Double minute chromosomes in an invasive adenocarcinoma of the prostate

Extrachromosomal Circular DNA: A New Target in Cancer

Genomic instability and amplification are intrinsically important traits determining the development and heterogeneity of tumors. The role of extrachromosomal circular DNA (eccDNA) in tumors has recently been highlighted. EccDNAs are unique genetic materials located off the chromosomal DNA. They have been detected in a variety of tumors. This review analyzes the mechanisms involved in the formation of eccDNAs and their genetic characteristics. In addition, the high-copy number and transcriptional levels of oncogenes located in eccDNA molecules contribute to the acceleration of tumor evolution and drug resistance and drive the development of genetic heterogeneity. Understanding the specific genomic forms of eccDNAs and characterizing their potential functions will provide new strategies for tumor therapy. Further research may yield new targets and molecular markers for the early diagnosis and treatment of human cancer.

Deletion (1)(q12) and double minutes in a metastatic adenocarcinoma of the prostate

Cytogenetic analysis after short-term cultures were performed on an invasive and moderately-differentiated prostatic adenocarcinoma. The results showed a normal male chromosomal complement in most metaphases examined. Furthermore, several abnormalities were found, including del(1)(q12), double minute and ring chromosomes, acentric fragments, triradial figures, and near-tetraploid cells.

Chromosomal basis of adenocarcinoma of the prostate

Prostate cancer is the most frequent malignancy and the second leading cause of cancer deaths among males in the Western world. The clinical course of the disease is highly complex, and genetic factors underlying tumorigenesis are poorly understood. The challenge that lies ahead is to identify the important gene(s) that causes adenocarcinoma of the prostate. Chromosomal findings by cytogenetic and molecular methods, including Southern blotting, microsatellite analysis, fluorescence in situ hybridization, and comparative genomic hybridization, revealed a high frequency of chromosomal aberrations of heterogeneous nature, including: -1, +1, -1q, +4, -6q, -7, +7, -8, -8p, -8q, +i(8q), -9, -9p, -10, +10, +11, -12, -13q, -16, -16q, +16, -17, +17, +17q, -18, +18, -18q, +19p, +20q, +X, -Xq, -Y, and +Y. Specific chromosomal regions of alterations were 1q24-25, 2cen-q31, 5cen-q23.3, 6q14-23.2, 7q22-q31, 8p12-21, 8p22, 8q24-qter, 10q22.1, 10q23-25, 11p11.2, 16q24, 17p13.1, 18q12.2, and Xq11-12. Recently, a predisposing gene for early onset has been localized on 1q42.2-43. The losses of heterozygosity at specific chromosomal loci from chromosomes 5q, 6q, 7q, 8p, 8q, 10q, 13q, 16q, 17p, 17q, and 18q are generally correlated with poor prognosis in advanced tumor stage. In addition, an abnormal function of known tumor suppressor genes from these regions have been observed in prostate cancer. Although, the amplification of the androgen receptor gene at Xq11-13 and HER-2/neu gene at 17q11.2-q12 are novel findings, no single gene has been implicated in harboring prostate cancer. Frequent inactivation of PTEN/MMAC1 tumor suppressor gene at 10q23, MXI-1 at 10q25, KAI-1 at 11p11.2, Rb at 13q14.2, and p53 at 17p13.1 and deregulation of c-myc oncogene at 8q24 have recently been the subject of intense scrutiny and debate.

Detection of double minute chromosomes in a child with acute lymphoblastic leukemia

A child with acute lymphoblastic leukemia (ALL) whose predominant leukemic clone demonstrated double minute chromosomes (dmin) is presented. The patient had no history of mutagen or carcinogen exposure and responded well to combination chemotherapy. Although dmin have been described in acute myelogenous leukemia and various solid tumors in adults, their presence in childhood neoplasms is less frequent and limited primarily to neurogenic tumors. This is the first documentation of dmin in childhood ALL, suggesting that there may be an unrecognized subgroup of ALL patients with gene amplification.

Highly complex chromosomal aberrations in bone marrow of a patient with metastatic prostate neoplasm

Prostate cancer is the single most common malignancy among men in North America. Nevertheless, cytogenetic evaluation of bone marrow in patients with metastatic prostate neoplasm has been rare and, to date, only five such patients have been reported. We report an additional case where chromosomal abnormalities of a bizarre nature were found in the bone marrow. Though cytogenetic findings in prostate cancer are heterogeneously complex, the chromosome regions involved include 1p, 1q, 7q, 8p, 10q, 12p, and 17q and are considered hot spots. What is the significance of these so-called hot spots in metastasis of prostatic cancer to the bone marrow? At present, no meaningful conclusion can be drawn, as data are limited, but accumulation of such cases may provide valuable information concerning the role of chromosomal abnormalities in patients--specifically with metastatic stage--and may help urologists during therapeutic decision making, particularly if a genetic marker for aggressiveness can be determined.

Cytogenetic abnormalities are frequent in uncultured prostate cancer cells

Despite attempts by several laboratories to identify consistent chromosome abnormalities in cancer of the prostate, relatively few clonal changes have been found. We compared analysis of metaphases from uncultured specimens of primary prostate cancer (direct preparations) with those obtained from short-term culture using various media. While the number of metaphases in uncultured specimens was low, and chromosome morphology fair to poor, structural chromosome changes could be identified as clonal in 5 of 14 specimens (36%). In contrast, while clonal abnormalities were found in 20 of 61 (33%) specimens analyzed after short-term culture, these abnormalities were predominantly numerical and simple structural changes. Two tumors metastatic to lymph nodes were studied using direct preparations; both were near tetraploid, with multiple structural abnormalities, including isochromosome 8q in both and del(8)(p21) in one. Cytogenetic analyses of metastatic prostate tumors have been very limited, and these data suggest that formation of an i(8q) may be the mechanism by which loss of heterozygosity of 8p, reported frequently in molecular analyses, occurs. Our findings indicate that prostate cancers, like most solid tumors, do have clonal chromosome abnormalities that are frequently complex, but the method that reproducibly yields representative karyotypes from this particular tumor remains to be identified.