Although cancer classification has improved over the past 30 years, there has been no general approach for identifying new cancer classes (class discovery) or for assigning tumors to known classes (class prediction). Here, a generic approach to cancer classification based on gene expression monitoring by DNA microarrays is described and applied to human acute leukemias as a test case. A class discovery procedure automatically discovered the distinction between acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL) without previous knowledge of these classes. An automatically derived class predictor was able to determine the class of new leukemia cases. The results demonstrate the feasibility of cancer classification based solely on gene expression monitoring and suggest a general strategy for discovering and predicting cancer classes for other types of cancer, independent of previous biological knowledge.

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Molecular classification of cancer: class discovery and class prediction by gene expression monitoring.

Chemotherapeutics are the most effective treatment for metastatic tumours. However, the ability of cancer cells to become simultaneously resistant to different drugs--a trait known as multidrug resistance--remains a significant impediment to successful chemotherapy. Three decades of multidrug-resistance research have identified a myriad of ways in which cancer cells can elude chemotherapy, and it has become apparent that resistance exists against every effective drug, even our newest agents. Therefore, the ability to predict and circumvent drug resistance is likely to improve chemotherapy.

/pdf/multidrug-resistance-in-cancer-role-of-atp-dependent-1hpqky19xf.pdf

Multidrug resistance in cancer: role of ATP–dependent transporters

The doxorubicin-selected lung cancer cell line H69AR is resistant to many chemotherapeutic agents. However, like most tumor samples from individuals with this disease, it does not overexpress P-glycoprotein, a transmembrane transport protein that is dependent on adenosine triphosphate (ATP) and is associated with multidrug resistance. Complementary DNA (cDNA) clones corresponding to messenger RNAs (mRNAs) overexpressed in H69AR cells were isolated. One cDNA hybridized to an mRNA of 7.8 to 8.2 kilobases that was 100- to 200-fold more expressed in H69AR cells relative to drug-sensitive parental H69 cells. Overexpression was associated with amplification of the cognate gene located on chromosome 16 at band p13.1. Reversion to drug sensitivity was associated with loss of gene amplification and a marked decrease in mRNA expression. The mRNA encodes a member of the ATP-binding cassette transmembrane transporter superfamily.

https://science.sciencemag.org/content/sci/258/5088/1650.full.pdf

Overexpression of a transporter gene in a multidrug-resistant human lung cancer cell line

The design of cancer chemotherapy has become increasingly sophisticated, yet there is no cancer treatment that is 100% effective against disseminated cancer. Resistance to treatment with anticancer drugs results from a variety of factors including individual variations in patients and somatic cell genetic differences in tumors, even those from the same tissue of origin. Frequently resistance is intrinsic to the cancer, but as therapy becomes more and more effective, acquired resistance has also become common. The most common reason for acquisition of resistance to a broad range of anticancer drugs is expression of one or more energy-dependent transporters that detect and eject anticancer drugs from cells, but other mechanisms of resistance including insensitivity to drug-induced apoptosis and induction of drug-detoxifying mechanisms probably play an important role in acquired anticancer drug resistance. Studies on mechanisms of cancer drug resistance have yielded important information about how to circumvent this resistance to improve cancer chemotherapy and have implications for pharmacokinetics of many commonly used drugs.

Mechanisms of cancer drug resistance

Disruption of the mouse mdr1a P-glycoprotein gene leads to a deficiency in the blood-brain barrier and to increased sensitivity to drugs

Chemotherapy has proven to be an effective treatment for the cure and palliation of some human cancers (Chabner, 1982). Some tumors, however, appear to be intrinsically resistant to chemotherapy. For cancers that can be treated with chemotherapy, based on the hypothesis that resistance to single agents occurs with high frequency, protocols involving multiple drugs with different intracellular targets have been designed. In many cases, such as acute lymphocytic leukemia and neuroblastoma (Simone et al., 1982), Hodgkin’s disease (De-Vita and Hellman, 1982), and germ cell cancers (Paulson et al., 1982), dramatic results have been achieved with such protocols. However, all too frequently relapse occurs after such therapy and the recurrent tumors are resistant to further chemotherapy. In effect, such tumors develop a multidrug resistance (MDR) phenotype that is very similar to the intrinsic resistance of some primary cancers.

Expression of Multidrug Resistance Gene in Human Cancers

A specific chromosomal abnormality, t(2;13)(q35;q14), was discovered in five cases of advanced rhabdomyosarcoma It was identified directly in cells that had metastasized from bone marrow in one patie

A specific chromosomal abnormality in rhabdomyosarcoma

Ganglioneuroma may occur spontaneously or after therapy for neuroblastoma. This lesion may be metastatic or unresectable in the primary site. The rarity of this situation and lack of understanding of the biology of this benign condition may lead to extensive, potentially life-threatening attempts at surgical resection or the futile use of chemotherapy or radiotherapy to try to cause regression or control growth. The authors present here several cases which demonstrate the multiple presentations of ganglioneuroma and the potential problems which may arise in their management.

https://acsjournals.onlinelibrary.wiley.com/doi/pdf/10.1002/1097-0142%2819890315%2963%3A6%3C1211%3A%3AAID-CNCR2820630628%3E3.0.CO%3B2-1

Clinical manifestations of ganglioneuroma

Abnormalities of chromosome 1 were found in 32 of 46 pediatric solid tumors including Ewing's sarcoma, Wilms' tumor, rhabdomyosarcoma, primitive neuroectodermal tumor, and hepatoblastoma. Trisomy of 1q was the most common abnormality, and breakpoints were most frequent in the region 1cen to 1p22. Abnormalities of chromosome 1 are not specific to any type of tumor. However, their frequent occurrence indicates that they may endow a clonal advantage in the development of cancer.

Chromosome 1 Abnormalities: A Common Feature of Pediatric Solid Tumors

• Between 1968 and 1985, we treated 20 children for fibromatosis (also called desmoid tumor and aggressive fibromatosis). The primary sites included head and neck (seven patients), extremity (seven patients), and trunk (six patients). Lesions ranged from 3 to 18 cm in diameter. The tumors were smaller than 5 cm in 13 patients, and in seven patients they were larger than 5 cm. A total resection was not feasible in any of the patients with lesions larger than 5 cm. Ten of the 11 patients treated with wide local resection, in whom the margins were clearly negative or close, remained free of disease for six to 16 years. Nine patients required additional treatment with radiotherapy (nine patients) and chemotherapy (five patients). Two died of local disease progression. In the remaining seven children, the disease was controlled. We describe our strategies for managing this disease in a pediatric population. ( Arch Surg 1987;122:1296-1298)

Alexander A. Green

Papers

Expression of Multidrug Resistance Gene in Human Cancers

A specific chromosomal abnormality in rhabdomyosarcoma

Clinical manifestations of ganglioneuroma

Chromosome 1 Abnormalities: A Common Feature of Pediatric Solid Tumors

Challenges in the Treatment of Childhood Fibromatosis