Bis-triphosphatase also known as fragile histidine triad protein (FHIT) is an enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 that in humans is encoded by the FHIT gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

Function

FHIT is also known as human accelerated region

Human accelerated regions

Human accelerated regions , first described in August 2006, are a set of 49 segments of the human genome which are conserved throughout vertebrate evolution but are strikingly different in humans. They are named HAR1 through HAR49 according to their degree of difference between humans and chimpanzees...

 10. It may, therefore, have played a key role in differentiating humans from apes.

This gene, a member of the histidine triad gene family, encodes a diadenosine 5',5-P1,P3-triphosphate hydrolase involved in purine metabolism

Purine metabolism

-Biosynthesis:Purines are biologically synthesized as nucleotides and in particular as ribotides, i.e. bases attached to ribose 5-phosphate. A key regulatory step is the production of 5-phospho-α-D-ribosyl 1-pyrophosphate by PRPP synthetase, which is activated by inorganic phosphate and...

. The gene encompasses the common fragile site FRA3B on chromosome 3, where carcinogen

Carcinogen

A carcinogen is any substance, radionuclide, or radiation that is an agent directly involved in causing cancer. This may be due to the ability to damage the genome or to the disruption of cellular metabolic processes...

-induced damage can lead to translocations and aberrant transcripts of this gene. In fact, aberrant transcripts from this gene have been found in about half of all esophageal, stomach, and colon carcinoma

Carcinoma

Carcinoma is the medical term for the most common type of cancer occurring in humans. Put simply, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that generally arises from cells originating in the endodermal or ectodermal germ layer during...

s.

Though the exact molecular function of FHIT is still partially unclear, the gene works as a tumor suppressor

Tumor suppressor gene

A tumor suppressor gene, or anti-oncogene, is a gene that protects a cell from one step on the path to cancer. When this gene is mutated to cause a loss or reduction in its function, the cell can progress to cancer, usually in combination with other genetic changes.-Two-hit hypothesis:Unlike...

 as it has been demonstrated in animal studies. Furthermore FHIT has been shown to synergize with VHL, another tumor suppressor, in protecting against chemically - induced lung cancer.

FHIT also acts as a tumor suppressor of HER2/neu

HER2/neu

HER-2 also known as proto-oncogene Neu, receptor tyrosine-protein kinase erbB-2, CD340 or p185 is an enzyme that in humans is encoded by the ERBB2 gene. Over expression of this gene is correlated with higher aggressiveness in breast cancers...

driven breast cancer.