) overexpression not confined to the nucleoli, as confirmed by confocal microscopy, and that was associated with high levels of p53 and Hdm2. A genetic study of these cases failed to show any alteration in the p14(ARF) gene, but revealed the presence of p53 mutations in over 50% of these cases. An increased growth fraction and a more aggressive clinical course, with a shortened survival time, also characterized the group of tumors with p14(ARF) nuclear overexpression. Moreover, this p14(ARF) expression pattern was more frequent in tumors displaying accumulated alterations in the p53, p16(INK4a), and p27(KIP1) tumor supressors. These observations, together with the consideration of the central role of p14(ARF) in cell cycle control, suggest that p14(ARF) abnormal nuclear overexpression is a sensor of malfunction of the major cell cycle regulatory pathways, and consequently a marker of a high tumor aggressivity.

Overall Survival in Aggressive B-Cell Lymphomas Is Dependent on the Accumulation of Alterations in p53, p16, and p27

Different studies have already shown that the isolated inactivation of p21, p16, or p27 cyclin-dependent kinase inhibitors (CKIs) is associated with increased growth fraction, tumor progression, or decreased overall survival in cases of non-Hodgkin's lymphoma. In this study we linked molecular study of the p53 and p16 genes with immunohistochemical analysis of p27 expression in a group of aggressive B-cell lymphomas [large B-cell lymphomas (LBCLs) and Burkitt's lymphomas]. This was done to analyze the relationship between p53 and p16 silencing, p27 anomalous overexpression, and clinical follow-up, testing the hypothesis that the accumulation of CKI alterations could confer to the tumors a higher aggressivity. In a group of 62 patients, p53 inactivation as a result of mutation was observed in 11 cases (18%) and p16 silencing was seen in 27 cases (43.5%) as a result of methylation (20 of 62), 9p21 deletion (7 of 44), or p16 mutation (2 of 62). The simultaneous inactivation of p53 and p16 was detected exclusively in five LBCL cases. Anomalous expression of p27, which has been proven to be associated with the absence of p27/CDK2 complexes and the formation of p27/cyclin D3 complexes where p27 is inactivated, was detected in 19 of 61 cases (31%). Cases characterized by p27 anomalous expression display concurrent inactivation of p21 (provided by p53 mutations) and/or p16 CKIs in 11 of 14 LBCL cases (P = 0.040). When the relationship between the association of inactivated CKIs and overall survival was considered, a significant relationship was found between a lower overall survival probability and an increased number of inactivated CKIs in LBCL cases, with the worst prognosis for the cases displaying concurrent p53, p16, and p27 alterations. This proves that simultaneous inactivation of different tumor suppressor pathways does indeed take place, and that tumor aggressiveness takes advantage of this CKI-concerted silencing. In this same series of data, Burkitt's lymphoma patients seem to behave in a different way than LBCLs, with p53 and p16 alteration being mutually exclusive and the association with p27 anomalous expression not being clinically significant. These facts seem to support that the additive effect of the inactivation of different CKIs could be dependent of the histological type.

Ovarial cancer: best timing and applications of debulking surgery

Ovarian Cancer is the fifth leading cause of death in women in the United States and the most common cause of death in women with gynaecological malignancies in most Western countries. Despite the significant advances in surgery, chemotherapy and radiotherapy, the resulting overall 5-year survival is about 40-50% [1]. In addition, millions of women remain fearful and concerned about being diagnosed with this too often fatal disease. While early detection improves the chances that ovarian cancer can be treated successfully, early cancers of the ovaries rarely cause symptoms that women would notice, or the symptoms are mistaken for menopausal ailments or intestinal illness. As a result, almost 75% of women with ovarian cancer are not diagnosed until the disease is advanced in stage with only 15-20% chances of reaching 5-year survival. Investigative efforts for the new millennium involve the areas of basic science and translational research, genetic susceptibility and prevention, diagnostic imaging, screening and diagnosis and, finally, therapy. Unfortunately, at present, results of treatment are still far from optimal. Integration of surgery with chemotherapy are crucial in the treatment of ovarian cancer and the recommended treatment strategy for patients with advanced ovarian cancer is radical cytoreductive surgery followed by 6 cycles of platinum-based combination chemotherapy [2]. The role of whole-abdominal radiation therapy in the treatment of ovarian cancer is still controversial. In particular, evidence that radiation therapy is curative in patients with advanced disease is lacking while severe toxicity is reported [3]. Critics of this modality have argued that the dose of radiation that can be safely delivered is low and unlikely to eradicate more than microscopic disease. Despite the fact that during the last two decades the cytoreductive ability of gynaecological oncologists has increased and an higher response rate to platinum-based chemotherapy can be obtained, the state of the art treatment fails to cure the vast majority of patients with advanced disease. In order to minimise the tumour burden before chemotherapy, cytoreductive (or debulking) surgery is usually performed upfront. Possible benefits from upfront cytoreductive surgery include: (a) improvement of tumour response to further therapy due to improved tumour perfusion and increased growth fraction. Smaller tumour masses require fewer cycles of chemotherapy with less chance of induced drug-resistance. Clones of phenotypically resistant cells may be removed also; (b) immediate treatment, or prevention of complications arising from tumour masses, i.e. bowel obstruction and ascites; (c) enhancement of the immunological competence of the patient. The immunogenicity of ovarian cancer has been demonstrated in vivo and cytoreduction may help the patient to mobilise her own immune response to the cancer [4]; (d) psychological benefit to the patient of knowing that the tumour bulk has been removed [5]. Several non randomised studies showed improved survival of patients with less than 1 cm diameter of residual tumour after primary surgery, as compared with patients with larger lesions. In a case-control study of patients with minimal residual disease, . Eisenkop et al. reported a longer survival for patients whose small lesions were completely resected rather than for those patients whose similar lesions were not completely removed [6]. Conversely, both Hoskins [7] and Hacker [8] reported that, despite optimal cytoreduction, the survival of patients with large intra-abdominal metastases before resection was significantly worse than that observed in patients with initially small intra-abdominal lesions. These observations suggested that intrinsic tumour factors are of prognostic importance in addition to residual disease after cytoreduction and also raised the question of whether cytoreduction has a significant effect on survival among patients with the same size tumours and the same intrinsic prognostic factors. Moreover, the problem still under debate is whether the observed survival benefits for cytoreduced patients are a function of surgical skill, tumour biology or both.

Cell kinetics and repopulation parameters of irradiated xenograft tumours in SCID mice: comparison of two dose-fractionation regimens

The extent and mechanism(s) of repopulation were assessed in SiHa (human cervical squamous cell carcinoma) xenografts in SCID mice for two fractionated irradiation regimens. Mice in one arm of the study received 50 Gy in 20 fractions over 23 days with a 14 day split between 10 fraction, 5 day courses. The other tumours were treated with 50 Gy in 20 fractions over 10 consecutive days. Cell kinetics and tumour regrowth parameters were monitored during and after treatment by measuring tumour volume and analysing cellular DNA content and proliferation parameters with flow cytometry. Repopulation occurred rapidly, beginning during irradiation and largely attributable to an increased growth fraction and decreased potential doubling time, apparently triggered by increased cell loss. Cell cycle time, in contrast, remained relatively constant throughout. Extrapolation of these results to humans suggests that treatment times should be minimised whenever possible, since regrowth rates exceeded those predicted from pretreatment T pot measurements.

Repopulation characteristics and cell kinetic parameters resulting from multi-fraction irradiation of xenograft tumors in SCID mice

Purpose: Cell kinetics and repopulation rates during multifraction irradiation have previously been measured in SiHa human cervical carcinoma cells grown as spheroids. The current study applied similar techniques to SiHa tumor xenografts with the ultimate goal of assessing the clinical prognostic value of in situ cell kinetics. Methods and Materials: SiHa (human squamous cell cervical tumor) cells were inoculated subcutaneously in the flank or back of SCID mice. When tumors reached a size of 200–300 mg, they received 25 Gy in 10 fractions over 5 days. Tumor regrowth and cell kinetics parameters were followed during treatment, and for 10 days after completion by measuring tumor volume and analyzing cellular BrdUrd and IdUrd incorporation with flow cytometry. Results: Tumor volume was of limited use in assessing response to irradiation. The fraction of proliferating cells increased early during irradiation as did the labeling index; potential doubling time (T pot) decreased during treatment and returned to the pre-irradiation value after treatment. Cell cycle time remained relatively constant throughout the experiments. Conclusion: These results confirm the feasibility of evaluating cell cycle kinetics and repopulation parameters in a murine tumor model undergoing a fractionated course of irradiation. Repopulation of clonogenic tumor cells occurred more rapidly than predicted by pretreatment measurements, primarily due to an increased growth fraction and consequent decrease in T pot.

Cell kinetics and repopulation mechanisms during multifraction irradiation of spheroids

Background and purpose: The objective of the present study was to evaluate the predictive potential of cell kinetic parameters and repopulation rates determined by flow cytometry during multifraction irradiation of spheroids, a system in which the fate of all cells can be determined with high precision. Ultimately, similar analytical techniques should provide a reproducible and prognostically significant clinical predictive assay. Materials and methods: Multicellular spheroids of Chinese hamster V79 lung cells were irradiated with 2.5 Gy of 250 kVp X-rays twice daily to a total dose of 25 Gy. Repopulation parameters and cell kinetic parameters were followed throughout the irradiation period and for 5 days after completion of exposure. Results: (1) Regrowth (RG) took place early during multifraction irradiation. (2) Potential doubling time ( T pot) decreased steadily from the early part of treatment, remaining of short duration until the spheroids almost attained the pre-treatment number of clonogenic cells. (3) Accelerated repopulation was mainly due to a decreased cell loss factor ( Φ) and increased growth fraction (GF), although a modest decrease in cell cycle time ( t c) was suggested. (4) Φ decreased during exponential RG. (5) Other parameters such as observed doubling time ( t d) and labelling index (LI) paralleled these findings. Conclusions: Clonogen repopulation that began early in the irradiation scheme and accelerated rapidly is not consistent with the prevailing view that accelerated repopulation begins several weeks into clinical protocols. Also, pre-treatment T pot did not adequately estimate the repopulation speed in the spheroids. Equivalent studies in animal tumour systems, and then in the clinic, are consequently indicated and of some urgency.

Analysis of crypt cell proliferation in coeliac disease using MI-B1 antibody shows an increase in growth fraction.

This study aimed to investigate the pattern of cellular proliferation and to calculate the growth fraction of small intestinal crypts in 24 patients--eight with untreated coeliac disease (CD), six with treated CD, and 10 controls with normal villous architecture. Duodenal biopsy specimens were stained with MI-B1 antibody using an immunoperoxidase method. Positive stained crypt cells were counted and their position within each intact crypt column was noted. These were used to construct proliferation index distribution curves for each cell position from which the crypt growth fraction for each group of patients was calculated. The crypt growth fraction was found to be higher in the untreated CD group (0.57) than in the treated patients (0.39) and the controls (0.44). The mean (SEM) proliferative index for each crypt was significantly higher in the untreated group (42.3 (10.8)%; p < 0.05) than in the treated CD (21.7 (8.5)%) and control (19.7 (7.5)%) groups and correlated closely with the surface:volume index and enterocyte cell height measurements in all three groups. An increased growth fraction may contribute to other changes in crypt cell kinetics to produce the histological changes seen in untreated CD.

Proliferating cell nuclear antigen in malignant and pre-malignant lesions of epithelial origin in the oral cavity and the skin: an immunohistochemical study.

Proliferating cell nuclear antigen (PCNA) is a nuclear protein synthesized in the late G1 and S phase of the cell cycle and immunohistochemical detection of the protein represents a useful marker for the proliferating fraction of cells in tissue specimens. A series of malignant and pre-malignant lesions of the oral cavity and skin were evaluated by the streptavidin biotin immunoperoxidase method for detection of this protein. Monoclonal anti-PCNA antibody (PC 10) labelled proliferating cells in all cases with varying intensity of nuclear staining. In squamous cell carcinoma (n = 48), PCNA positivity correlated with the differentiation and atypia of the tumour cells; however, in poorly differentiated tumours, the relationship between PCNA expression and proliferation was lost. Basal cell carcinoma showed an increased growth fraction in tiny epithelial nests (mean 43.8, SD 6.0, n = 20) than in neoplastic basal cells (mean 30.1, SD 6.9, n = 8). The growth fractions were significantly higher in the pre-malignant lesions (leukoplakia, mean 22.3, SD 7.7, n = 14; Bowen's disease, mean 45.2, SD 11.7, n = 12; senile keratosis, mean 41.2, SD 7.0, n = 12) than in the normal mucosa (mean 9.8, SD 4.9, n = 10), suggesting that cellular growth fractions correlate with the degree of dysplasia in pre-malignant lesions.

Growth potential of endometrial cancers assessed by a Ki-67 Ag/DNA dual-color flow-cytometric assay

Ki-67 is a monoclonal antibody directed against a nuclear antigen present only in proliferating cells. To assess the growth potential of uterine endometrial cancer, the population of cells in proliferating cycle (%PC) was examined with Ki-67, using flow cytometry. The %PC of 27.18 ± 12.00% in 22 endometrial cancers was significantly higher than the 14.5 ± 5.94% found in 28 normal endometrial tissues. In premenopausal endometrial tissue, the %PC in the proliferatory phase was significantly higher than the %PC found in the secretory phase. In endometrial cancers, an increase of %PC was found in cases with deep myometrial invasion, and the %PC was elevated in groups containing histologically poorly differentiated types when compared to groups of well-differentiated and moderately differentiated types. Sorted cells reactive with Ki-67 antibody were large and had a high nuclear/cytoplasmic ratio. On the bases of these results, it was concluded that a Ki-67 Ag/DNA dual-color assay would be useful to examine the growth fraction in endometrial carcinoma and that an increased growth fraction was related to deep myometrial invasion or poorly differentiated types.

Ki67 Antigen Expression Correlates with Tumor Progression and HLA-DR Antigen Expression in Melanocytic Lesions

Advanced steps of tumor progression are generally characterized by an increased growth fraction within the neoplastic cell population. The presence of a relevant growth fraction is also related to widely accepted prognostic parameters in some human malignancies. Our aims were to evaluate the presence of a growth fraction with Ki67 monoclonal antibody (MoAb), and to correlate it with tumor progression and HLA-DR antigen expression in 88 melanocytic lesions. The lesions were 19 acquired melanocytic nevi, 58 primary melanomas [divided into 26 superficial spreading melanomas (SSM), 24 superficial spreading melanomas with nodular areas (SS + NM), and five nodular melanomas (NM)], and 11 metastases from malignant melanomas. Ki67 MoAb stained 16%, 19%, 71%, 100%, and 82% of nevi, SSM, SS + NM, NM, and metastases, respectively. Among primary melanomas, Ki67 MoAb stained 12%, 28%, 50%, and 70% of tumors less than 0.75, 0.75-1.49, 1.5-2.9, and greater than or equal to 3 mm thick, respectively. A concordant reactivity pattern for Ki67 and HLA-DR antigens was found in 72% of lesions (p less than 0.0001). We have shown that a representative growth fraction (ie, Ki67 reactivity) is present in melanocytic lesions only in advanced steps of tumor progression and correlates with HLA-DR antigen expression. Despite the different biologic values of Ki67 and HLA-DR antigens, we suggest the joint evaluation of both antigens as a useful marker of aggressive behavior in melanoma.

A sequential double immunoenzymic staining procedure to obtain cell kinetic information in normal and hyperproliferative epidermis.

A sequential double immunoenzymic staining procedure was developed using the monoclonal antibody anti-BrdUrd and Ki67 in order to determine whether hyperproliferative skin disorders, such as psoriasis, are characterized by an increased growth fraction rather than a much shorter cell cycle time of all germinative cells. Ki67 binds to a proliferation-associated nuclear antigen in a variety of human cell types, and anti-BrdUrd can be used to identify DNA-synthesizing cells. Although in hyperproliferative epidermis the absolute numbers of BrdUrd-positive cells as well as Ki67-positive cells were grossly increased, the ratio of these values was not changed compared to the ratio found in the epidermis of the clinically uninvolved skin of psoriatic patients and in normal epidermis. This suggests an increased growth fraction in hyperproliferative epidermis. Our data show that immunohistochemical double-staining techniques can be a valuable tool in the study of cell cycle kinetics in epithelial tissues.

RNA, DNA, and Cell Surface Characteristics of Lesional and Nonlesional Psoriatic Skin

We have measured the RNA and DNA content and examined cell surface characteristics of human epidermal cells derived from normal skin, and lesional and nonlesional areas of psoriatic skin prior to and following treatment on a modified Goeckerman protocol. Our results show that cells from active psoriatic lesions contain greater numbers of basal keratinocytes when compared with either nonlesional skin from the same patients or skin from healthy volunteers and individuals with other inflammatory skin lesions. Follow-up measurements 2-3 weeks after the initiation of therapy showed that the numbers of basal keratinocytes in resolving psoriatic lesions had decreased and approached normal levels. Multiparameter RNA/DNA flow cytometric analysis on parallel samples from the same psoriasis patients revealed an increased growth fraction and proportion of cycling cells in both the nonlesional and lesional skin compared with controls. Furthermore, the cellular RNA content was elevated in lesional psoriatic skin when compared with either nonlesional or normal skin. Flow cytometric examination of nonlesional and lesional epidermal cells obtained 2-3 weeks after the commencement of therapy revealed that the growth fraction and mean RNA content of the keratinocytes from resolving psoriatic plaques decreased in response to therapy. In contrast, the proportion of keratinocytes within the S + G2 + M phases of the cell cycle remained elevated. These data indicate that "uninvolved" psoriatic skin exhibits characteristics more closely resembling lesional psoriatic skin than normal skin. The results further suggest that quantitation of cellular RNA content and basal cell number might be sensitive indicators of early treatment response in psoriasis.

Hepatocyte cell cycle transitions during the age-related development of type I hepatic adenomas in the genetically predisposed C3H mouse

Normal aging in the mammalian liver is associated with the progressive establishment of a predominant G1Q (quiescent G1) substate in the diploid hepatocyte population and a marked reduction in the cycling G1 compartment (G1A and G1B stage cells) (Higgins, Age 8:122–126, 1985). The C3H mouse, however, exhibits a genetic predisposition to the development of age-related proliferative lesions (adenomas) in the liver. Multiparameter flow cytometric computer models of the cell division cycle of normal young, normal old, and adenoma-derived liver cells were constructed using data obtained from acridine orange-based cytochemical measurements of hepatocyte RNA and DNA content. Compared to normal hepatocytes from young and age-matched old animals, liver cells derived from hepatic adenomas were characterized by an increased growth fraction (% cells involved in DNA synthesis), an increase in the proportion of cells in the immediate pre-DNA synthetic (G1B) phase of the cell cycle, and, most dramatically, the complete absence of a cytochemically-defined G1Q substate. Identical results were obtained by contour mapping of the RNA and DNA content of the isolated nuclear fraction of normal and adenomatous liver cells. Particularly evident was the fact that adenomas generally were comprised of a hepatocyte population with a predominantly tetraplold DNA content. The combined analyses on both intact hepatocytes and isolated nuclei clearly indicated that the G1 compartment of adenomatous hepatocytes in aged C3H mice consists solely of liver cells of the G1A and G1B phenotypes. In contrast, the uninvolved distal normal liver tissue in adenoma-bearing mice exhibited a predominant G1Q condition in the diploid hepatocyte complement as is characteristic of normal aging in this organ. Cell cycle distributions in adenomas, thus, appear to reflect the proliferative potential of such lesions.

Glycoprotein Composition of Psoriatic Epidermis in Relation to Growth Control

The composition of isolated [3H]-fucose- and [3H]-glucosamine-labeled glycopeptides from psoriatic lesion, psoriatic uninvolved, regenerating-normal, and normal epidermis (subdivided into basal and differentiated cells) has been analyzed according to molecular weight and affinity to concanavalin A. Basal cells from normal skin have a higher sialic acid content of their "biantennary" fucose-labeled glycoproteins than differentiated cells. Fucose-labeled glycoproteins from regenerating normal skin show an increased molecular weight of their carbohydrate moieties which precedes entrance of the cell into S-phase. In psoriatic uninvolved skin, glycoproteins with more highly branched carbohydrate structures are present in reduced quantity. The previously reported increase in percentage of high-molecular-weight fucose-labeled glycopeptides for psoriatic lesions appears to be specific in that its composition cannot be explained in terms of an increased growth fraction.

Growth characteristics of human melanoma xenografts

The growth of twelve human malignant melanomas in athymic nude mice was studied. Gompertz curves were fitted to volumetric growth data. DNA histograms were obtained with flow cytometry. Each of the twelve melanomas exhibited a characteristic growth pattern, indicating that inherent properties of the tumours are important for the growth control. The theoretical maximum volumes (Vmax) ranged from 208 to 12,900 mm3, the volume doubling times (Td) from 2.8 to 15.3 days (V = 50 mm3) and from 3.8 to 64.6 days (V = 200 mm3), and the fraction of cells in S from 5 to 21%. Tumours with short Td were characterized by a higher growth fraction and probably by a lower cell loss factor than those with long Td. The growth was also influenced by the nude mouse host, as indicated by the values for Vmax, which were similar to those reported for mouse tumours (geometric mean = 8100 mm3), but considerably lower than the volumes of many tumours in man. Also the Td-values for the xenografts were generally lower than those reported for tumours in man, presumably due to a lower cell loss factor. During serial transplantation the growth rate of one of the melanomas increased abruptly, probably because of both an increased growth fraction and a reduced cell loss factor. The latter result demonstrates the necessity of keeping basic biological parameters of xenografts under observation during serial transplantation.