Nobel lecture. Retroviruses and oncogenes. I

Versatile function of NF-ĸB in inflammation and cancer

Nuclear factor-kappaB (NF-ĸB) plays a crucial role in both innate and adaptive immune systems, significantly influencing various physiological processes such as cell proliferation, migration, differentiation, survival, and stemness. The function of NF-ĸB in cancer progression and response to chemotherapy has gained increasing attention. This review highlights the role of NF-ĸB in inflammation control, biological mechanisms, and therapeutic implications in cancer treatment. NF-ĸB is instrumental in altering the release of inflammatory factors such as TNF-α, IL-6, and IL-1β, which are key in the regulation of carcinogenesis. Specifically, in conditions including colitis, NF-ĸB upregulation can intensify inflammation, potentially leading to the development of colorectal cancer. Its pivotal role extends to regulating the tumor microenvironment, impacting components such as macrophages, fibroblasts, T cells, and natural killer cells. This regulation influences tumorigenesis and can dampen anti-tumor immune responses. Additionally, NF-ĸB modulates cell death mechanisms, notably by inhibiting apoptosis and ferroptosis. It also has a dual role in stimulating or suppressing autophagy in various cancers. Beyond these functions, NF-ĸB plays a role in controlling cancer stem cells, fostering angiogenesis, increasing metastatic potential through EMT induction, and reducing tumor cell sensitivity to chemotherapy and radiotherapy. Given its oncogenic capabilities, research has focused on natural products and small molecule compounds that can suppress NF-ĸB, offering promising avenues for cancer therapy.

50th anniversary of the discovery of reverse transcriptase

The simultaneous discovery in 1970 of reverse transcriptase in virions of retroviruses by Howard Temin and David Baltimore was perhaps the most dramatic scientific moment of the second half of the 20th century. Ten years previously, Temin's observation of cells transformed by Rous Sarcoma virus led him to the conclusion that retroviruses replicate through a DNA intermediate he called the provirus. This heretical hypothesis was greeted with derision by fellow scientists; Temin and Baltimore performed a simple experiment, rapidly reproduced, and convincing to all. Its result was a major paradigm shift-reversal of the central dogma of molecular biology. It immediately grabbed the attention of both the scientific and lay press. It also came at a key time for cancer research, at the start of the "War on Cancer." As a theoretical base and fundamental molecular tool, it enabled a decade of (largely fruitless) search for human oncogenic retroviruses but laid the foundation for the discovery of HIV 13 years later, leading to the development of effective therapy. I had the good fortune, as a student in Temin's lab, to witness these events. I am honored to be able to share my recollection on the occasion of their 50th anniversary.

Targeting apoptosis in cancer therapy

For over three decades, a mainstay and goal of clinical oncology has been the development of therapies promoting the effective elimination of cancer cells by apoptosis. This programmed cell death process is mediated by several signalling pathways (referred to as intrinsic and extrinsic) triggered by multiple factors, including cellular stress, DNA damage and immune surveillance. The interaction of apoptosis pathways with other signalling mechanisms can also affect cell death. The clinical translation of effective pro-apoptotic agents involves drug discovery studies (addressing the bioavailability, stability, tumour penetration, toxicity profile in non-malignant tissues, drug interactions and off-target effects) as well as an understanding of tumour biology (including heterogeneity and evolution of resistant clones). While tumour cell death can result in response to therapy, the selection, growth and dissemination of resistant cells can ultimately be fatal. In this Review, we present the main apoptosis pathways and other signalling pathways that interact with them, and discuss actionable molecular targets, therapeutic agents in clinical translation and known mechanisms of resistance to these agents.

Scientific discovery and scientific reputation: the reception of Peyton Rous' discovery of the chicken sarcoma virus

This article concerns itself with the reception of Rous' 1911 discovery of what later came to be known as the Rous Sarcoma Virus (RSV). Rous made his discovery at the Rockefeller Institute for Medical Research which had been primarily established to conduct research into infectious diseases. Rous' chance discovery of a chicken tumor led him to a series of conjectures about cancer causation and about whether cancer could have an extrinsic cause. Rous' finding was received with some scepticism by the scientific community that held that cancer was not infectious and favored explanations which located the origins of cancer in the inner mechanism of the cell. After 4 years of unsuccessful effort to isolate and further determine the virus Rous felt compelled to discontinue his work on cancer viruses. When 55 years later, the significance of Rous's discovery was attested by the award of the Nobel Prize, it opened up debates about the issues of delayed recognition and scientific reputation. This article also considers why Rous' hypothesis of a viral origin of cancer could not be incorporated into the existing body of knowledge about cancer before the 1950s.

Spatial segregation of Ras signaling: new evidence from fission yeast

The Ras GTPases act as binary switches for signal transduction pathways that are important for growth regulation and tumorigenesis. Despite the biochemical simplicity of this switch, Ras proteins control multiple pathways, and the functions of the four mammalian Ras proteins are not overlapping. This raises an important question--how does a Ras protein selectively regulate a particular activity? One recently emerging model suggests that a single Ras protein can control different functions by acting in distinct cellular compartments. A critical test of this model is to identify pathways that are selectively controlled by Ras when it is localized to a particular compartment. A recent study has examined Ras signaling in the fission yeast Schizosaccharomyces pombe, which expresses only one Ras protein that controls two separate evolutionarily conserved pathways. This study demonstrates that whereas Ras localized to the plasma membrane selectively regulates a MAP kinase pathway to mediate mating pheromone signaling, Ras localized to the endomembrane activates a Cdc42 pathway to mediate cell polarity and protein trafficking. This study has provided unambiguous evidence for compartmentalized signaling of Ras.

Phosphorylation state-specific antibodies: applications in investigative and diagnostic pathology

Until recently, the investigation of protein phosphorylation was limited to biochemical studies of enzyme activities in homogenized tissues. The availability of hundreds of phosphorylation state-specific antibodies (PSSAs) now makes possible the study of protein phosphorylation in situ, and is opening many exciting opportunities in investigative and diagnostic pathology. This review illustrates the power of PSSAs, especially in immunohistochemical applications to human disease and animal models. Technical considerations, including antibody specificity and lability of phosphoepitopes, are covered, along with potential pitfalls, illustrated by a case study. In the arena of oncology, PSSAs may prove especially valuable in directly demonstrating the efficacy of chemotherapies targeted at protein kinase cascades. Novel applications of PSSAs are also beginning to reveal molecular mechanisms of inflammatory, degenerative, and toxin-induced diseases.

Solution structure and dynamics of the Rous sarcoma virus capsid protein and comparison with capsid proteins of other retroviruses

The solution structure and dynamics of the recombinant 240 amino acid residue capsid protein from the Rous sarcoma virus has been determined by NMR methods. The structure was determined using 2200 distance restraints and 330 torsion angle restraints, and the dynamics analysis was based on (15)N relaxation parameters (R(1), R(2), and (1)H-(15)N NOE) measured for 153 backbone amide groups. The monomeric protein consists of independently folded N- and C-terminal domains that comprise residues Leu14-Leu146 and Ala150-Gln226, respectively. The domains exhibit different rotational correlation times (16.6(+/-0.1) ns and 12.6(+/-0.1) ns, respectively), are connected by a flexible linker (Ala147-Pro149), and do not give rise to inter-domain NOE values, indicating that they are dynamically independent. Despite limited sequence similarity, the structure of the Rous sarcoma virus capsid protein is similar to the structures determined recently for the capsid proteins of retroviruses belonging to the lentivirus and human T-cell leukemia virus/bovine leukemia virus genera. Structural differences that exist in the C-terminal domain of Rous sarcoma virus capsid relative to the other capsid proteins appear to be related to the occurrence of conserved cysteine residues. Whereas most genera of retroviruses contain a pair of conserved and essential cysteine residues in the C-terminal domain that appear to function by forming an intramolecular disulfide bond during assembly, the Rous sarcoma virus capsid protein does not. Instead, the Rous sarcoma virus capsid protein contains a single cysteine residue that appears to be conserved among the avian C-type retroviruses and is positioned in a manner that might allow the formation of an intermolecular disulfide bond during capsid assembly.

Expression of the c-erbB-2 (HER-2/neu) oncoprotein in human prostatic carcinoma

The objective of this study was to determine the expression of the c-erB-2 oncoprotein via immunohistochemistry of archival clinically localized human prostate cancers and to compare these results to known clinical prognostic factors. In addition, positive staining cases were subjected to differential polymerase chain reaction to assess for c-erbB-2 gene amplification. Immunohistochemical staining with a polyclonal antibody (pAb 1) was performed on archival radical prostatectomy specimens. To standardize the staining, positive and negative control material was generated using c-erbB-2 transfected NIH3T3 cells grown on agar plugs, formalin fixed, paraffin embedded and processed on glass slides for immunohistochemistry. Definite positive membranous staining was detected in 18 of 53 neoplastic cases (34%). In addition, 9 cases of benign prostatic hyperplasia were stained without evidence of c-erbB-2 expression detected. Either focal or diffuse membranous staining was identified in 6 of 27 (22%) well, 8 of 20 (40%) moderately and 4 of 6 (66%) poorly differentiated tumors (p = 0.03, chi-square test for trend). Positive staining occurred in 6 of 18 patients (33%) with pathological stage B and 12 of 33 (36%) with pathological stage C disease. At a mean of 36 months, complete followup was available for 16 of the 18 positive cases and 30 of the 35 negative cases. For stage B 1 of 6 positive (16.7%) versus 1 of 12 negative (8%) staining cases showed progression (p = 1.0). For stage C 7 of 12 positive (58.3%) versus 9 of 21 negative (42.9%) cases showed progression (p = 0.48). Deoxyribonucleic acid was extracted from the exact same archival paraffin blocks for the c-erbB-2 protein positive cases and subjected to differential polymerase chain reaction analysis, which revealed no c-erbB-2 gene amplification. This study demonstrates that approximately a third of all clinically localized prostate cancers express the c-erbB-2 oncoprotein via immunohistochemistry using pAb-1 on archival material, c-erbB-2 oncoprotein expression does not appear to be a prognostic marker for prostate cancer although our results are preliminary and, although oncoprotein expression was detected, no positive case demonstrated deoxyribonucleic acid amplification.