Transplacental carcinogenesis is a series of

genotypic The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...

and/or

phenotypic In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

changes in the cells of a

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...

due to ''

in utero ''In Utero'' is the third and final studio album by American rock band Nirvana. It was released on September 21, 1993, by DGC Records. After breaking into the mainstream with their second album, ''Nevermind'' (1991), Nirvana hired Steve Albin ...

'' exposure to

carcinogens A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...

. Specifically, these changes are identified as malignant by virtue of their

metastatic Metastasis is a pathogenic agent's spread from an initial or primary site to a different or secondary site within the host's body; the term is typically used when referring to metastasis by a cancerous tumor. The newly pathological sites, then, ...

potential.

Transplacental transfer

The link between a pregnant mother and the fetus is such that "at all sites of direct cell-to-cell contact, maternal tissues (

decidua The decidua is the modified mucosal lining of the uterus (that is, modified endometrium) that forms every month, in preparation for pregnancy. It is shed off each month when there is no fertilised egg to support. The decidua is under the influen ...

and

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood in the cir ...

) are juxtaposed to extraembryonic cells (

trophoblast The trophoblast (from Greek : to feed; and : germinator) is the outer layer of cells of the blastocyst. Trophoblasts are present four days after fertilization in humans. They provide nutrients to the embryo and develop into a large part of the p ...

).” According to Cunningham, "after conception, a biomolecular communication system is established between the fetus and mother that is operative from before the time of nidation and continues through and beyond the time of

parturition Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...

." This communication system is essential to all facets of the

pregnancy Pregnancy is the time during which one or more offspring develops (gestation, gestates) inside a woman, woman's uterus (womb). A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Pregnancy usually occur ...

. " Physiological processes such as fetal nutrition and

fetal development Prenatal development () includes the development of the embryo and of the fetus during a viviparous animal's gestation. Prenatal development starts with fertilization, in the germinal stage of embryonic development, and continues in fetal devel ...

progress directly from embryonic/fetal tissue-directed modifications of maternal responses." Notably, the

placenta The placenta is a temporary embryonic and later fetal organ that begins developing from the blastocyst shortly after implantation. It plays critical roles in facilitating nutrient, gas and waste exchange between the physically separate mate ...

is the principal site of transfer between mother and fetus. A fetus is exposed via the placenta to all substances which are present in the peripheral circulation of the mother. Overall, the abundance of

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849 ...

s contained within cigarette smoke that is inhaled by the mother exerts a direct impact by altering the placental and fetal cell proliferation and differentiation. The vital balance of cellular activity is disrupted. "The association of in utero exposure to such

carcinogen A carcinogen is any substance, radionuclide, or radiation that promotes carcinogenesis (the formation of cancer). This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes. Several radioactive subs ...

s and the subsequent development of

cancer Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal b ...

has been reported for all

childhood cancer Childhood cancer is cancer in a child. About 80% of childhood cancer cases can be successfully treated thanks to modern medical treatments and optimal patient care. However, only about 10% of children diagnosed with cancer reside in high-income cou ...

s combined and particularly for childhood acute lymphoblastic leukemia,

lymphoma Lymphoma is a group of blood and lymph tumors that develop from lymphocytes (a type of white blood cell). In current usage the name usually refers to just the cancerous versions rather than all such tumours. Signs and symptoms may include enla ...

, and brain tumors."

Fetal cell sensitivity

Fetal cells are most sensitive to carcinogens during the early stages of gestation. Notably, early in the gestational period, there is a high rate of

cell division Cell division is the process by which a parent cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukaryotes, there ar ...

. Additionally, the cells exhibit undifferentiated characteristics. These compounding factors illustrate the basis for this heightened cellular sensitivity to

genotoxic Genotoxicity is the property of chemical agents that damage the genetic information within a cell causing mutations, which may lead to cancer. While genotoxicity is often confused with mutagenicity, all mutagens are genotoxic, but some genotoxic s ...

agents. For example, it has been proven that during exposure

nicotine Nicotine is a natural product, naturally produced alkaloid in the nightshade family of plants (most predominantly in tobacco and ''Duboisia hopwoodii'') and is widely used recreational drug use, recreationally as a stimulant and anxiolytic. As ...

binds to receptors of the fetal cells through which developmentally important signaling occurs in many developing

organs In biology, an organ is a collection of tissues joined in a structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue and an organ system. Tissues are formed from same type cells to act together in a f ...

and tissues. Because the binding of these receptors is unanticipated by the regulated activity of the fetal cells it can be inferred that this is a disruption in the cellular process which can lead to detrimental effects such as the deregulation of vital signaling, expression, or repair. As indicated above, should this exposure occur during the early stages of gestation, the fetus will be more susceptible to such damage. In addition to receptor binding, it has also been proven that fetal tissues are suspected as "privileged targets of

neoplastic A neoplasm () is a type of abnormal and excessive growth of tissue. The process that occurs to form or produce a neoplasm is called neoplasia. The growth of a neoplasm is uncoordinated with that of the normal surrounding tissue, and persists ...

changes" in light of the vast amount of cell proliferation and differentiation taking place. Notably, tumors are arrived at via proliferating cells. In the event that proliferating cells become uncontrolled, by any measure, this mutated activity would certainly be characteristic of an increased risk in one's chances of developing

Transplacental transfer

Fetal cell sensitivity

References

Further reading