What are metastasis from a META-Health point of view? Is a new understanding developing that might expand on the current traditional metastasis theory of malignant cells spreading from one cancer location to another organ?
This article by Gaetana Tonti, biologist and stem cell research proposes a completely new perspective on the cause and process of Metastasis.
Metastasis derives from the Greek META: beyond, and STASIS: to place, and is used to describe the spread of cancer cells from the primary site to another organ/part of the body. To do this, cancer cells from the first site need to move and invade the secondary site.
There has been some debate about the existence of cancerous cells circulating in peripheral blood, especially in the META-Medicine world; so it might be interesting to briefly report the most recent discoveries and hypotheses, and discuss META-stases from a META-perspective.
The first point is that cancer cells do exist out of the primary cancer, even though they are very rare. They are defined either as disseminated tumor cells (DTCs), which are cells deriving from the primary tumor found in bone marrow, or as circulating tumor cells (CTCs), which means found circulating in the peripheral blood. CTCs and DTCs have been found in many different carcinoma patients and are not present in healthy subjects or patients with benign diseases.
Even though the development of disseminated metastatic diseases has been traditionally viewed as a sequential rather than concurrent process, (i.e. the disease initially occurs at the primary site, followed by local growth with dissemination to distant sites much later in time (1)), emerging data is challenging this theory (2, 3), suggesting that the presence of CTCs and DTCs is a very early, if not concomitant phenomenon, to the onset of the primary tumor. Bone marrow has revealed to be a common homing organ for metastatic cells, independent of the primary tumor site and the pattern of overt metastases (4). This suggests a causal link and a specific meaning for the presence of DTCs in the bone marrow. In fact, DTCs in bone marrow have been detected in all solid tumor types suggesting that the bone marrow might be a preferred reservoir for blood-borne DTCs.
However, up to now it is unknown which environmental and internal factors can promote the recirculation of DTCs from the bone marrow niche into other distant organs – such as liver or lungs, which are common sites of metastatic spread.
These tumor cells detached from the primary tumor flow in the peripheral blood and reach the bone marrow in a dormant state until internal and/or external signals enable them to move and grow out to overt metastases at different organs (5-7).
Little is known about these dormant cells and the conditions required—environmental factors (e.g., immune system, dietary changes…..stress, emotional traumas….. repair of damaged tissues in a regeneration phase) — for their ‘‘awakening’’ from the dormant phase into the dynamic phase of metastasis formation. According to conventional science the dormant state might be disturbed by both changes within the DTCs (e.g., additional DNA mutations) and the surrounding micro-environment (e.g., decrease in immune surveillance or increased angiogenetic potential (8, 9).
But what if a more bio-logical and meaningful reason existed for the explanation of this phenomenon?!
Messages from the environment
Cancer cell behaviors are not regulated by a linear series of commands, but rather by networks of molecular interactions that involve positive and negative reinforcement. Switching between different cell fates that are critical for cancer (e.g., growth, differentiation, increased motility) can be triggered in normal and transformed cells, by changes in extracellular matrix (ECM) structure and cell shape distortion (10-14), ‘non-specific’ chemical solvents and electrical ion flows (15-17) that influence multiple gene activities, as well as by distinct molecular factors or specific gene mutations. There are many studies in experimental systems suggesting that cancers can be induced to become quiescent, differentiate, die or form completely normal tissues, if provided with the correct set of complex signals, as conveyed by embryonic tissues or other micro environmental cues (18). This means that for some reason the environment surrounding the primary tumor becomes ‘‘activated,’’ and it can release cancer and metastasis-inducing signals. This scenario represents a clear example of the acquisition of highly malignant cell biological traits through an adaptive mechanism, arguing strongly for adaptation/response as the prime driving force that underlies the acquisition of highly malignant traits by neoplastic cells.
A new META-perspective on cancer and META-stases
On these bases a very challenging hypothesis has been proposed: cancer as a natural wound healing related process where the outcome of the cancer mechanism is either healing the wound or exhausting the whole system (death). The wound signaling molecules present in a tissue cause over-expression of the existing cancer-related genes, leading to the changes of certain chromosomes and cancer cell traits (19). Therefore, a new cancer theory (wound–oncogene–wound healing (WOWH)) can be logically speculated: cancer formation is a natural process that organisms have used in wound healing. Briefly, when defined wounds occur in mammals, the body starts the complicated wound healing process . Molecules such as growth factors, cytokines, and other proteins from the cells in the wound area interrupt the balance of normal molecular metabolism, leading to the activation of corresponding cancer-related genes and inducing cancerization in some cells. The cells with activated genes can secrete molecules to recruit other cells, stimulate cell proliferation, and enhance cell differentiation to repair the wound. Mostly, the wound is healed after above efforts. However, if the wound conditions are still persistent this WOWH mechanism will not stop and more cancer cells (over-activation of the canre-related genes transformed normal cells into malignant cells (21, 21) are divided to secrete more molecules for wound healing, forming a clinical cancer mass. After the wound is healed, the molecules of a healed environment initiate cancer cell differentiation or death.
This model leads also to a new concept of metastasis. Based on the idea that cancer cells are present to repair a wound, a META explanation of metastasis is that cancer cells in the primary tumor site can “sense