Enzymatic measurements revealed an increase in pyruvate kinase vmax activities in renal clear-cell carcinomas (RCCs) compared to normal renal cortex taken from the same patient.

Vmax activities of pyruvate kinase
in homogenates
of normal renal cortex and RCCs
 

Vmax activities were measured spectrophotometrically according to the following
reaction:

In normal renal tissues immunohistochemical localization of PK isoenzymes reveals a selective expression of pyruvate kinase type L (L-PK) in the epithelia of the proximal tubules whereas the pyruvate kinase isoenzyme type M2 (M2-PK) is only detectable in distal tubules, the loops of Henle and collecting tubules.

L-PK staining in proximal renal tubules

M2-PK staining in distal renal tubules

M2-PK staining in the loops of Henle and collecting tubules of the renal medulla

Renal cell carcinomas of clear cells and chromophilic cells are characterized by a homogeneous expression of M2-PK and a heterogeneous expression of L-PK.

L-PK staining in RCCs

M2-PK staining in RCCs

The observation that L-PK, which is a specific proximal renal tubule differentiation molecule, is expressed in clear-cell and chromophilic RCCs provides further evidence that the majority of clear cells and chromophilic RCCs in humans derive from proximal tubules.

Immunohistochemical staining of PK isoenzymes: Gösta Fischer

Tumor M2-PK concentrations
in EDTA-plasma samples
from patients with renal clear-cell carcinomas
Correlation between Tumor M2-PK values and staging

By courtesy of : Gerhard Maximilian Oremek

Tumor M2-PK concentrations
in EDTA-plasma samples
Follow-up study of a patient with a RCC with metastases
Complete Remission

By courtesy of : Hans Wilhelm Wechsel

Tumor M2-PK concentrations were measured with a sandwich ELISA from
ScheBo Biotech AG, Giessen, Germany.

References

Tumor M2-PK: Clinical relevance for metabolic profiling of tumors

Pyruvate kinase isoenzymes: M2-PK

Metabolic tools for tumor diagnosis